strangeandbouncy

Re: Neumann OA10 discrete op-amp (in API 2520 etc. format)
« Reply #40 on: July 27, 2010, 04:23:38 AM »
Hi Guys,


   many thanks again for your input and help. This story has a happy ending. YAY! I have a working OA10, stuffed it into a mic-pre, and first impressions are very favourable. I can't wait to try it out properly. I am looking forward to trying it in a pultec-type eq for 20dB of gain, and see whether the higher slew-rate/less compensation makes any difference.


     Wonderful!



       ANdyp
. . . . RUH ROH . . . . .


strangeandbouncy

Re: Neumann OA10 discrete op-amp (in API 2520 etc. format)
« Reply #41 on: July 27, 2010, 08:05:44 AM »
HI,


       Got these in my LA-Z MPA pre. I won't be replacing the Peters DOA's anytime soon, 'cos there is some serious mojo for me in them. This platform does give the the perfect bed to test on, since I am only changing 2 DOA's, everything else the same. These OA10's are the shizzle! I have only DI'd a gtr and done some BV's so far. They are really warm and smooth, and first impression is that they are slightly quieter. Maybe the noise is just shifted to a less audible freq range(?) I will measure later. I am recording a vocal with an artist I know this afternoon, and will be able to tell far more then.

 
       Audiox, you are a marvel! Thank you so much.



    Kindest regards,


      ANdyP
. . . . RUH ROH . . . . .

Re: Neumann OA10 discrete op-amp (in API 2520 etc. format)
« Reply #42 on: July 27, 2010, 08:11:59 AM »
Good news! Was it the output transistors?

strangeandbouncy

Re: Neumann OA10 discrete op-amp (in API 2520 etc. format)
« Reply #43 on: July 27, 2010, 08:59:13 AM »
Yessir! Output transistors
. . . . RUH ROH . . . . .

geoff004

Re: Neumann OA10 discrete op-amp (in API 2520 etc. format)
« Reply #44 on: July 27, 2010, 08:50:55 PM »
does anyone have a source for these transistors in the US?
the dealers I've checked are either not stocked or have them labeled 'obsolete'.

dissonantstring

Re: Neumann OA10 discrete op-amp (in API 2520 etc. format)
« Reply #45 on: July 28, 2010, 01:07:24 PM »
geoff004,
seems like digikey has them.  BC327NOS-ND and BC337NOS-ND

strangeandbouncy

Re: Neumann OA10 discrete op-amp (in API 2520 etc. format)
« Reply #46 on: August 02, 2010, 05:08:19 PM »
Hi,


  I've been using these all week. I really like them. Very smooth and warm with compensation. I can't wait to try un-compensated.


  I have experienced a strange thing. twice, they went very noisy. I would describe the noise as "windy". This goes away if you turn off and on. ANy suggestions how to cure? More de-coupling of power rails perhaps?


   Kindest regards,


    ANdyP
. . . . RUH ROH . . . . .

Tweekhead

Re: Neumann OA10 discrete op-amp (in API 2520 etc. format)
« Reply #47 on: September 20, 2010, 01:57:17 AM »
Hello!

I'm trying to source parts for the DOA and learn as much as I can about reading schematics along the way. Anyways, I was wondering, as I can get the BC327-ND, and the BC337-ND from digikey, and  I cannot find the BC212B, could I use one of Mousers substitutions? What would I need to look for? They have options for : Package / Case, DC Current Gain hFE Min, Maximum Operating Frequency, Collector- Emitter Voltage VCEO Max, Emitter- Base Voltage VEBO, Continuous Collector Current, and Power Dissipation! I'm trying to teach myself electronics Kung Fu, so I apologize in advance for any nub questions, but I've learned so much from this forum already I feel like I'm so close to finally understanding!!!! You guys rule and that's not just the liquor talking.)
 
 

Tweekhead

Re: Neumann OA10 discrete op-amp (in API 2520 etc. format)
« Reply #48 on: September 21, 2010, 01:03:31 AM »
Hello again,

Could I substitute 2N3906BU for the BC212B?

Re: Neumann OA10 discrete op-amp (in API 2520 etc. format)
« Reply #49 on: September 21, 2010, 07:20:20 AM »
If you can sit tight for a bit, I'm working on picking up some BC212B's in bulk. Did anyone ever clear up which mill max pins are a proper fit?
There's nothing like the right tool for the job.
And -usually- that's what I end up using...
..nothing like the right tool for the job!


RedNoise

Re: Neumann OA10 discrete op-amp (in API 2520 etc. format)
« Reply #50 on: September 21, 2010, 08:45:03 AM »
pins holes are too big...Two solutions :
solder a femelle pin (as on the board , same hole diameter) then add a male one between the females.(!)
Or : solder 1N4XXX pins on both main and DOA pcb ...
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] ( ;-) )

Tweekhead

Re: Neumann OA10 discrete op-amp (in API 2520 etc. format)
« Reply #51 on: September 21, 2010, 10:43:55 AM »
grantlack,

Excellent news! Did you have a time frame of when you might be getting the bulk order?

dmp

Re: Neumann OA10 discrete op-amp (in API 2520 etc. format)
« Reply #52 on: September 21, 2010, 10:50:26 AM »
I ordered a bunch of the BC212b transistors from:
http://www.awatronic.co.uk/bc212b/prod_19829.html


Tweekhead

Re: Neumann OA10 discrete op-amp (in API 2520 etc. format)
« Reply #53 on: September 21, 2010, 12:28:21 PM »
Thank you!

Re: Neumann OA10 discrete op-amp (in API 2520 etc. format)
« Reply #54 on: September 21, 2010, 02:48:21 PM »
grantlack,

Excellent news! Did you have a time frame of when you might be getting the bulk order?

Just paid today, they don't have far to travel so if shipping is timely I should be able to send some out early next week. How many do you need?
There's nothing like the right tool for the job.
And -usually- that's what I end up using...
..nothing like the right tool for the job!

Tweekhead

Re: Neumann OA10 discrete op-amp (in API 2520 etc. format)
« Reply #55 on: September 21, 2010, 07:07:07 PM »
Sorry, I followed dmp's suggestion and ordered them from http://www.awatronic.co.uk/bc212b/prod_19829.html

Thanks anyways.

Re: Neumann OA10 discrete op-amp (in API 2520 etc. format)
« Reply #56 on: September 21, 2010, 07:55:18 PM »
no worries, they'll go to good use.  come to think of it, i could probably do parts kits if there's interest...  anybody?
There's nothing like the right tool for the job.
And -usually- that's what I end up using...
..nothing like the right tool for the job!

Re: Neumann OA10 discrete op-amp (in API 2520 etc. format)
« Reply #57 on: September 25, 2010, 04:38:50 PM »
When home etching a two layer board like this OA10 API style , what is the best method
for keeping the top and bottom layer aligned ?
curiousaudioparts at  gmail  dot  com
https://sites.google.com/site/diypartsstore/

geoff004

Re: Neumann OA10 discrete op-amp (in API 2520 etc. format)
« Reply #58 on: September 25, 2010, 07:02:08 PM »
no worries, they'll go to good use.  come to think of it, i could probably do parts kits if there's interest...  anybody?

interested
I've got 4 of these PBCs I'd rather see assembled and working.

Moses

Re: Neumann OA10 discrete op-amp (in API 2520 etc. format)
« Reply #59 on: September 25, 2010, 08:15:06 PM »
no worries, they'll go to good use.  come to think of it, i could probably do parts kits if there's interest...  anybody?

Are you thinking of doing full kits (ie, PCBs included)? If so I would be interested...

Mo


 

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