GroupDIY

General Discussions => The Lab => Topic started by: Sammas on July 21, 2005, 10:42:40 AM

Title: Anyone interested in some API 500 format projects??
Post by: Sammas on July 21, 2005, 10:42:40 AM
I've been thinking i'd like to tackle something small, with minimal wiring fuss... API 500 series format seems pretty straight forward, and I have some modules to work off for dimensions, etc...

I was looking at Kev's & PeterC's F110 (apparently similar or inspired by fokuswright 110). Nice clean utility preamp...

http://recording.org/users/kev/mic_pre_general.htm  (The top one...)

Looks straight forward enough and up to running on the +-16v from the rack.

I'm going to start working on the PCB layout very shortly and will also add a phase and pad switch...

Is anyone else interested in building one? I plan on putting pads just after the edge pins so they can easily be wired for operation without an API rack.


Any other projects that could run nicely off 16v?
Title: Anyone interested in some API 500 format projects??
Post by: jho-audio on July 21, 2005, 10:56:45 AM
the gssl (with external power as included in your rack scheme) might fit on a 312 style card?

I would love to see this type of project mature into a full compliment of cards - eq, comp, pres, bus, oscillator ..  This would free up the choice of packaging into a rack cage setup, stand-alone components or the ability to build a full console around such components.
Title: Anyone interested in some API 500 format projects??
Post by: Family Hoof on July 21, 2005, 11:27:30 AM
I think it's about f**kin' time the 500 was adopted for DIY. I've been looking for fine dimensions, but couldn't find any. Was going to buy or rent a module. Anyone have the info? This question has been asked here before, but without any responses.

Not interested in that pre myself, but good luck Sammas! :thumb:
Title: Anyone interested in some API 500 format projects??
Post by: Infernal_Death on July 21, 2005, 11:39:25 AM
Right now i am also working on a EQ project and thought about doing some kind of module rack case and just finish the eq's like i need them and having them in a rack case which is freely configurable.
Then i realized that fitting a single eq on such a module is nearly impossible if you don't go with dual concentric switches and pots. That's the reason i changed my plan and now i am going with the old fashioned rack cases.

However i think with pre's it's quite different as normally you have a gain switch and some small switches like 48V, polarity and phase and those should be easy to fit on a module frontpanel. I guess it gets again quite tricky if you want to make compressors with meters.

Just some food for thoughts.

Flo
Title: Anyone interested in some API 500 format projects??
Post by: drpat on July 21, 2005, 12:06:31 PM
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Title: Anyone interested in some API 500 format projects??
Post by: Family Hoof on July 21, 2005, 12:12:01 PM
Title: Anyone interested in some API 500 format projects??
Post by: jspartz on July 21, 2005, 12:57:09 PM
I am very interested in a 500 series project.   I would be willing to buy a couple circuit boards if someone can get a few extra.  I have two modules in my 11 space rack.  They need some company!  

Jason
Title: Anyone interested in some API 500 format projects??
Post by: drpat on July 21, 2005, 01:02:42 PM
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Title: Anyone interested in some API 500 format projects??
Post by: Family Hoof on July 21, 2005, 01:11:55 PM
Okay, well a 312 seems pretty boring IMHO since many forum members have already built it in other formats and you can buy the BAE or OSA versions new. But if that's what the people want, then I'm happy to contribute.

How about we start a new thread with a poll to see what designs people are most interested in? Then once a general parts list for the chosen circuit is available I can start the layout.
Title: Anyone interested in some API 500 format projects??
Post by: MikoKensington on July 21, 2005, 01:35:15 PM
What about a simple fixed frequency 3-band EQ like the API 553?  The parts would be easy to source and the layout looks kinda simple.  No fancy switches.  Just cost effective tone.  Though the 2503/4804 may be hard to get these days.
Title: Anyone interested in some API 500 format projects??
Post by: drpat on July 21, 2005, 02:08:43 PM
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Title: Anyone interested in some API 500 format projects??
Post by: fum on July 21, 2005, 02:16:05 PM
Quote from: "drpat"


I haven't seen any completed A*P*I DIY pres in the card format. I've been waiting with bated breath since BAE is no longer selling this particular card and I love the way it sounds on drums. Otherwise, I would have just bought new ones.


http://www.shinybox.com/product_info.php?products_id=33

I got these close to being drop in my lunchbox compatible, and decided I'd rather have a 1U case, as I've been told my 4 space lunchbox doesn't like a mic pre in slot 4 (noise).

API 553 is my vote.... all the way =)

That, or simply doing up a card layout with pins labeled, for the group to draw up it's own circuits on.



ju
Title: Anyone interested in some API 500 format projects??
Post by: daArry on July 21, 2005, 02:18:20 PM
Fabios' 312 layout is a standard 100x160mm eurocard as far as i know - I'm doin mine the same way so I can fit them in a modular 3U vero rack chassis...KM6 type range I think. It's a nice solution and the fabrication of the chassis is pretty straightforward...

You can use fully enclosed metal modules or just slide the pcb bare on the guide rails, then alls you need is a tiny frontpanel made up for the controls n whatnot...

http://www.farnell.com/datasheets/7561.pdf
Title: Anyone interested in some API 500 format projects??
Post by: Carl_Huff on July 21, 2005, 04:48:26 PM
The ToneLux VRack looks rather interesting.  Anybody familiar with this product?  On paper it looks like a good platform to grow a complete modular system.  Anybody have a schematic?  What do they cost?
Title: Anyone interested in some API 500 format projects??
Post by: matta on July 21, 2005, 05:38:45 PM
Guys,

I was actually talking to a fellow board member about this the other day, it is not the first time it has been mentioned here before. I think it is awesome and a great way forward!

Maybe the designed of some of the current projects would let others have a go and redoing some layouts to fit these specs. Imagine a rack with a pultec, opto comp EQ and pres!

And if you run out you can just pop out the modules and put in a new one! Brilliant idea!

Kudos... now the thing is how do we all agree on a standard. I like the idea of Vero rack, but you got to think longevity as well. Will the Vero rack be around forever, at least the 500 series racks seems to be popular and both BAE and OSA make racks as well, plus you can get them on Ebay.

What do you think? I like the idea of the front panels, we could maybe standardize them for the various projects, maybe rope on Frank and his wisdom ;-) I'm sure they will be cheaper to do than say a 2 or even 1U faceplate.

Keep up the creative thoughts! I for one hope this comes to fruition.

Cheers

Matt
Title: 550a
Post by: thestudio on July 21, 2005, 06:58:28 PM
I'm interested in about 8 cards of the 312 pre if they fit inside a 500 chassis.

Also, I have some 550a cards, face plates, chassis and parts that I never had time to finish but would add here in this thread.......Does anyone have a complete 550a?   :thumb:
Title: Anyone interested in some API 500 format projects??
Post by: Sammas on July 21, 2005, 10:10:16 PM
Quote from: "jho-audio"
the gssl (with external power as included in your rack scheme) might fit on a 312 style card?

I would love to see this type of project mature into a full compliment of cards - eq, comp, pres, bus, oscillator ..  This would free up the choice of packaging into a rack cage setup, stand-alone components or the ability to build a full console around such components.


I have done a few mono GSSL 500 format layouts but they still need a bit of work with specific components in mind. Particularly the front panel switches and an LED GR meter so that it can fit nicely done one side of the faceplate... Im also open to any thoughts on how to obtain a stereo link, remembering that there is only one input and output for each card...

I'd much rather see some alternate gear being made into 500 series cards instead of just clones of whats already avaliable in the format. I guess it is open to a lot of design possibilities though.

fum's idea of getting together just a 500 series blank card with labelled pinouts could allow people to create there own and possibly share it with everyone else.
Title: Anyone interested in some API 500 format projects??
Post by: Family Hoof on July 22, 2005, 01:23:44 AM
Quote from: "Sammas"
I'd much rather see some alternate gear being made into 500 series cards instead of just clones of whats already avaliable in the format. I guess it is open to a lot of design possibilities though.

fum's idea of getting together just a 500 series blank card with labelled pinouts could allow people to create there own and possibly share it with everyone else.

I agree! Adopt the 500 format because it is an ESTABLISHED standard, compatible with a lot of long-standing and widely used commercial gear.
Title: Anyone interested in some API 500 format projects??
Post by: drpat on July 22, 2005, 02:14:32 AM
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Title: Anyone interested in some API 500 format projects??
Post by: Sammas on July 22, 2005, 02:35:40 AM
Quote from: "drpat"
Ok, so I measured, and here's what I came up with.

entire card length = 108mm
entire card width at it's widest point = 70mm
connector width = 64mm
connector depth = 13mm
board thickness = 2mm
connector traces = 2mm
trace spacing = aprox. 2mm
1st and last trace begin 3mm from edge of connector

I'm drawing this up now for better understanding.



