GroupDIY

Project Specific Discussions => Filters/Equalizers => Topic started by: audiox on November 28, 2009, 01:35:06 PM

Title: Studer 169 EQ in API 500 format
Post by: audiox on November 28, 2009, 01:35:06 PM
(http://sites.google.com/site/audioxxx/_/rsrc/1260024407119/pictures/169_EQ_500_pic_1.jpg)

Why? I had some spare time yesterday. And my friend is planning to build an API format console and he likes this eq. I know that he probably never actualises his plans but it was quite fun to do this...

Low shelving filter +/- 15dB. Default frequency is 20 Hz as in the original circuit,
but you can select a new value for C6 from this graph to change it:
http://audioxxx.googlepages.com/EQ_169_STD_frq_selection_lo_filter.pdf

High shelving filter +/- 15dB. Default frequency is 20 kHz as in the original circuit,
but you can select a new value for C4 and C5 from this graph to change it:
http://audioxxx.googlepages.com/EQ_169_STD_frq_selection_hi_filter.pdf

Presence/absence filter +/- 12dB. Frequency adjustable from 150 Hz to 7 kHz.

Schematic (see the layout drawings for the input section component values)
http://docs.google.com/fileview?id=0B_XBYPfmG8pVZGViZTg4YmQtMDM0Yi00M2IzLTkwYTYtOWE4Zjg2YTk0MDE3&hl=en

Layout with components designations
http://docs.google.com/fileview?id=0B_XBYPfmG8pVYTI0MWQ0NTEtYzVmOC00ODU4LTkzODQtZDBhYTFkYTc3N2U0&hl=en

Layout with components values (active balanced input)
http://docs.google.com/fileview?id=0B_XBYPfmG8pVNzM2OGQxMDEtZGM4MS00ZjYwLThlYjEtNWYzNzE1NGQyNTlk&hl=en

Layout with components values (transformer balanced input)
http://docs.google.com/fileview?id=0B_XBYPfmG8pVMmRhZmNkZWEtMjU2ZS00YmI1LWFjNTYtY2ExY2Y4NDFjY2Vh&hl=en

Copper layer for home etchers (the board is single sided)
http://docs.google.com/fileview?id=0B_XBYPfmG8pVM2U5MzM3ODEtN2E1Yy00NTBhLWE5ZTEtZGNlZWU3ZTUzYzJl&hl=en

PCB drill sizes:
Switch and potentiometers 1.3mm
Discrete op-amps 2.3mm
Transformer 1.0mm
Mounting holes 3.2mm
All others 0.8mm

Front panel
http://docs.google.com/fileview?id=0B_XBYPfmG8pVNWZlNzA1ZjktOTA3ZS00Nzg5LWI2NWMtMzEzMjAyNmEyMjkw&hl=en

Front panel supporting hardware
http://docs.google.com/fileview?id=0B_XBYPfmG8pVMjVkMDYzNTEtYzdhMS00ZDlkLWJjNWMtZGZjMGFiODAzYTNl&hl=en

---

Boards are available from Gustav:
http://www.groupdiy.com/index.php?topic=37783.0
http://www.groupdiy.com/index.php?topic=10776.0

Potentiometers are 16mm Omegs (to keep the costs down):
P1 = 2x 22K LIN center detent (order code OM-01-023)
P2, P3 = 2x 10K LIN center detent (order code OM-01-005)
P4 = 2x 100K REV LOG (order code OM-01-059)
http://www.audiomaintenance.com/acatalog/potentiometers_carbon_16mm_diameter_dual_gang.html

Switch is C&K (ITT Schadow), Alps etc.
http://classicapi.com/catalog/product_info.php?cPath=51_52&products_id=88

Transformer Studer 1.022.405.00 = Neutrik NTL1
http://www.neutrik.com/fl/en/audio/210_197961/NTL1_detail.aspx
http://www.canford.co.uk/Products/23-003_NEUTRIK-NTL1-TRANSFORMER-Analogue-audio-PCB-line-input
http://uk.farnell.com/neutrik/ntl1/transformer-1-1/dp/8314659
or ask your local dealer: http://www.neutrik.com/content/contact/worldwideagents.aspx

Discrete op-amp sockets
http://classicapi.com/catalog/product_info.php?cPath=71_77&products_id=122


As usual, I don't sell anything related to this project. All the information is provided "as is".

If you need stepped level and frequency settings but you don't need presence/absence filter, please check this:
http://www.groupdiy.com/index.php?topic=33996.0

**********

My other projects:

Neumann W492 EQ
http://www.groupdiy.com/index.php?topic=28332.0

Studer 169 EQ (stepped gain and frequency selection)
http://www.groupdiy.com/index.php?topic=33996.0

Neumann OA10 discrete op-amp
http://www.groupdiy.com/index.php?topic=34105.0

Balanced 12 input summing amplifier
http://www.groupdiy.com/index.php?topic=29082.0

Balancing/unbalancing amplifier
http://www.groupdiy.com/index.php?topic=29333.0
Title: Re: Studer 169 EQ in API 500 format
Post by: okgb on November 28, 2009, 02:05:57 PM
if you can squeeze the preamp in there i'd be in for two
Title: Re: Studer 169 EQ in API 500 format
Post by: [silent:arts] on November 28, 2009, 02:08:06 PM
cool!
and so much PCB space left  ;)
ever thought of (optional) DOA footprints (your OA10 comes to mind), or some input and / or output transformers?
Title: Re: Studer 169 EQ in API 500 format
Post by: Mike D on November 28, 2009, 03:25:48 PM
Nice! I just finished a pair of your standard 169 and  I'm very happy with them. It's good to see this EQ coming to the 500 format.
Title: Re: Studer 169 EQ in API 500 format
Post by: Joechris on November 28, 2009, 07:48:27 PM
"if you can squeeze the preamp in there i'd be in for two"
rule of the tumb, maximum 4 knobs for a 500 series thing.

:-)
Title: Re: Studer 169 EQ in API 500 format
Post by: mylesgm on November 28, 2009, 08:02:58 PM
very cool...
Title: Re: Studer 169 EQ in API 500 format
Post by: Mbira on November 28, 2009, 11:25:04 PM
How are people doing the metalwork on these 500 series?  Is there a group buy I'm missing, or some inezpensive method?  This eq look really nice!  Thanks for sharing!
Title: Re: Studer 169 EQ in API 500 format
Post by: matta on November 29, 2009, 07:25:00 AM
+1 for the mic pre, makes for a great channel strip... and not much extra to add the pre, there is space on the PCB, panel spac is ata  premium though. Why not move the EQ IN switch to an off board toggle switch? Should clear up some space for a grayhill for the mic pre?

Cheers

Matt
Title: Re: Studer 169 EQ in API 500 format
Post by: audiox on November 29, 2009, 10:32:41 AM
if you can squeeze the preamp in there i'd be in for two

and not much extra to add the pre, there is space on the PCB

rule of the tumb, maximum 4 knobs for a 500 series thing.

I knew this... Joechris already answered, but seemingly not clearly enough.

Yes, there is enough space on PCB for the Studer mic pre. But you should also be able to fit the following controls to the front panel (in addition to the existing 4 pots and a switch)

- rotary switch for the coarce gain
- potentiometer for the fine gain
- phase invert switch
- phantom switch
- high-pass filter switch

Any volunteers to try that?
Title: Re: Studer 169 EQ in API 500 format
Post by: mpc3000limited on November 29, 2009, 11:09:09 AM
I think it is fine as is, no need to complicate a good thing! there are plenty of pre's out there to choose from making a dual purpose eq/pre wasn't what you were after! Nice job as always you make useful PCB layouts for gear otherwise left to the wayside!
Title: Re: Studer 169 EQ in API 500 format
Post by: desol on November 29, 2009, 11:20:32 AM
I think it is fine as is, no need to complicate a good thing! there are plenty of pre's out there to choose from making a dual purpose eq/pre wasn't what you were after! Nice job as always you make useful PCB layouts for gear otherwise left to the wayside!

Yep, looks good to me to. I'm sure adding more in the way of discrete opamps, transformers, etc, would involve more re-design than easily suggested...and probably would make little to no difference...maybe worse. Keeps it affordable as well.

Bunch of board real estate left? Draw a naked girl holding a beer.

I've never had to pleasure to hear these...but i'm probably down for a pair. Cheers.
Title: Re: Studer 169 EQ in API 500 format
Post by: mpc3000limited on November 29, 2009, 11:30:07 AM
Bunch of board real estate left? Draw a naked girl holding a beer.

X2 ;D
Title: Re: Studer 169 EQ in API 500 format
Post by: ChrioN on November 29, 2009, 11:30:50 AM
Optional DOAs and input/output transformers and its a sweet unit :)

If making all those choices up to the builder, it can be either very simple or pretty simple.
Title: Re: Studer 169 EQ in API 500 format
Post by: Baltimore on November 29, 2009, 11:36:28 AM
I think selectable frequencies for the high and low bands would be a better addition than the mic pre. And would make the eq much more versatile.  Either way, I'll probably build a pair.   Looks awesome!

Add transformer I/O and DOA option and I'll build more than a pair!
Title: Re: Studer 169 EQ in API 500 format
Post by: 2Low on November 29, 2009, 11:41:20 AM
I think it is fine as is, no need to complicate a good thing!

me too !
Title: Re: Studer 169 EQ in API 500 format
Post by: audiox on November 30, 2009, 06:18:11 AM
ever thought of (optional) DOA footprints (your OA10 comes to mind), or some input and / or output transformers?

Optional DOAs and input/output transformers and its a sweet unit :)

Add transformer I/O and DOA option and I'll build more than a pair!

The discrete op-amp idea came into my mind too but... In my mastering version prototype of this same circuit I included a socket for plug-in op-amp boards. My friend and his colleagues made comparison between NE5534 and NTP M-100 discrete op-amp but there was no difference. I understand the discrete op-amp concept in high gain applications like mic preamps but in eq circuit like this there is no real benefit.

Adding transformers... The nature of this eq is very neutral and adding quality transformers wouldn't change it much. I actually have a layout version which has a Studer 1.022.405.00 = Neutrik NTL1 (the original Studer 169 line input trafo) at the input and active balanced output. The line input trafo configuration of the 169 is not zero-field like in later Studers, so it adds a little coloration. But the effect is still quite minimal...

I publish the transformer version since there are so many who like the idea. The extra cost for those not assembling the trafo is only two wire links.
Title: Re: Studer 169 EQ in API 500 format
Post by: okgb on November 30, 2009, 08:55:20 AM
the idea to add the mic pre
was just like extending the other thread
about making the studer channel strip
if i was up to speed and smart enough
i'd help with the design
ever use a 550 a or b  , thats small
Title: Re: Studer 169 EQ in API 500 format
Post by: matta on November 30, 2009, 09:00:55 AM
I know front panel real estate is tough, though it can be done... this for me pushes the limits, 10 knobs, 4 push buttons:

(http://www.greatriverelectronics.com/image/DSCF1598retcrop.jpg)

It is Dan's new 500 series Harrison Eq, talk about fitting alot into a SMALL space!

Matt
Title: Re: Studer 169 EQ in API 500 format
Post by: audiox on November 30, 2009, 09:36:21 AM
I know front panel real estate is tough, though it can be done... this for me pushes the limits, 10 knobs, 4 push buttons

I never said that it is impossible. I have designed that kind of puzzles too, when I worked as an electronic designer. Doable but takes a lot of time.

But now we are talking about DIY project which must be easy to assemble, contain only minimum of mechanical parts and most importantly components must be cheap and easily available.

Do you remember the whining when I used (small but expensive) Sfernice potentiometers in the Neumann W492 project?
Title: Re: Studer 169 EQ in API 500 format
Post by: Brizco on November 30, 2009, 10:51:32 AM
Thanks for all the infos. Very interesting project!
I'd go for more space for different caps. just a wish ;)
Title: Re: Studer 169 EQ in API 500 format
Post by: strangeandbouncy on November 30, 2009, 11:20:54 AM
Hi Audiox,


    I am NOT really qualified to make this comment other than as an end user of vast amounts of outboard, and I would hate to disagree with you guys who A B'ed with 5534 and m100. After all, I wasn't there. But in my experience, you often can't hear much difference, 'til you have a long processing chain on, say a vocal, where the sibilance tends to rear it's ugly head at the end of the chain. Then, it can make a lot of difference as to what op-amp you use. I don't mean Discrete op-amp good, ic bad either . . . .


   I also like the idea of using DOA so that you can halve the input level, and operate away from the extremes of voltage swing, making up +6dB with a tranny. Also seems to make things sound a bit "faster"(wholly un-qualified statement btw!). (Could this be that the op-amp limited slewrate effectively has less effect, 'cos you are not asking it to make so much voltage gain in the same timeframe?)


    I certainly don't mean to criticise. I will be building itwith 5534 or anything else! There are I'm sure others who subscribe to the idea of a discrete in there, and personally I am itching to try out your OA10!


     Many many thanks, and Kindest regards,


      ANdyP



    . . . . there is also the Kudos of knowing that there is a discrete sitting in there . . . .


Title: Re: Studer 169 EQ in API 500 format (DOA & trafo added)
Post by: audiox on December 03, 2009, 11:28:43 AM
ever thought of (optional) DOA footprints (your OA10 comes to mind), or some input and / or output transformers?

Optional DOAs and input/output transformers and its a sweet unit

Add transformer I/O and DOA option and I'll build more than a pair!

There are I'm sure others who subscribe to the idea of a discrete in there, and personally I am itching to try out your OA10!

Several meetings were cancelled yesterday and I had almost a whole workday left. Well, I have electronics CAD installed in my laptop...

I added discrete op-amp option in the eq section. I am not convinced that it makes a huge difference but at least it allows to do some op-amp experiments. The pinout is compatible with API2520 and many others (including my version of Neumann OA-10 http://www.groupdiy.com/index.php?topic=34105.0 ).

I also included an option for the original Studer 169 input transformer (Studer 1.022.405.00 = Neutrik NTL1).

(See the first post in this thread for a new picture and refresh your browser if you still see the old one.)
Title: Re: Studer 169 EQ in API 500 format (DOA & trafo added)
Post by: mitsos on December 03, 2009, 12:15:24 PM
RE: hosting, if you don't need a lot of space you could use a free webhost.  Like PeterC's tripod page
1176neve.tripod.com

Has pop-ups but it's free, I think. There are probably others too. 
Title: Re: Studer 169 EQ in API 500 format (DOA & trafo added)
Post by: [silent:arts] on December 03, 2009, 12:16:15 PM
...I added discrete op-amp option in the eq section. I am not convinced that it makes a huge difference but at least it allows to do some op-amp experiments. The pinout is compatible with API2520 and many others (including my version of Neumann OA-10 http://www.groupdiy.com/index.php?topic=34105.0 ).

I also included an option for the original Studer 169 input transformer (Studer 1.022.405.00 = Neutrik NTL1)

cool, thank you.
I will take some ;D
Title: Re: Studer 169 EQ in API 500 format (DOA & trafo added)
Post by: gang of elk on December 03, 2009, 12:56:36 PM
i'm looking for a simple eq for a line-level console project and i think this might be the one! 
Title: Re: Studer 169 EQ in API 500 format
Post by: matta on December 03, 2009, 01:00:55 PM

Hey Audiox,

Just pointing it out as a reference, do as you see fit. We all thank you for the time effort you spend on these projects, FREE of charge! I agree that the vast majority are looking for cheaper/easier projects to build.

Cheers

Matt

I know front panel real estate is tough, though it can be done... this for me pushes the limits, 10 knobs, 4 push buttons

I never said that it is impossible. I have designed that kind of puzzles too, when I worked as an electronic designer. Doable but takes a lot of time.

But now we are talking about DIY project which must be easy to assemble, contain only minimum of mechanical parts and most importantly components must be cheap and easily available.

Do you remember the whining when I used (small but expensive) Sfernice potentiometers in the Neumann W492 project?
Title: Re: Studer 169 EQ in API 500 format (DOA & trafo added)
Post by: strangeandbouncy on December 03, 2009, 05:15:43 PM
Hi Audiox,


     you really are a superstar! That's just wonderful! Thank you so so much for this. I am certain that there will be many many happy bunnies out there.


       Awesome!



            ANdyP
Title: Re: Studer 169 EQ in API 500 format (DOA & trafo added)
Post by: strangeandbouncy on December 03, 2009, 05:40:00 PM
For your info,


   Canford Audio do the Neutrik trannies


   http://www.canford.co.uk/Products/23-003_NEUTRIK-NTL1-TRANSFORMER-Analogue-audio-PCB-line-input



       kindest regards,


        ANdyP
Title: Re: Studer 169 EQ in API 500 format (DOA & trafo added)
Post by: [silent:arts] on December 03, 2009, 05:46:20 PM
now we have to talk Gustav in doing the PCBs (incl. the OA10)
if he doesn't want to do then I will have a look in it.

Not only Canford, even Conrad, Farnell and Thomann sell the NTL1 (at very different prices)
Since I'm a new born Neutrik dealer I will ask for a quote too  8)
Title: Re: Studer 169 EQ in API 500 format (DOA & trafo added) + SCH
Post by: audiox on December 05, 2009, 09:59:12 AM
Here is the schematic (hosted by Google docs):
http://docs.google.com/fileview?id=0B_XBYPfmG8pVZGViZTg4YmQtMDM0Yi00M2IzLTkwYTYtOWE4Zjg2YTk0MDE3&hl=en

Components values in this schematic are for active balanced input (wire links assembled instead of transformer). Any comments welcome...

Colin promised to check the potentiometer dimensions before I publish the PCB documents.

I am certain that there will be many many happy bunnies out there.

Thanks for the kind words.
Title: Re: Studer 169 EQ in API 500 format (DOA & trafo added) + SCH
Post by: strangeandbouncy on December 05, 2009, 02:59:48 PM
Hi Audiox,

    many thanks for posting schematic. Just wondering about  components R24 and R25, and C27? there are no values shown.


    KIndest regards,


      ANdyP
Title: Re: Studer 169 EQ in API 500 format (DOA & trafo added) + SCH
Post by: Gustav on December 06, 2009, 11:38:02 AM
Got a mail from Volker about this. Im totally in if you guys are cool with having me make some boards.

Gustav
Title: Re: Studer 169 EQ in API 500 format (DOA & trafo added) + SCH
Post by: kazper on December 06, 2009, 11:52:39 AM
Got a mail from Volker about this. Im totally in if you guys are cool with having me make some boards.

Gustav

ummm... yes....

Things move so quickly here....
Title: Re: Studer 169 EQ in API 500 format (DOA & trafo added) + SCH
Post by: strangeandbouncy on December 06, 2009, 01:17:58 PM
Hi Gustav,



    Yes Please! Yessirree!!! . . . . especially with some OA10's as well . . . .


     Kindest regards,


        ANdyP
Title: Re: Studer 169 EQ in API 500 format (DOA & trafo added) + SCH
Post by: 2Low on December 06, 2009, 03:04:29 PM
Got a mail from Volker about this. Im totally in if you guys are cool with having me make some boards.

Gustav

Great ;D
Title: Re: Studer 169 EQ in API 500 format (DOA & trafo added) + SCH
Post by: Gustav on December 07, 2009, 05:57:26 AM
Is there a gerber?

Gustav
Title: Re: Studer 169 EQ in API 500 format (DOA & trafo added) + SCH
Post by: audiox on December 07, 2009, 07:24:53 AM
Just wondering about  components R24 and R25, and C27? there are no values shown.

Those components are for transformer option only. R24 (wire link) is for grounding one side of secondary. R27 and C27 are for damping network.
Title: Re: Studer 169 EQ in API 500 format (DOA & trafo added) + SCH
Post by: audiox on December 07, 2009, 07:47:15 AM
Is there a gerber?

The layout is ready but someone could make a prototype first. The board is single sided so it is easy and cheap to DIY.

I am not worried about the electrical functionality but the mechanical dimensions are based on documents found on the internet. I am quite sure that the dimensions are correct but it is still better to check before manufaturing a large batch or boards.

One question before creating the Gerber files:
Which is the hole diameter that I should use for the discrete op-amps? The socket pin diameter varies from one manufacturer to another...
Title: Re: Studer 169 EQ in API 500 format (DOA & trafo added) + SCH
Post by: [silent:arts] on December 07, 2009, 08:00:32 AM
...
One question before creating the Gerber files:
Which is the hole diameter that I should use for the discrete op-amps? The socket pin diameter varies from one manufacturer to another...
I would suggest:
http://classicapi.com/catalog/product_info.php?cPath=71_77&products_id=122
Title: Re: Studer 169 EQ in API 500 format - documents published
Post by: audiox on December 10, 2009, 03:02:09 PM
Component layout drawings & copper layer pdf for home etchers published. See the first post in this thread.
Title: Re: Studer 169 EQ in API 500 format - documents published
Post by: [silent:arts] on December 10, 2009, 05:28:24 PM
 8) 8) 8)

you are in contact with Gustav?
I can't home etche ...
Title: Re: Studer 169 EQ in API 500 format - documents published
Post by: Matthew Jacobs on December 10, 2009, 07:19:57 PM
Component layout drawings & copper layer pdf for home etchers published. See the first post in this thread.

Thanks audiox. Thanks very much. I may just give this a try as my first home etch...

I'm thinking of combining this with you other "mastering studer 169 EQ". IIRC you design that circuit with that in mind right?

J
Title: Re: Studer 169 EQ in API 500 format - documents published
Post by: audiox on December 12, 2009, 11:33:43 AM
you are in contact with Gustav? I can't home etche ...

Gerber files are ready, but I hope that someone checks the mechanical dimensions first. Most likely they are OK, but better to ensure before manufacturing the boards. Maybe someone involved in the 51X rack project could do that. I think dxf file would be the easiest way...
Title: Re: Studer 169 EQ in API 500 format - documents published
Post by: [silent:arts] on December 12, 2009, 12:04:07 PM
Gerber files are ready, but I hope that someone checks the mechanical dimensions first. Most likely they are OK, but better to ensure before manufacturing the boards. Maybe someone involved in the 51X rack project could do that. I think dxf file would be the easiest way...
pm me your email address and I will mail you the outline of Jeffs MicPre (http://classicapi.com/catalog/product_info.php?cPath=22_47_55_57_64&products_id=96) in dxf format for comparison.
Title: Re: Studer 169 EQ in API 500 format - documents published
Post by: audiox on December 12, 2009, 05:25:14 PM
I will mail you the outline of Jeffs MicPre (http://classicapi.com/catalog/product_info.php?cPath=22_47_55_57_64&products_id=96) in dxf format for comparison.

Thanks. Your dwg file opened perfectly...
Title: Re: Studer 169 EQ in API 500 format - documents published
Post by: jsteiger on December 12, 2009, 09:48:44 PM
Thanks. Your dwg file opened perfectly...
;) Good. I hope all was correct for you.

This will be an excellent project. Thanks for all of your hard work audiox! No home etch for me either. I will be looking to buy a few boards.  ;D
Title: Re: Studer 169 EQ in API 500 format (DOA & trafo added) + SCH
Post by: audiox on December 13, 2009, 07:48:35 AM
Is there a gerber?

Gerber files e-mailed to Gustav.

What has been the practice with the card edge connector contacts on the PCB? Hard gold plating is quite expensive...
Title: Re: Studer 169 EQ in API 500 format (DOA & trafo added) + SCH
Post by: jsteiger on December 13, 2009, 11:09:22 AM
Gerber files e-mailed to Gustav.

What has been the practice with the card edge connector contacts on the PCB? Hard gold plating is quite expensive...

I do gold fingers on my mic preamp cards, on the bottom side only. Peter Purpose brought up a good idea in his 1084 thread. Only plate the actual used contacts. This will give you 9 for your eq and 10 for a preamp requiring 48V. It's not a huge saving but it all adds up!  8)

I wish Peter would have thought about this a year ago.

Jeff
Title: Re: Studer 169 EQ in API 500 format - documents published
Post by: audiox on December 14, 2009, 11:23:58 AM
I do gold fingers on my mic preamp cards ... Only plate the actual used contacts ...

Could you contact Gustav and explain him the details? I think that would be the best way to ensure that we get the right type of plating with decent price.
Title: Re: Studer 169 EQ in API 500 format - documents published
Post by: peterc on December 14, 2009, 12:23:37 PM
These are pins & sockets I use for my DOA stuff, from RS:

434-712 socket
433-860 pins

Regards

Quote

One question before creating the Gerber files:
Which is the hole diameter that I should use for the discrete op-amps? The socket pin diameter varies from one manufacturer to another...
Title: Re: Studer 169 EQ in API 500 format - documents published
Post by: audiox on December 17, 2009, 10:42:07 AM
I think selectable frequencies for the high and low bands would be a better addition than the mic pre. And would make the eq much more versatile.

I also think Baltimore's suggestion is much better than the preamp addition.. selectable frequencies are always good, if it's easy to do..

Earlier today I had time to think about the frequency selection option. There is actually space enough for two on-off-on miniature toggle switches in the front panel. Not the prettiest solution but could be worse too. Picture attached (you must be logged in to see it).

Only a little manual wiring and you get 3 selectable frequencies which should be enough most purposes. When I designed the board I included some extra pads to make the wiring easier. I will publish some documentation about it when I have time.

- - -

I e-mailed the Gerber files to Gustav 5 days ago. No answer so far... Someone (jsteiger?) could also talk to him about gold finger plating. I have ordered boards with hard gold long time ago and things have probably changed a lot from those days.
Title: Re: Studer 169 EQ in API 500 format - selectable frequencies...
Post by: [silent:arts] on January 24, 2010, 02:27:01 PM
any news on this ...
Title: Re: Studer 169 EQ in API 500 format - selectable frequencies...
Post by: audiox on January 24, 2010, 04:25:34 PM
any news on this ...

