Neumann OA10 discrete op-amp (in API 2520 etc. format)
« on: June 15, 2009, 02:01:30 PM »


Classic Neumann OA10 discrete op-amp converted to more usefull API2520 (and many others) format. This is something that I designed a few years ago and I even built a prototype but never had time to do the listening tests...

Documents:

Schematic
http://audioxxx.googlepages.com/OA10_schematic.pdf

Component layout with designations
http://audioxxx.googlepages.com/OA10_layout_designations.pdf

Component layout with values
http://audioxxx.googlepages.com/OA10_layout_values.pdf

Pinout and dimensions
http://audioxxx.googlepages.com/OA10_pinout_and_dimensions.pdf

Compensation
http://audioxxx.googlepages.com/OA10_compensation.pdf

Top copper layer pdf for home etchers
http://docs.google.com/fileview?id=0B_XBYPfmG8pVYmQxYjAyMTctMTViZC00MjMzLWIzMjYtZTg0Y2E2ZTczYjMz&hl=en

Bottom copper layer pdf for home etchers
http://docs.google.com/fileview?id=0B_XBYPfmG8pVNTBhYzFjM2YtNTlhMi00MmY0LTlkMTMtNGNmZTE0NjQ1ZThh&hl=en


**********

My other projects:

Studer 169 EQ
http://www.groupdiy.com/index.php?topic=33996.0

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

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

« Last Edit: January 22, 2010, 06:11:31 AM by audiox »


strangeandbouncy

Re: Neumann OA10 discrete op-amp (in API 2520 etc. format)
« Reply #1 on: June 15, 2009, 04:01:40 PM »
Hi,



   wow, that's very cool indeed! another flavour . . . .



    MAny thanks,



        ANdyP
. . . . RUH ROH . . . . .

strangeandbouncy

Re: Neumann OA10 discrete op-amp (in API 2520 etc. format)
« Reply #2 on: June 15, 2009, 04:14:31 PM »
Hi Audiox,



    so could you explain about the "external compensation" R3 and C1? are they not "on-board" then? Looks kinda cramped to bolt them on, and there aren't any pins for them. Can we just ignore them?



     Kindest regards,


       ANdyP
. . . . RUH ROH . . . . .

Re: Neumann OA10 discrete op-amp (in API 2520 etc. format)
« Reply #3 on: June 15, 2009, 04:36:37 PM »
so could you explain about the "external compensation" R3 and C1?

After posting the documents I thought that someone is going to ask it sooner or later, so I started to make a drawing of it. It shows how to connect the compensation components:

http://audioxxx.googlepages.com/OA10_compensation.pdf

They are only required in unity or low gain applications. In case you are building a mic amp, you can leave them out.

There is really no space for compensation components in the board as you can see. It was quite a puzzle to fit even those essential parts...
« Last Edit: June 15, 2009, 04:41:30 PM by audiox »

Walrus

Re: Neumann OA10 discrete op-amp (in API 2520 etc. format)
« Reply #4 on: June 15, 2009, 04:43:20 PM »
It will be just like the original 2520 then, bits bolted on over the top of the main components!   ;)
Kevin.

strangeandbouncy

Re: Neumann OA10 discrete op-amp (in API 2520 etc. format)
« Reply #5 on: June 15, 2009, 05:25:14 PM »
Hi Audiox,



   you are the best!


      Thank you very much for this.



      ANdyP
. . . . RUH ROH . . . . .

[silent:arts]

Re: Neumann OA10 discrete op-amp (in API 2520 etc. format)
« Reply #6 on: June 15, 2009, 05:45:02 PM »
cool.

thought of doing this too, while working on a Neumann OA12 based MicPre.
since the OA10 is the only available schematic ...
and all (original Neumann) replacements for OA10 or OA12 / 20 are the same with different footprints ...

great work. if I release the OA12 based Pre I will contact you  ;D

Re: Neumann OA10 discrete op-amp (in API 2520 etc. format)
« Reply #7 on: June 16, 2009, 10:44:40 AM »
all (original Neumann) replacements for OA10 or OA12 / 20 are the same with different footprints ...

I didn't know that there was an official replacement available. Maybe some later Neumann thick-film op-amp mounted on a small PCB?

In the 90s I designed replacements for Neumann op-amps (they were impossible to get and the internal circuit was not available). My solution was a tiny board with NE5532 and buffer stage made of transistors. In most cases the buffer was not assembled since the two op-amps in parallel could give enough current.