Cool work drpat! I know the pins are 3.96mm apart centre to centre if you wanted the exact measurement.
Title: Anyone interested in some API 500 format projects??
Post by: drpat on July 22, 2005, 02:49:51 AM
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Title: Anyone interested in some API 500 format projects??
Post by: drpat on July 22, 2005, 02:51:13 AM
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Title: Anyone interested in some API 500 format projects??
Post by: Sammas on July 22, 2005, 02:52:17 AM
Quote from: "drpat"
Ok, so I measured, and here's what I came up with.

entire card length = 108mm
entire card width at it's widest point = 70mm
connector width = 64mm
connector depth = 13mm
board thickness = 2mm
connector traces = 2mm
trace spacing = aprox. 2mm
1st and last trace begin 3mm from edge of connector

I'm drawing this up now for better understanding.



I have a pair of OSA'a which look a lot larger than whats written. Are those measurements for a 500series card or from an original 312?

Im sure we can use larger cards just as long as they fit in the chassis with the appropriate pin outs... API has there 500 series modules measured as 1.5"x5.25"x6" deep... The PCB's, give an inch to include the knobs and vertical space for  the thumbscrews and mounting bracket can be pretty big it appears.

I can measure the card size of my OSA but that won't be until monday or tuesday when im next in my little studio...
Title: Anyone interested in some API 500 format projects??
Post by: drpat on July 22, 2005, 02:58:36 AM
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Title: Anyone interested in some API 500 format projects??
Post by: Sammas on July 22, 2005, 03:03:17 AM
Quote from: "drpat"
Quote from: "Sammas"


I have a pair of OSA'a which look a lot larger than whats written. Are those measurements for a 500series card or from an original 312?

Im sure we can use larger cards just as long as they fit in the chassis with the appropriate pin outs... API has there 500 series modules measured as 1.5"x5.25"x6" deep... The PCB's, give an inch to include the knobs and vertical space for  the thumbscrews and mounting bracket can be pretty big it appears.

I can measure the card size of my OSA but that won't be until monday or tuesday when im next in my little studio...


This is just the card, sans the metal bracket that extends the card and holds the front panel on.


oh ok! gotcha!

Any chance of a dimension from the back of the faceplate to the far end of the edge pins?

I was thinking about using a PCB a bit larger... particular for something like a mono GSSL...

like this...

(http://www.oldschoolaudio.com/images/mp1_new.gif)
Title: Anyone interested in some API 500 format projects??
Post by: drpat on July 22, 2005, 03:11:47 AM
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Title: Anyone interested in some API 500 format projects??
Post by: Sammas on July 22, 2005, 03:25:56 AM
Quote from: "drpat"
Quote from: "Sammas"

oh ok! gotcha!

Any chance of a dimension from the back of the faceplate to the far end of the edge pins?




Aprox 153mm front to back
face plate is 133mm x 38mm

so it sounds like bigger cards will fit in the same rack!



Excellent! thanks a lot!  It appears there is quite a decent amount of space to layout everything out...
Title: Anyone interested in some API 500 format projects??
Post by: MikoKensington on July 22, 2005, 03:40:39 AM
Just something that seems like a very do-able avenue.  The 553.

From our strangeandbouncy  (but cleaned up by me)
http://img.photobucket.com/albums/v473/MikoKensington/API553.jpg

From our boy, Seth.
http://img.photobucket.com/albums/v473/MikoKensington/553c.jpg
http://img.photobucket.com/albums/v473/MikoKensington/553b.jpg
http://img.photobucket.com/albums/v473/MikoKensington/553a.jpg
Title: Anyone interested in some API 500 format projects??
Post by: drpat on July 22, 2005, 06:57:59 AM
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Title: Anyone interested in some API 500 format projects??
Post by: drpat on July 22, 2005, 07:27:42 PM
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Title: Anyone interested in some API 500 format projects??
Post by: MikoKensington on July 22, 2005, 07:40:45 PM
(http://www.soniccircus.com/store/graphics/00000001/bignails/api553_big.gif)

Essentially a fixed frequency 550.
Title: Anyone interested in some API 500 format projects??
Post by: strangeandbouncy on July 22, 2005, 07:44:17 PM
All ready there guys!


     but only as a hashed up bodge, with paxolin as a front panel! I have built a pair of 553 based passive eq's. 6 positions switchable HF from @10k to 24kHz thatv fit my API rack. Unbelievable! I am saving up for a multi-value inductor for LF Sowter loadsa dosh, but what I want. again, i want to have switchable frequencies. Other option is one frequency as a shelf, and switchable bells using one value of inductor, say cinemag. i have  no room for MF on my front panel, but i've added two more frequencies on my original 553 by doubling/halving the capacitance in the mid-range. Sounds great to me. so @5kHz/2k5Hz/1k2Hz, and bells sound similar(unmeasured). I believe Mr Wolff said that this was practical . . .


       Sadly no phantom available on my rack, cos its a BBE rack. Bah! I wish I still had access to the BBEQ;s that I used 15 years ago. full of chips, but SO sweet! API 500 sized. Never seen anymore. I would love to clone some of them . . . . .

     I'm with them lot above me on the page!


       ANdyP
Title: Anyone interested in some API 500 format projects??
Post by: drpat on July 22, 2005, 07:56:10 PM
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Title: Anyone interested in some API 500 format projects??
Post by: strangeandbouncy on July 22, 2005, 08:00:25 PM
553 is NOT fixed freq 550.

    they are very different. 553 is passive, 550 active. it is easy to make a 553 with variable frequencies. 550 would ba a bastard to do! SO tightly packed, and still bein made . . . .albeit as 550b. Also, 553 needs only one [email protected]@[email protected](see Fabio) If you are not familiar with passive eq;s, check this one out, even if it only has fixes frequencies. SO tight in da bottm, SO smooth at da top . . . .
Title: Anyone interested in some API 500 format projects??
Post by: strangeandbouncy on July 22, 2005, 08:03:39 PM
how 'bout an optical comp like Forssell or What Comp? should fit. i think it would be very hard to fit GSSL without v v expensive dual shafted pots/switches due to size . . . .
Title: Anyone interested in some API 500 format projects??
Post by: drpat on July 22, 2005, 08:04:12 PM
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Title: Anyone interested in some API 500 format projects??
Post by: strangeandbouncy on July 22, 2005, 08:11:31 PM
drpat,

   my home brew passive 553's with switchable frequencies have the most incredible HF I have EVER heard outside of a mastering room . . . . pure AIR at 24kHz. Awesome on vocals or across mixbus . . . . I can't afford to build proper front panels, not because of cash, but because i NEED them so bad . . . . .
Title: Anyone interested in some API 500 format projects??
Post by: drpat on July 22, 2005, 08:18:15 PM
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Title: Anyone interested in some API 500 format projects??
Post by: strangeandbouncy on July 22, 2005, 08:24:49 PM
much too embarassed to post piccies! such a lash-up!
Title: Anyone interested in some API 500 format projects??
Post by: drpat on July 22, 2005, 08:32:23 PM
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Title: Anyone interested in some API 500 format projects??
Post by: Family Hoof on July 22, 2005, 08:32:28 PM
So what do we do about inductors and output trafo for this 553? What are you using, strangeandbouncy?

As I already told Miko, I think I can make a PCB layout for this very easily once a BOM and measurements have been presented. Unfortunately I don't have access to a 2520 or any of these parts right now, but maybe next month. If someone wants to lend me one for a week I can copy the board almost exactly. Gerbers and etch-your-own pdf to be posted here upon completion.
Title: Anyone interested in some API 500 format projects??
Post by: drpat on July 22, 2005, 08:49:31 PM
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Title: Anyone interested in some API 500 format projects??
Post by: Sammas on July 22, 2005, 09:42:25 PM
...I like the idea of the 553 as first project  :thumb:

I'll continue the working on the layout for a mono GSSL... it'll be a few weeks though.
Title: Anyone interested in some API 500 format projects??
Post by: drpat on July 23, 2005, 12:56:33 AM
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Title: Anyone interested in some API 500 format projects??
Post by: Sammas on July 23, 2005, 04:17:24 AM
Quote from: "drpat"
Quote from: "Sammas"
...I like the idea of the 553 as first project  :thumb:


For sure, minimal components, 2520 boards already available, schematic available, good transformer subs available, sounds like the PCB will be the most difficult part. Anybody else want in?