I e-mailed Gerber files to Gustav more than a month ago. No answer so far.

A pdf file for home etching can also be found in the first post in this thread. So I guess it is up to you guys...
Title: Re: Studer 169 EQ in API 500 format - selectable frequencies...
Post by: dmp on February 15, 2010, 06:53:08 PM
I'm curious about the Opamp for the balanced output? There might be space on the board to add an option for an output transformer in the upper corner? (Maybe one like EA2623?) If there was room for the cutout (~1.1"x1.3") the builder could do either.
I'm new, maybe someone can shed some light.
Title: Re: Studer 169 EQ in API 500 format (mechanical docs published)
Post by: audiox on February 22, 2010, 09:44:26 AM
Mechanical documents published.

Front panel:
http://docs.google.com/fileview?id=0B_XBYPfmG8pVNWZlNzA1ZjktOTA3ZS00Nzg5LWI2NWMtMzEzMjAyNmEyMjkw&hl=en

Since L bracket is not easy to DIY, I have used a different approach to support the front panel (mounting block made of hexagonal spacer):
http://docs.google.com/fileview?id=0B_XBYPfmG8pVMjVkMDYzNTEtYzdhMS00ZDlkLWJjNWMtZGZjMGFiODAzYTNl&hl=en
Title: Re: Studer 169 EQ in API 500 format (mechanical docs published)
Post by: shot on February 22, 2010, 09:57:49 PM
Silly question... I'm wondering why are potentiometers P2 and P3 (high and mid gain) double 10K lin?
Why not a single 4K7 linear? Shouldn't it perform almost same? (or I don't quite understand it yet...)
Are their pins supposed to be wired oppositely maybe?

 ::)
Title: Re: Studer 169 EQ in API 500 format (mechanical docs published)
Post by: audiox on February 23, 2010, 04:37:39 AM
Silly question... I'm wondering why are potentiometers P2 and P3 (high and mid gain) double 10K lin? Why not a single 4K7 linear?

Dual unit is used for mechanical reasons. (I also noticed that dual 10K is easier to get than single 4K7, which is not available from Audiomaintenance web shop).
Title: Re: Studer 169 EQ in API 500 format (mechanical docs published)
Post by: Gustav on February 23, 2010, 05:02:33 AM
I just wanna say I started a feeler thread on this in the black market, and the files have been sent for fabbing now. It wont take long.

The gold fingers wont add much to the cost. Ill keep the price down. Doing a few less fingers wouldnt change the price - it would add some manual work covering up those areas when doing the gold plating I think.

Gustav
Title: Re: Studer 169 EQ in API 500 format (mechanical docs published)
Post by: regularjohn on February 25, 2010, 05:47:07 PM
I just breadboarded this circuit to try it out and see how it sounds before I go through the process of making a pcb.

I've noticed that the level with the eq switched in and all three boost/cuts at 0 is several dB higher than with the eq bypassed.  Has anyone else had this experience?  Any suggestions for trimming down the level?

It's a great sounding eq otherwise!   :)
Title: Re: Studer 169 EQ in API 500 format (mechanical docs published)
Post by: Snatchman on February 25, 2010, 09:29:30 PM
I just breadboarded this circuit to try it out and see how it sounds before I go through the process of making a pcb.

I've noticed that the level with the eq switched in and all three boost/cuts at 0 is several dB higher than with the eq bypassed.  Has anyone else had this experience?  Any suggestions for trimming down the level?

It's a great sounding eq otherwise!   :)
Hey Dustin..Check your PM........!
Title: Re: Studer 169 EQ in API 500 format (mechanical docs published)
Post by: audiox on February 26, 2010, 08:07:29 AM
I just breadboarded this circuit to try it out and see how it sounds before I go through the process of making a pcb.

I've noticed that the level with the eq switched in and all three boost/cuts at 0 is several dB higher than with the eq bypassed.  Has anyone else had this experience?  Any suggestions for trimming down the level?

It's a great sounding eq otherwise!

The input stage has gain of -6dB. The filter stages have unity gain when the controls are in the middle position. The output stage has gain of +6dB. Use this information to locate the source of error. Most likely wrong resistor value or wiring mistake, since we are talking about breadboarded circuit.
Title: Re: Studer 169 EQ in API 500 format (mechanical docs published)
Post by: boji on February 26, 2010, 09:05:13 AM
Very comprehensive submission, thank you for your hard work in bringing this together for us!
Title: Re: Studer 169 EQ in API 500 format (mechanical docs published)
Post by: regularjohn on February 26, 2010, 11:11:01 AM
The input stage has gain of -6dB. The filter stages have unity gain when the controls are in the middle position. The output stage has gain of +6dB. Use this information to locate the source of error. Most likely wrong resistor value or wiring mistake, since we are talking about breadboarded circuit.

Thanks so much for the info!  Time to fire up the scope!

I had a chance recently to play with a couple real 169 channels and the EQ was amazing, which was why I impatiently breadboarded the circuit instead of waiting for pcb's.  I actually combined your mastering version circuit and the 500 version circuit, so it's 3 bands and the hi and lo have six selectable frequencies each. 
Title: Re: Studer 169 EQ in API 500 format (mechanical docs published)
Post by: audiox on February 26, 2010, 12:05:28 PM
I actually combined your mastering version circuit and the 500 version circuit, so it's 3 bands and the hi and lo have six selectable frequencies each. 

Please note that you can use the original PCB and still get selectable high and low frequencies. There are pads on the PCB for wiring external switch/capacitor assembly.

I have posted a layout drawing (earlier in this thread) how to fit two toggle switches in the original front panel. On-off-on toggle switches provide 3 selectable frequencies.

If you use double width front panel (two module spaces) there is plenty of space for rotary switches (up to 12 frequencies, in case someone needs so many).
Title: Re: Studer 169 EQ in API 500 format (mechanical docs published)
Post by: strangeandbouncy on April 16, 2010, 06:18:16 AM
HI,


    just lashed my first one together, I am ignoring the mid band, and at the moment have it running with a 2520 'til I can find the silicon for the OA10's It is unbalanced in/out. I have 6 selectable frequencies at top and bottom. This is truly fantastic eq. Eventually I will have switches for gain, carnhill 10k input tranny, and 2503 1:2 output tranny. It is rocking now! I remember Audiox giving a warning about leads flying everywhere and oscillations/stability. No problems reported here, and I don't even have a front panel yet! (Looks a bit like my API lunchbox has been sick, throwing up a couple of switches and cables. Hmmm . . .)

 
    An absolutely massive thanks to Audiox and Gustav - you guys rule! ;D ;D ;D ;D ;D ;D ;D ;D ;D ;D ;D ;D ;D


     ANdyP
Title: Re: Studer 169 EQ in API 500 format (mechanical docs published)
Post by: [silent:arts] on April 17, 2010, 04:49:28 AM
ANdyP, show us some pics :D

Audiox, what are the values for R24/25 & C27?
and should all other part values stay the same using the transformer option?
Title: Re: Studer 169 EQ in API 500 format (mechanical docs published)
Post by: strangeandbouncy on April 17, 2010, 05:28:47 AM
Hi,


   I will send piccies later. No Bluetooth at studio. I have tried this out on a variety of sources. It is really really good eq! Acoustic gtr, kick drum, and esp lead vocal. I am mixing a track with part of the lead vocal from the demo. Slightly harsh and yet a tad dull sounding compared to the vocals I have recorded. This is so smooth and gentle, I can easily match 'em up. Yum!


   Gustav, you'd better stock up! As soon as the economy allows. i will be building some more. I will be doing a mastering version with switched steps for sure. Hope I can get some Lorlins into the 500 space, 'cos I'd like recallability on these puppies for sure!.Can't really afford anything smaller/sexier.


   Damn. Yet another eq i need in abundance . . . . .


    Kindest regards,


        ANdyP
Title: Re: Studer 169 EQ in API 500 format
Post by: audiox on April 18, 2010, 06:26:24 AM
Audiox, what are the values for R24/25 & C27? and should all other part values stay the same using the transformer option?

Layout drawing for those using the transformer option:

http://docs.google.com/fileview?id=0B_XBYPfmG8pVMmRhZmNkZWEtMjU2ZS00YmI1LWFjNTYtY2ExY2Y4NDFjY2Vh&hl=en

R4 (5.6k nominally) may need adjustment so that the overall gain of the input stage is exactly -6dB.
Title: Re: Studer 169 EQ in API 500 format
Post by: strangeandbouncy on April 18, 2010, 10:34:27 AM
Here it is!


   It is now stuck as it is 'til the mix comes off the board! It is on the lead vocal . . . Can't drill he holes 'til I can find someone with a vice to hold the front plate - Doh!


       ANdyP
Title: Re: Studer 169 EQ in API 500 format
Post by: strangeandbouncy on April 18, 2010, 10:35:33 AM
And again
Title: Re: Studer 169 EQ in API 500 format
Post by: strangeandbouncy on April 25, 2010, 10:21:20 AM
Couldn't find a vice, so I screwed the blank plates to  a lump of wood. Worked a treat!


   Now the proud owner of a working pair of these. My initial worries as to a 6dB loss have been assuaged. - Nothing to do with my build/everything to do with Digidesign 192's, and their inability to drive an un-balanced input. I am staggered, but there you go! In the end, I am running un-balanced in/ impedance balanced out, no mid eq, 6 switchable frequencies top and bottom, and I am using 2520. I am keen to try the OA10 boards that came with the boards, but haven't got the silicon yet. I have also tried it with a NE5524. It sounds amazing with this, but the top is just sweeter with the 2520, especially at max boost at 27kHz, a setting it will be virtually stuck on, i do believe . . . It sounded great with a 2503(4804) 1:2 make-up transformer to compensate for the digidesign design failure, but after much listening, I prefer it transformerless, which is fortunate 'cos I need them for something else, and they would be a bugger to mount on the board anyway.


   Gotta re-iterate, this is amazing eq! Where so many of our friendly neighbourhood eq's stamp there own Quality and Colour firmly on the subject, this is very very transparent. Just adding a dB or so in the bass is barely noticable on individual tracks in solo, that then leap out of the mix un-soloed. Not a replacement for the usual suspects, but a great bedfellow and companion.


     Audiox, you rock! - and Gustav, so do you!


       ANdyP
Title: Re: Studer 169 EQ in API 500 format
Post by: Holger on May 01, 2010, 03:34:36 AM
My version

(http://audiofor.tv/diy/ProjectFotoFolder/169/front_2.jpg)

(http://audiofor.tv/diy/ProjectFotoFolder/169/rear.jpg)

I had to make some mods to use my pots with the front panel layout provided by audiox.
I've soldered some components on the back to get some additional space for the pots.

Some more pictures:

(http://audiofor.tv/diy/ProjectFotoFolder/169/back.jpg)

(http://audiofor.tv/diy/ProjectFotoFolder/169/knobs.jpg)



Title: Re: Studer 169 EQ in API 500 format
Post by: [silent:arts] on May 01, 2010, 04:12:36 AM
Holger Du Schuft ;D ;D ;D

I did the same "mod" with a trimmer to set unity gain.
transformer based input here.
transformer output in planing stage 8)

btw, someone else have problems with the way too large holes for the pins on the OA10 DOA PCB?

anyway Holger, nice & fast work - as always :D
Title: Re: Studer 169 EQ in API 500 format
Post by: audiox on May 01, 2010, 05:18:40 AM
btw, someone else have problems with the way too large holes for the pins on the OA10 DOA PCB?

In my OA10 Gerber tool file there was no specific value given, but a note "select according to the pin size". I told Gustav that he should ask Jsteiger what is the correct drill size for a pin which mates this socket:
http://classicapi.com/catalog/product_info.php?cPath=71_77&products_id=122

I did the same "mod" with a trimmer to set unity gain.

Did you measure the resistance value which provided the correct gain?
Title: Re: Studer 169 EQ in API 500 format
Post by: [silent:arts] on May 01, 2010, 05:28:13 AM
btw, someone else have problems with the way too large holes for the pins on the OA10 DOA PCB?
In my OA10 Gerber tool file there was no specific value given, but a note "select according to the pin size". I told Gustav that he should ask Jsteiger what is the correct drill size for a pin which mates this socket:
http://classicapi.com/catalog/product_info.php?cPath=71_77&products_id=122
drill size of the DOA pins are the same like the sockets now :o
the sockets fit fine btw :D

I did the same "mod" with a trimmer to set unity gain.
Did you measure the resistance value which provided the correct gain?
once I'm passing audio I will do the measuring, and post the result.
Title: Re: Studer 169 EQ in API 500 format
Post by: Slenderchap on May 08, 2010, 02:15:40 AM
P4 = 2x 100K REV LOG (order code OM-01-059)
http://www.audiomaintenance.com/acatalog/potentiometers_carbon_16mm_diameter_dual_gang.html


...That explains why I keep getting asked about the OM-01-059's.... they are a very slow seller (used for Trident 65?) that was only ever kept in small quantity.... so of course there are now none left.... I will get some more.... but currently lead time for these is about 6-8 weeks.....

Colin
www.audiomaintenance.com

Title: Re: Studer 169 EQ in API 500 format
Post by: bobine on May 09, 2010, 07:02:31 PM
The 16mm 100K pots (OM-01-059) were sold out when I ordered, but Colin pointed me to a 20mm pot (OM-01-072). I ordered a pair of these and modified them slightly to stand in until the proper size is available. With some snipping, filing, and bending you can get these larger pots near to the centerline and flush with the front plane.

Not knowing better, I also ordered some 16mm 47K and 470K pots. Can anyone predict how these might behave in the circuit if they were substituted? (I'm reluctant to solder and unsolder these too many times or I'd just try it.)

thanks to audiox and gustav for realizing this project. The EQ is gentle yet generous. Umm.
Title: Re: Studer 169 EQ in API 500 format
Post by: bobine on May 09, 2010, 07:07:35 PM
And this shows the amount of bending required to get front/back alignment.

Title: Re: Studer 169 EQ in API 500 format
Post by: bobine on May 09, 2010, 07:11:15 PM
and here is the working EQ (no trafo, no DOAs)
Title: Re: Studer 169 EQ in API 500 format
Post by: strangeandbouncy on May 12, 2010, 05:33:36 AM
Hi,


   just for sh*ts and giggles, 'ere is my humble offering! I am almost ashamed next to Holger's BEAUTIFUL front panel layout! I haven't had time to cut the pot and switch shafts, or draw my panel BY HAND with a White Pen, and the top knobs will be replaced with the same size as the lower ones as soon as I can! I actually like the "anonimity" of my builds, and take great pride in people asking "what the hell is that?", then HEARING it . . . .


   I am in lerv with this eq!( but don't tell all the others in my possession, even though they aren't in any danger anyway!)


    ANdyP
Title: Re: Studer 169 EQ in API 500 format
Post by: strangeandbouncy on May 12, 2010, 05:34:25 AM
And again
Title: Re: Studer 169 EQ in API 500 format
Post by: strangeandbouncy on May 12, 2010, 05:57:43 AM
Hmmm,



   you'll have to crane your necks, I rotated the images here and saved them, so gawd knows why they're topsy-turvy!



      AndyP
Title: Re: Studer 169 EQ in API 500 format
Post by: dmp on May 20, 2010, 03:39:16 PM
Andy,
What caps / freqs did you use for your 6 position switches? What are you finding the most useful for different applications?
I am an amateur with recording so any insight is appreciated...
Dan
Title: Re: Studer 169 EQ in API 500 format
Post by: strangeandbouncy on May 20, 2010, 04:08:10 PM
Hi,



  in bass, 330nF, 220nF, 150nF, 100nF, 68nF, and 47nF, giving 19Hz, 28Hz, 40Hz, 60Hz, 85Hz and 120Hz.

  in Treble, 47nF, 33nF, 22nF, 15nF, 10nF and 6.8nF, giving 4k1, 5k9, 8k8, 12k7, 18k9, and27k3


   I am using 28Hz and 18k9 quite a lot. I am using them across drum sub-bus post comp, mix bus duties, and especially on vocals.  They are awesome an individual drums too! Kick, Snare and toms - yum!  wish I had not come up/down so much, but had more choice at the extremes really. I wish I had 22k7 especially! I will be doing this on my next pair. I used Wimas for what it's worth. Available at Maplins!

  I would recommend NOT doing what I did if you want something general. The mid band would be extremely useful, and I would be very happy with say, bass set at 28Hz, and treble at 18k9. If you follow Audiox's front panel, and have 3 or even just 2 different frequencies top and bottom, you would be very happy, I am sure.

    I can recommend using API 2520 for this. It definitely adds a certain je ne sais quois . . . I am looking forward to trying the OA10 too! If you want to just use an NE5534, this sounds great too!, but a bit more brittle at extreme gain in the HF.



   Good luck! this is a very simple build, no power supply required if you have an API lunchbox, so very much safer too. It is not rocket science, and you will instantly love them ,i promise!


   Good luck,


    ANdyp
 
Title: Re: Studer 169 EQ in API 500 format
Post by: dmp on May 20, 2010, 05:28:48 PM
Cool! thanks for the advice.
I'll would like to keep the midband, and try to add selector switches for the high and low frequencies.
So maybe...
high: 12nf (15.8kHz), 10nf (18.9 kHz), 8.2nf(22.7kHz)
low: 220nf (28Hz), 100nf (60Hz), 47nf (120 Hz)

(edited to correct typo...)

 
Title: Re: Studer 169 EQ in API 500 format
Post by: strangeandbouncy on May 20, 2010, 05:33:36 PM
Just go for it!


  You can always change 'em to taste . . .



           Kindest regards,


     
                 ANdyP
Title: Re: Studer 169 EQ in API 500 format
Post by: Davo on May 20, 2010, 08:37:21 PM
dmp, you meant "nf" values rather than uf right?
just makin sure
Title: Re: Studer 169 EQ in API 500 format
Post by: sunmen on May 21, 2010, 03:34:12 AM
Hi everyone,

Very nice project, and very nice versions you guys !   8)
I've just seen this thread, I'm would be in for two.
Does someone know if some people are gathering for a new batch here ?


Thank you so much and bravo ! 
Title: Re: Studer 169 EQ in API 500 format
Post by: Davo on May 21, 2010, 03:41:09 AM
Hi sunmen,

You can get em from Gustav, here's a link: http://www.groupdiy.com/index.php?topic=10776.0

cheers,
dave
Title: Re: Studer 169 EQ in API 500 format
Post by: strangeandbouncy on May 21, 2010, 03:42:24 AM
Hi,

  sorry, i MEANT nF not uF


   forgive any confusion!



     ANdyP
Title: Re: Studer 169 EQ in API 500 format
Post by: Davo on May 21, 2010, 03:51:30 AM
Hi ANdyP,

Naw, you got your values correct :)... just makin sure that dmp doesn't have a bunch of lytcs hangin off the board, wondering
why it's not workin right

cheers,
dave
Title: Re: Studer 169 EQ in API 500 format
Post by: sunmen on May 21, 2010, 06:30:16 AM
Thank you very much Dave !
Title: Re: Studer 169 EQ in API 500 format
Post by: dmp on May 21, 2010, 08:23:36 AM
Yes. thanks! I typed them wrong
Title: Re: Studer 169 EQ in API 500 format
Post by: RedNoise on May 21, 2010, 03:07:43 PM
Hi everyone,

Very nice project, and very nice versions you guys !   8)
I've just seen this thread, I'm would be in for two.
Does someone know if some people are gathering for a new batch here ?


Thank you so much and bravo !  


Hi Suman !

Welcome!!Use PM if u wanna be in contact!french guy right??

Sorry for the little hijack...
Title: Re: Studer 169 EQ in API 500 format
Post by: kingj on May 23, 2010, 11:23:40 PM
So I kind of want to do a narrow/wide switch for the middle band. From my understanding it would just be a switch and a resistor but does anyone have an idea as to where I would want to place this? thanks a lot guys.
Title: Re: Studer 169 EQ in API 500 format
Post by: Holger on May 26, 2010, 11:36:36 AM
My next one:

- changed front panel design
- added LED for EQ in

(http://audiofor.tv/diy/ProjectFotoFolder/169/bfrontside.jpg)

The OPAmps are not final, ignore the violet wire.

(http://audiofor.tv/diy/ProjectFotoFolder/169/bside.jpg)

(http://audiofor.tv/diy/ProjectFotoFolder/169/bfronttop.jpg)

(http://audiofor.tv/diy/ProjectFotoFolder/169/bfrontbottom.jpg)

Front panel made by Frank Röllen/NRG Recording.

Does anyone know a good source for cool looking small knobs, especially for the 4mm shaft pots?
Title: Re: Studer 169 EQ in API 500 format
Post by: okgb on May 26, 2010, 01:22:01 PM
gonna need some panels somehow
Do you know how much or mind
if franks sells some more  ?
Title: Re: Studer 169 EQ in API 500 format
Post by: ethervalve on July 15, 2010, 05:34:52 PM
I just finished my 169 using ne5534s throughout. What a simple, affordable and great-sounding project--thanks Audiox and Gustav!
Now, if only some enterprising individual were to jump in and start selling cheap and simple front panels...
Title: Re: Studer 169 EQ in API 500 format
Post by: RedNoise on July 15, 2010, 05:50:58 PM
4mm knobs ??
cheapest one :
http://www.banzaimusic.com/Mini-Fluted-ABS-knob-black.html
more expensive one :
http://www.banzaimusic.com/Davies-Knob-1900.html
Title: Re: Studer 169 EQ in API 500 format
Post by: skipwave on July 15, 2010, 05:56:20 PM
4mm knobs ??
cheapest one :
http://www.banzaimusic.com/Mini-Fluted-ABS-knob-black.html
more expensive one :
http://www.banzaimusic.com/Davies-Knob-1900.html

Those both show "Shaft diameter: 6,3mm"
Title: Re: Studer 169 EQ in API 500 format
Post by: RedNoise on July 15, 2010, 05:58:07 PM
My bad , sorry for the stupid reply... :-[

Or add these :
http://www.banzaimusic.com/Axis-Converter-PL-63.html
http://www.banzaimusic.com/Axis-Converter-6-3mm-4mm.html

NB : plastic ones are on back order...
Title: Re: Studer 169 EQ in API 500 format
Post by: skipwave on July 15, 2010, 06:00:31 PM
Hmmm,



   you'll have to crane your necks, I rotated the images here and saved them, so gawd knows why they're topsy-turvy!



      AndyP

That's probably because Apple Preview does not actually re-save the file with image rotated, it just adds the orientation to the file header somehow. Incredibly annoying.

Download one of the lovely freeware image editor options for quick edits.
Title: Re: Studer 169 EQ in API 500 format
Post by: skipwave on July 15, 2010, 06:01:19 PM
My bad , sorry for the stupid reply... :-[

Or add these :
http://www.banzaimusic.com/Axis-Converter-PL-63.html
http://www.banzaimusic.com/Axis-Converter-6-3mm-4mm.html

NB : plastic ones are on back order...

Now that's very cool. Thanks for adding!

I ended up ordering these for use with the audiomaintenance pots: https://www.mouser.com/Search/ProductDetail.aspx?R=C150H-09-R4virtualkey55000000virtualkey550-C150H09R4
Title: Re: Studer 169 EQ in API 500 format
Post by: RedNoise on July 15, 2010, 06:03:24 PM
I have to say that ABS knobs (the cheapest) feel and look what they cost...not very well...
Title: Re: Studer 169 EQ in API 500 format
Post by: strangeandbouncy on July 15, 2010, 06:08:35 PM
Skipnoise,

   I rotated them in an certain application called Photoshop . . . . erm . . . . .should have worked methinks . . .
Title: Re: Studer 169 EQ in API 500 format
Post by: skipwave on July 15, 2010, 06:40:04 PM
Hahaha! Skipnoise....... wish I'd thought of that.

Well that's awfully weird about Photostop not saving the rotated image.  ???
Title: Re: Studer 169 EQ in API 500 format
Post by: strangeandbouncy on July 19, 2010, 10:03:10 AM
Hi,


    question to Audiox, I notice that in the mastering version, the "feedback caps" at the input stage are 22pF, and the on the "filter" feedback is 10pF. On the 500 series version, the values are much higher, 47pF in each place. Is there a reason for this, and can I use the smaller settings, and hopefully increase bandwidth on the 500 series eq?



     KIndest regards,


         ANdyP
Title: Re: Studer 169 EQ in API 500 format
Post by: strangeandbouncy on July 22, 2010, 06:43:41 AM
Bump . . .
Title: Re: Studer 169 EQ in API 500 format
Post by: dbeeson on July 24, 2010, 02:05:07 AM
Does anyone know where to find the 2g 100k rev log pot?  I've got all the other parts I need, but this one is very tough to source.  Or is there a suitable replacement? Thanks.
Title: Re: Studer 169 EQ in API 500 format
Post by: dmp on July 24, 2010, 01:17:22 PM
Colin at AMT told me he has these on order and should have them in stock in a few weeks.
Title: Re: Studer 169 EQ in API 500 format
Post by: audiox on July 24, 2010, 01:55:22 PM
in the mastering version, the "feedback caps" at the input stage are 22pF, and the on the "filter" feedback is 10pF. On the 500 series version, the values are much higher, 47pF in each place. Is there a reason for this, and can I use the smaller settings, and hopefully increase bandwidth on the 500 series eq?