Re: Neumann OA10 discrete op-amp (in API 2520 etc. format)
« Reply #8 on: June 16, 2009, 12:29:16 PM »
wow, that's very cool indeed. Curious to hear it. I have heard that opamps with PNP on the input are lower noise than their NPN counterparts (2520 for example), but looking at the BC212, it is much lower hFE than, say the 550C commonly used as the input pair in the 2520.  Anyway, I'd like to try this one. Is it a dual sided board? Any chance of a home-etch version, or will you offer these for sale?

What voltage does this run at?

Thanks for bringing back another Neumann board!

[silent:arts]

Re: Neumann OA10 discrete op-amp (in API 2520 etc. format)
« Reply #9 on: June 16, 2009, 12:37:55 PM »
I didn't know that there was an official replacement available. Maybe some later Neumann thick-film op-amp mounted on a small PCB
yes - here you find a picture. the blue OA100 was adapted to OA10 and OA12 / 20. the NE5532 works great, it is my replacement at work.

I have an Neumann clone MicPre in work for the 51X series, but only around 20 to 30 original OA12.
your OA10 should work in there too - do you have plans for offering them?
will include the footprint ...


Re: Neumann OA10 discrete op-amp (in API 2520 etc. format)
« Reply #10 on: June 16, 2009, 01:04:20 PM »
do you have plans for offering them?

No, I am just sharing my layout. If someone wants to manufacture these boards, he/she should contact me to get the Gerber files.

Is it a dual sided board? Any chance of a home-etch version, or will you offer these for sale?

Yes it is double sided (there are only a few traces on the top side, so single sided board plus some wires is possible but not recommended). I will post the copper layers in pdf for home etchers.

What voltage does this run at?

+/-2.5V to +/-22V (6.5mA typically, no load, +/-15V)

Re: Neumann OA10 discrete op-amp (in API 2520 etc. format)
« Reply #11 on: June 16, 2009, 01:52:28 PM »
do you have plans for offering them?


No, I am just sharing my layout. If someone wants to manufacture these boards, he/she should contact me to get the Gerber files.
I vote to give the Gerbers to good old Gustav!

Quote
Is it a dual sided board? Any chance of a home-etch version, or will you offer these for sale?

Yes it is double sided (there are only a few traces on the top side, so single sided board plus some wires is possible but not recommended). I will post the copper layers in pdf for home etchers.

Sounds cool..  I've been wanting to try my hand at etching dual sided...

What voltage does this run at?
Quote

+/-2.5V to +/-22V (6.5mA typically, no load, +/-15V)

yes! So it can run on a 9V battery!!  Is the rest of the circuit just textbook opamp circuit or are there any peculiarities that you know of??

Thanks again!


RedNoise

Re: Neumann OA10 discrete op-amp (in API 2520 etc. format)
« Reply #13 on: January 22, 2010, 06:31:31 AM »
Thank you so much !  ;D
If your neighbour is hunger : don't give him fish , teach him how to fish ...
if you don't like it don't buy it ;-)  [Wolker Texas Ranger] ( ;-) )

xmvlk

Re: Neumann OA10 discrete op-amp (in API 2520 etc. format)
« Reply #14 on: January 22, 2010, 07:15:03 AM »
Schematic
http://audioxxx.googlepages.com/OA10_schematic.pdf
I do not understand, why output overcurrent protection is
done rather unipollary in this op amp?
Why not to do this?


Ptownkid

Re: Neumann OA10 discrete op-amp (in API 2520 etc. format)
« Reply #15 on: January 22, 2010, 10:00:40 AM »
I'd be happy to do a run of these with your permission

ChrioN

Re: Neumann OA10 discrete op-amp (in API 2520 etc. format)
« Reply #16 on: January 22, 2010, 10:06:32 AM »
Nice! Do they work?  ;D
"All PCB traces are curved to emulate the electrical response of point-to-point wiring" -Drip

Re: Neumann OA10 discrete op-amp (in API 2520 etc. format)
« Reply #17 on: January 22, 2010, 10:11:41 AM »
thanks Audiox! now I just need to get me some more ACID!  the etching kind of course!  :D

xmvlk

Re: Neumann OA10 discrete op-amp (in API 2520 etc. format)
« Reply #18 on: January 23, 2010, 07:00:53 AM »
I'd be happy to do a run of these with your permission
For me??? It is only idea, I have not tested it. Use it without warranty  :)

Ptownkid

Re: Neumann OA10 discrete op-amp (in API 2520 etc. format)
« Reply #19 on: January 24, 2010, 10:01:36 AM »
I was actually talking to audiox...but I always test ;)


 

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