Shucks, I guess my dreams of having another 4 of the pres just got shot dowm by myself!



I'd be happy to work up some PCB layouts, but it would be handy if someone could source exact parts (well, none R & C parts). DOA pinouts are pretty straight forward, as too are the 10K pots (i think they are 10K, i haven't looked at the schem since yesterday) but i've never used inductors before so if someone could point me to an appropriate data sheet with pin out dimensions i'd be happy to get to work...  

The switch looks like a 4P2T switch which i can probably put in pin placements for a couple of different types.

The Transformer... there is the Profile version, and i assume lundahl might have one that does the same. Joe from JLM has one too. He might be willing to give us a group discount if we can get a few people in for a purchase...
Title: Anyone interested in some API 500 format projects??
Post by: drpat on July 23, 2005, 05:14:18 AM
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Title: Anyone interested in some API 500 format projects??
Post by: peterc on July 23, 2005, 09:55:39 AM
Hi all

On the 533 EQ:

Can anyone tell me what the components should be that go between points 6 & 7 (marked Gain Trim) ?

Many thanks
Peter
Title: Anyone interested in some API 500 format projects??
Post by: drpat on July 23, 2005, 11:52:27 AM
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Title: Anyone interested in some API 500 format projects??
Post by: fum on July 23, 2005, 12:26:39 PM
man, I can't jump in on this as I'll be on a boat for a week starting tonight, but looks like I'll have some cool stuff to look forward to.

On the inductors, you may want to leave a somewhat widely spaced pair fo pads to mount the two wires of the inductor to.  something on the 15mm range.

In this fashion, people can wind their own inductors, or if you can find a stocked part somewhere for the inductors, that could be cool too.

Regards

ju
Title: Anyone interested in some API 500 format projects??
Post by: drpat on July 24, 2005, 07:12:01 AM
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Title: Anyone interested in some API 500 format projects??
Post by: Sammas on July 24, 2005, 07:57:05 AM
Quote from: "drpat"
Quote from: "fum"
man, I can't jump in on this as I'll be on a boat for a week starting tonight, but looks like I'll have some cool stuff to look forward to.

On the inductors, you may want to leave a somewhat widely spaced pair fo pads to mount the two wires of the inductor to.  something on the 15mm range.

In this fashion, people can wind their own inductors, or if you can find a stocked part somewhere for the inductors, that could be cool too.

Regards

ju



Fukem (oops, did I just say that) let's wind our own! Is this DIY or DIT (do it themselves)? Personally, I like bragging about making my own components! Even if it's just a 0? resistor. HaHa!



 :shock:  

Thats probably a little more than im willing to do... but i can leave the space needed...  Anyone know where there is a data sheet or pin dimensions for the inductors we need?
Title: Anyone interested in some API 500 format projects??
Post by: TomWaterman on July 24, 2005, 09:29:03 PM
Hey guys - good idea for the bucket modules.

Peter, according to some datasheets for the API5xx eq modules at danalexander, pins 6 & 7 marked gain trim (I guess on all eq modules) are NC = not connected.....

Anyways just thought I'd mention it. Not been with it lately.

Does anyone know if the 553 will accept an unbalanced input to the Hi connection with the Lo in grounded? I'm trying to cook up a 312/553 hybrid...

Cheers Tom
Title: 312
Post by: thestudio on July 25, 2005, 11:20:16 AM
Nobody build 312 pcb's for 500 series rack??????  :idea:
Title: Re: 312
Post by: Family Hoof on July 25, 2005, 12:15:41 PM
[EDIT] Didn't materialize
Title: Anyone interested in some API 500 format projects??
Post by: Sammas on July 25, 2005, 11:31:28 PM
Ok, i just measure my OSA's. Probably the biggest PCB that you'll fit into a 500 series rack. Its 115mm high and 150mm from the faceplate to the end of the edge pins.


drpat... regarding input transformers on the 553... I was under the assumsion that they'd be 10K:10K?

I've got the rough layout down, bar the different variations for input/output trannys and the inductors but i've left plenty of room to play so i'll add it in when i get an idea of what people would like...
Title: Anyone interested in some API 500 format projects??
Post by: drpat on July 26, 2005, 01:54:05 AM
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Title: Anyone interested in some API 500 format projects??
Post by: strangeandbouncy on July 26, 2005, 02:15:32 AM
Sorry, Guys,
   
    I somehow missed your comments/questions. i used empty 325 line amp cards, Fabio's 2520RC, Profile tx's, Paxolin board for front panel(!), and fastened it into my Lunchbox with Stickytape!!! THAT's why i don't wanna show! I have only built the HF part so far, with switched caps to vary freq from @10kHz up to @24kHz. Inductors for LF, I have looked at a Sowter multitapped to give variable Freq, but too pricey for me right now!. Cheapest option seems to be a Cinemag 2H at @20$. This would give @80-100Hz shelf, and I was going to try making a 1xFreq Shelf/Switchable Bell(by adding different caps in series). At the mo, I cannot affrod either the inductor, or to take them out of the rack for completion, since they ROCK on the top end of vocals, drum bus, or mix.
   I don't know why you would want to add extra cost/reduced space by adding an input tranny. sounds amazing to me as is, and I have never had a noise problem. You should be giving 'em a hefty old level in my book!

     Keepin' it Real for da peepul . . .


      ANdyP
Title: Anyone interested in some API 500 format projects??
Post by: drpat on July 26, 2005, 03:13:51 AM
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Title: Anyone interested in some API 500 format projects??
Post by: TomWaterman on July 26, 2005, 08:14:48 AM
Andy duuuuude are you running yours unbalanced or balanced in?
I'd like to see your botch job anyway - I'm sure its coolios.

If peeps were going to turn this into a full-blown project what would be the preference for inductors....wilco, cinemag or sowter?

-Tom
Title: Anyone interested in some API 500 format projects??
Post by: Sammas on July 26, 2005, 08:59:27 AM
Quote from: "TomWaterman"
Andy duuuuude are you running yours unbalanced or balanced in?
I'd like to see your botch job anyway - I'm sure its coolios.

If peeps were going to turn this into a full-blown project what would be the preference for inductors....wilco, cinemag or sowter?

-Tom


Yeah! I'd still like to see photos too! Everyone has a "black sheep" in there studio...



Tom, I've got the PCB layout pretty much done except for the inductors and some tranny options. What do you want to use?

It would be cool to get some tapped inductors for switchable frequencies... Is it as simple as i think it is? just put a single pole multiple position switch between the seperate "tappings"... so each time you turn the switch it shortens the length of wire windings in the inductor that are being used??  :?:   Strangeandbouncy? maybe you can clue me in?

I'm actually swinging towards tapped cinemags... or if not... maybe we could try and organise a group order for cinemag trannies and inductors. They might be able to give us a deal.

regarding transformers...

here is a small list i've put together but im not sure if they are all appropriate for our purposes.

- OEP Z3002E (optional input)
- Jensen Jt-11p-1 (optional input)
- Lundahl LL1540 (optional input)
- Profile 4804 (output)
- Sowter 9825 (output)
- API 2503 (output), Dan Alexander has 20 for sale...
- Cinemag CMOB-2S (output) (SCA are using this instead of the 4804).

any others?
Title: Anyone interested in some API 500 format projects??
Post by: TomWaterman on July 26, 2005, 09:51:06 AM
Hey sammas thats nice and quick. I'm wanting to do a layout for a pre/eq on one board but yours sounds cool.

I think you are correct, concerning the inductors and switching. If you used wilco inductors you could have separate ones for each freq, as opposed to having a tapped job. I think this would allow for more closely matched curves at all freqs....maybe, maybe not a good thing.

As andy said originally, the Sowter LF Neve inductor has three taps and should give something like 50, 100 and 180Hz on the LF. Its expensive at approx 35 quid.

The cinemag is cheaper but not tapped I think just 1.2H? So different caps will be switched for the freq and the curves will change slightly I think(?).

Wilcos will take up more board space and I'm not sure about purchasing from them but they would have enough values for both the LF and MF....

3 LF freqs
6 MF freqs
3 HF freqs

would be cool and require two 1 pole 3 way rotaries and a 1 pole 6 way...lorlins would do.

-Tom
Title: Anyone interested in some API 500 format projects??
Post by: TomWaterman on July 26, 2005, 10:12:44 AM
Two Sowter inductors for LF:

T1230 - 9805. 2H, tapped at 1.2H and 0.7H.
T1530 - 9312. 2H, tapped at 1.1H and 0.45H.