Even with the 47p caps the -0.5 dB point is around 100 kHz. Do you have a bat as a customer?
Title: Re: Studer 169 EQ in API 500 format
Post by: mitsos on July 24, 2010, 02:01:28 PM
 
Does anyone know where to find the 2g 100k rev log pot?  I've got all the other parts I need, but this one is very tough to source.  Or is there a suitable replacement? Thanks.
Don't know what pots fit this PCB but smallbearelec.com sells dual 100K rev log Alpha pots.
Title: Re: Studer 169 EQ in API 500 format
Post by: strangeandbouncy on July 24, 2010, 03:20:45 PM
Audiox,


    LOL!



   no, but plenty of rats . . . I was just wondering. I know i should be able to calculate the turnover point . . . .


   kIndest regards,



    ANdyP
Title: Re: Studer 169 EQ in API 500 format
Post by: regularjohn on August 03, 2010, 09:52:49 AM
Does anyone know of anyone that sells the dual 10K lin pots and the 22k lin pot with a 1/4" shaft?  I've been searching the net with no success.  I know small bear has the dual 100k rev log with 1/4" shaft.  I just hate those tiny potshafts from the audiomaintenance pots.  I like big vintage knobs, man!  With those tiny pots it's kinda like throwing a hotdog down a hallway, hehe  ;D
Title: Re: Studer 169 EQ in API 500 format
Post by: Sammas on August 03, 2010, 09:23:11 PM


Slightly off topic from your question, regularjohn...


but would it be possible to just bang a 127k resistor in parallel with the 470k rev log potentiometer to get 100k rev log??
Title: Re: Studer 169 EQ in API 500 format
Post by: wolfgang on August 04, 2010, 01:53:40 PM
Ohms value would be right, but the rev log law would change!!! Dont now how the pot would act with this mod!!


regards,
Wolfgang
Title: Re: Studer 169 EQ in API 500 format
Post by: mitsos on August 04, 2010, 02:24:16 PM
Smallbear has dual 10K alphas:

Http://www.smallbearelec.com/Detail.bok?no=736

They also have 25K single, not sure what difference this would make, otherwise Omeg makes 22K pots and you can get them direct.

hth!
Title: Re: Studer 169 EQ in API 500 format
Post by: regularjohn on August 04, 2010, 04:17:28 PM
yeah, but they don't have center detents (the only one that doesn't matter for is the 100k dual rev log since it's the frequency sweep).  the detents are nice because then I know that when the knob is at 0 it's actually no cut or boost.
Title: Re: Studer 169 EQ in API 500 format
Post by: strangeandbouncy on August 04, 2010, 04:29:05 PM
HI,


   just because there is a centre detent, doesn't mean that it will be zero boost/cut . . .mine are NOT zero at 12 o clock. more like 12,30 or even 1 o clock. . .


   just my pennies worth.


    ANdyP
Title: Re: Studer 169 EQ in API 500 format
Post by: mitsos on August 04, 2010, 04:42:47 PM
yes, most of these pots have 20% tolerance.  In any case, I believe you can request center detents at Omeg, not 100% sure though.

cheers!
Title: Re: Studer 169 EQ in API 500 format
Post by: dbeeson on August 05, 2010, 08:56:48 AM
Yes, you can get center detents from Omeg, but you're better off getting all the pots from Audio Maintenance, as they will be (believe it or not) cheaper.  I was quoted 4.86 pounds each for a minimum of 10 from Omeg for the same pot.  Colin from Audio Maintenance advised me that the 16mm dual rev 100k will be back in stock in a week or two.  I've done some serious hunting for these pots, and always come back to Audio Maintenance.  With center detents on 2 and a rev log on the other, they're all very hard to source. 
Title: Re: Studer 169 EQ in API 500 format
Post by: regularjohn on August 05, 2010, 01:43:02 PM
Without center detents, I can get all the pots here in the US for cheaper than audio maintenance, and with 1/4" potshafts.  The center detents are just a cool feature, IMO.  But I hate those tiny potshafts.  Guess I'll go without detents...
Title: Re: Studer 169 EQ in API 500 format
Post by: dbeeson on August 06, 2010, 09:27:10 AM
Can anyone recommend a switch cap that will fit the 10mm hole on the front panel?  I've ordered some switches from classicapi but I'm assuming their switch caps have a much smaller diameter of 10mm.  Also, anyone have another front panel layout they'd like to share? 
Title: Re: Studer 169 EQ in API 500 format
Post by: 3nity on August 06, 2010, 11:37:54 AM
Can someone please post some audio samples of this? just 1 sample and dialing all knobs...
i dont know seems very interesting eq...
Thanks...
Title: Re: Studer 169 EQ in API 500 format
Post by: geoff004 on August 06, 2010, 05:39:14 PM
Can anyone recommend a switch cap that will fit the 10mm hole on the front panel?  I've ordered some switches from classicapi but I'm assuming their switch caps have a much smaller diameter of 10mm.

I had front panels made (from the drawings on page 1) and ordered switch caps from ClassicAPI and can tell you they're way too small.  I should have paid a little attention to that.
I know those larger caps are out there - my Demeter reverb uses both red and chrome caps.
Any ideas?
Title: Re: Studer 169 EQ in API 500 format
Post by: regularjohn on August 06, 2010, 05:59:58 PM
this one's 8.8mm diameter.  i think those ones from classic api are 7mm or thereabouts.
not sure if your switches are C&K.  If not you might need to look for the ones for your brand of switch.
http://search.digikey.com/scripts/DkSearch/dksus.dll?Cat=1115298&k=f0201
Title: Re: Studer 169 EQ in API 500 format
Post by: jsteiger on August 06, 2010, 06:38:26 PM
Hey guys,

Yes mine are the bullet caps and they are about 7mm at the bottom and taper to 5mm at the top.

Try searching Digi for the following.

F11010102 (white)
F11010106 (yellow)
F11010107 (blue)
F11010108 (green)
F11010112 (orange)

You will need to check out the F-series data sheet to see them as no one seems to have a product pic. They are 9.94mm in diameter.

I have never used these myself but they are very similar to the old Schadow "fish-eye" caps. Out position color is black and depressed color is what I have shown. Digi does not have them all but they have 3 or 4 colors. They are not cheap either.  ???

Cheers, Jeff
Title: Re: Studer 169 EQ in API 500 format
Post by: dbeeson on August 07, 2010, 12:22:47 PM
Cool. Thanks for the info Jeff.
It looks like they have the green, orange and white caps.  Are you saying that these particular caps are "fish eye" style?  I have an old MCI tape machine that has those.  They're really cool.  They are a little expensive though, almost twice the price of the switch! But since I'm only building a pair, it's no biggie. 
Title: Re: Studer 169 EQ in API 500 format
Post by: regularjohn on August 07, 2010, 01:24:51 PM
Keep in mind that those fish eye caps need some sort of "catch" installed behind the panel in order for the eye to open and close, which is triggered by a small hook that protrudes from the switch cap.

If you don't have something in place to catch the hook (too many fishing puns here!) that eye will not open and close when you press the switch.
Title: Re: Studer 169 EQ in API 500 format
Post by: jsteiger on August 07, 2010, 01:29:10 PM
An 1/8" or 3mm hole, properly placed in the PCB is enough to catch the hook on the fish-eye style. If that is possible. I am not super familiar with the switch location and what tracks may be under the switch for this particular PCB.

It appears like the F11 style don't need a catch? Anybody ever used these before?
Title: Re: Studer 169 EQ in API 500 format
Post by: regularjohn on August 07, 2010, 01:36:13 PM
The F11's need a catch as well.  The "hook" on these comes out from underneath the switch cap and sheaths over the end of the switch like a plastic square condom, so the "catch" would need to stick up from the pcb and hug the end of the switch under the switchcap.  If you look at the datasheet, the left diagram of the F11 has the "hook" up inside the cap, and the right diagram has the "hook" slid out.  It kinda looks like two little legs in the drawing.

I went through almost every option with these switch caps with a custom build I did recently that used the C&K 6pdt pushbutton switch.
I had ordered most of them and played around to see which one I liked best.
Title: Re: Studer 169 EQ in API 500 format
Post by: dbeeson on August 07, 2010, 03:48:08 PM
Jeff, would this style of cap be the cap with the "hook" you're talking about?  http://search.digikey.com/scripts/DkSearch/dksus.dll?Detail&name=CKN10020-ND  It's the F08 style, with a 9.94mm diameter. The spec sheet has pics. Looks almost the same with a top and bottom notch on the color insert.  Would this work better? I like the idea of strategically drilling a hole in the pcb for the hook to catch.  These also come in 3 colors from Digi. 
John, did you find it finicky with the square condom style on the f11 buttons? 
Title: Re: Studer 169 EQ in API 500 format
Post by: jsteiger on August 07, 2010, 04:08:14 PM
Yes, F08 is the winky with the hook that needs a hole.
Title: Re: Studer 169 EQ in API 500 format
Post by: dbeeson on August 07, 2010, 04:58:19 PM
Jeff you dirty dog,  Thanks man.  ;D

Guys, is there a simple way to link 2 modules (dials from one unit controlling both units) so they could be used in a mix/mastering situation? 
Title: Re: Studer 169 EQ in API 500 format
Post by: dbeeson on August 08, 2010, 04:05:43 PM
I thought I'd share this link with you guys looking for the 100k 16mm rev log pots in North America: http://www.newoldsounds.com/index.php?main_page=product_info&products_id=1137
 
Title: Re: Studer 169 EQ in API 500 format
Post by: dbeeson on August 16, 2010, 11:40:08 AM
Audiox,
How would I go about installing switches for the 3 selectable frequencies?  I'd like to do this, but don't really know how.  Excellent build btw, got them up and running last night and they sound excellent.  Need to mess with the resistance for unity gain, but it's not far off.  Thanks again, to you and Gustav.
Title: Re: Studer 169 EQ in API 500 format
Post by: audiox on August 17, 2010, 03:06:43 PM
How would I go about installing switches for the 3 selectable frequencies?  I'd like to do this, but don't really know how.

Low filter: Use a single pole on-off-on toggle switch. The first "on" position connects a capacitor in parallel with C6 and the other "on" position connects another value capacitor in parallel with C6. In the middle "off" position there is C6 alone. Now you have 3 selectable frequencies.

High filter: Same idea but you need a two pole on-off-on switch since there are two capacitors which determine the frequency (C4 and C5).

Note that I have included some extra pads on the PCB to make wiring easier.
Title: Re: Studer 169 EQ in API 500 format
Post by: dmp on August 17, 2010, 03:17:08 PM
if using the input transformer, is U1 needed?
Title: Re: Studer 169 EQ in API 500 format
Post by: dbeeson on August 17, 2010, 03:53:30 PM
Thanks Audiox! What values would I use for the frequencies you put on the front panel?
Title: Re: Studer 169 EQ in API 500 format
Post by: Sammas on August 21, 2010, 04:38:17 AM


Does anyone have a front panel express file for the 169 layout? I'm looking forward to these builds!
Title: Re: Studer 169 EQ in API 500 format
Post by: strangeandbouncy on August 21, 2010, 10:48:39 AM
Hi,


      just finished my second pair, again with 6 way switchable frequencies top and bottom, no mid. Again, I used two DOA's, with the one that should be for the mid-band re-wired as balanced input. The output is impedance balanced. My first pair has 2520's, and this pair has the OA10's. BOth sound really good, the 2520's are a bit more "forward" in the mids, and the OA10's are very silky smooth and warm sounding. I have also tried it with 5534's, and it sounded pretty amazing too. My favourite is the OA10 version. It is just a tad more subtle.

    For what it is worth,  I rarely use anything but one frequency top and bottom, normally 28Hz at bottom, and 19kHz at top.


     I am very fond of these eq's. They are very simple, and very effective.


   Kindest regards,


    ANdyP
Title: Re: Studer 169 EQ in API 500 format
Post by: geoff004 on August 29, 2010, 10:17:07 PM
I just finished up 1 of 2 EQs and it seems to be working OK except:
when I turn the mid frequency knob full counter-clockwise I get some serious oscillation - almost sounds like feedback.
Any ideas?

I need to get a couple more caps to finish out my high and low frequency selection - I'll post pictures after I've got them both finished up.
Title: Re: Studer 169 EQ in API 500 format
Post by: Tweekhead on September 11, 2010, 05:38:02 PM
Hello!

I'm going to try to build 2 channels of these EQs, and I was wondering if anyone could help me out with a BOM for the transformer balanced input version of the unit. I looked at the component layouts and got all the values written down, but I'm very new to electronics and trying to learn to read schematics, so I'm not sure what spacing I would need to go with for the pcb foot prints, or voltages I should be looking for.

Thanks,

Arthur
Title: Re: Studer 169 EQ in API 500 format
Post by: regularjohn on September 11, 2010, 07:30:08 PM
My first pair has 2520's, and this pair has the OA10's. BOth sound really good, the 2520's are a bit more "forward" in the mids, and the OA10's are very silky smooth and warm sounding. I have also tried it with 5534's, and it sounded pretty amazing too. My favourite is the OA10 version. It is just a tad more subtle.

I really like it with the LME49710.  You have to add psu decoupling for em, but it's ultra transparent.  Definately one of my favorite EQ's for mixbuss applications.
Title: Re: Studer 169 EQ in API 500 format
Post by: RedNoise on September 12, 2010, 02:32:17 AM
Hello!
...if anyone could help me out with a BOM for the transformer balanced input version of the unit...
Arthur

Hi Arthur , are talking about ALL the components , or only the input transformer?
Title: Re: Studer 169 EQ in API 500 format
Post by: Tweekhead on September 12, 2010, 11:12:30 AM
Hello Rednoise!

I'm looking for all the components, as I ordered 2 of the Neutrik NTL1 transformers already. I'm so new to all of this I didn't realize I could build the unit without the transformer option until after I placed the order :-[ Lead time in the US is 8 weeks, so I ordered it from the UK, and it was pricey. I'm confident I could find all of the resistors, but I was looking for possible help on the capacitor selection. I've used Wimas in other projects and would like to use them on this, but again, I'm not sure which ones would be the best for the application.

Thanks,

Arthur
Title: Re: Studer 169 EQ in API 500 format
Post by: audiox on September 13, 2010, 04:26:41 AM
I looked at the component layouts and got all the values written down, but I'm very new to electronics and trying to learn to read schematics, so I'm not sure what spacing I would need to go with for the pcb foot prints, or voltages I should be looking for.

- resistors 1% metal film
- 100n power decoupling caps, ceramic multilayer 50V or higher R=5mm
- pF range capacitors, ceramic, any voltage R=5mm
- nF range capacitors, polyester, any voltage R=5mm
- 10u electrolytics, 25V or higher R=2.5mm
- 100u electrolytics, any voltage R=2.5mm
Title: Re: Studer 169 EQ in API 500 format
Post by: Tweekhead on September 13, 2010, 09:13:23 AM
Audiox,

Thank you so much!



Arthur
Title: Re: Studer 169 EQ in API 500 format
Post by: geoff004 on September 13, 2010, 09:28:35 PM
I finished up my pair tonight and they sound great except:
with one of the EQs when the mid freq knob is full counter-clockwise and the mid gain is up about 3 o'clock the thing just puts out a loud tone.
I checked component values and solder joints and I'm not really coming up with any explanations.  I also switched op amps around and no change.
Any ideas?
Anyone???

I'll post pictures when my switch button-caps come in.
Title: Re: Studer 169 EQ in API 500 format
Post by: Matthew Jacobs on September 20, 2010, 08:39:47 AM
Hi Everyone,

I'm thinking of getting 2 of these boars from Gustav to make a stereo EQ.

Can I add another Mid band simply by adding another mid section in series? Sort of repeat everything in between C9 and R16?

Do I need to isolate each section with a 100uF cap?

I'm thinking of building a EQ that does Low Shelf, Mid, Mid, High Shelf

Is that possible? I think so, right?

J
Title: Re: Studer 169 EQ in API 500 format
Post by: strangeandbouncy on September 20, 2010, 09:39:00 AM
Hi,


     I think you might get some interaction between the mid-bands(?) if you try this . . . .iirc an earlier discussion.



    Kindest regards,



   ANdyP
Title: Re: Studer 169 EQ in API 500 format
Post by: Matthew Jacobs on September 20, 2010, 06:05:12 PM
Thanks ANdyP

I tried to search, but found nothing. Is it somewhere in this thread?

I know you just bypassed the whole mid section. Do you find you don't miss it?

I was thinking of using these boards to build a "mastering version" as the official "mastering version" doesn't have pinouts for DOAs.

I need to investigate having 2 mid bands, cause it's something I think I'd want...

JD
Title: Re: Studer 169 EQ in API 500 format
Post by: dbeeson on September 20, 2010, 07:43:34 PM
I've finished a stereo pair of these babies and they sound fantastic.  Very neutral, not harsh at all. I'm just wondering, I used the larger omeg plastic pots for the build and the knobs stick out a little further than I'd like them to.  I have the other pots that will fit better except the dual 22k...would it be ok to use a dual 25k there instead?  Once again, great build!
Title: Re: Studer 169 EQ in API 500 format
Post by: Matthew Jacobs on September 21, 2010, 04:18:06 AM
I used the larger omeg plastic pots for the build and the knobs stick out a little further than I'd like them to.

Is it simply that the shafts are little to long. If so you can easily cut them to length. I usualy put some electrical tape to seal the joint between the shaft and the body so that cuttings don't go into the pot. Yeah, but simply use a saw to cut the shaft.

JD
Title: Re: Studer 169 EQ in API 500 format
Post by: dbeeson on September 22, 2010, 10:58:46 PM
Yeah, it's not the shaft that is the issue.  I've already cut it down nicely, but the threads are really high on the pots so they stick out past the front panel.  They don't look that bad really. I just wanted a more professional look I guess.  So no go on the 25k?  I guess I could try it out.
Title: Re: Studer 169 EQ in API 500 format
Post by: Matthew Jacobs on September 23, 2010, 02:11:02 AM
Yeah, it's not the shaft that is the issue.  I've already cut it down nicely, but the threads are really high on the pots so they stick out past the front panel.  They don't look that bad really. I just wanted a more professional look I guess.  So no go on the 25k?  I guess I could try it out.

Put some washers behind the panel so that the pots sit a little further back...
Title: Re: Studer 169 EQ in API 500 format
Post by: dbeeson on September 23, 2010, 02:07:31 PM
ahh yes, but the issue is that the front panel will no longer sit flush with the lunchbox.  I'll try it out and see what happens
Title: Re: Studer 169 EQ in API 500 format
Post by: Matthew Jacobs on September 23, 2010, 04:29:26 PM
ahh yes, but the issue is that the front panel will no longer sit flush with the lunchbox.  I'll try it out and see what happens

Oh woah... didn't realize the the API 500 format was that tight... not much room for moving things around... is it because of the pin thing at the back?
Title: Re: Studer 169 EQ in API 500 format
Post by: geoff004 on September 26, 2010, 10:31:27 PM
here's my pair.
There's still something a little funny with one of them, with the feedback and all.  I guess no one can help.
Anyhow, they're intended for tracking purposes.  Stuffed with the GAR1731 op amp and they sound real nice.
(http://www.hazelriggbrothers.com/picts/500EQ.JPG)
Title: Re: Studer 169 EQ in API 500 format
Post by: 3nity on October 02, 2010, 02:19:15 PM
where you get those push buttons caps...??
if you compare the good one vs the not so good then i'd say swap the pot..
THanks..
Title: Re: Studer 169 EQ in API 500 format
Post by: geoff004 on October 02, 2010, 04:15:56 PM
where you get those push buttons caps...??

where indeed...
Actually, if you go back a page to my other post you'll see - one of my other pieces of outboard just happened to lose 2 of it buttons!  I got some replacements.
Title: Re: Studer 169 EQ in API 500 format
Post by: dmp on October 08, 2010, 11:29:42 AM
geoff004,
Do you have a side picture? It looks like you put in on-off-on switches to select the high / low frequencies?
Thanks
Title: Re: Studer 169 EQ in API 500 format
Post by: dmp on November 03, 2010, 12:04:07 AM
I finished a pair of these using the Omeg pots and am finding the center detents do not give a flat response...
I've double checked that they are in the right places & the components are the right values.
Title: Re: Studer 169 EQ in API 500 format
Post by: dmp on November 03, 2010, 12:05:06 AM
And the high / low frequencies boosted (with the stock capacitor values)
Title: Re: Studer 169 EQ in API 500 format
Post by: audiox on November 03, 2010, 09:48:01 AM
I finished a pair of these using the Omeg pots and am finding the center detents do not give a flat response...

Potentiometer mechanical center is not necessarily the same as electrical center.

And the high / low frequencies boosted (with the stock capacitor values)

Real world imperfections again. Potentiometer tolerance +/-20%, capacitor tolerance +/-10%.
Title: Re: Studer 169 EQ in API 500 format
Post by: dmp on November 03, 2010, 12:40:45 PM

Quote
Real world imperfections again.
I thought the stock cap values would give 28Hz at bottom and 19kHz at the top. I'm surprised that the high and low are so  different than this (high is +25% at ~2kHz, the low is +25% at ~150Hz)
Am I misunderstanding something?
The pots don't affect the frequency - I'm am using 10% caps with 1% resistors.
Title: Re: Studer 169 EQ in API 500 format
Post by: dbeeson on November 15, 2010, 09:09:51 AM
Just thought I'd share a pic of my build.  I finished these a few months back but finally got around to snapping some shots.  They sound fantastic.  Very clean, excellent for tracking instruments.  Thanks to Audiox for the great build and everyone on the forum for helping out.
Title: Re: Studer 169 EQ in API 500 format
Post by: janvanvolt on January 29, 2011, 10:22:52 PM
Apologies for some questions ( as i am building this at the moment, and definitely not a PRO, so please excuse stupid questions ):

- If i use Yamaha DOA, do i have to stuff the bare wires underneath or not (not sure about this).
- I cannot find C1 mentioned on the schematics, what value is that ?

Thanks then :-)
Title: Re: Studer 169 EQ in API 500 format
Post by: Sammas on January 29, 2011, 11:26:29 PM

Quote
Real world imperfections again.
I thought the stock cap values would give 28Hz at bottom and 19kHz at the top. I'm surprised that the high and low are so  different than this (high is +25% at ~2kHz, the low is +25% at ~150Hz)
Am I misunderstanding something?
The pots don't affect the frequency - I'm am using 10% caps with 1% resistors.




The stock cap values have given 28hz bottom and 19khz top looking at your graph. It looks almost bang on where the peaks lay! The 20% variation in the pots will affect the gain in these curves.


Title: Re: Studer 169 EQ in API 500 format
Post by: audiox on January 31, 2011, 04:54:43 AM
The pots don't affect the frequency - I'm am using 10% caps with 1% resistors.

The gain pot tolerance affects the (min/max) gain and therefore the position of e.g. +3dB point on the frequency axis. (Sorry for the late answer, I don't check this thread very often.)


If i use Yamaha DOA, do i have to stuff the bare wires underneath or not (not sure about this).

It could be a good idea if there is a risk that e.g. the metal parts of the op-amp short the wires. But if that is the case you could also insulate the link wires or increase the distance between the op-amp and the board or find some other solution.

I cannot find C1 mentioned on the schematics, what value is that ?

There are two component value layout drawings: the first is for active balanced input version and the second for traditional transformer balanced version. See the first page of this thread.

(Before asking please check all the documents on the first page and read through the whole thread. It is very likely that the answer is in the documents or someone has asked the same question before.)
Title: Re: Studer 169 EQ in API 500 format
Post by: Songguy on April 09, 2011, 09:35:54 PM
Hi all,
Anyone happen to have an FPD file for the 500 faceplate?
Cheers,
Chris
Title: Re: Studer 169 EQ in API 500 format
Post by: Songguy on April 10, 2011, 11:05:55 AM
hey, that wasnt too difficult. ;D

 It only has the drill holes w/counter sinks though. if anyone wants the FPD file send me a note.
Title: Re: Studer 169 EQ in API 500 format
Post by: isophase on April 13, 2011, 05:18:52 AM
Hi guys,
i just bought a pair of these i got confused with the 500 format, i thought i was buying the "normal" PCB strip from gustav (with the lorlin switches).
does any one know if i can adapt this eq in a normal 1U rack space without too much difficulties ?
thanks
Title: Re: Studer 169 EQ in API 500 format
Post by: isophase on April 13, 2011, 07:50:47 AM
Hi guys,
i just bought a pair of these i got confused with the 500 format, i thought i was buying the "normal" PCB strip from gustav (with the lorlin switches).
does any one know if i can adapt this eq in a normal 1U rack space without too much difficulties ?
thanks

???
anyone
???
Title: Re: Studer 169 EQ in API 500 format
Post by: [silent:arts] on April 13, 2011, 07:58:38 AM
Hi guys,
i just bought a pair of these i got confused with the 500 format, i thought i was buying the "normal" PCB strip from gustav (with the lorlin switches).
does any one know if i can adapt this eq in a normal 1U rack space without too much difficulties ?
thanks

???
anyone
???
where is the problem?
buy a pair of card edge connectors and a PSU,
build it in a 1U rack ???
Title: Re: Studer 169 EQ in API 500 format
Post by: isophase on April 13, 2011, 08:16:35 AM
thank you Silent:arts,
i will do this :-)
Title: Re: Studer 169 EQ in API 500 format
Post by: isophase on April 14, 2011, 10:17:02 AM
Hi guys,
i will soon receive my boards from gustav and i'm already thinking of doing some little tweaking to adapt these little EQs for my needs. i'm thinking of bypassing the mid band section on the 169 EQ, from looking at the schematic, do i connect the output of C9 to R16 ? is that the way to do it ? or can i bypass the C9 coupling cap all together and connect the junction R7/C8/etc.. directly to R16 ?
i read this whole thread and saw that one of you (i think AndyP) also left out the Mid section in their build. if they could enlight me :-)
also i would like to implement switches instead of the pots for the gain. i know this is going to require a little bit of thinking but i thought maybe one of you smart guys could guide me in the right direction.
thank you !
Title: Re: Studer 169 EQ in API 500 format
Post by: MikeClev on April 14, 2011, 05:23:44 PM
You can skip the mid stage as you describe, but I think the output polarity will be reversed, so you may need to fix that on the input or output somehow...
Title: Re: Studer 169 EQ in API 500 format
Post by: isophase on April 15, 2011, 06:22:22 PM
thank you! i find the schematic from the strip board version easier to read than the 500 format version, looking forward to start this project
Title: Re: Studer 169 EQ in API 500 format
Post by: Indecline on July 17, 2011, 06:43:07 PM
Just built my first of two the other night. Fired up on the first.... i mean, second try  :) (didn't wire the jumpers under the DOA, Doh!)

