Studer 169 EQ in API 500 format

[geoff004]

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.

 

[dmp]

geoff004,
Do you have a side picture? It looks like you put in on-off-on switches to select the high / low frequencies?
Thanks

 

[dmp]

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.

 

[dmp]

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

 

[audiox]

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%.

 

[dmp]

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.

 

[dbeeson]

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.

 

[janczmok]

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

 

[Sammas]

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.

 

[audiox]

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.)

 

[Songguy]

Hi all,
Anyone happen to have an FPD file for the 500 faceplate?
Cheers,
Chris

 

[Songguy]

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.

 

[isophase]

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

 

[isophase]

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
???

 

[[silent:arts]]

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 ???

 

[isophase]

thank you Silent:arts,
i will do this

 

[isophase]

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 !

 

[MikeClev]

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...

 

[isophase]

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

 

[Indecline]

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! 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?