With PCB pins they both cost 39.83 GBP....a lot of money. I expect three Wilco inductors would cost less than that. They would also allow more scope for tailoring freq choices as the board space would mean builders are not forced into using the expensive tapped iron on the PCB with only one set of values.

-Tom
Title: Anyone interested in some API 500 format projects??
Post by: Sammas on July 26, 2005, 10:22:15 AM
hmmm... the only problem i can see is the lack of real estate. The card is only 115mm by 130mm one you take into account the edge pins. Plus the DOA and Tranny or two...

It might be a tight squeeze on the front panel to fight 3 rotary swtiches and 3 pots.

I'll have to ponder it for a bit... the best thinking i do is when i am about to go to sleep which is shortly.

I'll chime in tomorrow morning... (well in about 8 hours or so).
Title: Anyone interested in some API 500 format projects??
Post by: TomWaterman on July 26, 2005, 11:14:50 AM
The largest Wilco appears to be 1H BSL series and I'm not sure if that will be a good match. Its 74ohm DC which is similar to the Sowters at the largest tap but it only handles 56mA if I understand right.

Is that good or bad?

Also inductance is measured at 1kHz. Is it likely that it will be higher or lower at lower freqs such as the 100Hz in this EQ. Anyone know, CJ?

-Tom
Title: Anyone interested in some API 500 format projects??
Post by: drpat on July 26, 2005, 11:35:51 AM
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Title: Anyone interested in some API 500 format projects??
Post by: TomWaterman on July 26, 2005, 12:28:28 PM
Sorry yeah I wasn't thinking about the 500 series format when I suggested lorlins....however you can get small Elma's and Grayhills (which API uses) in those configs direct from Farnell.

Trouble is a $1 switch just became a $10 one....

Tekay had some Neve EQs which used toggles, and its a good plan if only a couple of freqs are used I guess.

-Tom
Title: Anyone interested in some API 500 format projects??
Post by: drpat on July 26, 2005, 01:16:06 PM
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Title: Anyone interested in some API 500 format projects??
Post by: Family Hoof on July 26, 2005, 01:32:35 PM
Quote from: "drpat"
Can you get us a part number on those switches?

I'm not sammas, but I believe he's talking about Elma type 01 and Grayhill series 50 or 56

..or if we wanted right angle PCB mount it would be Elma type 08 and Grayhill series 71
Title: Anyone interested in some API 500 format projects??
Post by: drpat on July 26, 2005, 01:59:27 PM
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Title: Anyone interested in some API 500 format projects??
Post by: TomWaterman on July 26, 2005, 02:01:17 PM
Yep dems the ones.....just checked they are almost $20...

Actually a way to save cost would be to have 3pole toggles on LF and HF and a 1pole 6way Elma 01 series for 6 MF freqs. That would be a good compromise of features and size / cost.

BTW are those linear 10k pots centre detented for 0dB cut/boost or what? I can't seem to find any centre tapped pots.

-Tom
Title: Anyone interested in some API 500 format projects??
Post by: TomWaterman on July 26, 2005, 02:07:03 PM
oopps I mean the elmas and grayhills not the digikey part you picked above.

You would need the 2 pole switch for MF I think if you only use a tapped inductor and needed to switch taps and caps at the same time. With one inductor and switched caps only, a 1 pole switch would work after the inductor switching a diff combo (cap / resistor) to ground (I think).

You'd need a 2P3T toggle for 3 LF positions and a 1P3T toggle for HF as I understand it.

-Tom
Title: Anyone interested in some API 500 format projects??
Post by: Family Hoof on July 26, 2005, 02:21:36 PM
DP3T can also cost close to $20
Title: Anyone interested in some API 500 format projects??
Post by: drpat on July 26, 2005, 02:31:10 PM
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Title: Anyone interested in some API 500 format projects??
Post by: MikoKensington on July 26, 2005, 02:33:11 PM
I like the idea of fixed HF and LF with a selectable mid.  It still keeps it simple and relatively cheap.  My enthusiasm for the 553 idea, was based on two factors.  Cheap and simple.
Title: Anyone interested in some API 500 format projects??
Post by: drpat on July 26, 2005, 02:50:00 PM
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Title: Anyone interested in some API 500 format projects??
Post by: TomWaterman on July 26, 2005, 02:55:35 PM
I believe it is 100Hz, 3kHz and 10kHz for the 553 original.....

May as well go for the Cinemag 1.2H inductor if you want a fixed freq LF.

-Tom
Title: Anyone interested in some API 500 format projects??
Post by: drpat on July 26, 2005, 03:08:22 PM
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Title: Anyone interested in some API 500 format projects??
Post by: TomWaterman on July 26, 2005, 03:33:32 PM
Not exactly, the original has a 1H inductor for 100Hz. It will be trial and error a little due to the fact the inductance will differ at 100Hz compared to the value given by manufacturers (taken at 1kHz).

1.2H and an appropriate cap will make 100Hz with a diff. curve I think...but don't quote me on that I'm a noobie!

Tom
Title: Anyone interested in some API 500 format projects??
Post by: peterc on July 26, 2005, 04:10:08 PM
What about an Opamp labs inductor. 800mH should get you close.

http://www.opamplabs.com/87.htm

Cheap too.

Peter
Title: Anyone interested in some API 500 format projects??
Post by: MikoKensington on July 26, 2005, 04:19:54 PM
Quote from: "peterc"
Cheap too.


I like your style.
Title: Anyone interested in some API 500 format projects??
Post by: Family Hoof on July 26, 2005, 04:31:55 PM
I'm pretty clueless when it comes to inductors, so bare with me here...

but shouldn't we be considering things other than just the 1H value? like well... uhhh... let's see... um... core material? winding pattern? Q factor? The "pure air" and other fabulous things that strangeandbouncy had to say about the 553 could disappear with the use of a different part. Anyone who's heard the difference between a cheap inductor and a good inductor in an EQ knows what I'm talking about. One is unpleasant to listen to while the other one sounds awesome, both possessing the same inductance value.

That said, I think we need to either A) shell out the cash for something that's guaranteed to sound great, regardless of how similar it sounds to the original A*P*I parts, OR B) get an original 553 and send the inductors to Jenrick for analysis so we'd then have the proper data to be shopping for a substitute.

If it's going to sound like it's cheap pricetag then why the f**k would want to build it? Because when it comes to coils you are almost always paying for performance. Just some food for thought. :guinness:
Title: Anyone interested in some API 500 format projects??
Post by: MikoKensington on July 26, 2005, 04:43:12 PM
I hear what your're saying.  Component quality becomes crutial in a passive circuit.  But there has to be a balance or a bargain.
Title: Anyone interested in some API 500 format projects??
Post by: drpat on July 27, 2005, 01:07:49 AM
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Title: Anyone interested in some API 500 format projects??
Post by: Sammas on July 27, 2005, 01:25:42 AM
"service unavaliable"  :evil:


Anyway... I hear what you are saying F.H! I don't mind paying a more for inductors if its going to make it much nicer to use... I'm not very fussed about how accurate it is to the original either...


Last night in the dying stages of awareness I started thinking about push/pull & push/push Pots... you know, the ones with switches in them. They could be used for the LF & HF frequencies to get 2 different frequenies choices... It is probably just as easy and cheaper to do it with a simple toggle switch though. If we used the 1.2H from cinemag you could just switch cap values to vary the LF curve... same as the HF... (strangeandbouncey??)


I wonder how the Cinemag CML-150T would fair for the MF. Here's a diagram off there website indicating the tappings

(http://www.cinemag.biz/inductors/images/CML-150T.gif)

The original value for the 553 MF inductor is 100mH isnt it?


hmmm im not sure. I think i might order a cinemag 1.2H inductor as well as there CMOB-2 output trannies (2 birds with one stone as they say)... Try and put the LF part together over the next week or two... as well as the HF...
Title: Anyone interested in some API 500 format projects??
Post by: Family Hoof on July 27, 2005, 01:31:25 AM
Isn't the all steel CMOB-2 their 2503 equivalent? If you get dimensions for the PCB holes for that thing please let me know.
Title: Anyone interested in some API 500 format projects??
Post by: Sammas on July 27, 2005, 01:36:56 AM
Quote from: "Family Hoof"
Isn't the all steel CMOB-2 their 2503 equivalent? If you get dimensions for the PCB holes for that thing please let me know.



yeah it is... SCA have started using it since the little Profile/Api dispute started...