Man these things sound awesome! Especially good on kick and vocals, but worked nicely for bass and just about everything else. tested it out with a gar1731 & gar2520, electronically balanced in and out. I didn't add the switches for multiple frequencies high and low, and i don't think i'll miss them either! :-p Thanks to everyone in the thread, especially Audiox for making it happen!

I did notice that when it is switched in i lose about 6db in volume. i remember reading one of AndyP's post mentioning using a 2:1 transformer to make up the 6db loss of the DOA, but it was sort vague and no one else has mentioned it so far. Any ideas?

Title: Re: Studer 169 EQ in API 500 format
Post by: andre tchmil on July 17, 2011, 07:06:15 PM
In case someone needs Neutrik NTL1's for this project, I'm selling some in the black market .
Title: Re: Studer 169 EQ in API 500 format
Post by: dmp on July 17, 2011, 09:11:24 PM
Quote
I did notice that when it is switched in i lose about 6db in volume. i remember reading one of AndyP's post mentioning using a 2:1 transformer to make up the 6db loss of the DOA, but it was sort vague and no one else has mentioned it so far. Any ideas?
My pair do not have a 6dB loss... maybe double check that the are connected w / balanced in / out correctly.
Title: Re: Studer 169 EQ in API 500 format
Post by: andre tchmil on July 19, 2011, 05:59:18 PM
Few Neutrik trannies left.
Title: Re: Studer 169 EQ in API 500 format
Post by: JamesW on August 13, 2011, 10:55:45 AM
Thanks for this project sounds great. Here is a pic of the extra caps on daughter boards that worked out quite well. I used knobs and "L" bracket from Classic API.
Title: Re: Studer 169 EQ in API 500 format
Post by: Indecline on August 22, 2011, 08:50:14 PM
Thanks for this project sounds great. Here is a pic of the extra caps on daughter boards that worked out quite well. I used knobs and "L" bracket from Classic API.
that's pretty nifty! How are you liking the extra frequencies?
Title: Re: Studer 169 EQ in API 500 format
Post by: JamesW on August 22, 2011, 09:39:59 PM
They get used for tracking and the extra frequencies get used.
Title: Re: Studer 169 EQ in API 500 format
Post by: reboot on September 05, 2011, 08:02:24 AM
hello

sorry for that question ...
if i want to use doa , do i have to remove the amp op under them ?
i put everything and my doa's burnt . :-\
thank you.
Title: Re: Studer 169 EQ in API 500 format
Post by: Indecline on September 05, 2011, 07:43:22 PM
hello

sorry for that question ...
if i want to use doa , do i have to remove the amp op under them ?
i put everything and my doa's burnt . :-\
thank you.
ouch! Yea the 5534 needs to be pulled out if you're using doa's
Title: Re: Studer 169 EQ in API 500 format
Post by: reboot on September 06, 2011, 03:51:47 PM
ok , i'll keep you informed ..

thank you .
Title: Re: Studer 169 EQ in API 500 format
Post by: rmaier on September 25, 2011, 09:25:29 PM
Newbie question here, so I apologize in advance...

I'm planning on racking a pair of these in a 1u case to use for stereo applications, so I'd like to use stepped switches throughout. Can I use single-gang throughout, including the mid sweep (P4)? If so, do I need to recalculate the resistance?

Thanks.
Title: Re: Studer 169 EQ in API 500 format
Post by: MikeClev on September 25, 2011, 11:04:41 PM
Mid frequency sweep (P4a and P4b) needs to be dual gang. The others can be single gang. If you look at the schematic, 'HI' (Dual 10k Linear) and 'MID' (Dual 10K Linear) are wired so each gang/track is in parallel, so Hi (P2A and B) is working like a 5k single track linear pot, Mid (P3A and B) is also like a 5k single track linear pot. Only one half of P1 is used so it is acting like a single track 22k linear pot. P4 is the only one that really takes advantage of both tracks fully.
Title: Re: Studer 169 EQ in API 500 format
Post by: rmaier on September 26, 2011, 12:22:39 AM
Thanks, Mike.
Title: Re: Studer 169 EQ in API 500 format
Post by: rmaier on January 03, 2012, 06:42:46 PM
Another question... Is it possible to limit the amount of cut/boost by simply changing the value of a few resistors, as in the sontec mod? I'm not likely to need more than 5 or 6db.
Title: Re: Studer 169 EQ in API 500 format
Post by: rmaier on January 06, 2012, 07:02:28 PM
No?
Title: Re: Studer 169 EQ in API 500 format
Post by: economycar on March 06, 2012, 01:05:42 PM
I am going to build two of these fairly soon and even though I haven't heard them yet, I have a feeling that they might be suitable for a home built mixer application. Any thoughts on building 8 channels of these to run into a neumann summing amp? Just wondering if these are 'universal' enough to use on a multiple channels/sources with or without the neutrik tranny. Any opinions/suggestions?
Thanks.
Title: Re: Studer 169 EQ in API 500 format
Post by: dmp on March 06, 2012, 01:25:16 PM
Quote
Another question... Is it possible to limit the amount of cut/boost by simply changing the value of a few resistors, as in the sontec mod? I'm not likely to need more than 5 or 6db.
Yes. You can always reduced the range of a pot by replacing with a smaller value pot, with resistors on both sides.
For example, if you want to reduce the range of a 1000 ohm pot by 1/2, substitute a 500 ohm pot with 250 ohm resistors on both sides in series. Then your circuit still sees the same total resistance, but your adjustment is reduced.
You can also put a resistor in parallel with a pot to reduce it's value.
If the pot is log scaled, the math is different, but you might still be able to achieve a similar effect.

With an Excel spreadsheet and the series/parallel equations for combining resistances, you should be able to come up with something.

 
 
Title: Re: Studer 169 EQ in API 500 format
Post by: Indecline on March 09, 2012, 12:19:28 PM
My pair do not have a 6dB loss... maybe double check that the are connected w / balanced in / out correctly.

I double checked and they are balanced i/o correctly. i have two modules built, one with xfr and one without and both modules exhibit the same behavior (so the error shouldn't be in the input stage). I tried swapping opamps in the i/o, and i've double checked the component values and all seem okay. It has to be a wrong component value somewhere though, as the symptom is present on both modules.

any ideas of where to look? both are using doa's, maybe i should try swapping to ic chips and see if the clears up the symptom?
Title: Re: Studer 169 EQ in API 500 format
Post by: dmp on March 13, 2012, 01:59:02 PM
A few thoughts -
Losing 6dB means that your signal is dropping in half. 6 dB is also the amount the output balancing stage will add -  why? Because the unbalanced signal (input to r16 on the schamatic) is inverted by the U4 opamp stage to create the (-) for the balanced signal. Think of your unbalanced as a simple waveform - create it's opposite phase - and then the  (+) (-) when seen by a balanced input has the voltage doubled.
So where to look? Is U4 working correctly? You should be getting 6dB of gain from the unbalanced to balanced signal there at the output. 
Title: Re: Studer 169 EQ in API 500 format
Post by: dmp on March 13, 2012, 02:29:54 PM
Also, to help understand the circuit, the input amp, U1, is a differential inverting amp stage. It creates an output based on the differences in the (+) & (-) input. Because the input r1, r2 are 20k, and the feedback r3 r4 are 10k, the gain of the stage is 0.5, so there is a 6dB decrease.
Title: Re: Studer 169 EQ in API 500 format
Post by: Indecline on March 13, 2012, 08:39:35 PM
A few thoughts -
Losing 6dB means that your signal is dropping in half. 6 dB is also the amount the output balancing stage will add -  why? Because the unbalanced signal (input to r16 on the schamatic) is inverted by the U4 opamp stage to create the (-) for the balanced signal. Think of your unbalanced as a simple waveform - create it's opposite phase - and then the  (+) (-) when seen by a balanced input has the voltage doubled.
So where to look? Is U4 working correctly? You should be getting 6dB of gain from the unbalanced to balanced signal there at the output.
Also, to help understand the circuit, the input amp, U1, is a differential inverting amp stage. It creates an output based on the differences in the (+) & (-) input. Because the input r1, r2 are 20k, and the feedback r3 r4 are 10k, the gain of the stage is 0.5, so there is a 6dB decrease.

Thanks for putting me on the right track! I dug back into it and worked from U4 through the circuit. Come to find out, there's a huge difference between 680 and 680k!! :o 

I should be able to get a couple 680k resistors tomorrow, i will let you know!
Title: Re: Studer 169 EQ in API 500 format
Post by: rmaier on March 19, 2012, 02:48:38 PM
Finally done! Thanks for everyone's help. I used rotary switches throughout, with 3 frequencies each for high and low, and 7 for the mid. Cut/boost values for the lows and highs were taken from AudioX's mastering version, and I based the mid cut/boost on those numbers as well. The unit works very well, so I think I managed to get pretty close on the math. Thanks for your input, DMP. Unfortunately it came after I had made up all my switches, but I'm sure I'll be able to use it in another project.

As far as the sound goes, I have to agree with the general consensus: this is a lovely sounding EQ. It seems capable of gentle, transparent sculpting and is forgiving enough that its pretty hard to make it sound bad without really working at it. AudioX's incorporation of a midrange was a great addition to the original version - it seems extremely versatile and will see a lot of use in the future, I'm sure. The highs sound particularly sweet to my ears, even on tricky sources like violin. The lows are nice for gentle boosting as well - made a grand piano sound a couple of feet longer, without getting pushy.
Title: Re: Studer 169 EQ in API 500 format
Post by: rmaier on March 19, 2012, 03:09:10 PM
A few pics (sorry they're a bit large):
Title: Re: Studer 169 EQ in API 500 format
Post by: rmaier on March 19, 2012, 03:13:42 PM
Channel:
Title: Re: Studer 169 EQ in API 500 format
Post by: rmaier on March 19, 2012, 03:17:02 PM
Inside:
Title: Re: Studer 169 EQ in API 500 format
Post by: rmaier on March 19, 2012, 03:18:39 PM
Open front:
Title: Re: Studer 169 EQ in API 500 format
Post by: rmaier on March 19, 2012, 03:19:30 PM
Open view from the back:
Title: Re: Studer 169 EQ in API 500 format
Post by: rmaier on March 19, 2012, 03:20:26 PM
A good view of the rotary switches:
Title: Re: Studer 169 EQ in API 500 format
Post by: rmaier on March 19, 2012, 03:21:20 PM
Mnats little PSU:
Title: Re: Studer 169 EQ in API 500 format
Post by: Indecline on March 19, 2012, 05:42:18 PM
Thanks for putting me on the right track! I dug back into it and worked from U4 through the circuit. Come to find out, there's a huge difference between 680 and 680k!! :o 

I should be able to get a couple 680k resistors tomorrow, i will let you know!

okay, I'm an idiot, the 680k resistors were correct... i read the meter wrong!!

I swapped the feedback resistor on the output balancing amp to 5k to try and boost the output. It did nothing, so dmp you are correct, the output balancing amp isn't functioning correctly. I followed the power rails with a continuity test and all doa's and ic's are getting power from both + and - voltages. Output from the 5534 also passes through to pin 4 on the card. input can be traced back through the 10k input resistor to the doa's output passing a continuity test. I'm stumped!  :o

i guess the next thing would be to get a power supply to test voltages for opamps?

the saga continues.....  :D
Title: Re: Studer 169 EQ in API 500 format
Post by: dmp on March 21, 2012, 10:50:49 AM
Wow - looks great! Good job rmaier.

If you sweep the response I'd be curious how well the channels match. (I did this with RMAA and found my channels didn't match very well - probably due to the pots)
Title: Re: Studer 169 EQ in API 500 format
Post by: rmaier on March 21, 2012, 04:18:47 PM
Thanks, DMP. I'm humbled by the kind of great work I see around here, so thanks indeed.  Thanks also for pointing out the rmaa software. I'll try to give it a go and see how the eq stacks up.

I can say I was pretty obsessive about matching resistors when I did up the switches, so I have a feeling things are pretty tight. We'll see...
Title: Re: Studer 169 EQ in API 500 format
Post by: dirtyhanfri on February 01, 2013, 03:23:05 AM
I just built a pair of this eq's  in a 2u enclosure, something like what rmaier showed some posts ago (Thanks for the info on the rotary switches and everything else)

I have to recheck mi wiring in one channel, it's loosing some db's, even in bypass mode, but the eq looks to work nice.

Well, everybody wants porn
(http://imageshack.us/a/img819/9384/20130201090943.jpg)

Now I'll design the front pannel, I will silk screen it and wait for some 20mm. knobs wich are slowly coming from China.

Thanks audiox for publishing all this stuff (I built your 2 studer eqs this month), and rmaier for sharing the info and kindly answering all my questions.

EDIT: I've been playing with the eq with a few voices and it's just amazing, a very worth build
Title: Re: Studer 169 EQ in API 500 format
Post by: iprovlek on February 03, 2013, 04:54:06 AM
Is there a gerber files for this Studer 169(500 series)?

Thanks!

Title: Re: Studer 169 EQ in API 500 format
Post by: dirtyhanfri on February 04, 2013, 02:18:35 AM
I don't think so since Gustav sells the boards on his page (great quality for sure, I 've done a pair of projects with his pcbs, and the boards are just great). But the copper layer is published on the first post, maybe you can get done with that.
Title: Re: Studer 169 EQ in API 500 format
Post by: iprovlek on February 04, 2013, 08:16:24 AM
Thanks you a lot....
Title: Re: Studer 169 EQ in API 500 format
Post by: Dr nEon on February 21, 2013, 05:18:15 AM
Hey Guys,

I have a question regarding making the mid frequency sweep switchable:-

I intend to replace the dual 100k pot with a dual wafer switch (12 way).  I have measured the pot, and found that at each of the centre frequencies that I want, the needed resistance is always one of the standard values, luckily. This means that I could use my switch to simply select a pair of fixed resistors for a given frequency. ( It would be the same arrangement as the way the capacitors are selected in the HF section of the mastering version, but with a 'branch' of resistors hanging instead).

When we make the gain controls switchable, we have to build a cumulative string of resistors to mimic a pot, because this is when the pot is a potential divider.  This frequency pot is a two ganged variable resistor, and so I believe it probably isn't necessary to build a resistor chain. In my case, it will be more accurate/easier to switch between standard values, than trying to get the increments of a chain where I want them.

In practice, one side of each resistor will go to it's switch terminal, and the other side of all the resistors will be tied together.

So my only doubt/question is: Could this branch of open resistors potentially induce more noise into the circuit, than a closed resistor chain? Or is the difference probably negligible..?

I'm making the thing switchable, to use on my mix buss, of course, so I want to keep it as clean as possible.

I'd appreciate any thoughts on this one.

Cheers

nEon.


Title: Re: Studer 169 EQ in API 500 format
Post by: druu on February 21, 2013, 08:48:45 AM
This should explain it well:

http://www.goldpt.com/attenuator_types.html

A lot of the guys usually go for series type with 1% resistors and work fine.
Title: Re: Studer 169 EQ in API 500 format
Post by: Dr nEon on February 21, 2013, 02:19:03 PM
Hey druu, thanks...that link is about attenuators though, and I'm not sure if it applies here...

I am asking about the frequency controlling dual ganged "variable resistor" in the Wien bridge portion of the mid band, and whether my suggested(see above) switching arrrangement is likely to be susceptible to, say, RF pickup, or other internal stray noise.

I'm also thinking that switching single resistors rather than chaining them, shouldn't affect impedance, in this part of the circuit, but I could be wrong, and would like to be corrected , if so..

Cheers again!

nEon.
Title: Re: Studer 169 EQ in API 500 format
Post by: Harpo on February 21, 2013, 02:30:31 PM
This should explain it well:

http://www.goldpt.com/attenuator_types.html

A lot of the guys usually go for series type with 1% resistors and work fine.
...for attenuators.
None of the pots in this 169EQ circuit is an attenuator.
Title: Re: Studer 169 EQ in API 500 format
Post by: druu on February 21, 2013, 08:04:44 PM
Ahh my mistake, carry on!
Title: Re: Studer 169 EQ in API 500 format
Post by: shabtek on February 26, 2013, 01:07:31 AM
doc neon, i wold not worry too much about noise...
but pop or thump when switching would be a small concern
Title: Re: Studer 169 EQ in API 500 format
Post by: Dr nEon on February 26, 2013, 07:09:35 AM
Thanks Shabtek,

Since last week I decided to just breadboard it both ways and see... I loved the idea of just using the selected resistor pair , but in practice it was a little noisy, even keeping connections as short as poss. As soon as I switched to the 'closed' resistor chain, it was really clean, so i've settled on this arrangement.

Thanks for chiming in!

Cheers

nEon.
Title: Re: Studer 169 EQ in API 500 format
Post by: druu on March 23, 2013, 12:18:44 PM
Doc, can you elaborate on your closed design? I'm trying to create the same method for high/low pass filters on a design and interested to see how you went. Cheers!
Title: Re: Studer 169 EQ in API 500 format
Post by: iprovlek on March 26, 2013, 11:27:44 AM
Hi guys!

My question about this Studer 169 is!Can i use 25k LIN instead 22k LIN pot!

And thanks for any response....
Title: Re: Studer 169 EQ in API 500 format
Post by: Dr nEon on March 27, 2013, 06:13:24 AM
Hi druu!

By 'closed' chain, I was just referring to the standard way in which most people replace pots with rotary switches...that is, a chain of resistors around the rotary terminals,with each switch position having it's own cumulative resistance, this representing a particular wiper position on a pot.

It's just the standard thing, pretty well documented around here.

Have a look at the mastering version of the 169..

Cheers

nEon.
Title: Re: Studer 169 EQ in API 500 format
Post by: iprovlek on May 01, 2013, 02:49:24 PM
Here is my Studer 169!

Its sound fantastic, i use 5534 instaed DOA but planing to try some....

Im not satisified with front panel and will change the knobs for better looking ones!

I put 6mm omegs and must expand the Audiox hole for pots!

Try 25klin and 22klin and there is no difference!
Title: Re: Studer 169 EQ in API 500 format
Post by: Indecline on May 10, 2013, 03:11:59 PM
Here is my Studer 169!

Its sound fantastic, i use 5534 instaed DOA but planing to try some....

Im not satisified with front panel and will change the knobs for better looking ones!

I put 6mm omegs and must expand the Audiox hole for pots!

Try 25klin and 22klin and there is no difference!

Nice job! I used ic's and some Neutrik NTL1's and they sound damn good. For vocal's they're a great tool, just enough functionality to remove the mud and add some presence to SM7's.
Title: Re: Studer 169 EQ in API 500 format
Post by: iprovlek on May 10, 2013, 03:44:59 PM
Thanks Indecline!

Yes you right with IC's sound awsome!But im so curious about some DOA's with this EQ!

Planing to put Neutrik's to mine to...

Maybe a stupid question but is there someone who use this EQ for 2 buss?
Title: Re: Studer 169 EQ in API 500 format
Post by: Sammas on August 23, 2013, 04:53:17 AM


I don't suppose anyone has an .fpd file for this project that they would like to share?
Title: Re: Studer 169 EQ in API 500 format
Post by: irfrench on August 28, 2013, 03:47:35 PM
Hi,

Am thinking about building these (they look like they would be REALLY helpful for tracking) after the glorious summer we've had and am to looking to confirm a couple of things.  I want to build these using the OA10 DOAs and with active balanced I/O.  I really just wanted to confirm a few points - I've looked but cannot see an explicit answer anywhere so my apologies for the dumb questions:


Hopefully that makes sense.  Any help would be very much appreciated.

Thanks, Ian.
 :)
Title: Re: Studer 169 EQ in API 500 format
Post by: Indecline on September 11, 2013, 07:42:28 PM
Hi,

Am thinking about building these (they look like they would be REALLY helpful for tracking) after the glorious summer we've had and am to looking to confirm a couple of things.  I want to build these using the OA10 DOAs and with active balanced I/O.  I really just wanted to confirm a few points - I've looked but cannot see an explicit answer anywhere so my apologies for the dumb questions:

  • 1/4w resistors are OK throughout?
  • Omit U2 and U3
  • Leave jumpers under DOA
  • C16 & C17 are for ICs but can be left in (any effect on DOA?)
  • C22 and C21 are power filter caps and should be left in

Hopefully that makes sense.  Any help would be very much appreciated.

Thanks, Ian.
 :)
Hey Ian,

1/4W are fine. Omit U2 and U3 for DOA's and jumpers under DOA's should be installed. C16 & 17 are the compensation caps for the two IC's, leave them out for DOA's, they connect to nothing other than the IC. C22 and C23 I believe are for power filtering (noise filtering?), leave those in.
Title: Re: Studer 169 EQ in API 500 format
Post by: irfrench on September 12, 2013, 04:13:43 AM
That's great - thanks. 

I'll probably install the compensation caps so I can test the EQ with ICs to make sure it works, and then swap ICs for DOAs as/when they get built.


Ian

:)
Title: Re: Studer 169 EQ in API 500 format
Post by: taliska on September 18, 2013, 11:57:52 AM
Going to build a pair of these soon, and was wondering...

Which variant does everyone prefer, with or without transformer? (Neutrik NTL1)

<edit>

Been doing some reading. As far as I can tell, the transformer is mainly useful if you're working with unbalanced i/o. They (the NTL1s) don't seem to be particularly "colourful" from the various reviews I read about them, and the only thing that jumps out at me when I look at the spec sheet is the change in impedance as the winding ratio is just 1:1 and they don't seem to distort much either (1% if memory serves).

I'm new to this stuff so might be way off base here, but I'm going to go out of a limb here and say that judging by the spec sheet they don't look like they do an awful lot to the sound.

Has anyone built both versions of the build? Which sounded better to you?

</edit>

Cheers,

Kaz
Title: Re: Studer 169 EQ in API 500 format
Post by: Indecline on September 22, 2013, 02:53:27 PM
The Neutrik's give the signal a little color but it's still pretty transparent. I basically chose between DOA's and the xfr for color, and went with the transformer. Maybe I'll swap the opamps but I'm happy with just the Neutriks for now.

I have noticed on mine the mid parametric is touchy with the gain. I barely cut and the scoop is pretty pronounced (it's also pretty narrow). I'm looking in trying to adust the q and max/min gain but it's not a simple 'swap this' type of mod. Could make them more versitile but I'm pretty happy with them as is.
Title: Re: Studer 169 EQ in API 500 format
Post by: taliska on September 23, 2013, 09:03:41 AM
Thanks for the info indecline. I've decided to go for the +transformer option too, as I figured more is always better!  ;)

I've got some of the OA10 boards too, but am going with the ICs initially. I am planning on building those OA10s sometime, but getting hold of the various transistors is tricky if you don't want your wallet to have a heart attack (relative to non-obsolete, better spec'd transistors). I can't remember which substitutions I've settled on off the top of my head, but at best it means my DOAs will only ever be mutant OA10s...but I like the idea of experimenting with them anyway, you know, just for kicks!

Oh, and those holes on the OA10 boards for the pins are HUGE...

<edit>

Ignore what I said about the transistors being expensive. I must have been smoking something/looking in the wrong places. Just checked ebay and they seem to be both cheap and plentiful. Hope they're decent as I've ordered 80 bc212bs and 40 bc182bs...worth a punt anyway for the cost ;)  (everything else I'll get through mouser)

</edit>
Title: Re: Studer 169 EQ in API 500 format
Post by: Indecline on September 24, 2013, 11:25:36 AM
You can always post spare transistors on the Black Market. I'm sure you'd sell a few to people with OA10 boards. If I still had my boards I would buy some! :)

There are a few solutions to the oversized pin holes in the OA10 thread. Some clever people soldered socks on the DOA and eq board, then made the connection with pins.
Title: Re: Studer 169 EQ in API 500 format
Post by: iprovlek on October 04, 2013, 08:03:51 AM
Please help guys!

I built 5 Neumann OA10 , use ITT bc212b ,ITT 182b and bc337, bc327  transistors are fliped of, on a my PCB,and none one PCB dont work!

So Im confused...

I dont know what to do!

I made this OA10 here in my country PCB company with all gerbers and files...with all schematics which Audiox gave here on forum...

Title: Re: Studer 169 EQ in API 500 format
Post by: taliska on October 11, 2013, 07:27:15 AM
Just wanted to come back to this thread after firing up my first channel and playing with it for a few minutes...

(had to wait on parts, so that's why there has been a bit of a delay getting it going)

Anyway, I built the IC + transformer option, and I have to say that it IS nice as reported by many others! ;)

Obviously it's hard to know the worth of something you haven't heard or built before, and as a newbie, I just had to give it a go and live with the (good or bad) results. For me it was pretty much immediately clear that these are going to be nice additions to my tracking chain.

Anyway, highly recommend this build. Now I've just got to decide on how to finish off the hardware and have a think about whether the hi/lo shelf frequency toggles are worth it or whether it's better to keep the units nice and simple...

Oh, and for those of you who don't check-out the links at the bottom of people's posts, I also highly recommend visiting irfrench's blog. He's got details of his Studer build there, and it's not only informative, but good looking too!

Thanks to audiox for doing a great job with these.

Kaz
Title: Re: Studer 169 EQ in API 500 format
Post by: irfrench on October 11, 2013, 01:33:00 PM
 :-[ :-[ :-[

Awww shucks!  You're too kind.  Although now I know someone is actually reading that I'll have to be more careful with what I say!

Glamour shot:

(http://media.tumblr.com/2dc26e7f8f6083e35078c30564072af6/tumblr_inline_muilm2mTKq1r2bfgn.jpg)

Shame I can't seem to get my OA-10 DOA to not set fire to itself!?!  The 10ohm R8 resistor is the poor soul.  If anyone has built this EQ using the OA-10s - can they confirm the wattage they used for R8 please?

Pretty please?

Oh and as for the switch-able High and Low shelf frequencies?  In my initial listens the Low is definitely worth having options for (although the upper selection is more useful for cutting), the High selection is a little more subtle so may well not be worth the tiny-hassle it was to add it.  All in all though I'd say if I were to build another couple of channels I'd still add the switching.

These EQ's are really nice though. So thanks to all - esp. Audiox and Gustav - for making these so accessible.

Ian.
Title: Re: Studer 169 EQ in API 500 format
Post by: irfrench on October 15, 2013, 10:44:34 AM
Hi all,

I can't remember having seen freq. sweeps for these EQs here - and I wanted to work out how to do it on PC (not MAC) - so it seemed like a good idea.

This includes the switch-able additional LF and HF shelf frequencies with lowest/middle/highest freq. select for the mid-band section.

Enjoy?  ;D

(http://imageshack.us/a/img845/6707/dr4p.png)

(http://imageshack.us/a/img842/8407/2ktk.png)

(http://imageshack.us/a/img59/2843/xv5y.png)

At least it explains why I heard the HF shelf differences as being quite subtle!   ;)


Ian,
 8)
Title: Re: Studer 169 EQ in API 500 format
Post by: kante1603 on October 15, 2013, 12:34:18 PM
Enjoy?
Yes.
Title: Re: Studer 169 EQ in API 500 format
Post by: taliska on October 15, 2013, 02:22:16 PM

...

This includes the switch-able additional LF and HF shelf frequencies with lowest/middle/highest freq. select for the mid-band section.

Enjoy?  ;D

At least it explains why I heard the HF shelf differences as being quite subtle!   ;)


Ian,
 8)

That's not only great work Ian, but also great timing as I haven't gotten around to modding my units yet... :)

Extrapolating somewhat from your lowest setting on the LF shelf (28hz), I suspect that stock (20hz) is actually pretty much perfect for my needs as only judging by my eyes, it looks like even the 28 hz setting is a bit too strong a bit too high up in the low frequency range (though obviously that's just my own preference and probably a result of having done most of my eq'ing in daws where it's a more precise instrument).

Going by your graphs (and assuming I'm interpreting them correctly), I probably won't choose to mod the freqs on my units, but if I were to play with it, I think I'd be tempted to go lower rather than higher... (15, 20, 25 perhaps...or whatever the alternate values (330 & 470 nF) work out at!)

Kaz
Title: Re: Studer 169 EQ in API 500 format
Post by: Sammas on October 22, 2013, 06:39:33 AM


I just finished two of these little beauties! Original Studer transformers with 5534's for now.

Tasty! Though one doesn't work due to a busted primary winding on the transformer.
Only limited use so far but on snare that sound great!


Here is a front panel file since know one else seemed particularly keen to share theirs. It has rear cutouts to hide potentiometer nuts.

https://www.dropbox.com/s/zqapmn7neidrcrf/169K5%20The%20Lab.fpd

Title: Re: Studer 169 EQ in API 500 format
Post by: audiox on October 28, 2013, 08:34:46 AM

At least it explains why I heard the HF shelf differences as being quite subtle!   ;)

(http://media.tumblr.com/2da5046a29881f5e89da0fa00bddef61/tumblr_inline_mups2cmUut1r2bfgn.png)


Quote from: irfrench in his blog

This is how the modded caps need to be added in. No probs.

(http://media.tumblr.com/68994c9b88bd085b2aa61c55e3fe3ca5/tumblr_inline_mtn3tvTovd1r2bfgn.jpg)


Yes probs. That doesn't work. For the high filter you need to switch C4 and C5. A double pole switch for the high filter and a single pole for the low filter will do the job (one side of each capacitor is permantly connected). Also note in your frequency calculations that the capacitor(s) on the PCB are in parallel with the capacitor selected by the switch: Ctotal = Cpcb + Cswitch.


Title: Re: Studer 169 EQ in API 500 format
Post by: irfrench on October 28, 2013, 09:14:24 AM
Audiox,

Thanks for pointing this out - it explains why I didn't get the results I expected.  I'll update the blog and make sure no-one else uses this.

So to make the HI switchable I can modify the switch as it is already (because C4 and C5 on the PCB are both already 10n) and replicate the 4n7 and 2n2 using both halves of the switch?:

(http://media.tumblr.com/1821a225f53e8ac8de947dbabb1d5a3b/tumblr_inline_mvdrdbZsWC1r2bfgn.jpg)

Thanks again for pointing this out.

Ian
 :)

Title: Re: Studer 169 EQ in API 500 format
Post by: irfrench on November 06, 2013, 11:29:15 AM
Me again  :o

Just a quick note to say I made the changes (above?) and the EQ curves became:

(http://media.tumblr.com/a4aee26469f12a28de7672607ebf416e/tumblr_inline_mvei2pvGQa1r2bfgn.png)

A bit more separation and the differences now are definitely less subtle!  ;)

I also wanted to do a comparison (for my own curiosity) between the IC and DOA options - so I ran a short recorded acoustic passage out to the same EQ, once with IC's once with DOA's.  I hope it is of interest:

https://soundcloud.com/minoian/sets/oa10-comparison  https://soundcloud.com/minoian/sets/169eq-doa-comparison

Thanks,

Ian
 :)



EDIT:  LINK UPDATED SEE REASONS BELOW
Title: Re: Studer 169 EQ in API 500 format
Post by: Dylan W on November 06, 2013, 01:00:59 PM
Me again  :o

Just a quick note to say I made the changes (above?) and the EQ curves became:

(http://media.tumblr.com/a4aee26469f12a28de7672607ebf416e/tumblr_inline_mvei2pvGQa1r2bfgn.png)

A bit more separation and the differences now are definitely less subtle!  ;)

I also wanted to do a comparison (for my own curiosity) between the IC and DOA options - so I ran a short recorded acoustic passage out to the same EQ, once with IC's once with DOA's.  I hope it is of interest:

https://soundcloud.com/minoian/sets/oa10-comparison

Thanks,

Ian
 :)

The OA10 sounds like it has something wrong (or it's just way noisier....)
Title: Re: Studer 169 EQ in API 500 format
Post by: irfrench on November 06, 2013, 04:45:58 PM
Yeah the noise difference is definitely noticeable - I'd not heard any direct comparisons made like this hence why I thought it may be useful to compare them.

I'll try swapping the OA10s around a bit tomorrow and see if anything changes with each DOA.

Has anyone else got similar comparisons they can share?

Ian
Title: Re: Studer 169 EQ in API 500 format
Post by: kante1603 on November 06, 2013, 07:12:05 PM
The noise sounds more like coming from a dynamics tool because it is fading in/"coming back" during the long sustain phases only,doesn't seem to be a static noise floor.Maybe the original recording has been treated during or after capturing.

Best,

Udo.
Title: Re: Studer 169 EQ in API 500 format
Post by: irfrench on November 07, 2013, 04:09:32 AM
Hi.

Listening back I hadn't realised the noise was that prominent - I really need to be double checking everything and not rushing things... Helpfully I hadn't saved those source wavs so had to redo with a different section.  Did the same thing as last time (I'll remove the previous link) making sure no compression was on anything-anywhere, as kante says I think there was some loudness maximisation going on.

https://soundcloud.com/minoian/sets/169eq-doa-comparison

Ian.
Title: Re: Studer 169 EQ in API 500 format
Post by: kante1603 on November 07, 2013, 05:05:47 AM
Hi Ian,

thanks for posting the new samples!
From what I hear (using headphones atm) the difference is very small,it seems the NE5534 sounds a little bit more "boomy" at the low note at sec.7 to 8,but it could be a body/room resonance as well.
Both versions sound really nice and aren't off from each other too much.
I would like to know how these will sound when running a bit more complex material through it.
For me just another indicator that using an "old" NE5534 in a good design is still an excellent choice,isn't it?

Best regards and have fun,

Udo ;)
Title: Re: Studer 169 EQ in API 500 format
Post by: irfrench on November 07, 2013, 07:43:28 AM
You're absolutely right, the NE5534s sound pretty darn good! 

I do however *think* or *feel* I prefer the OA10s more though - I did a few blind AB'ing tests and ended up picking the OA10s all the time, they seem to add a bit of bite(?)/complexity to it.

If anyone is thinking about building these - do it!  They really are great EQs.

Thanks again to Audiox/Gustav for making these so accessible.


Ian
Title: Re: Studer 169 EQ in API 500 format
Post by: Bonsaimaster on November 08, 2013, 04:37:05 PM
Ok looking for some help as I must have done something stupid. Seems like an easy build so I build two. One with transformer and 2520's and one without transformer and 5534p. Both are doing the same thing. My 500API rack won't power up when they are plugged in. Any thoughts?

Thanks in advance

Daniel

Title: Re: Studer 169 EQ in API 500 format
Post by: Bonsaimaster on November 08, 2013, 04:38:54 PM
THe other
Title: Re: Studer 169 EQ in API 500 format
Post by: 3nity on November 09, 2013, 09:10:05 AM
Do you have a way to test it outise the rack? like a card extender?
Is there any smoke? do all modules run fine without the 169 inside?

Check continuity from + to 0v and - to 0v.

Just my opinion!
Title: Re: Studer 169 EQ in API 500 format
Post by: Bonsaimaster on November 09, 2013, 06:37:07 PM
Yes I have an extender card. The rack runs without them in the rack. Will test the connection.

Daniel
Title: Re: Studer 169 EQ in API 500 format
Post by: dirtyhanfri on November 19, 2013, 12:42:03 PM
Hi

I´m thinking in adding a HPF on this EQ, would it work inserting it before C3 (after the first IC)?

This is the Filter schematic:
(http://s.eeweb.com/members/circuit_projects/blog/2012/01/12/20Hz-to-200Hz-variable-high-pass-filter-1326382791.gif)

My only reason to use this is because it´s the easier I´ve found right now, I don´t need nothing fancy, just filter some low freqs. Also, I think the TL072 will drive finely the eq or I´m wrong?

Any ideas/suggestions?
Title: Re: Studer 169 EQ in API 500 format
Post by: Harpo on November 19, 2013, 04:22:54 PM
I´m thinking in adding a HPF on this EQ, would it work inserting it before C3 (after the first IC)?
ignoring level mismatch by missing/not shown bypassing of the HPF, probably yes.
Quote
My only reason to use this is because it´s the easier I´ve found right now, I don´t need nothing fancy, just filter some low freqs. Also, I think the TL072 will drive finely the eq or I´m wrong?
Drop the gain of the balanced line receiver by 3dB to compensate for the HPF filter boost (maybe solder 23K71 resistors in parallel to the 10Ks R3 and R4 for ideal close matched value 7K071s). Sourcing dual rev.log 47K pots might be the hardest part. A dual pole switch for one or more HPF freq. might be easier to source. Don't leave the other half of the TL072 unconnected. Maybe have a look at the Barry Porter NetEQ HPF section for a similar/bypassable approach.
Title: Re: Studer 169 EQ in API 500 format
Post by: dirtyhanfri on November 20, 2013, 03:39:23 AM
Thanks for the answer Harpo

Well, maybe i didn't explain my plan ok.

The idea is using a Lorlin 2 way 6 positions switch for the freq selection.

To bypass it I was thinking in a simple dpdt.

For the other half of the TL072, what do you suggest? route to ground the three pins?

And the level mistmatching you mention, would be gone with the hpf bypassed? (Sorry, but I'm still learning a lot of concepts) So, there's a boost in the schematic attached? Maybe messing with the value of the resistor between pins 1 & 2 of the IC will solve it?

I'm modding the audiox pcb design to include it, I could share it if there's interest, it's quite ugly right now, as I don't need the API 500 format I reduced it a bit, I think I can make a stereo version in a eurocard.

Title: Re: Studer 169 EQ in API 500 format
Post by: Harpo on November 20, 2013, 06:02:25 AM
The idea is using a Lorlin 2 way 6 positions switch for the freq selection.
To bypass it I was thinking in a simple dpdt.
As suggested and not shown on your pic. If you make the full CCW setting of your switched HPF low enough, this might operate like a bypass.

Quote
For the other half of the TL072, what do you suggest? route to ground the three pins?
Place a -3dB voltage divider in front and use the TL072 2nd.half to buffer this attenuator if you want to implement a bypass switch. With HPF always in circuit, dropping the gain of the balanced line receiver as previously described seems the easier solution. (as previously mentioned, have a look at the NetEQ).

Quote
And the level mistmatching you mention, would be gone with the hpf bypassed? (Sorry, but I'm still learning a lot of concepts) So, there's a boost in the schematic attached? Maybe messing with the value of the resistor between pins 1 & 2 of the IC will solve it?
Your pic shows an equal value sallen-key filter. This type has gain in the pass band. Sallen-key filters with unity gain in the pass band will not have equal values for the frequency setting C and R parts values.
Title: Re: Studer 169 EQ in API 500 format
Post by: dirtyhanfri on November 20, 2013, 04:25:58 PM
Thanks.

I've been having a look at Net Eq schematic, and I preffer to use a section of another eq rather than a circuit I just found on the web.

So, should I drop the gain in the line receiver using this design? I will use a DPDT switch for bypassing it.

Time to read about filters. ..
Title: Re: Studer 169 EQ in API 500 format
Post by: Harpo on November 20, 2013, 07:12:20 PM
So, should I drop the gain in the line receiver using this design? I will use a DPDT switch for bypassing it.
No. Gain in line receiver can stay at 0.5 (-6dB) if you want to have the HPF (whatever this design might refer to) bypassable, else the 169EQ circuit wouldn't be unity gain with level pots centered.
Title: Re: Studer 169 EQ in API 500 format
Post by: dirtyhanfri on November 21, 2013, 05:05:56 AM
(whatever this design might refer to)

I was refering to BP Net EQ HPF section

Thanks, I will build it in a perf board and try to calculate values for the rotary switch
Title: Re: Studer 169 EQ in API 500 format
Post by: electrisizer on December 03, 2013, 12:40:01 PM
hello im building 3 of them right now...


i have left over some caps from another project and would like to use them in these EQs

the caps are 8n2 with 630V rating so they are a bit big for a 500 modul ;) but my freq will be switchable i think i can mount them...

is a 630V cap a good choice for a HF section? the wimas are @63v or 100v... does this volt rating matter?
Title: Re: Studer 169 EQ in API 500 format
Post by: kante1603 on December 03, 2013, 01:54:19 PM
hello im building 3 of them right now...


i have left over some caps from another project and would like to use them in these EQs

the caps are 8n2 with 630V rating so they are a bit big for a 500 modul ;) but my freq will be switchable i think i can mount them...

is a 630V cap a good choice for a HF section? the wimas are @63v or 100v... does this volt rating matter?
No,it's just big.Capacitance does.
Funny detail:Will start building three of them soon,same as you,hahaha.....
Christmas time I'd say.

Best,

Udo.
Title: Re: Studer 169 EQ in API 500 format
Post by: electrisizer on December 04, 2013, 03:45:32 AM
@kante  ;D lunchbox slutz we are!
thanks for answer...

what config are you going to build?

mine have 5534, trafo in, 3x freq switch for HF, 2x freq switch for LF...

if interested im posting my FP later this day
Title: Re: Studer 169 EQ in API 500 format
Post by: electrisizer on December 04, 2013, 02:54:21 PM
heres my FP...
its not produced yet. i hope it will fit ;)

https://app.box.com/s/u9f4borkfr1ffg5kyz2h
Title: Re: Studer 169 EQ in API 500 format
Post by: kante1603 on December 04, 2013, 03:20:26 PM
heres my FP...
its not produced yet. i hope it will fit ;)

https://app.box.com/s/u9f4borkfr1ffg5kyz2h
Hi,

looking nice so far,but why not make the low swich do three frequencies?I think a low one as in the 20+ Hz area could be very useful.At least I´ll start there (the original value) and have it on single IC-sockets temporarily for easy exchange.
Despite of that I´ll have the transformers too,same as you,got them cheap and new from evil b**,a pair for 29,95-Euros,cool!
Will start with NE5534s too and listen,maybe later do some trials with doas,got some sockets on the way from Volker right now.
Think I´ll start with them around christmas or so ("die stille Zeit") ;)

Keep us posted!

Best,

Udo.
Title: Re: Studer 169 EQ in API 500 format
Post by: electrisizer on December 04, 2013, 04:06:21 PM
heres my FP...
its not produced yet. i hope it will fit ;)

https://app.box.com/s/u9f4borkfr1ffg5kyz2h
Hi,

looking nice so far,but why not make the low swich do three frequencies?I think a low one as in the 20+ Hz area could be very useful.At least I´ll start there (the original value) and have it on single IC-sockets temporarily for easy exchange.

got the trafos cheap too... btw neutrik was used in studer 169 too. no need to look for vintage trafos. neutrik = studer with anothe sticker...

i choose the frequencies from my mixing expirience... 60hz is the lowest freq i ever used. some eqs here have lower freqs too - i tried often but returned to 60hz for lowest - even in deep bass hiphop tracks - AND its my favorite freq on my console too (i want to replace the console with the bunch of 500 boxes sometimes).

its kind of special that the default freq is so low for a broadcast mixer. perhaps it is used in combination with the low cut switch of an original 169 channel? i have a racked predecessor (studer 189) channel strip here and the fixed lows are @ 80hz
Title: Re: Studer 169 EQ in API 500 format
Post by: electrisizer on December 17, 2013, 08:30:35 AM
really dont know whats going on here...

i finished my 1st unit and my 511 rack burned the +/- 16v fuses...

i begin checking the board and every(!) card pin connector does have a connection to every other card pin connector  :o is this a faulty batch of boards?



Title: Re: Studer 169 EQ in API 500 format
Post by: electrisizer on December 17, 2013, 08:51:39 AM
YES it is a bad batch of boards - but ive found the problem... with solution  :D

the copper pins connect to each other. the boards are not cutted the right way.

i cut the copper connection with a knife. perhaps one can do this with a rasp? its important to make a clean cut. look at the picure (circuits sign the cut)
Title: Re: Studer 169 EQ in API 500 format
Post by: kante1603 on December 17, 2013, 09:59:24 AM
Wow!

Thanks for sharing!

Haven't completed mine yet but it's worth to take a closer look.

Best,

Udo.
Title: Re: Studer 169 EQ in API 500 format
Post by: kante1603 on December 17, 2013, 02:00:16 PM
O.k.,have my three boards checked,two of them have full continuity over all pins!
The third one doesn't,it is looking more yellowish and has a better silkscreen than the others.
A big thanks to you electrisizer,I might have run into huge trouble!
It is really hard to see,so best to check them people.
Will try the "rasp"- method soon and report back here.

Best,

Udo.

Edit:CONFIRMED!A small rasp does the trick.
Title: Re: Studer 169 EQ in API 500 format
Post by: Gustav on December 18, 2013, 06:04:07 AM
electrisizer mailed me to inform me about this problem.

I am SO sorry about this.

In standard production, the boards are probe tested for shorts and opens. Since testing happens while the boards are still in their production panels, and routing is done afterwards, this problem was not caught. (The connectors are shorted for chemical gold plating).

The last batch of boards is sold out, and I will have a new batch back this week (We still send the boards out of house for gold plating). I'll make sure to check up on this on the new batch, and once again - really sorry about this problem.

Gustav
Title: Re: Studer 169 EQ in API 500 format
Post by: Bonsaimaster on December 20, 2013, 08:56:18 AM
Yea I had the same problem about 20 threads ago! Thanks for solving the problem. I will also try the rasp method. Been racking my brain about these boards.

Bonsaimaster
Title: Re: Studer 169 EQ in API 500 format
Post by: Bonsaimaster on December 22, 2013, 05:20:43 PM
Eureka! The rasp worked! Two boards are now singing the the case! I thought I was crazy trying to figure out what was wrong!! Thanks so much for the help. A month of head scratching for a 5 sec fix!!! Ugh. Well here is my assessment. Build one with transformer and 2520's and one without. The non-transformer version is harsher and the trans one is smoother. I actually like the non-transformer version better. Much more to work with.

Bonsaimaster
Title: Re: Studer 169 EQ in API 500 format
Post by: rmaier on December 22, 2013, 05:53:59 PM
Very cool that you got them working and that you like them. Cheers!
Harsh? Really? I built a pair and gotta say I've never found them to be harsh in any way.
Title: Re: Studer 169 EQ in API 500 format
Post by: Bonsaimaster on December 23, 2013, 09:04:11 AM
I guess harsh would mean aggressive compared to the transformer version.
Title: Re: Studer 169 EQ in API 500 format
Post by: kante1603 on January 22, 2014, 02:06:27 PM
Mine are done too,here a pic.
Thanks to audiox for this great eq,Frank for the panels,Gustav for the pcbs and last but not least our member electrisizer for his excellent hint!

Cheers,

Udo.

Edit:Forgot to mention that these eqs are really great sounding.Mine are non-doa but with ntl1 transformers.Although they look so simple they do an excellent job when it comes to sweetening.
I went with the original frequencies for low and high shelf after tests with other values.Absolutely no need for me to make them switchable,so around 20Hz and 19,xxx Khz it is.The low band drops in soft like butter,the high band creates a nice air band.Since the mid bandwidth is pretty wide lowering the 1 to 2k area and giving a slight boost on high and low gives you a nice hifi-style loudness curve if you're after that.
These guys aren't surgeons.....they are musicians.
Highly recommended!
Title: Re: Studer 169 EQ in API 500 format
Post by: taliska on March 08, 2014, 12:58:19 PM
Hey all,

Been a while since I built my 169s, but haven't been able to post a pic as they were missing a switch cap until now. Anyway, now I can finally check them off the list with the switch caps + unity gain trimmers installed, so I just wanted to come back and thank everyone before I forgot! Thanks to audiox for designing them...I went with the IC + NTL1 option, and thanks to Gustav for providing the pcbs. Panels used the provided layout and fabricated by Frank.

Anyway, I tend to keep things fairly by the book and standard, so nothing interesting to see here, but for what it's worth, see the attached pic! ;)

Cheers,

Kaz



Title: Re: Studer 169 EQ in API 500 format
Post by: kante1603 on March 08, 2014, 01:13:10 PM
Congrats Kaz!
May I ask if the knobs are Sifams?

Best regards and have fun (nice sounding eqs,aren't they?),

Udo.
Title: Re: Studer 169 EQ in API 500 format
Post by: taliska on March 08, 2014, 01:36:46 PM
Congrats Kaz!
May I ask if the knobs are Sifams?

Best regards and have fun (nice sounding eqs,aren't they?),

Udo.

Thanks Udo!

Yeah, the knobs are Sifams. I got those ones from canford in the UK, but I've got a lot of other Sifams that I got from RadioSpares too. In fact, you can't quite see it, but below them are EQN's which I've used all black Sifams on and it looks really good and understated. I think in hindsight I might have gone with the ones with the fins on them, as it's a pain having to look at them whilst adjusting them, but that's just my own inexperience showing up!

They're pleasant sounding EQs without a doubt and I've currently used them more than my EQNs, but that's just down to having a lack of time to experiment. I'm currently building up my collection so I'm also building a pair of Igor's He69s at the moment, so I'm looking forward to comparing the 169s to the He69s and the EQNs soon. Should be a lot of fun! ;)

BTW, your 169s look fantastic! Really sturdy looking too!

Cheers,

Kaz

Title: Re: Studer 169 EQ in API 500 format
Post by: dogma on March 26, 2014, 09:22:32 PM
Can these be turned into baxendall filters easily? Afaik there's a guy called regular Jon recordings who does a lot of custom work and he does a 2 channel bax and apparently used this circuit.
So I really want a bax eq as my next eq - can anyone point me in the right direction?
Title: Re: Studer 169 EQ in API 500 format
Post by: dogma on March 27, 2014, 05:54:01 PM
Bump :)
Title: Re: Studer 169 EQ in API 500 format
Post by: Indecline on March 29, 2014, 01:38:16 AM
It is a Baxandall circuit, with a mid sweep filter added on.

You'll want two.. Trust me  ;)
Title: Re: Studer 169 EQ in API 500 format
Post by: dogma on April 04, 2014, 05:26:48 PM
Do your guys think you could fit a channel of the Harrison ford filter as well? By the looks of them it should fit - might be a bit of a squeeze...
Title: Re: Studer 169 EQ in API 500 format
Post by: Indecline on April 05, 2014, 03:28:16 PM
Do your guys think you could fit a channel of the Harrison ford filter as well? By the looks of them it should fit - might be a bit of a squeeze...