Will do...
Title: Anyone interested in some API 500 format projects??
Post by: Family Hoof on July 27, 2005, 02:06:39 AM
Quote from: "Sammas"
Last night in the dying stages of awareness I started thinking about push/pull & push/push Pots... you know, the ones with switches in them.

I searched all the U.S. catalogues for a push-pull pot for my last project and could only find the linear Alpha ones that Mouser stocks. It was DPDT, which was great, but also a cheap piece of crap and pretty unusable in practice.

These folks (http://www.potentiometer.com/) can do custom push-pull CP pots to spec, but I'm not sure what prices would be like. Probably high. I got this in an e-mail -- "We can assemble most requirements within 3 weeks and we have no minimum order; $50.00 set up charge on less than 25 pieces"

[EDIT] It is a good idea, though! Certainly much cheaper than dual concentric. If you pick good frequencies then you only need two, i.e. 60 and 120Hz lo shelf, 10k and 16kHz hi shelf.
Title: Anyone interested in some API 500 format projects??
Post by: drpat on July 27, 2005, 02:21:11 AM
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Title: Anyone interested in some API 500 format projects??
Post by: peterc on July 27, 2005, 02:43:33 AM
Quote
but shouldn't we be considering things other than just the 1H value? like well... uhhh... let's see... um... core material? winding pattern? Q factor?


I must admit I have not tried Opamplabs stuff, but from what I have heard, it is quality stuff. It is healthily sized & has a good Q factor. Pity they do not give a DC resistance, but it looks like a good product.

The only way to be sure is to try one out :wink:

Quote
Isn't the all steel CMOB-2 their 2503 equivalent?


Anyone know the price of these units?

Many thanks
Peter
Title: Anyone interested in some API 500 format projects??
Post by: Sammas on July 27, 2005, 03:06:29 AM
Peter, I don't know the cost but I do know they are most expensive than the Profile 4804. I've sent an email about buying one so i'll let you know when i get the reply.


drpat, you're right... it is probably easier to stick closer to the original in terms of having fixed frequencies. There is a fair amount of space left on the PCB for people to modify there EQ to suit there needs. It will be a lot easy to just start with a working fixed band eq and add your variations then to try and create something that is going to suit everyone...
Title: Anyone interested in some API 500 format projects??
Post by: drpat on July 27, 2005, 03:23:57 AM
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Title: Anyone interested in some API 500 format projects??
Post by: Sammas on July 27, 2005, 03:29:41 AM
Quote from: "drpat"
Quote from: "Sammas"
drpat, you're right... it is probably easier to stick closer to the original in terms of having fixed frequencies. There is a fair amount of space left on the PCB for people to modify there EQ to suit there needs. It will be a lot easy to just start with a working fixed band eq and add your variations then to try and create something that is going to suit everyone...


I'm only talking about the HF and LF bands. I still think the selectable mid band would be a good Idea for the basic build. The extra Grayhill rotary switch is only $11, and there would be plenty of room on the panel for it. What do you think?



Im keen as mustard... Just point me to a source of appropriate inductors and im there  :wink:  :green:

 :thumb:

It seems it is the last remaining hurdle...
Title: Anyone interested in some API 500 format projects??
Post by: Sammas on July 27, 2005, 03:36:06 AM
Sowter has a few that could fit the MF nicely.

9815 Neve T1280 EQ Inductor
A 200mH inductor tapped at 160, 100, 80, and 50 mH

9858 Pultec MEQ-5 EQ Inductor
A 420 mH inductor tapped at 420/277/145/108/61/34 mH

9325 Pultec EQP-1A EQ Inductor
A 150 mH inductor tapped at 150/82/68/47/33/27 mH


But they aren't cheap  :mad:
Title: Anyone interested in some API 500 format projects??
Post by: drpat on July 27, 2005, 04:00:53 AM
...
Title: Anyone interested in some API 500 format projects??
Post by: drpat on July 27, 2005, 04:12:18 AM
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Title: Anyone interested in some API 500 format projects??
Post by: Sammas on July 27, 2005, 04:24:51 AM
the MEQ-1 EQ uses a 6 tap inductor in series with 11 different cap values to get the 11 different frequencies... In the MEQ-1 the 11 mid frequencies range from 200hz right up to 7khz. It covers quite some ground. You could use just 5 or 6 caps to get 6 different mid freq's.


Or there is the CEQI as you suggested if someone is willing to calculate some values?
Title: Anyone interested in some API 500 format projects??
Post by: drpat on July 27, 2005, 04:44:18 AM
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Title: Anyone interested in some API 500 format projects??
Post by: Sammas on July 27, 2005, 04:55:01 AM
Quote from: "drpat"
Quote from: "Sammas"
the MEQ-1 EQ uses a 6 tap inductor in series with 11 different cap values to get the 11 different frequencies... In the MEQ-1 the 11 mid frequencies range from 200hz right up to 7khz. It covers quite some ground. You could use just 5 or 6 caps to get 6 different mid freq's.


Or there is the CEQI as you suggested if someone is willing to calculate some values?


I've never used an MEQ-1. Are you talking about the MEQ-5?

Anyway, I calculated some cap values for the 9858 (MEQ-5) inductor and came up with the following.

420mH tap- 1.5mfd = 200Hz
277mH tap- 572nF = 400Hz
145mH tap- 357nF = 700Hz
108mH tap- 26nF = 3k
61mH tap- 17nF = 5k
34mH tap- 12nF = 8k

These are just suggested frequencies. Also, I may be waaaay off considering I've never done this before, so somebody may need to check my work.



yes, yes... i mean the MEQ-5  :oops:

There will be 6 caps spaces on the board anyway, so people could choose what they'd like to use.


Nice work! :thumb:
Title: Anyone interested in some API 500 format projects??
Post by: Sammas on July 27, 2005, 04:59:27 AM
Nice work indeed!

People can choose there values with this...

http://www.opamplabs.com/cfl.htm


 :thumb:
Title: Anyone interested in some API 500 format projects??
Post by: drpat on July 27, 2005, 05:41:50 AM
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Title: Anyone interested in some API 500 format projects??
Post by: Sammas on July 27, 2005, 06:07:31 AM
Quote from: "drpat"
Quote from: "Sammas"


There will be 6 caps spaces on the board anyway, so people could choose what they'd like to use.


Nice work! :thumb:


It may be a good idea to put an extra cap space on each inductor tap for anybody who really wants to go there!

Do you have everything you need to continue, Sammas?



Will do!

Yup! Looks like we are set!  I'll put in an extra cap space or two if there is enough room for the LF & HF just incase people want to add a toggle switch for a little variation!

 :thumb:
Title: Anyone interested in some API 500 format projects??
Post by: drpat on July 27, 2005, 06:39:02 AM
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Title: Anyone interested in some API 500 format projects??
Post by: Sammas on July 27, 2005, 08:30:56 AM
Guys, 2-3week lead time on the Sowter MEQ-5 inductors... It appears they are made to order...  Seem like a good bunch though. Real quick on the replies.


Still waiting for a reply on the Cinemag stuff but i'll let you guys know how much they are...
Title: Anyone interested in some API 500 format projects??
Post by: drpat on July 27, 2005, 08:58:33 AM
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Title: Anyone interested in some API 500 format projects??
Post by: Sammas on July 27, 2005, 09:26:14 AM
Quote from: "drpat"
Hey Sammas,

Where are you located, and are you working on a BOM for this?

-Patrick



I'm in Sydney...

I was going to do a BOM as well...

I'm trying to find some appropriate, yet easily accessable switches for bypass and LF & HF frequencies so everyone can source them.

I was thinking these from digikey http://rocky.digikey.com/scripts/ProductInfo.dll?Site=US&V=401&M=PHA4UEE

I dunno... they are really cheap, but i dunno how good they'll be  :?

It appears the E-switch discontinued the ones that i wanted to use  :mad:
Title: Anyone interested in some API 500 format projects??
Post by: drpat on July 27, 2005, 09:55:32 AM
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Title: Anyone interested in some API 500 format projects??
Post by: drpat on July 27, 2005, 10:56:03 AM
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Title: Anyone interested in some API 500 format projects??
Post by: TomWaterman on July 27, 2005, 12:11:15 PM
Coming along nicely I see guys.

I just thought I'd mention this as I didn't see it addressed from earlier on. I agree that different inductors will totally change the sound.  Matthias's excellent Pultec inductor test illustrated this nicely. Thats why I suggested the Wilco's as they came out best in his round up....seemed smoothest.