It would be easier to add a switched passive hpf instead of active variable. Less trace cutting and routing of power, not to mention front panel considerations and stereo matching... It would definitely be a nice addition for bus duties.
Title: Re: Studer 169 EQ in API 500 format
Post by: Kimster on April 14, 2014, 05:15:45 PM
Hi!

Does anyone here know how to connect a NTP m100 DOA to this circuit? I think I read that someone had tried that and I have a couple of NTPm100 that I would like to try. There is a lot more pins on the ntp and I´m not sure how to connect it the best way.
Title: Re: Studer 169 EQ in API 500 format
Post by: Gustav on April 20, 2014, 03:55:51 AM
Finished up two channels..

Not much to it, just thought I'd share.

Gustav
Title: Re: Studer 169 EQ in API 500 format
Post by: kante1603 on April 20, 2014, 04:16:29 AM
Finished up two channels..

Not much to it, just thought I'd share.

Gustav
Very nice Gustav,

may I ask if you have put in the compensation components (c1/r3) on the doas?

Best regards,

Udo.
Title: Re: Studer 169 EQ in API 500 format
Post by: Gustav on April 20, 2014, 04:39:10 AM
Finished up two channels..

Not much to it, just thought I'd share.

Gustav

may I ask if you have put in the compensation components (c1/r3) on the doas?


Not yet.

Gustav
Title: Re: Studer 169 EQ in API 500 format
Post by: kante1603 on April 20, 2014, 06:40:59 AM
Not yet.

Gustav
Thanks for the reply Gustav,

just found it's not needed on unity or low gain circuits (I should have read the doa thread better.....I'm getting old ;D).

Have a nice day,

Udo.
Title: Re: Studer 169 EQ in API 500 format
Post by: Indecline on April 21, 2014, 09:42:07 AM
Hi!

Does anyone here know how to connect a NTP m100 DOA to this circuit? I think I read that someone had tried that and I have a couple of NTPm100 that I would like to try. There is a lot more pins on the ntp and I´m not sure how to connect it the best way.

Do you have the pinout available?
Title: Re: Studer 169 EQ in API 500 format
Post by: [silent:arts] on April 21, 2014, 10:40:00 AM
Does anyone here know how to connect a NTP m100 DOA to this circuit? I think I read that someone had tried that and I have a couple of NTPm100 that I would like to try. There is a lot more pins on the ntp and I´m not sure how to connect it the best way.

Hard to fit in height in a 500 rack with an additional adapter PCB or bend leads.
For a pinout, look here:
http://www.silentarts.de/DIY/OV560/OV560-DOA-Options.pdf
Title: Re: Studer 169 EQ in API 500 format
Post by: [silent:arts] on April 21, 2014, 01:25:25 PM
Top View, how I did it somewhere else:
Title: Re: Studer 169 EQ in API 500 format
Post by: Kimster on April 21, 2014, 04:52:31 PM
Thanks a lot! Gonna try this, Just waiting for some other parts to arrive! I know it´s going to be a tight fit if it´s possible at all…

 :)
Title: Re: Studer 169 EQ in API 500 format
Post by: Gustav on April 23, 2014, 12:39:30 AM
Thanks a lot! Gonna try this, Just waiting for some other parts to arrive! I know it´s going to be a tight fit if it´s possible at all…

 :)

Lots of space to drill holes on the PCB -  so, drill and add jumper-wires to connect?

Gustav
Title: Re: Studer 169 EQ in API 500 format
Post by: goetzmd on April 26, 2014, 04:44:17 AM
I thought I share my Mouser project with you all.  :)
http://www.mouser.com/ProjectManager/ProjectDetail.aspx?AccessID=9ed4371b7b

It includes all resistors, capacitors, ICs, IC sockets, the push-button and both the Mill-Max pins and sockets. It doesn't include the pots, transformer, knobs or anything for the DOAs except the Mill-Max pins.

I tripple-checked everything but I'm still a beginner so it may have some errors.

Cheers,
Goetz
Title: Re: Studer 169 EQ in API 500 format
Post by: pvision on April 26, 2014, 05:40:07 AM
I thought I share my Mouser project with you all.  :)
http://www.mouser.com/ProjectManager/ProjectDetail.aspx?AccessID=9ed4371b7b

Nice to share a project!  It's hard work putting together a list so thanks for sharing it

Nick Froome
Title: Re: Studer 169 EQ in API 500 format
Post by: kante1603 on April 26, 2014, 05:48:06 AM
Hello,thanks for sharing the bom.
Haven't checked it but please be aware that some parts will be different depending on how you build it,so with or without transfomer,doa etc.
Just meant as a hint.

Best regards and have fun building them,they're great!

Udo ;)
Title: Re: Studer 169 EQ in API 500 format
Post by: goetzmd on April 26, 2014, 06:18:27 AM
Thanks guys! :-) It's the BOM for the version with the Neutrik transformer.

Servus nach Minga
Goetz
Title: Re: Studer 169 EQ in API 500 format
Post by: kante1603 on April 26, 2014, 06:24:08 AM
Thanks guys! :-) It's the BOM for the version with the Neutrik transformer.

Servus nach Minga
Goetz
Cool,thanks,pfüati,

Udo.
Title: Re: Studer 169 EQ in API 500 format
Post by: dogma on April 27, 2014, 02:29:01 PM
OK so im going to build a pair. Is there a BOM about ( a mouser cart would be amazing) - so are you guys using transformers? And how much per channel should I allow for? Finally - PCBs from Gustav? What about front panels? Thank you - this will be my FIRST build. Please help me loose my cherry!
Title: Re: Studer 169 EQ in API 500 format
Post by: goetzmd on April 27, 2014, 02:33:23 PM
I thought I share my Mouser project with you all.  :)
http://www.mouser.com/ProjectManager/ProjectDetail.aspx?AccessID=9ed4371b7b

It includes all resistors, capacitors, ICs, IC sockets, the push-button and both the Mill-Max pins and sockets. It doesn't include the pots, transformer, knobs or anything for the DOAs except the Mill-Max pins.

I tripple-checked everything but I'm still a beginner so it may have some errors.

I shared my project yesterday – it's for one unit but you can add it multiple times to your cart.

Goetz
Title: Re: Studer 169 EQ in API 500 format
Post by: dogma on April 27, 2014, 02:54:46 PM
Thank you so much! thank you.
Title: Re: Studer 169 EQ in API 500 format
Post by: kante1603 on April 27, 2014, 02:56:13 PM
OK so im going to build a pair. Is there a BOM about ( a mouser cart would be amazing) - so are you guys using transformers? And how much per channel should I allow for? Finally - PCBs from Gustav? What about front panels? Thank you - this will be my FIRST build. Please help me loose my cherry!
Hello,

I think reading through this thread should answer all your questions.
It's a simple build and sounds great.
For the transformer it seems most of us used them,personally I did it in mine.
You can do your own panels,I think somebody here once posted an fpd file?

Have fun,

Udo.
Title: Re: Studer 169 EQ in API 500 format
Post by: bruce0 on April 27, 2014, 03:51:51 PM
I thought I share my Mouser project with you all.  :)
http://www.mouser.com/ProjectManager/ProjectDetail.aspx?AccessID=9ed4371b7b

It includes all resistors, capacitors, ICs, IC sockets, the push-button and both the Mill-Max pins and sockets. It doesn't include the pots, transformer, knobs or anything for the DOAs except the Mill-Max pins.

I tripple-checked everything but I'm still a beginner so it may have some errors.

I shared my project yesterday – it's for one unit but you can add it multiple times to your cart.

Goetz


FYI not sure the C&K switch is correct in mouser project. 

I think it is 6 pole, shouldn't it be 2 pole?

Also you probably need to order the switch cap.
Title: Re: Studer 169 EQ in API 500 format
Post by: goetzmd on April 27, 2014, 05:24:22 PM
bruce0, I guess you're right. Could this be the correct switch?

http://de.mouser.com/Search/ProductDetail.aspx?R=51281virtualkey61170000virtualkey611-F2UEE

I didn't include the switch cap cause I'm still working on a custom front panel and don't know the colour jet.

I ordered the pcb and the parts and I'll update the mouse project...
Title: Re: Studer 169 EQ in API 500 format
Post by: bruce0 on April 27, 2014, 07:07:26 PM
bruce0, I guess you're right. Could this be the correct switch?

http://de.mouser.com/Search/ProductDetail.aspx?R=51281virtualkey61170000virtualkey611-F2UEE

I didn't include the switch cap cause I'm still working on a custom front panel and don't know the colour jet.

I ordered the pcb and the parts and I'll update the mouse project...

I think so, I have not built one just going from the pictures on this thread though.  You had the F6ueetb before. The "tb" is a nicer switch sealed top and bottom, keeps flux cleaner and tumbleweeds  out, but until it is old tb or no tb works just exactly the same.  Classicapi has the sealed ones I think.
Title: Re: Studer 169 EQ in API 500 format
Post by: goetzmd on May 03, 2014, 05:53:09 PM
This is the correct push-button:
http://de.mouser.com/Search/ProductDetail.aspx?R=FLT2UEETBvirtualkey61170000virtualkey611-FLT2UEETB

I have one question regarding DOAs:
If I'm using DOAs I need to remove U2, U3, C21, C22, C16 and C17, but I don't remove any wire bridges, right?!
Title: Re: Studer 169 EQ in API 500 format
Post by: dogma on May 07, 2014, 06:07:41 PM
What's required as far as calibrating after building?
Title: Re: Studer 169 EQ in API 500 format
Post by: kante1603 on May 07, 2014, 09:45:33 PM
What's required as far as calibrating after building?

Nothing to calibrate except you have the trimpot in which is for level matching ( eq on/bypass).

Best,

Udo.
Title: Re: Studer 169 EQ in API 500 format
Post by: Gustav on June 04, 2014, 02:27:48 AM

Also you probably need to order the switch cap.

Got an item number for those? Its all I need to finish, so Id rather not order the wrong ones :)

Gustav
Title: Re: Studer 169 EQ in API 500 format
Post by: bruce0 on June 04, 2014, 02:48:09 AM
If you look at the data sheet for the F2UEE switches, and scroll to the bottom, the switch caps are there.... Cubes, Cylinders or Clipped Conical.  I think they also have a series of lighted choices but they have always been too complicated to figure out, and they are large.
Title: Re: Studer 169 EQ in API 500 format
Post by: goetzmd on June 04, 2014, 05:32:36 AM
These switch caps fit:

Grey:
http://de.mouser.com/Search/ProductDetail.aspx?R=PV_GYvirtualkey61170000virtualkey611-PVGY

Black:
http://de.mouser.com/Search/ProductDetail.aspx?R=PV_BKvirtualkey61170000virtualkey611-PVBK

White:
http://de.mouser.com/Search/ProductDetail.aspx?R=PV_WHvirtualkey61170000virtualkey611-PVWH
Title: Re: Studer 169 EQ in API 500 format
Post by: goetzmd on June 26, 2014, 11:31:53 AM
Unfortunately my front panels and pcbs got lost in the mail. I just wanted everyone to know that Marek was 200% professional about it: he answered every mail within a couple hours, was always very nice and offered to make me another pair of panels and pcbs free of charge. They arrived today in perfect condition!

Don't hesitate to order from him – I can highly recommend his service! Thanks, Marek!!  :)

Cheers,
Goetz
Title: Re: Studer 169 EQ in API 500 format
Post by: taliska on June 26, 2014, 12:42:54 PM
Unfortunately my front panels and pcbs got lost in the mail. I just wanted everyone to know that Marek was 200% professional about it: he answered every mail within a couple hours, was always very nice and offered to make me another pair of panels and pcbs free of charge. They arrived today in perfect condition!

Don't hesitate to order from him – I can highly recommend his service! Thanks, Marek!!  :)

Cheers,
Goetz

Apologies if this has been mentioned elsewhere...but who is this Marek you speak of? I'm building some more stuff soon and can always make use of anyone who can provide custom panels! ;)

Cheers,

Kaz
Title: Re: Studer 169 EQ in API 500 format
Post by: goetzmd on June 26, 2014, 12:47:53 PM
Apologies if this has been mentioned elsewhere...but who is this Marek you speak of? I'm building some more stuff soon and can always make use of anyone who can provide custom panels! ;)

Hi Kaz, Marek made the frontpanels and pcbs – you'll find his info somewhere in this thread.
Cheers,
Goetz
Title: Re: Studer 169 EQ in API 500 format
Post by: goetzmd on June 26, 2014, 12:49:26 PM
Finished mine with custom front panels and aluminum knobs. I wanted a late 70s look… :) Only the LED light pipe is missing.
Title: Re: Studer 169 EQ in API 500 format
Post by: taliska on June 26, 2014, 01:00:03 PM
Apologies if this has been mentioned elsewhere...but who is this Marek you speak of? I'm building some more stuff soon and can always make use of anyone who can provide custom panels! ;)

Hi Kaz, Marek made the frontpanels and pcbs – you'll find his info somewhere in this thread.
Cheers,
Goetz

Ok, but can't seem to find it unfortunately. Can you point me to the specific post?

(I built my studers a while back so I occasionally check in on this thread out of curiosity...which is why I asked, because I, like a lot of people got my pcbs from Gustav and didn't realise there was anyone else supplying them!)

Cheers,

Kaz

P.S. Those are really slick looking ones you've got there! :)
Title: Re: Studer 169 EQ in API 500 format
Post by: Indecline on June 26, 2014, 02:57:04 PM
Apologies if this has been mentioned elsewhere...but who is this Marek you speak of? I'm building some more stuff soon and can always make use of anyone who can provide custom panels! ;)

Hi Kaz, Marek made the frontpanels and pcbs – you'll find his info somewhere in this thread.
Cheers,
Goetz

Ok, but can't seem to find it unfortunately. Can you point me to the specific post?

(I built my studers a while back so I occasionally check in on this thread out of curiosity...which is why I asked, because I, like a lot of people got my pcbs from Gustav and didn't realise there was anyone else supplying them!)

Cheers,

Kaz

P.S. Those are really slick looking ones you've got there! :)

Check your pm's!

Those panels are mighty impressive!! Makes me want to retrofit my faceplate ;)
Title: Re: Studer 169 EQ in API 500 format
Post by: ForthMonkey on July 12, 2014, 03:09:22 PM
Why i can't find bom?  ???
Title: Re: Studer 169 EQ in API 500 format
Post by: kante1603 on July 12, 2014, 03:19:15 PM
Why i can't find bom?  ???
Because there is none.
Look on the first page,all the info is there:
https://docs.google.com/file/d/0B_XBYPfmG8pVNzM2OGQxMDEtZGM4MS00ZjYwLThlYjEtNWYzNzE1NGQyNTlk/edit?usp=drive_web&hl=en&pli=1
and
https://docs.google.com/file/d/0B_XBYPfmG8pVMmRhZmNkZWEtMjU2ZS00YmI1LWFjNTYtY2ExY2Y4NDFjY2Vh/edit?usp=drive_web&hl=en&pli=1

Not too hard....

Udo.
Title: Re: Studer 169 EQ in API 500 format
Post by: ForthMonkey on July 12, 2014, 03:25:47 PM
Why i can't find bom?  ???
Because there is none.
Look on the first page,all the info is there:
https://docs.google.com/file/d/0B_XBYPfmG8pVNzM2OGQxMDEtZGM4MS00ZjYwLThlYjEtNWYzNzE1NGQyNTlk/edit?usp=drive_web&hl=en&pli=1
and
https://docs.google.com/file/d/0B_XBYPfmG8pVMmRhZmNkZWEtMjU2ZS00YmI1LWFjNTYtY2ExY2Y4NDFjY2Vh/edit?usp=drive_web&hl=en&pli=1

Not too hard....

Udo.

Hmm no part list.I see.Thanks.

Title: Re: Studer 169 EQ in API 500 format
Post by: kante1603 on July 12, 2014, 03:43:59 PM
Hmm no part list.I see.Thanks.
Correct.
Not many parts,most is standard stuff.Don't have my "bom" anymore,sorry.At the time when I built mine it took just about 10 minutes or so to write it on a piece of paper. I used Wimas for the caps (except the lythics of course),and metallfilm resistors (1%) throughout.Hope that helps?

Best,

Udo.

P.S.:I highly recommend this eq!

Title: Re: Studer 169 EQ in API 500 format
Post by: ForthMonkey on July 12, 2014, 03:55:36 PM
Hmm no part list.I see.Thanks.
Correct.
Not many parts,most is standard stuff.Don't have my "bom" anymore,sorry.At the time when I built mine it took just about 10 minutes or so to write it on a piece of paper. I used Wimas for the caps (except the lythics of course),and metallfilm resistors (1%) throughout.Hope that helps?

Best,

Udo.

P.S.:I highly recommend this eq!

Thanks!

But i have a question.Maybe it's like foolish...

How should i use DOAs and other op amps?Should i use DOA and NE5532 at the same time? Or should i choose DOA or NE5532?
Title: Re: Studer 169 EQ in API 500 format
Post by: audiox on July 12, 2014, 04:10:57 PM
Hmm no part list.I see.

You get what you pay for...

Actually there are so many alternatives, that ten different parts list wouldn't be enough. With or without transformer, IC or discrete op-amps, high and low filter frequencies (see the selection graphs) etc.
Title: Re: Studer 169 EQ in API 500 format
Post by: audiox on July 12, 2014, 04:13:27 PM
How should i use DOAs and other op amps?Should i use DOA and NE5532 at the same time? Or should i choose DOA or NE5532?

DOA or NE5532
Title: Re: Studer 169 EQ in API 500 format
Post by: ForthMonkey on July 12, 2014, 04:20:13 PM
How should i use DOAs and other op amps?Should i use DOA and NE5532 at the same time? Or should i choose DOA or NE5532?

DOA or NE5532

Thank you!

And last question.

I will use DOA.When i use DOAs,i won't use part under DOAs,right?

C22,C17,C21,C16 and jumpers?
Title: Re: Studer 169 EQ in API 500 format
Post by: kante1603 on July 12, 2014, 04:27:48 PM
Thanks!

But i have a question.Maybe it's like foolish...

How should i use DOAs and other op amps?Should i use DOA and NE5532 at the same time? Or should i choose DOA or NE5532?
Either DOAs or NE55xx,look at the schematic:Although it is drawn in "parallel" only one path each is used.
Personally I went for all NE55xx way and the NTL1.Some people here stated clearly that the sonic difference is very subtle.
I´m very happy with mine,they sound wonderful!

Udo.

Edit:OOOOOPPPSSSSS,double post,excuse me Max!
Title: Re: Studer 169 EQ in API 500 format
Post by: audiox on July 18, 2014, 11:07:27 AM
C22,C17,C21,C16 and jumpers?

Just install them all. In case of discrete op-amp C16 and C17 do nothing, but they are good to have if you some day want to try the 5534.
Title: Re: Studer 169 EQ in API 500 format
Post by: ForthMonkey on July 21, 2014, 11:37:12 AM
C22,C17,C21,C16 and jumpers?

Just install them all. In case of discrete op-amp C16 and C17 do nothing, but they are good to have if you some day want to try the 5534.

Thank you.

By the way what about Studer A101? I'm making it 2520 style to using with this eq.
Title: Re: Studer 169 EQ in API 500 format
Post by: avieira on July 26, 2014, 12:13:44 PM
Just got a pair of these PCBs from Gustav.  I’d like to turn this into a “mastering version” with .5dB stepped gain switches and selectable frequency switches.  Can anyone recommend good rotary switches for the gain section?

Also, I’ve compared the schematics between this version and the mastering 1U version and am unclear which resistors/caps and their accompanied values need to be changed to modify this 500 series unit.  Can someone much smarter than I point me in the right direction for this?   Kind of a noob here so anything will probably help.  :D
Title: Re: Studer 169 EQ in API 500 format
Post by: iprovlek on July 26, 2014, 12:25:01 PM
Lorlin switch is just ok for this project!

And value resitors you can use from STANDARD and MASTERING 169 EQ!


Cheers
Title: Re: Studer 169 EQ in API 500 format
Post by: avieira on July 26, 2014, 12:56:24 PM

And value resitors you can use from STANDARD and MASTERING 169 EQ!


Thanks for the switch recommendation!

I meant to say: specifically which resistors on the 500 version need to have their values changed?  They are numbered differently between the two schematics (500 version and 1U version) and so I'm not sure which resistors to change.  Thanks!
Title: Re: Studer 169 EQ in API 500 format
Post by: rmaier on July 26, 2014, 01:30:30 PM
I did something like this with mine, although the values of my gain switches ended up being +/- 1,2,3,6,15 dB for the high and low, and +/- 1,1.5.2.5,5,12 (or thereabouts) for the mid. There's plenty of info on this thread and the standard/mastering version of this eq to help you determine which capacitor values to choose, should you wish to make one with selectable high and low frequencies (I used 3 for the highs and lows). I also made up a stepped switch for the mid sweep, but be advised that the values of the resistors need to be calculated if you want to have precise selection of the frequencies (mine were significantly different than the values on the faceplate - wish I could help you there...). In any case, see if the information on pages 10-11 of this thread give you some ideas. It's a very worthwhile build.
Cheers,
Ralph
Title: Re: Studer 169 EQ in API 500 format
Post by: avieira on July 27, 2014, 01:55:52 PM
I did something like this with mine, although the values of my gain switches ended up being +/- 1,2,3,6,15 dB for the high and low, and +/- 1,1.5.2.5,5,12 (or thereabouts) for the mid. There's plenty of info on this thread and the standard/mastering version of this eq to help you determine which capacitor values to choose, should you wish to make one with selectable high and low frequencies (I used 3 for the highs and lows). I also made up a stepped switch for the mid sweep, but be advised that the values of the resistors need to be calculated if you want to have precise selection of the frequencies (mine were significantly different than the values on the faceplate - wish I could help you there...). In any case, see if the information on pages 10-11 of this thread give you some ideas. It's a very worthwhile build.
Cheers,
Ralph

Thanks for the great info, Ralph.

Do you remember / can you post the resistor values and their corresponding frequencies that you used for your mid sweep?

Thanks!
Title: Re: Studer 169 EQ in API 500 format
Post by: CemD on September 23, 2014, 01:45:49 PM
Greetings to all.
I built this magnificent project. Collected two pieces. One works well.
Other problem.
In EQ mode everything works fine. But in bypass mode EQ (bypass) the impact (crank it up to +10 dB) of low, medium and high a loud squeak and rumble (is excited).
Please help. How can I fix this?

(http://groupdiy.com/gallery/0/thumb_40420-230914134122.jpeg) (http://groupdiy.com/index.php?action=gallery;sa=view;id=279)

(http://groupdiy.com/gallery/0/thumb_40420-230914134010.jpeg) (http://groupdiy.com/index.php?action=gallery;sa=view;id=278)
Title: Re: Studer 169 EQ in API 500 format
Post by: Fablab on September 28, 2014, 04:33:51 AM
Hello, does anyone tried to put a different input transformer?
In the past I tried these Neutrik transformers that are not bad but I prefer a the Lundahl LL1540
Title: Re: Studer 169 EQ in API 500 format
Post by: kante1603 on September 28, 2014, 04:49:14 AM
Hello, does anyone tried to put a different input transformer?
In the past I tried these Neutrik transformers that are not bad but I prefer a the Lundahl LL1540
Hello,


what's wrong with the Neutriks when you say "...not bad..."?I'm very happy with mine.....


Best,


Udo.
Title: Re: Studer 169 EQ in API 500 format
Post by: Fablab on September 28, 2014, 05:00:59 AM
Hello Udo, I have not tried these transformers on this project (I am still building it) but in another project I have compared the Neutriks with Lundahl LL1540 and I have preferred the Lundahl ... but that's just my opinion and I don't want to convince anyone  :)
Title: Re: Studer 169 EQ in API 500 format
Post by: kante1603 on September 28, 2014, 05:21:37 AM
Hello Udo, I have not tried these transformers on this project (I am still building it) but in another project I have compared the Neutriks with Lundahl LL1540 and I have preferred the Lundahl ... but that's just my opinion and I don't want to convince anyone  :)
No problem at all ;)


So if you haven't built them,why not give it a try,technically it should work with the primaries and secondaries in series each,should not be too far off from the Neutrik specs.
Seeing it from the financial side Lundahls are more expensive at least over here.
And the pcb is made for the ntl1 anyway so if you're going for 1540 you'll have to mount it a different way somehow I guess.
Personally I have done three so far and wouldn't change it,fits like a glove mechanically and sonically.


Tell us what you end up with,


best regards and happy trials,


Udo.

Title: Re: Studer 169 EQ in API 500 format
Post by: Fablab on September 28, 2014, 05:47:36 AM
Udo, have you tried the difference with NE5534 and opamp?
I'd like to try with an output transformer, too
Best regards
Title: Re: Studer 169 EQ in API 500 format
Post by: kante1603 on September 28, 2014, 06:00:10 AM
Udo, have you tried the difference with NE5534 and opamp?
I'd like to try with an output transformer, too
Best regards
No,but from what I remember  the results with non-transformer units seem to have been very good too.I think there were some audio samples flying around here?
The only trials I did on my first one was altering the caps for different frequencies,I ended up in using the suggested parts as per bom,fitted my needs best by far.If I want to do something different I can choose from a bunch of other eqs (lucky me).


Best,


Udo.

Title: Re: Studer 169 EQ in API 500 format
Post by: Fablab on September 28, 2014, 06:52:07 AM
Thank you
Title: Re: Studer 169 EQ in API 500 format
Post by: Strawtles on October 16, 2014, 12:46:35 AM
Hello, what happens if I put a 100k Linear pot instead of 100k Rev. log pot?
Title: Re: Studer 169 EQ in API 500 format
Post by: dissonantdissident on October 28, 2014, 02:08:23 PM
I've had a hard time lining up my bank account with the times that Audio Maintenance has the 10k Lin pot in stock.  I couldn't help but notice that Classic API has these Bourns pots of the same value, with a center detent.  Has anyone tried these on the PCBs, from PCBGrinder?  I'd like to get this project done, and Omeg is apparently not making enough to keep up with demand, if Audio Maintenance is having such a hard time keeping them in stock.