Anyway, someone was mentioning the 'air' that Andy was on about and how that could dissapear with different iron. The HF has no iron, its just RC filters, so that fabulous air should stay there no matter what inductor we use. Perhaps Andy's sounds so nice and airy as its the only filter network he has. No LF, MF networks to cloud the signal path? Maybe that increases the purity?

This clone will never sound just like a 553 but it may sound excellent in its own right.

-Tom
Title: Anyone interested in some API 500 format projects??
Post by: drpat on July 27, 2005, 01:21:11 PM
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Title: Anyone interested in some API 500 format projects??
Post by: strangeandbouncy on July 27, 2005, 03:19:36 PM
Tom,

   I have so ay tht the Assumtion that my 553 HF is my only "filter" is a serious case of jumping to conclusions! - Helios, Siemens, Neve, Focusrite(Blech!), Maselec, SSL, Pultec, API, APSI, Sony, Avantic, Lang, Audix, Trident, etc, etc, etc. Not quite sure what impression I am giving off . . .
  For what it's worth, a while ago, I diconnected the LF and MF of my 553, and this makes no difference to the hf at all. And as for the iron, WHAT iron? the only thing that can possibly really affect the HF is the output tx, and since it is a Profile 2503, and has a repsonse from dc to ultraviolet light, and will handle +30dB, I cannot conceive any other "iron" having any effect. My original 553 sounds identical to my lash-up, providing that you put the same caps in each. The biggest difference for me is in the cap you use for the HF. Polystyrene pisses on anything else i have tried, and, since they are available in 1 percent tolerences, you can match channels with no phase diferences on the Slope regoin.


   BLah Blah B;lah


  ANdyP
Title: Anyone interested in some API 500 format projects??
Post by: TomWaterman on July 27, 2005, 05:23:34 PM
Hey!

I didn't even think I was helping - just confusing myself and others!  :thumb:

Looking at the schemo again, I presume pins 6 & 7 actually go to ground? Has anyone determined exactly where they go - the info at Dan Alexander says NC but they have to go somewhere I reckon?

Also when using the online calculator from opamp labs I'm was surprised by the results....was wondering if it was something to do with the resistor to ground.

If you plug in 47uF and 1H for the LF, the freq given is around 23Hz....seems a little low for a 100Hz peak no?

Anyway, after looking in H&H, it appears to be a 'series LC notch' filter creating a 'trap' for signals at or near to the resonant frequency by shorting them to ground.

Formula is given as:

Resonant frequency = 1/(2pi(LC^0.5))

Which surprisingly gives the same values as the opamp labs calculator, 23.2 Hz for the LF with a 47uF cap and 1H inductor.

According to H&H its a sharp peaking filter with losses in the cap and inductor smoothing the peak out. I presume that the further addition of the resistor to ground adds a Q-spoiling effect which increases the BW of the peak.

So maybe you can play with the 'Q' of the filters by adjusting the resistor to ground, 1.8k and 680R respectively for LF and MF.

I know this goes against the front panel space of the 500-type idea here but maybe a 1/2k pot in place of the MF 680R resistor would allow for variable mid Q too......

Maybe I'm misunderstanding so someone correct me if I'm wrong.

Back to the 23.2Hz for the LF - it seems low to me, is there a chance that the 1.8k resistor makes it wide BW and work more like a shelf with its -3dB point close to 100Hz?

The Q can apparently be calculated by:

Q = (WoL)/R

where Wo=1/(sqr root(LC)) I think.....maybe thats a parallel filter. I'm afraid j and w numbers confuse the hell outta me, imaginary bullsh*t!!

With these calcs I get a Q of 0.08, thats pretty wide ain't it?

Might be wrong though...hope I'm fishing in the right pond

-Tom
Title: Anyone interested in some API 500 format projects??
Post by: TomWaterman on July 27, 2005, 05:34:17 PM
Andy, woah nelly! :grin:

I meant that as you have not built the LF and MF parts in your '553' clone (as you don't have any inductors), the HF is the 'only filter' you have in that box.[/i] I was wondering if thats why your HF sounds so airy, as you've increased the frequency choices to get where the 'air' is and have no LF, MF 'iron' [read: inductors] to perhaps mess with the tone. Meaning the signal path is more pure.

Hence my assumption of the greater purity in your lashed up clone. I was in no way insinuating that the 553 HF clone is the only filter you've ever heard.....I was fully aware of your mahoosive collection!!!  :thumb:

Glad to know that disconnecting the LF and MF off the original makes no difference to the perceived 'air', thats a good sign that inductor choice in the lower bands will not Fcuk with the tone Family Hoof was wanting to ensure remained....which makes sense as the 'trap' circuits are in parallel with each other....

Very cool to know the original sounds identical to your clone!  :thumb:  :green:

-Tom
Title: Anyone interested in some API 500 format projects??
Post by: strangeandbouncy on July 27, 2005, 05:38:57 PM
553 LF is a Shelf, with a HPF at whatever the frequency the cap is. Mine has a 470uF cap . . . i think that the cap has too low a value to make a bell shape with the inductor.

    jm1/2p'sworth,


      ANdyP.

   ps if you'd like to borrow my 553, yous would be very welcome, if you live in da UK.

    btw, my 553 uses cheap green, Mylar caps. I have put these back in 'cos i like the sound for some things. very agressive compared to phillips orange polyester ones, or the incredibly smooth sounding polystyrenes i've used in my lash-ups.
Title: Anyone interested in some API 500 format projects??
Post by: strangeandbouncy on July 27, 2005, 05:57:55 PM
Tom,

   No offence taken, so, easy, now, jus' checkin' you are awake! - Arf Arf arf . . .

     I would have built some kinda LF, preferably switchable, but i can't afford it at da mo, at least that's what my wife says, and she IS the boss when it comes to money! I have an agreement with her not to buy anything new. This means i can build what I like, but £38 x 2 for Sowter iron is NOT acceptible at the 'mo, since we are negotiating for a house in Italy . . . .

   When i said "Identical", i have not yet tried swapping every single component!. swapping caps makes a big difference. i have to say that mine are sweeter. that is partly the styrene caps, and partly Fabio's Fab 2520's. i do not have any spare original 2520;s at the mo, and i haven;t got time to swap em from anything else. besides, i don;t think they like to be desoldered that much! I have many different types, and they all sound different. perhaps some have drifted, perhaps some have a different arangement. Anyhow, the one Ihave in my 553 does not seem to have the same hf extrension as Fabios. you are welcome to borrow it,  as i said.

    Keepin' it real fo' da People!


     ANdyP
Title: Anyone interested in some API 500 format projects??
Post by: TomWaterman on July 27, 2005, 06:01:49 PM
Thanks for the offer Andy - I am in the UK - in Brum at the mo but moving in a two weeks....maybe I'll take you up on the offer at somepoint.

Could you explain how the LF network makes a shelf and then the HPF? I think we're both talking about the same thing essentially. In effect it is a very broad peaking response, rolling off smoothly towards 20Hz....

Are you sure you have a 470uF cap in there? Its listed as 47uF on the schem....that would put the resonant freq at 7Hz!!

-Tom
Title: Anyone interested in some API 500 format projects??
Post by: strangeandbouncy on July 27, 2005, 06:20:43 PM
Tom,
 
   yes, I think we are talking about the same thing . . . i am no wizz, but i am certain that the LF respose is a shelf, not a bell . i suspect that the cap is to prevent instability at very low frequency - too low to really interact with the inductor. tomorrow, I;ll try to listen to the eq with the cap bypassed. that should show up something . . .

    I am certain that Op-amp labs circuit does not have a cap there.


     Blah,

     ANdyP
Title: Anyone interested in some API 500 format projects??
Post by: Sammas on July 27, 2005, 08:49:38 PM
Hey Guys... hectic day today...


Just thought I'd let you guys know that Cinemag 1.2H inductors and the CMOB-2S (steel core will give a sound closer to API sound than the 50%/100% nickel trannies will - for better or worse) tranny are both a little under $22us a piece...  

Tom, I was thinking the same think regarding the 47uF cap being too big... but im not sure, maybe the resistor does have some affect on bandwidth. I Thought maybe 4.7uF was more appropriate...


Anyways... be back on in about 8 hours...  :thumb:
Title: Anyone interested in some API 500 format projects??
Post by: drpat on July 29, 2005, 05:04:40 AM
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Title: Anyone interested in some API 500 format projects??
Post by: Sammas on July 29, 2005, 06:31:45 AM
yeah i'll give it ago...  

Most of the parts on are on there way now except for the Sowter inductor which is a few weeks off... hopefully most the stuff arrives during next week so i can put together the top and bottom frequencies...


Im having trouble finding a 5uF cap (for c9) though... I'll give a 4.7uf a go with and without a 300nf in parallel to see if there is a dramatic difference between the two...

Also can someone check R13 for me? Either looking at the schem (or an actual 553) is R13 a 10K? I thought it was 11K but think its just missing some ink... i think its ment to be the same as 614 which is 10K.


Hope you guys don't mind, but i'd like to build a working unit before posting the layouts? Just to make sure everything works, etc, etc before other people jump in on a potentially trouble riddled project. The Sowter inductor is still a few weeks away so it might be 2 weeks or so before i post the goods up...  Unless any of you are willing to be a ginea pig  :twisted:
Title: Anyone interested in some API 500 format projects??
Post by: drpat on July 29, 2005, 08:59:07 AM
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Title: Anyone interested in some API 500 format projects??
Post by: peterc on July 29, 2005, 10:24:24 AM
Hi all

With all this interest in this API project, anyone want to get some original style input transformers?

Any one remember this post (thaks Adrian)?

Quote
The Altran C-3402-2 (standard transformer in sheilded can with pin on bottom)
http://www.altrancorp.com/
Is probability the cheapest route


& again (thanks again, Adrian):

Quote
Did anyone read my last post!
I dangled a carrot in your face and no one even read it??????

I think the Altran are in the low $20's


from this thread

http://www.groupdiy.com/index.php?topic=242&postdays=0&postorder=asc&highlight=altran&start=0

I emailed Altran the other day, & the transformers are $27 each (qty 30) or else $20 ea (qty 75).

Anyone interested in doing a Group Buy? I cant coordinate a group buy from South Africa, 'else I would do it.

I would take 8 at least if it were to happen....


 :wink:  :wink:  :wink:

Peter
Title: Anyone interested in some API 500 format projects??
Post by: Sammas on July 29, 2005, 10:47:17 AM
Quote from: "drpat"
Quote from: "Sammas"
Im having trouble finding a 5uF cap (for c9) though... I'll give a 4.7uf a go with and without a 300nf in parallel to see if there is a dramatic difference between the two...


I'd buy the closest value above that too just in case.

Quote from: "Sammas"
Also can someone check R13 for me? Either looking at the schem (or an actual 553) is R13 a 10K? I thought it was 11K but think its just missing some ink... i think its ment to be the same as 614 which is 10K.


Looks like 10k to me from the schematic.

Quote from: "Sammas"
Hope you guys don't mind, but i'd like to build a working unit before posting the layouts? Just to make sure everything works, etc, etc before other people jump in on a potentially trouble riddled project.


Good plan, sounded like that was what was happening anyways. BTW: What is the final format that you're shooting for? IE: what mid band frequencies are you shooting for? Are you switching the hi and low bands? Are you adding an input tranny? Ice dispenser? etc...

Great work so far Sammas!



Hopefully it will tie my shoelaces too  :wink:

This is what i've planned for the first one

- sowter meq-5 inductor with 8.361k, 5.261k, 3.265k, 728Hz, 367Hz, 201Hz selection (drpat's suggestion)...
- cinemag 1.2h inductor on the LF with switchable 80hz & 120hz
- switchable high end frequencies (haven't calculated those yet...)
- cinemag cmob-2 tranny
- JLM 99V DOA (gotta support local products ya know  :wink: )
- and find out what the flippin' deal is with the "gain trim" pins... what the hell that 47uF cap is doing on the LF inductor... Find out if 1.8K and 680R  do adjust the Q... see if it all actually works  :wink: (perhaps add another resistor space or pot place if it fits for people to adjust the Q).


I don't plan on adding an input tranny but i'll definately try and squeeze the pin configurations in for one  :thumb: The CMOB-2 is 49mmx41mm and the Sowter inductor is 34mm in diameter... haven't got the dimensions of the 1.2H inductor but they take up a fair amount of room... I'll try my hardest to make it all fit with some input tranny options :thumb:

All the deallies and stuff should be posted in a few weeks... detailed parts lists, schem, layout, photos of a working unit (touch wood), etc, etc...
Title: Anyone interested in some API 500 format projects??
Post by: drpat on July 29, 2005, 11:46:55 AM
...
Title: Anyone interested in some API 500 format projects??
Post by: MikoKensington on July 29, 2005, 12:02:46 PM
Hey guys little side tangent here, but one of the reasons this thread is 9 pages long is because you're quoting entire posts that are already quoting entire posts.  It gets hard to follow.

I'm done, sorry.   :thumb:   I like the parts list I'm seeing.  Except that Sowter price tag.  Maybe I'll just quit smoking and used my saved earnings to buy the Sowters.  

Sammas I'll be knocking on wood and crossing fingers.   :guinness:
Title: Anyone interested in some API 500 format projects??
Post by: drpat on July 29, 2005, 12:31:16 PM
...
Title: Anyone interested in some API 500 format projects??
Post by: CJ on July 29, 2005, 02:37:47 PM
Quote from: "drpat"
Quote from: "Sammas"

- sowter meq-5 inductor with 8.361k, 5.261k, 3.265k, 728Hz, 367Hz, 201Hz selection (drpat's suggestion)...
- cinemag 1.2h inductor on the LF with switchable 80hz & 120hz
- switchable high end frequencies (haven't calculated those yet...)
- cinemag cmob-2 tranny
- JLM 99V DOA (gotta support local products ya know  :wink: )
- and find out what the flippin' deal is with the "gain trim" pins... what the hell that 47uF cap is doing on the LF inductor... Find out if 1.8K and 680R  do adjust the Q... see if it all actually works  :wink: (perhaps add another resistor space or pot place if it fits for people to adjust the Q).


I like the whole configuration that you're planning on using. I'll probably build the original 2520 from Fabio's boards, and socket the pins for experimentation. I'm excited to try out the CMOB-2 tranny too.

As far as the HF selection goes, I'd stick with the original 10k and have it switchable to 12k or 16k or 20k... whatever strikes your fancy.

I wouldn't bang your head too much about the 47uF cap. Stick to the schematic and worry about it if it's not working as expected.

I believe, earlier in this post, somebody mentioned that the gain trim pins are not connected according to information on Dan Alexander's site, which I couldn't find.

According to 500 series rack specs, pin 11 is labeled as "gain adjust" 550b and 560b. I'm not sure what this means, as I don't see any type of external adjustment on the rack. I would just leave these floating and see what happens.

Another thing to take note of. I had the pin numbers reversed in one of my earlier posts. I've gone back and edited it to correct the error. So...


THE NEXT GUY WHO QUOTES GET'S SHOT BY ICE TEA! WE HAVE BRAINS, PEOPLE. BRAINS CONTAIN A SECTION CALLED MEMORY. NOT TO MENTION THE SCROLL BAR ON THE RIGHT.:razz:

Seriously, though. Sometimes all this quoting is harder to follow than just backing up a few posts/pages.

cj
Title: Anyone interested in some API 500 format projects??
Post by: soundguy on July 29, 2005, 04:51:07 PM
Quote from: "Sammas"

- JLM 99V DOA (gotta support local products ya know  :wink: )
.


I havent read this whole thread but would remind folks thart api lunchboxes have +/- 15v supplies, the 99v wants twice that.

dave
Title: Anyone interested in some API 500 format projects??
Post by: peterc on July 29, 2005, 06:34:13 PM
Here is some data on the Altran transformer:

(http://img.photobucket.com/albums/v318/peter_cornell2002/Altran.jpg)

Peter
Title: Anyone interested in some API 500 format projects??
Post by: drpat on July 29, 2005, 06:41:55 PM
Actually, they have +/-16V power supplies. Also I agree with Jimney, those bridge rectifiers are going to be a little hard to source. Maybe we could use the ones that Charles suggested instead.
Title: Anyone interested in some API 500 format projects??
Post by: Sammas on July 29, 2005, 08:34:27 PM
Quote from: "soundguy"



Hey Dave,

I spoke to Joe and he said he has used the 99v in the output of 550B's with good results before  :thumb:
Title: Anyone interested in some API 500 format projects??
Post by: drpat on August 01, 2005, 02:19:31 PM
...
Title: Anyone interested in some API 500 format projects??
Post by: peterc on August 01, 2005, 03:24:12 PM
Pat

What I left out of my post was the "mic pre input transformer" part   :?  I was enivisioning people building racks of mic pre's....

Got a bit lost within the whole thread, but the Altran  can be wired as a 1:8 mic input pre, that's what I was thinking of.

I assume you're referring to a line input transformer (1:1)?