Any other proven alternative would also be welcomed.

glenn
Title: Re: Studer 169 EQ in API 500 format
Post by: kante1603 on October 28, 2014, 02:26:00 PM
I've had a hard time lining up my bank account with the times that Audio Maintenance has the 10k Lin pot in stock.  I couldn't help but notice that Classic API has these Bourns pots of the same value, with a center detent.  Has anyone tried these on the PCBs, from PCBGrinder?  I'd like to get this project done, and Omeg is apparently not making enough to keep up with demand, if Audio Maintenance is having such a hard time keeping them in stock.

Any other proven alternative would also be welcomed.

glenn
Hi Glenn,


maybe they don't fit the pcb holes,but you can wire them off board of course.Don't have my modules here to compare (I do have some single bourns types here).
Have you seen the pdf at the bottom of jeff's homepage?If not here it is:


http://www.classicapi.com/catalog/images/gallery/pots/25K-CCW-AT/Bourns-51-53.pdf


Just measure and compare to the specs and you'll see how to mount them.
Seeing it from the quality and feel-side I must say they're excellent pots!Have a lot of them implemented in my summing/mixer project,highly recommended.And they're conductive plastic so from an electronics view perfect.


Best,


Udo.
Title: Re: Studer 169 EQ in API 500 format
Post by: goetzmd on October 28, 2014, 03:56:01 PM
I finished mine a couple of weeks ago. They don't look pretty on the inside but I learned a whole lot from how analog eqs work, how to source parts to designing my own faceplate. I'm going to add some DOAs soon.

(http://goetzmd.de/wp-content/uploads/2014/09/studer-eq-api-500-fertig.jpg)

(http://goetzmd.de/wp-content/uploads/2014/09/eq-im-api-500-format-selbst-gebaut.jpg)
Title: Re: Studer 169 EQ in API 500 format
Post by: dissonantdissident on October 28, 2014, 06:21:50 PM

[/quote]
Hi Glenn,


maybe they don't fit the pcb holes,but you can wire them off board of course.Don't have my modules here to compare (I do have some single bourns types here).
Have you seen the pdf at the bottom of jeff's homepage?If not here it is:


http://www.classicapi.com/catalog/images/gallery/pots/25K-CCW-AT/Bourns-51-53.pdf


Just measure and compare to the specs and you'll see how to mount them.
Seeing it from the quality and feel-side I must say they're excellent pots!Have a lot of them implemented in my summing/mixer project,highly recommended.And they're conductive plastic so from an electronics view perfect.


Best,


Udo.
[/quote]

Thanks, Udo!  I'm looking at the Classic API site and their picture of the pot has two rows of two leads, apiece(like the gain pot on the vp25/26 preamps).  The data sheet is showing a smaller pot with a single row of three leads, and it doesn't give mechanical info, for the various different pots.  I know it would be conjecture, but I'm guessing that the 10k pots from CAPI are the ones on CAPI's website.  If it is the two rows of two leads per row, then it seems I could just mount them on the panel and run some short wires, to the pads, if necessary.  Does that seem right to other folks?

glenn
Title: Re: Studer 169 EQ in API 500 format
Post by: kante1603 on October 29, 2014, 12:45:47 AM
Glenn,


you should read the pdf.All(!) mechanical info is there on pages 2 & 3.
The mentioned "second row" is nothing but a mounting bracket.
It can be easily removed,I did it with all my pots here.


Udo.
Title: Re: Studer 169 EQ in API 500 format
Post by: dissonantdissident on October 29, 2014, 10:30:48 AM
 :-[  Oops!!!
Title: Re: Studer 169 EQ in API 500 format
Post by: dissonantdissident on October 29, 2014, 11:01:22 AM
Looks like they came back in stock at Audio Maintenance, today.  I'm gonna get those, since they'll fit the pcb.
Title: Re: Studer 169 EQ in API 500 format
Post by: CarlT on October 31, 2014, 04:16:10 PM
I finished mine a couple of weeks ago. They don't look pretty on the inside but I learned a whole lot from how analog eqs work, how to source parts to designing my own faceplate. I'm going to add some DOAs soon.


hi can you give details regarding designing the face plate and where you had them done?

Also where the switchable frequencies hard to do?

Thanks


Thanks
Title: Re: Studer 169 EQ in API 500 format
Post by: tuanuibi on November 05, 2014, 02:45:38 AM
Hi guys,
Can you see any issues running this on +/-15v?
Title: Re: Studer 169 EQ in API 500 format
Post by: kante1603 on November 05, 2014, 12:00:58 PM
Hi guys,
Can you see any issues running this on +/-15v?
Hello and welcome to the forum.
No issues when running it from +/-15v,will work fine.


Best,


Udo.
Title: Re: Studer 169 EQ in API 500 format
Post by: Strawtles on November 13, 2014, 01:11:13 AM
Hello, I'd like to know if it is possible to use a 6 pin toggle switch instead of the DPDT pushbutton
Title: Re: Studer 169 EQ in API 500 format
Post by: kante1603 on November 13, 2014, 01:57:30 AM
Hello, I'd like to know if it is possible to use a 6 pin toggle switch instead of the DPDT pushbutton


http://groupdiy.com/index.php?action=dlattach;topic=36522.0;attach=25043

Title: Re: Studer 169 EQ in API 500 format
Post by: Strawtles on November 13, 2014, 05:58:13 AM
Great, thank you!
Title: Re: Studer 169 EQ in API 500 format
Post by: iprovlek on November 18, 2014, 10:04:30 AM
I have problem with my stereo of this Studer 169eq!

I made with Lorlin 1x12 switches instead potentiometer!

When I turn on EQ IN I get a attenuate sound ,but when I put it out in bypass my sound get increase!

That is little strange,cause I made 6 of this EQ's with potentiometers and never get attenuated sound!

Can this Lorlin switches cause that!?
Title: Re: Studer 169 EQ in API 500 format
Post by: KMB-AUDIO on November 25, 2014, 02:30:36 PM
I'm going to start building my pair soon, but I'm having a real hard time finding the rev log 100k dual.  Anybody got any leads? ?

Title: Re: Studer 169 EQ in API 500 format
Post by: kante1603 on November 25, 2014, 02:57:46 PM
I'm going to start building my pair soon, but I'm having a real hard time finding the rev log 100k dual.  Anybody got any leads? ?
Normally Colin at AML has them,but they are "temporarily out of stock".
Maybe you can ask him when and if they will be available again,his member name here is "slenderchap".
Would be nice if you can share your results here.


Good luck,


Udo.
Title: Re: Studer 169 EQ in API 500 format
Post by: KMB-AUDIO on November 25, 2014, 04:21:27 PM
I sent an email. I'll post here when I hear back.

I did find a local company that will make them for .72 each - but you need to order 1000 pieces!
Title: Re: Studer 169 EQ in API 500 format
Post by: KMB-AUDIO on November 26, 2014, 02:03:31 PM
Just received an email from Colin stating that they are back in stock!
Title: Re: Studer 169 EQ in API 500 format
Post by: iprovlek on November 26, 2014, 02:30:39 PM
You have stereo 100k REV Log on Musikding!
Title: Re: Studer 169 EQ in API 500 format
Post by: kante1603 on November 26, 2014, 03:10:51 PM
Just received an email from Colin stating that they are back in stock!
Thanks for sharing! ;)
Title: Re: Studer 169 EQ in API 500 format
Post by: dissonantdissident on December 05, 2014, 07:03:07 PM
Just finished up my build.  I went with the transformer option, and I used Whistle Rock BLU-18s for the DOAs and Phillips 5534s for the IC opamps.  I didn't go with switchable frequencies, or anything super fancy.  It's gonna be great on my master bus.  The EQ seems nice and subtle, and the transformers seem to be taking off some of the digital edge, from my ITB mixes.

(http://)

Now I've just gotta get this GSSL up and running, right :o!

glenn
Title: Re: Studer 169 EQ in API 500 format
Post by: 2Low on December 09, 2014, 03:23:45 PM
Two EQs finished
Easy to build, great sound, bang for the buck .. thanks Audiox !
Title: Re: Studer 169 EQ in API 500 format
Post by: dissonantdissident on December 10, 2014, 03:50:04 PM
Can anybody point me towards some knobs that fit the AML pots?  I've been ordering knobs and haven't found gotten it right, so I figured I'd ask if someone has an ebay link, or something. 

Alternately, does anybody in the USA have eight fitting aluminum knobs that they'd trade for eight clear pointer CAPI knobs:

http://classicapi.com/catalog/product_info.php?cPath=23_39&products_id=310

I've got 4 yellow and 4 amber inserts, for them.
Title: Re: Studer 169 EQ in API 500 format
Post by: kante1603 on December 10, 2014, 04:11:11 PM
Two EQs finished
Easy to build, great sound, bang for the buck .. thanks Audiox !
How do you call them,Supernovae maybe? 8)
Well done,


Udo.
Title: Re: Studer 169 EQ in API 500 format
Post by: 2Low on December 10, 2014, 05:43:32 PM
DISCO `74  ;)

[/quote]
How do you call them,Supernovae maybe? 8)
Well done,


Udo.
[/quote]
Title: Re: Studer 169 EQ in API 500 format
Post by: 2Low on December 10, 2014, 05:51:29 PM
i´ve used :   Sifam /  4mm


https://de.rs-online.com/web/p/potenziometer-knopfe/1258430/?searchTerm=S151+004B&relevancy-data=636F3D3126696E3D4931384E4272616E644D504E266C753D6465266D6D3D6D61746368616C6C26706D3D5E5B5C707B4C7D5C707B4E647D5C707B5A737D2D2C2F255C2E5D2B2426706F3D3526736E3D592673743D4B4559574F52445F4D554C54495F414C5048415F4E554D455249432677633D4E4F4E45267573743D53313531203030344226



Can anybody point me towards some knobs that fit the AML pots? 
Title: Re: Studer 169 EQ in API 500 format
Post by: dissonantdissident on January 10, 2015, 11:56:34 AM
Hey folks,

After I messed up and ordered the wrong knobs, I couldn't get the money for the SIFAM ones.  I did find these super cheap knobs on ebay that work:

http://www.ebay.com/itm/10-Pcs-4mm-Shaft-Insert-Dia-Brass-Tone-Core-Potentiometer-Control-Knobs-/321124814808?pt=LH_DefaultDomain_0&hash=item4ac487cfd8

They take a while to ship to USA and the paint job(for the markers) is horrible.  That being said, you can scrape off the excess paint with an exacto knife and you've got knobs that work, fit, and don't look terrible.  They tighten like the collet knobs, but they have a screw that you tighten(phillips or flat head) , instead of the funky little fitting that the collet knobs use.

Just figured that I'd pass it along, for folks trying to save $$$.
Title: Re: Studer 169 EQ in API 500 format
Post by: bruce0 on January 11, 2015, 03:53:39 PM
Those do look like nice cheap collet knobs.  I believe all the collet knobs have screws except the ones designed to (optionally) be the bottom of a concentric knob stack, which need the ring screw because the concentric shaft comes through the middle.  Pretty much all the 4mm knobs  have screws I think.
Title: Re: Studer 169 EQ in API 500 format
Post by: dissonantdissident on January 11, 2015, 05:34:17 PM
Fair enough.  The only other Collet knobs I've worked with were on old dbx stuff, and they didn't have a slot for a screw driver.  Instead, they have a fitting that you have to grip via slots located on either side of the shaft, which comes up the middle(more akin to a nut than a screw).  At least that's how I remember them.
Title: Re: Studer 169 EQ in API 500 format
Post by: assrael on February 15, 2015, 05:19:32 AM
I plan to build this unit with stepped controls.
Can anybody share the calculation for the resistors of MID FREQ in reference to the frequencies?
Title: Re: Studer 169 EQ in API 500 format
Post by: avieira on February 15, 2015, 12:45:44 PM
I'm planning out a mastering version of this EQ with stepped Grayhill switches. I had a friend get very precise with some calipers and use the curve from the data sheet of the original RLog pot to approximate the resistances. Hope this helps!
Title: Re: Studer 169 EQ in API 500 format
Post by: assrael on February 15, 2015, 04:01:12 PM
Thanks! That’s the workaround which I have planned to do if I can’t get the calculation.
I will also use Greyhill rotarys for the frequencies and most probably Elmas for the gain.
Title: Re: Studer 169 EQ in API 500 format
Post by: Trench Recordings on February 22, 2015, 07:34:22 AM
Just wondering if you could easily put the transformer on a toggle  switch ?
Title: Re: Studer 169 EQ in API 500 format
Post by: assrael on February 22, 2015, 08:34:26 AM
It’s possible, but it’s not an easy modification. You have to cut traces, add new ones…
Compare the layout values of the trafo layout and the standard layout to figure out what to do.
Title: Re: Studer 169 EQ in API 500 format
Post by: kante1603 on February 22, 2015, 09:51:57 AM
Just wondering if you could easily put the transformer on a toggle  switch ?
Member assrael is right,too many stuff to change for a nearly inaudible difference.
I'd leave it as it is,


just my 2ct,


Udo.
Title: Re: Studer 169 EQ in API 500 format
Post by: avieira on March 06, 2015, 09:54:26 AM
My next one:

- added LED for EQ in



Hey guys/gals. I've run into a small problem while putting the finishing touches on my EQ. I'm trying to tie in an LED on the bypass switch like Holder did but am running into an issue. Attached is a pic showing how I tried to wire it. The problem is that there's an attenuation in audio signal when I wire it like this - the LED switches correctly but it corrupts my audio signal. I'm sure this is a noob mistake. Any suggestions?
Title: Re: Studer 169 EQ in API 500 format
Post by: assrael on March 06, 2015, 10:56:24 AM
It seems to me, that you are using the cold signal for the LED ground. This is not a good idea.
Wire the LED to “real” ground and use a resistor inbetween.
Title: Re: Studer 169 EQ in API 500 format
Post by: kante1603 on March 06, 2015, 11:08:32 AM
Hey guys/gals. I've run into a small problem while putting the finishing touches on my EQ. I'm trying to tie in an LED on the bypass switch like Holder did but am running into an issue. Attached is a pic showing how I tried to wire it. The problem is that there's an attenuation in audio signal when I wire it like this - the LED switches correctly but it corrupts my audio signal. I'm sure this is a noob mistake. Any suggestions?
It won't work like this,seems you're mixing up switched dc for the led with the audio.
And as assrael stated you need a preresistor.
For the switch a third pole is needed to make the led work correct.


Best,


Udo
Title: Re: Studer 169 EQ in API 500 format
Post by: avieira on March 06, 2015, 11:17:46 AM
Ah ha. Thank you both assrael and Udo. I was operating under the assumption that someone else had successfully done it before me.

Cheers.
Title: Re: Studer 169 EQ in API 500 format
Post by: kante1603 on March 06, 2015, 11:25:25 AM
Ah ha. Thank you both assrael and Udo. I was operating under the assumption that someone else had successfully done it before me.

Cheers.
Seems Holger used a different switch,maybe 3 or 4pole dual throw.Looks like he has cut off the last pins on the switch bottom to make it fit the pcb.So the last pins don't go through pcb holes,just the top side is used for soldering the led wires.


Best,


Udo.
Title: Re: Studer 169 EQ in API 500 format
Post by: Trench Recordings on March 20, 2015, 11:48:04 AM
What caps did you guys use in C3 C7 C9 C13 ? electrolytic in the audio path yes ? 

Which caps should be film C4 C5 C6 C11? The rest ceramic is ok ?
Title: Re: Studer 169 EQ in API 500 format
Post by: Krcwell on March 30, 2015, 08:05:06 PM
Ah ha. Thank you both assrael and Udo. I was operating under the assumption that someone else had successfully done it before me.

Cheers.
Seems Holger used a different switch,maybe 3 or 4pole dual throw.Looks like he has cut off the last pins on the switch bottom to make it fit the pcb.So the last pins don't go through pcb holes,just the top side is used for soldering the led wires.

This is what I did, got a 4 pole switch from mouser, cut off the bottom pins for the back 3 rows, and wired the led and resistor into the top pins. Works perfectly.
Title: Re: Studer 169 EQ in API 500 format
Post by: iprovlek on May 19, 2015, 07:15:40 AM
I need help guys!

I wanna use switch for changing low an high freq on this Eq !

I saw that schamtics for this mod here, but dont understand how to solder correctly to get work!?


Thanks....
Title: Re: Studer 169 EQ in API 500 format
Post by: rmaier on May 19, 2015, 08:36:03 AM
Have you checked out the thread on the pre-500 version of the EQ? I made mine with switchable highs and lows, and found it really helpful:

http://groupdiy.com/index.php?topic=33996.0

Also check the photos of my build on page 11ish of this thread for a closer look at wiring the switches.

Cheers
Title: Re: Studer 169 EQ in API 500 format
Post by: iprovlek on May 19, 2015, 01:46:15 PM
I looked to your pics!
I saw that caps are solder on PCB, and than you put other caps on Lorlin switch!? Im right!?

C4,C5 and C6 caps are on PCB!?
Title: Re: Studer 169 EQ in API 500 format
Post by: rmaier on May 21, 2015, 12:23:31 AM
Yes, C4,5,6 are on the PCB.  Its been a few years since I looked at this, so my memory is pretty foggy, but from what I recall, the mods to add a couple of extra frequencies for the low shelf were pretty easy to implement. Those are the capacitors  soldered directly on to the lower rotary swiches. More detailed information should be somewhere on the first few pages of this thread.

Ralph
Title: Re: Studer 169 EQ in API 500 format
Post by: rmaier on May 21, 2015, 12:31:01 AM
How would I go about installing switches for the 3 selectable frequencies?  I'd like to do this, but don't really know how.

Low filter: Use a single pole on-off-on toggle switch. The first "on" position connects a capacitor in parallel with C6 and the other "on" position connects another value capacitor in parallel with C6. In the middle "off" position there is C6 alone. Now you have 3 selectable frequencies.

High filter: Same idea but you need a two pole on-off-on switch since there are two capacitors which determine the frequency (C4 and C5).

Note that I have included some extra pads on the PCB to make wiring easier.

This is the mod I was trying to remember. Hope it helps. I was just using this eq the other day after not having used it for a while. I forgot how good it sounds!
Cheers.
Ralph
Title: Re: Studer 169 EQ in API 500 format
Post by: G-Sun on May 27, 2015, 10:37:07 AM
Low shelving filter +/- 15dB. Default frequency is 20 Hz as in the original circuit,
but you can select a new value for C6 from this graph to change it:
http://audioxxx.googlepages.com/EQ_169_STD_frq_selection_lo_filter.pdf

High shelving filter +/- 15dB. Default frequency is 20 kHz as in the original circuit,
but you can select a new value for C4 and C5 from this graph to change it:
http://audioxxx.googlepages.com/EQ_169_STD_frq_selection_hi_filter.pdf

Can someone explain the chosen frequencies for me?
I almost never use these values myself.
Is it creating some sort of wanted slope?
Are there any response curves pictures?
Title: Re: Studer 169 EQ in API 500 format
Post by: G-Sun on May 27, 2015, 11:38:28 AM
Is it something along these lines:
Title: Re: Studer 169 EQ in API 500 format
Post by: jasonallenh on May 27, 2015, 03:11:40 PM
Low shelving filter +/- 15dB. Default frequency is 20 Hz as in the original circuit,
but you can select a new value for C6 from this graph to change it:
http://audioxxx.googlepages.com/EQ_169_STD_frq_selection_lo_filter.pdf

High shelving filter +/- 15dB. Default frequency is 20 kHz as in the original circuit,
but you can select a new value for C4 and C5 from this graph to change it:
http://audioxxx.googlepages.com/EQ_169_STD_frq_selection_hi_filter.pdf

Can someone explain the chosen frequencies for me?
I almost never use these values myself.
Is it creating some sort of wanted slope?
Are there any response curves pictures?

These charts allow you to choose your own frequency for the high and low shelving filters. If you don't like the default/original frequencies, you can select a capacitor value from the chart that corresponds with the frequency you DO want.

Is it something along these lines:


Not quite- Your picture has Hi-pass/low pass filters. These are not the same as shelves.
Title: Re: Studer 169 EQ in API 500 format
Post by: G-Sun on May 27, 2015, 04:29:18 PM
These charts allow you to choose your own frequency for the high and low shelving filters. If you don't like the default/original frequencies, you can select a capacitor value from the chart that corresponds with the frequency you DO want.
Thanks! I've seen that. but I need to understand how the original design works first.
Quote
Not quite- Your picture has Hi-pass/low pass filters. These are not the same as shelves.
No, that's shelves I've used in my pictures.
Title: Re: Studer 169 EQ in API 500 format
Post by: dmp on May 27, 2015, 04:57:08 PM
I swept mine a few years back  -  see page 9. 

They affect frequencies more into the audio range than the 20 Hz / 20kHz would lead you to believe.
Title: Re: Studer 169 EQ in API 500 format
Post by: G-Sun on May 28, 2015, 02:25:21 AM
And the high / low frequencies boosted (with the stock capacitor values)
Thanks!
This is exactly what I was looking for :)
Now I understand much better.
Title: Re: Studer 169 EQ in API 500 format
Post by: Siegfried Meier on June 25, 2015, 12:58:14 PM
Hey guys,

R1 and C1 are shown as empty in the original docs.  Is this true?  Or am I missing a part here...I've left them out, I have no sound when engaged.

Thanks!
Sig
Title: Re: Studer 169 EQ in API 500 format
Post by: Siegfried Meier on June 25, 2015, 01:14:50 PM
I found a document online that states 10k and 10n respectively for R1 and C1...however, I did that and still no sound.  I get what sounds like a sinewave synth when I boost the midrange frequency and sweep it, which in the past has been an indication of a missing resistor for me. 

Any thoughts much appreciated...

Thanks!
Sig
Title: Re: Studer 169 EQ in API 500 format
Post by: Gustav on June 25, 2015, 02:15:42 PM
I found a document online that states 10k and 10n respectively for R1 and C1...however, I did that and still no sound.  I get what sounds like a sinewave synth when I boost the midrange frequency and sweep it, which in the past has been an indication of a missing resistor for me. 

Any thoughts much appreciated...

Thanks!
Sig

Hi Siegfried.

Answered your mail, will answer here as well.

I will do my best, but I dont think I am the most qualified person to get this sorted.

Did you check the overlays on page one? And which "version" are you building (transformerless? DOA?)

Gustav
Title: Re: Studer 169 EQ in API 500 format
Post by: rmaier on June 25, 2015, 11:51:00 PM
I'm even less qualified, so  take anything  I say with more than a grain of salt..,
There are lots of jumpers that need to be connected. Could you have missed one? The ones on my build on page 11 are pretty easy to spot - might help to have a peek?
Ralph
Title: Re: Studer 169 EQ in API 500 format
Post by: Siegfried Meier on June 26, 2015, 12:20:03 AM
I'm using the Neutrik transformer.  I'm nearly 100% positive I have all the links connected...

Are my C1 and R1 values correct from that document I found?  Not sure what else to check...?
Title: Re: Studer 169 EQ in API 500 format
Post by: rmaier on June 26, 2015, 12:58:09 AM
Not according to the schematic on page 1. C1 is 47p, R1 is 20k.  You're using another schematic?
Ralph

Edit: Weird... the layout diagram implies that C1and R1 are left unpopulated, but the schematic says otherwise.  I'm confused now, too.
Title: Re: Studer 169 EQ in API 500 format
Post by: Gustav on June 26, 2015, 03:19:05 AM
I'm using the Neutrik transformer.  I'm nearly 100% positive I have all the links connected...

Are my C1 and R1 values correct from that document I found?  Not sure what else to check...?

C1 and R1 should be omitted for the trafo balanced input version.

I dont think I ever looked at the schematic when I built mine. I just followed this blindly. So it should work.

https://drive.google.com/file/d/0B_XBYPfmG8pVMmRhZmNkZWEtMjU2ZS00YmI1LWFjNTYtY2ExY2Y4NDFjY2Vh/view?ddrp=1&hl=en

Gustav
Title: Re: Studer 169 EQ in API 500 format
Post by: Siegfried Meier on June 26, 2015, 01:27:38 PM
Ok, I will leave those values out then.

Still not sure why it's not working… I will check the opamps, but I did test them and they work in a VP28…I figured I'd get some sound at least, but it's literally nothing when I push in the bypass switch.  Works fine in bypass.
Title: Re: Studer 169 EQ in API 500 format
Post by: audiox on June 27, 2015, 10:34:20 AM
The standard version with active balanced input:

Schematic (see the layout drawings for the input section component values)
http://docs.google.com/fileview?id=0B_XBYPfmG8pVZGViZTg4YmQtMDM0Yi00M2IzLTkwYTYtOWE4Zjg2YTk0MDE3&hl=en

Layout with components values (active balanced input)
http://docs.google.com/fileview?id=0B_XBYPfmG8pVNzM2OGQxMDEtZGM4MS00ZjYwLThlYjEtNWYzNzE1NGQyNTlk&hl=en

Modifications required for the transformer option are shown only in this layout drawing:

Layout with components values (transformer balanced input)
http://docs.google.com/fileview?id=0B_XBYPfmG8pVMmRhZmNkZWEtMjU2ZS00YmI1LWFjNTYtY2ExY2Y4NDFjY2Vh&hl=en

The transformer modification adds proper loading for the transformer and replaces the differential input stage with a voltage follower.
Title: Re: Studer 169 EQ in API 500 format
Post by: Siegfried Meier on June 27, 2015, 04:38:21 PM
Ya, I followed that drawing to populate my boards.  Besides the opamp perhaps being a problem, I'm not sure what else to look at.  I'll send a pic of my boards. I did leave the opamp under the DOA out, as I'm using a DOA.  I understand these aren't necessary.