Peter
Title: Anyone interested in some API 500 format projects??
Post by: soundguy on August 01, 2005, 04:59:08 PM
finally had some time to read through this whole thread which is really interesting.  Just to point out the obvious-

the 553 used an air core inductor.  I think that unless you find a similar inductor you arent going to have a similar sounding band.

We should just design our own damn thing and free ourselves from trying to conform to that design since its going to sound different no matter how hard we try.  I see a lot of decisions being mulled over trying to get this to sound close to some old thing.  Since we'll never (Im assuming) find that exact part, seems like it woudl be way cooler to think out of the box and just do something cool as opposed to just doing what some other people did 20 years ago.

If we build one up with the cinemag pultec inductor, hows that not gonna sound cool?

The advantage of this project is so far as I see it:

a) not having to build a power supply

b) fill up empty spaces in your lunchbox

I have been wanting to build some stuff for my empty lunchbox slots but my whole motivation has been to build something that sounds DIFFERENT than from what I can go and buy, which commercially speaking, is all API inspired stuff, which is cool and all but Id rather be building something cool instead of something that we can just go and buy, doesnt make much sense to me.

cinemag inductor is not impossibly expensive, think it will fit, is readily available, and leaves us LOTS of options for designing something cool.

just some food for thought.

dave
Title: Anyone interested in some API 500 format projects??
Post by: drpat on August 01, 2005, 05:29:54 PM
...
Title: Anyone interested in some API 500 format projects??
Post by: peterc on August 02, 2005, 01:50:09 PM
Quote
Family Hoof and I are working on preamp PCB's in PM land. I'll buy one of these and try it, on your word that it's a good sounding x-former.


Ok, I must warn you that I've never tried these transformers......

Adrian intimated that these are the original part, might be worth contacting him & getting some more background from him.

Peter
Title: Anyone interested in some API 500 format projects??
Post by: MikoKensington on August 02, 2005, 03:22:00 PM
FWIW Altran is used by Old School Audio.
Title: Anyone interested in some API 500 format projects??
Post by: udo on August 03, 2005, 12:22:33 AM
Quote from: "TomWaterman"
So maybe you can play with the 'Q' of the filters by adjusting the resistor to ground, 1.8k and 680R respectively for LF and MF.

i believe you're right. looks like something similar (the 2K2 pot in series with some resistors) is used in the 'hi boost Q' control of the pultec circuit:
http://members.nuvox.net/~zt.robgrow/circuits/pulteceq.html
Quote from: "TomWaterman"
The Q can apparently be calculated by:
Q = (WoL)/R

i get the same result (0.08) using:
Q = inductive reactance / R
=> Q = (2pifL)/R

bandwidth is defined as  BW= f res / Q   = 23Hz/0.08 = 287Hz

therefore the -3dB points should be 287Hz apart from each other with the resonant frequency 23Hz in their center. as the lower cutoff frequency is not in the audio band this looks like a shelf even though a resonant LCR circuit is used.

somebody correct me if i'm wrong, please!
udo
Title: Anyone interested in some API 500 format projects??
Post by: TomWaterman on August 03, 2005, 06:50:05 AM
Awesome udo!

Thats what I was getting at - nice to see the other formula gives the same result. Thats a damn big LF BW...this is going to boost at up to 300Hz+.

Being able to change the Q could be a good addition to the EQ, especially the MF.

-Tom
Title: Anyone interested in some API 500 format projects??
Post by: strangeandbouncy on August 03, 2005, 12:43:24 PM
Soundguy,

    My 553 doesn't have seem to have air-cored inductors . . .


    ANdyP
Title: Anyone interested in some API 500 format projects??
Post by: jrmintz on August 03, 2005, 01:23:32 PM
On page 2 of this thread there are some pics of my 553 - aren't those air-cored toroidal inductors? Unless I'm misunderstanding the terminology, which is very possible.
Title: Anyone interested in some API 500 format projects??
Post by: strangeandbouncy on August 03, 2005, 03:24:01 PM
Seth,

   mine look just like that too. i am certain that they are ferite core, look how the coil is wound, around the core. If they were air-cored, they would have to be much bigger. Air-cored louspeaker cross-over inductors are huge in comparison to their ferite cored counterparts. and they would bewound the other way, round a bobbin, not round a solid core. i could be wrong. If i am wrong, please someone correct me!

    Sorry to be so pedantic!

     ANdyP
Title: Anyone interested in some API 500 format projects??
Post by: jrmintz on August 03, 2005, 04:39:36 PM
Not pedantic at all, Andy. I thought the hole was the air core....

 :oops:  :shock:  :oops:
Title: Anyone interested in some API 500 format projects??
Post by: soundguy on August 05, 2005, 02:59:26 PM
Im with seth, I had always understood a wound torroid like that to be an air core inductor.  Auditronics used them in their mid 70's consoles as well.

dave
Title: Anyone interested in some API 500 format projects??
Post by: NewYorkDave on August 05, 2005, 03:43:41 PM
Youse are on crack  :razz:

Those aren't air core. An air core 1H inductor--wound with any but the most microscopic magnet wire--would be huge.

The ferrite "donut", on which the toroid is wound, IS the core.
Title: Anyone interested in some API 500 format projects??
Post by: strangeandbouncy on August 05, 2005, 04:50:21 PM
Smug Smug Smug,

    :wink:  :grin:  :green:


       Thanks for clearing that up, NYD!



     ANdyP
Title: Anyone interested in some API 500 format projects??
Post by: jrmintz on August 05, 2005, 05:42:11 PM
I stands corrected. I wouldn't have bet money on it....

 :green:  :thumb:
Title: Anyone interested in some API 500 format projects??
Post by: synthetic on August 13, 2005, 07:03:32 PM
Great project, I'm watching this carefully. I have nothing to add, except for the person who couldn't find Dan Alexander's site:

http://www.danalexanderaudio.com/api.html

Lots of good API info on that page: pinouts, spec sheets, etc.

Oh, if you're collecting votes, I like the option of multiple frequencies on the HF and LF, even if they're toggles soldered to jumpers on the board. You could even do a three-way toggle, though it would be difficult to label on the cramped 5xx board.
Title: Anyone interested in some API 500 format projects??
Post by: Sammas on August 18, 2005, 08:20:25 PM
Ello ello...

Just an update.

Sowter & Cinemag inductors arrived yesterday, as too the Cinemag tranny.

Great quality stuff!

Wima's, Pots & switches are here also... PCB will be getting etched this weekend... just waiting on a DOA which i haven't ordered yet...

Hopefully it will be up and running be next weekend so i can share the layouts with you guys...
Title: Anyone interested in some API 500 format projects??
Post by: drpat on August 22, 2005, 10:18:43 PM
...
Title: Anyone interested in some API 500 format projects??
Post by: Sammas on August 22, 2005, 10:48:47 PM
Quote from: "drpat"
How'd the PCB etch go this weekend, Sammas?



Gee hahaha, searching through the back pages of the forums trying to find this thread and its on the front page  :grin:

The PCB came out nicely! But, there is a nice line through the middle of the copper... I dont know where if it was caused by my printer or if the copper layer of the PCB was flawed and i didnt notice it... Anyways i'll be picking up some more boards on my way home this afternoon so we should be right as rain tonight  :thumb:


Im getting anxious to hear this puppy  :cool:
Title: Anyone interested in some API 500 format projects??
Post by: drpat on August 22, 2005, 11:58:22 PM
...
Title: Anyone interested in some API 500 format projects??
Post by: Sammas on August 23, 2005, 01:58:05 AM
It's all spectulation at the moment... I've been told they can just be left unconnected, and also been told that you can put a pot in there to adjust the gain (calibration of sorts). The latter doesn't seem right, particularly when you compare it to the 312 schems...

I'm going to just leave them unconnected... if it doesn't work it's time to experiment...  :grin:
Title: Anyone interested in some API 500 format projects??
Post by: synthetic on September 19, 2005, 10:06:51 PM
Any update on this one? I was getting excited about tis project.
Title: Anyone interested in some API 500 format projects??
Post by: Sammas on September 20, 2005, 01:25:17 AM
Yes! should be here very soon. I have the first one almost up and working... I just have to work the the mechanics a little before i post the goods. Its just a little fiddly to mount the pots and switches so im changing a few things to make it go together easier.

I have some photos i'll put up shortly...
Title: Anyone interested in some API 500 format projects??
Post by: peter purpose on October 05, 2005, 02:49:21 PM
Ahem....cough cough
Title: Anyone interested in some API 500 format projects??
Post by: gar381 on February 27, 2006, 02:05:19 PM
BUMP

 :?:  :?:

GARY