Thanks,
Sig
Title: Re: Studer 169 EQ in API 500 format
Post by: Trench Recordings on June 27, 2015, 04:44:54 PM
U1 and U4 opamps are needed even with DOA...

Do not put in U2 and U3
Title: Re: Studer 169 EQ in API 500 format
Post by: Siegfried Meier on June 28, 2015, 01:02:12 AM
I assume U1 and U4 are the ones shown in this pic, and U2 and U3 are the ones under the DOA, correct?  If so, then that's exactly what I have.

http://audiofor.tv/diy/ProjectFotoFolder/169/rear.jpg (http://audiofor.tv/diy/ProjectFotoFolder/169/rear.jpg)
Title: Re: Studer 169 EQ in API 500 format
Post by: Trench Recordings on June 28, 2015, 07:13:04 AM
Hmmm... Well maybe the links underneath the DOA ? I'm just guessing

Here some pics of mine I'm working on. It tested and working

https://www.dropbox.com/sh/bvr8j4k5j87qksx/AACG6NnUroAbU_PRClv_nRora?dl=0
Title: Re: Studer 169 EQ in API 500 format
Post by: Siegfried Meier on June 28, 2015, 09:44:37 AM
Mine doesn't look all that different...I tried it today with a pair of 5534's instead of the 2520 DOA, still no sound at all when engaged...

The link beside DOA #2 has been made underneath, in case you're wondering.


(http://www.siegfriedmeier.com/electronics/Studer%20169.JPG)
Title: Re: Studer 169 EQ in API 500 format
Post by: Gustav on June 28, 2015, 10:14:30 AM
I may be way off here, since it seems too obvious (my fresh eyes may have spotted it, while you have been staring yourself blind)

Theres a jumper missing next to the opamp on the input. Without this link, you never complete the audio path, as far as I can tell.

I tried tracing the schematic with board in hand, and if I am not mistaken, you are making the missing connection through  C1/R1 when you place them, which is why that gave some weird signal through.

Its worth trying at least!?

Gustav



 
Title: Re: Studer 169 EQ in API 500 format
Post by: Siegfried Meier on June 28, 2015, 10:31:31 AM
Oh maaaa gawwwwddddddddd….
Title: Re: Studer 169 EQ in API 500 format
Post by: Siegfried Meier on June 28, 2015, 10:39:28 AM
You guys are amazing.  It works perfectly and sounds absolutely incredible, even with the 5534 chips instead of the 2520's…I have 3 extra trafos now, must build 3 more!!!

It is incredible that even when I looked at the picture I took on a large screen it became totally obvious where the missing link was, but I literally stared at the board for hours and saw nothing…

Thanks so much dudes!
Sig
Title: Re: Studer 169 EQ in API 500 format
Post by: Harpo on June 28, 2015, 10:47:02 AM
[image]http://www.siegfriedmeier.com/electronics/Studer%20169.JPG[/image]
Some cap values look like factor 1000 apart (FI 47pF (preferably c0g/np0) wanted, wima caps fitted look like maybe 47nF). Maybe only optical artifact or caps voltage rating withstanding lightning strikes for whatever silly reason.
Title: Re: Studer 169 EQ in API 500 format
Post by: Siegfried Meier on June 28, 2015, 11:44:54 AM
What knobs are you guys using on these?  I ordered the smaller shaft pots from Colin at Audio Maintenance, and I ordered shaft reducers from Jeff at CAPI but they don't fit together…I guess I should have paid more attention to my metric vs imperial…so unfortunately I can't  use my knobs that I had chosen.  Would love to know what other solutions there are out there.

Thanks guys!
Sig
Title: Re: Studer 169 EQ in API 500 format
Post by: Siegfried Meier on June 29, 2015, 03:15:27 AM
I found several vintage Trident knobs in my shop today that were supposed to be for an 80b EQ, but they fit the shaft sizes of Colin's pots perfectly.  I wasn't sure at first, but now I think the red knobs on the silver panel look absolutely killer!

(http://www.siegfriedmeier.com/electronics/Studer%20EQ%20500%20Rack.jpg)
Title: Re: Studer 169 EQ in API 500 format
Post by: Trench Recordings on June 29, 2015, 07:35:35 PM
Jealous.... Still trying to figure out knobs
Title: Re: Studer 169 EQ in API 500 format
Post by: kustohm on July 09, 2015, 12:42:58 PM
Hello everyboDIYers!

Maybe somebody asked this but what size for the AML pots?
-16mm?
-20mm?

I don't want to use brackets and so I need to solder the good stuff to the PCB to insure faceplate solidity!

About AML, others ideas for differents pots with the same values?

THANX
Title: Re: Studer 169 EQ in API 500 format
Post by: kustohm on July 09, 2015, 01:06:26 PM
OK, I just read the introduction...and sorry...I know now...is 16mm pots!
Title: Re: Studer 169 EQ in API 500 format
Post by: ctujoao on November 11, 2015, 12:09:49 PM
Hello,

This is the kind of desperate post none wants to make, but if there's any surviving soul on this topic, help is more than welcome.
I've build 2 of these that worked immediately. Then the 3rd one...
Hi and Low shelf are working, but the mid is just insane: I get very loud feedback as soon as past 12:00 (the signal is still in the background, buried deeply). It's kind of a resonance since no input signal is required to trigger the feedback.

So I poked, and I poked until my fingers were numb.
 I suppose the trick is to have C11 to vary between something like 7 to 15nF when turning the MID potentiometer.This is not the case.
I've reflowed every joints twice, cleaned them.
I've checked all values of component and the pots.
I've tried 3 different NE5534, all new.
I can't find a shortcut, everything look clean.

I just can't see it..

Many thanks for reading and any potential help.

PS: forgot to mention, it's NE 5534 all the way  and no transfo.
 
Title: Re: Studer 169 EQ in API 500 format
Post by: Potato Cakes on November 26, 2015, 03:27:24 AM
Here's a fun one...

So I got 2 of these boards from another member here and I finally got it assembled to the point where I could do some testing. At first no audio. Then some sort of pulsing audio. I checked my voltages on my op amps and I was getting  +16 on the V- connection and +1.5V on the V+. After lots of poking around and staring at it, I find that gold fingers 8-15 all had continuity with each other. And after some more time cutting traces and pulling components in vain, I finally just removed some PCB material between the fingers and that seemed to fix everything. The funny thing is that I could not see any sort of copper connecting the fingers, so I have no idea how they were all being connected. It just looked like every other 500 series card that I've seen. Unfortunately in the process, I fried something on the output of my SPL Madison that I was using to send out tone. The LED display says it's sending audio, but it is not actually producing output. The upside is that I got to watch one of the 10 ohm resistors catch on fire, and that's always kind of cool.

Has anyone else seen something like this with any of the 500 series PCBs? This was the only time I've had an issue where the problem wasn't some silly mistake I made.

Thanks!

Paul
Title: Re: Studer 169 EQ in API 500 format
Post by: kante1603 on November 26, 2015, 07:28:06 AM
Read the thread?
http://groupdiy.com/index.php?topic=36522.msg697139#msg697139 (http://groupdiy.com/index.php?topic=36522.msg697139#msg697139)
Udo.
Title: Re: Studer 169 EQ in API 500 format
Post by: Potato Cakes on November 26, 2015, 12:15:27 PM
Thanks, Udo!

I had glanced through the thread and usually when there been an error with the boards it's a simple jumper that needs to be made. I had never figured that this would be a possibility. I should have read more carefully!


Thanks!

Paul
Title: Re: Studer 169 EQ in API 500 format
Post by: kante1603 on November 26, 2015, 01:03:22 PM
 ;)
Title: Re: Studer 169 EQ in API 500 format
Post by: mhbunch on December 29, 2015, 02:49:44 AM
Finally finished my pair. Sound great!
Title: Re: Studer 169 EQ in API 500 format
Post by: maniman on January 07, 2016, 09:48:02 PM
Hi friends , I'm doing this project these days and trying to do the lo and hi freq selectable mod http://goetzmd.de/tontechnik/studer-169-eq-teil-5-finale-und-front-panel (http://goetzmd.de/tontechnik/studer-169-eq-teil-5-finale-und-front-panel) I'm seeing one thing ,

 - the C6 is the cap that low frequency depends on
 - on the layout C6 is 220 nF

20 Hz is the Low freq default frecuency and this is not true , or the C6 layout value is wrong , 22 nF maybe are 2X Hz but if you see the graph can see 220 nF is more something near 2X0 Hz .

Not ?
Title: Re: Studer 169 EQ in API 500 format
Post by: joshuabiehler on February 20, 2016, 09:05:03 PM
First time poster/long time lurker.

I finally got this bad boy together and it sounds AWESOME.

I have a couple of comments/build notes:

- I'd definitely put in a trimmer at R4 - I set it to 10K prior to soldering it in and was 6DB+ from the level when bypassed.
- I received my boards this month, and they still have the "all pins connected" issue. I wouldn't have thought to check that were it not for this thread!
- I didn't build it with an input trafo, but have tried out the lone DOA I have (GAR1731). It sounds great with just the NE5534s but there's a lot more "bark" with the DOA. I have it in the the DOA2 spot for now.

Obligatory gutshot, waiting for the faceplate to arrive.

Thanks, AudioX!
Title: Re: Studer 169 EQ in API 500 format
Post by: skeeler87 on May 17, 2016, 06:52:09 PM
Has anyone been able to source out knobs for the omeg pots? I'm having a hell of a time finding them.
Title: Re: Studer 169 EQ in API 500 format
Post by: wadesey on December 03, 2016, 01:31:25 PM
Curious if anyone has tried successfully to graft the 169 high pass filter circuit into this? Between C1 and C3 seems like where it would go? I see there's a lot of blank space on the PCB to possibly connect a little perfboard of it. Presuming there's no additional modifications needed... Worth the effort? Or better idea to just HPF some other way before the EQ?
Title: Re: Studer 169 EQ in API 500 format
Post by: iprovlek on December 04, 2016, 08:00:52 AM
Ok Guys!

I have this killer EQ for while now!!! This Eq is the bomb I like it a lot (right know Im planning to use DOA for input and output balancing) Forthmonkey gave me etch files for IC to DOA converter!!!

I try it with 5534, OA10, gar1731,gar2520, for me gar2520 is the best for this EQ!!! I use him a lot great for anything even mastering!!!

In beginning I have A BIG PROBLEM TO FIND POTS, so this the reason why Im writing this reply!!!!

There is no need for double POTS for this EQ ,only double POT you need it is to be 100K REV LOG for MID freq!!!

So I wanna share when can you buy POTS for this EQ....It is a little BIG but with little effort can be set very well!!!

http://www.musikding.de/Omeg-Pot-20mm-22k-lin_1

http://www.musikding.de/Alpha-Potentiometer-16mm-Stereo-100k-rev-log_1


This 16mm it is little smaller so I cut circle leg of it and solder on wires from resistors or anything that left from passive components!!!

You solder it on PCB by setting with other pots on frontpanel!!!

This Musikding is mostly for European countries, but if someone need from other countries this POTS I can send them ,cause they exist in my electronic shop in my neighbourhood!!!

Cheers
Title: Re: Studer 169 EQ in API 500 format
Post by: Greg S. on June 03, 2017, 12:08:51 PM
hi, built this unit and got offset at the outs! 12mV at the pos and -12mV at the neg. Checked the circuit and bridged c13(100uF E-Cap), worked fine after that mod!
Title: Re: Studer 169 EQ in API 500 format
Post by: Potato Cakes on June 03, 2017, 04:35:34 PM
Has anyone been able to source out knobs for the omeg pots? I'm having a hell of a time finding them.

OKW Enlclosures sells 4mm shaft collet style. Minimum order is 10. Only place I can find them easily. I have them on mine.

Thanks!

Paul
Title: Re: Studer 169 EQ in API 500 format
Post by: eriksunding on August 05, 2017, 11:48:05 AM
Hello! First time poster here, but I hope to get some help.

I'm building two of these and I just can't seem to get them to work. One is completely silent when eq is engaged and one just doesn't sound right. The frequencies are just wrong.

Something I did and later corrected was that I installed two LEDs, one for on and one for off, and I accidentally hooked the ground from those to the middle hole of the five holes connected to DOA 1 which lead to pin 4 of the bottom two 5534.
Could that possibly have destroyed some component and in that case, which?

I'd highly appreciate any help to get these things up and running.
Title: Re: Studer 169 EQ in API 500 format
Post by: Gustav on August 05, 2017, 12:01:01 PM
Hello! First time poster here, but I hope to get some help.

I'm building two of these and I just can't seem to get them to work. One is completely silent when eq is engaged and one just doesn't sound right. The frequencies are just wrong.

Something I did and later corrected was that I installed two LEDs, one for on and one for off, and I accidentally hooked the ground from those to the middle hole of the five holes connected to DOA 1 which lead to pin 4 of the bottom two 5534.
Could that possibly have destroyed some component and in that case, which?

I'd highly appreciate any help to get these things up and running.

First thing to check on these - A PBC batch had a problems with "hairs" between the connector fingers (pre 2017)

Gustav
Title: Re: Studer 169 EQ in API 500 format
Post by: eriksunding on August 05, 2017, 12:47:45 PM
First thing to check on these - A PBC batch had a problems with "hairs" between the connector fingers (pre 2017)

Gustav

I just ordered these a month ago and tested for that as well, so I don't believe that's the case.
Title: Re: Studer 169 EQ in API 500 format
Post by: Gustav on August 05, 2017, 12:54:56 PM
I just ordered these a month ago and tested for that as well, so I don't believe that's the case.

Just making sure its not an issue :-)

You can test the voltages on the circuit without the DOAs inserted to start with.

DOAs bought pre-assembled and tested, or possible trouble there too?

Gustav

Title: Re: Studer 169 EQ in API 500 format
Post by: eriksunding on August 05, 2017, 01:00:19 PM
Just making sure its not an issue :-)

You can test the voltages on the circuit without the DOAs inserted to start with.

DOAs bought pre-assembled and tested, or possible trouble there too?

Gustav

No DOAs. Just the four 5534s. But I accidentally hooked 16v to the DOA hole in the middle.
Title: Re: Studer 169 EQ in API 500 format
Post by: Gustav on August 05, 2017, 01:03:29 PM
No DOAs. Just the four 5534s. But I accidentally hooked 16v to the DOA hole in the middle.

In that case, test the voltages on the circuit without the ICs inserted...

Gustav
Title: Re: Studer 169 EQ in API 500 format
Post by: eriksunding on August 05, 2017, 01:05:01 PM
Great! I new to this so what can I expect to find?
Title: Re: Studer 169 EQ in API 500 format
Post by: eriksunding on August 12, 2017, 04:40:15 AM
I'm still battling these. I've built two and both of them are acting up in the same way. I've even had a really experienced tech look at it and he can't figure it out. He said all the voltages are looking ok and signal is passing through.

What's happening is the frequencies being all messed up. All three are acting weird.

Bass filter: if I send a 10khz sinewave in to the eq I can boost or the signal a couple of db which seems weird.

High filter: same as bass filter but the other way around. I can boost or cut a 20hz sine wave a couple of db.

Mid filter: Barley boosting when set to 150hz but the higher frequencies I choose the more I can boost.

I can't figure it out and it all just seems weird. What have I missed? What can I check for? Busted caps? Resistors?

Help!
Title: Re: Studer 169 EQ in API 500 format
Post by: eriksunding on August 13, 2017, 08:55:46 AM
Anyone? Please..
Title: Re: Studer 169 EQ in API 500 format
Post by: Gustav on August 13, 2017, 01:28:12 PM
Anyone? Please..

Its really odd that a tech could not pinpoint any problems.

If voltages are good, then you may have something set up incorrectly for the DOA vs IC configuration.
...or maybe the pots are not right...

Gustav
Title: Re: Studer 169 EQ in API 500 format
Post by: eriksunding on August 13, 2017, 03:19:34 PM
Could it possibly be the extra LED that is causing this?

The pot are the right ones and I'm not using any DOAs just the ic.
Title: Re: Studer 169 EQ in API 500 format
Post by: audiox on August 14, 2017, 06:24:59 PM
Bass filter: if I send a 10khz sinewave in to the eq I can boost or the signal a couple of db which seems weird.
The low filter peaks at low frequencies, nominally 20 Hz.

High filter: same as bass filter but the other way around. I can boost or cut a 20hz sine wave a couple of db.
The high filter peaks at high frequencies, nominally 20 kHz.

Mid filter: Barley boosting when set to 150hz but the higher frequencies I choose the more I can boost.
The mid filter peaks at 150 Hz - 7 kHz, depending on the frequency knob setting.


The test signal should match the frequency you are modifying.

I've even had a really experienced tech look at it and he can't figure it out. He said all the voltages are looking ok and signal is passing through.
Maybe it works just fine.

Title: Re: Studer 169 EQ in API 500 format
Post by: eriksunding on August 15, 2017, 02:56:25 AM
It doesnt work fine unfortunately.
If I send a 150hz test tone in to the eq and set the eq to modify 150hz nothing happens. But if I leave the eq setting to modify 150hz buy change the test tone to 3khz it's boost A LOT more.
The bass filter boost equally much at 3.6khz as it does at 20hz. That's can't be right, can it?
Title: Re: Studer 169 EQ in API 500 format
Post by: [silent:arts] on August 15, 2017, 04:16:41 AM
Check the values of the frequency setting capacitors.
Title: Re: Studer 169 EQ in API 500 format
Post by: eriksunding on August 15, 2017, 05:01:40 AM
Which is that exactly?
I've check and rechecked all of them 10 times by now. But maybe I'll just swap them. Which ones are the frequency settings capacitors?
Title: Re: Studer 169 EQ in API 500 format
Post by: eriksunding on August 15, 2017, 07:00:44 AM
I believe I solved it.
The store sent me 6k8 resistors instead of 680k. Never bothered to double check them before inserting them.
I havent tried it out yet with the right resistors, but it makes sence.
Thanks guys for your help.
Title: Re: Studer 169 EQ in API 500 format
Post by: eriksunding on August 15, 2017, 05:24:40 PM
So I replaced the faulty valued  resistors and it now works and sound amazing!! (Surprise...  ::))

Thanks Audiox and Gustav for a great eq!

Over and out.
Title: Re: Studer 169 EQ in API 500 format
Post by: Siegfried Meier on October 24, 2017, 10:41:52 AM
I'm brutally colorblind so I'm always forced to measure resistors first...it's probably a blessing in disguise.   ;D

So I replaced the faulty valued  resistors and it now works and sound amazing!! (Surprise...  ::))

Thanks Audiox and Gustav for a great eq!

Over and out.
Title: Re: Studer 169 EQ in API 500 format
Post by: kante1603 on October 24, 2017, 11:02:33 AM
I always check all parts that I'm able to check before assembly.....and I mean that.


Best,


Udo.
Title: Re: Studer 169 EQ in API 500 format
Post by: peterc on October 24, 2017, 11:57:30 AM
Learnt the hard way to check resistor values with a meter before insertion

Red and Orange can look very similar on some brands of resistors

Good to check the caps as well, gives an extra level of confidence to your builds

Peter
Title: Re: Studer 169 EQ in API 500 format
Post by: eriksunding on October 28, 2017, 05:17:03 AM
 Can I expect a volume drop if I build this eq without the transformer?
As soon as I engage the EQ the level drops significantly.
If it’s not the lack of transformer, what might it be?
Title: Re: Studer 169 EQ in API 500 format
Post by: eriksunding on November 22, 2017, 04:19:35 PM
Hello again.
Would changing the two 20k resistors to 22k make a big difference. I didn’t have any (and still don’t) 20k resistors at the time, so I popped 22k in instead. Could this cause my big volume drop?
Title: Re: Studer 169 EQ in API 500 format
Post by: Potato Cakes on December 08, 2017, 01:46:25 AM
Do you have 10K resistors? If you do just use a pair of those in series to get to 20k.

Thanks!

Paul
Title: Re: Studer 169 EQ in API 500 format
Post by: dustbro on January 23, 2018, 08:47:49 AM
Took a quick peek at the new schematic. C3 and C7 polarity appear to be reversed from the original schematic. Mistake? or is the original wrong?
Title: Re: Studer 169 EQ in API 500 format
Post by: Claudio on March 13, 2018, 04:40:07 PM
Hello everybody,

I’m about to build a pair of the 169 EQ. Since the dual 100k rev log potentiometer (P4) is a bit hard to find (apart from ordering from AML), I was wondering if I could ‘simulate’ it with a combination of a dual lin pot and a resistor. I’ve read a few pages about it, but for the life of me I can’t figure out the correct math. Could anyone in the know help me out? Which values do I need for the linear pot and the resistor? Or would I need two resistors here for the dual gang pot? And how do I go about the correct wiring?

Sorry if this has been discussed before. It’s hard to find the answer to a specific question when you have to browse dozens of pages... ;)

Thanks,
Claudio
Title: Re: Studer 169 EQ in API 500 format
Post by: Potato Cakes on March 13, 2018, 05:08:20 PM
Order the correct pots from AML. Seriously. Whatever you are trying to save as far as money will be overshadowed by the time needed to invest in research, math, and trial and error. And you'll have pair of great sounding EQ's.

Thanks!

Paul
Title: Re: Studer 169 EQ in API 500 format
Post by: Claudio on March 13, 2018, 05:16:07 PM
You might be right, Paul. On the other hand, I like to learn more about electronics, and DIYing my own rev log pot could as well be part of it. :)
Title: Re: Studer 169 EQ in API 500 format
Post by: Claudio on April 20, 2018, 04:19:50 AM
Hello everyone,

I’m sure this has been covered before, but I couldn’t find a quick answer: Why does the BOM for the Studer 169 EQ list dual-gang potentiometers for all controls, when the only pot that actually makes use of the dual-gang is P4? As for P2 and P3, pin row 1 and row 2 are directly connected on the PCB. The low shelf pot (P1) even uses the front row of pins only, i.e. there’s no path going from the second row. See attachment. So why use dual-gang pots?

If I’m right and we can replace them by simple 1-gang pots, do P2 and P3 have to be the same value as the dual-gang variants (i.e. 10k)? Or do the dual-gangs work like (variable) resistors in parallel here? Then the value for a 1-gang pot would have to be 5k instead of 10k, I guess [ Rtotal = R1 * R2 / (R1 + R2) ]. Or am I completely confused now?

On another note, how can I make use of the empty space on the PCB? This is all connected to ground, isn’t it? So if I want to install additional caps, for example, how do I prevent them from being connected to ground, when I drill some holes in there?

Sorry for the newbie questions, I’m only asking because I want to learn more about this. :)

Thanks,
Claudio
Title: Re: Studer 169 EQ in API 500 format
Post by: Vac11 on April 20, 2018, 04:42:08 AM
So why use dual-gang pots?

Mechanical reasons? Dual gang pot keep the pcb better...
Title: Re: Studer 169 EQ in API 500 format
Post by: Claudio on April 20, 2018, 04:45:56 AM
Mechanical reasons? Dual gang pot hold the pcb better...
Is this really the only reason? Then you could add some cheaper mechanical support instead...
Title: Re: Studer 169 EQ in API 500 format
Post by: Vac11 on April 20, 2018, 04:57:23 AM
Not only, there are some pots traces on the pcb that are in parallel configuration... Pleas check original schematic pots values against audiox schematic.
Title: Re: Studer 169 EQ in API 500 format
Post by: tmuikku on April 20, 2018, 07:50:52 AM
factor in quantity discount and limited component storage compartment count, audiox is a pro   ;)
Title: Re: Studer 169 EQ in API 500 format
Post by: Claudio on April 20, 2018, 10:08:23 AM
Seems like I found my answer in this old post. (https://groupdiy.com/index.php?topic=36522.msg575371#msg575371) Thanks, Mike!

Claudio
Title: Re: Studer 169 EQ in API 500 format
Post by: Chrisfromthepast on September 15, 2018, 06:30:53 PM
I finally built mine up after ordering the board and faceplate a long time ago. I got my DOA’s in the mail before the rest of the components, and soldered them directly to the pcb.
When the rest of the components came in, I rushed them onto the board and never looked at the jumpers that reside under the DOA’s but are integral to the signal path.
Double check all jumper connections, its a single sided PCB!
I thought I read through the build posts but i never saw that detail listed, so Im passing it on. Hope this helps. Great sounding eq, especially with the stock frequency on the bottom
Title: Re: Studer 169 EQ in API 500 format
Post by: Fujirume on January 20, 2019, 10:45:45 AM
Hi, can I use non centered type potentiometer? or only centered type? thanks!!
Title: Re: Studer 169 EQ in API 500 format
Post by: Potato Cakes on January 20, 2019, 04:41:22 PM
Hi, can I use non centered type potentiometer? or only centered type? thanks!!

You don't need center detent. They're just helpful for keeping unused frequency bands flat (within the potentiometer's tolerance) when the EQ is engaged.

Thanks!

Paul
Title: Re: Studer 169 EQ in API 500 format
Post by: Fujirume on January 22, 2019, 05:11:03 AM
thanks a lot!!

You don't need center detent. They're just helpful for keeping unused frequency bands flat (within the potentiometer's tolerance) when the EQ is engaged.

Thanks!

Paul