Neumann OA10 discrete op-amp (in API 2520 etc. format)

[grantlack]

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

Mo

Considered doing some slightly reworked boards to fit standard pins and maybe get compensation on board, but I'd have to discuss that w/ audiox and gustav. Don't want to step on any toes.

 

[strangeandbouncy]

Hi,


  i think you mean Audiox and Gustav . . . .


    Kindest regards,



  ANdyP

 

[maxwall]

Does anyone have part numbers for Millmax female and male pins and sources in US ?

 

[Ptownkid]

I was also considering adding this opamp to the roster as i have to order boards for about 3-4 other doa kits soon.

 

[maxwall]

Ptkid,

that would be great if you could put those into your online store. Would they be cheaper
than retail from another source ?
_______________________________

Also , these little Neumann OA10 discrete opamps look like they could easily be retrofitted into some old
recording consoles like MCI JH416, replacements for the Harris 2001, 901 running at +/- 24vdc.
just need to drop the power supply voltage down 2-3 volts.
_______________________________

Thanks to Audiox PCB layout, successfully made a dual sided pcb today using laser toner transfer method
which works very well and much cheaper than any other method I've used to date. Still need to stuff the board,
then test. Used API footprint on both sides to keep the alignment of the traces & pads as close as possible. Had
to predrill two of the holes and line up artwork by eye before heating the last negative to the top side of the board.
Then final stage into etching solution. Last step drill all holes with PCB drillbit smaller than  #60 I think. Holes are little
off center in some places , but once solder coats the pads, traces and components everything will be fine. The
top pads without traces are of no use I suppose. Need to figure out a method for doing a sheet of these boards
and keep them all aligned, instead of one offs like below. Board measures 28mm x 28mm.

Top

Bottom

Here is a schematic to help out with BOM or part value inquiries

 

[Ptownkid]

Where are they retailed?

 

[maxwall]

Mouser, Digikey or direct from Millmax?

Searching the lab, here's what others have used with for pins and part #'s

MILLMAX PART# 0344-2-19-01-34-27-10-0  (DIGIKEY PART#ED5021-ND)(Mouser Part # 575-034420)
This is the female pin for the main pcb.
http://www.mill-max.com/images/products/pdf/152N.pdf

MILLMAX PART# 3103-2-00-21-00-00-08-0 (DIGIKEY PART#ED5052-ND)( Mouser part # 575-310320)
This is the male pin for the 1731
http://www.mill-max.com/images/products/pdf/188N.pdf

 

[Ptownkid]

Ahhhh, you're talking about the pins...I was talking about opamp kits...

 

[maxwall]

Kits would be good too , since there time consuming to assemble, etching pcb etc.

 

[strangeandbouncy]

Hi Ptown ,



  I think you'd better chat to Audiox and Gustav!



  AndyP

 

[Ptownkid]

Did that a long time ago...

 

[maxwall]

About the BC337-25 and BC327-25 output transistor pair what is recommended
Hfe on these ? should they be gain matched too ? same with BC182, 212 etc ?

 

[strangeandbouncy]

Hi,



  I didn't match any transistors in mine, and I have built 10 so far. They all work perfectly(now!). Watch the orientation of the transistors. Some were other way round to Audiox's layout.


  I got everything I needed off eBay with no difficulties, but kits would be spiffing! I couldn't find any pins that fit( the holes are a bit big, i think).


  Yup, kits would be great, I am gonna be needing a whole heap of these puppies!


  Kindest regards,


    ANdyP

 

[Tweekhead]

I'll hopefully have all my parts by this weekend. Just to be sure I don't mess this up I have a quick question, since the  BC212B and BC2182B transistors I ordered pins are 1=C 2=B 3=E, I leave those orientated as on the silkscreen, but the BC327 and BC337 transistors I bought are 1=C 2=B 3=E, I just flip them around, right? Is it pretty easy to check the orientation with a digital multimeter? I had a few beers while I ordered the parts so I have several data sheets on my desktop to sort through, but all of the BC327 and BC337 seem to have the same orientation.

 

[strangeandbouncy]

Hi,


  my bc327-25 and 337-25 were just as you described. I tested with a really cheep digital meter that has tester built in.


    Kindest regards,


      ANdyP

 

[Tweekhead]

Andy, so you just had to flip them around then, right? Did you ever sort out the windy sound you described from an earlier post?

Thanks!


Arthur

 

[strangeandbouncy]

Hi,



  yes I just rotated them through 180 degrees.


  ashamed to say windy noise was NOTHING to do with OA10s . . . faulty channel in mixer! I neglected to eliminate other causes . . .


  Kindest regards,


    ANdyP

 

[Tweekhead]

Andy, Thank you for the replies!

 

[strangeandbouncy]

Hi,


  for once it is great to be able to contribute, instead of just milking everyone else! You won't regret building these puppies, I promise. they really sound great.



    ANdyP ;D

 

[grantlack]

  i think you mean Audiox and Gustav . . .

Edited, I've been reading a lot of analag's posts recently .

Thusfar I've got enough bits and pieces on order for about 100 kits of everything but the BC182B, still shopping around for a good price on available stock. I'd probably lay claim to a few kits myself, so after that and testing for duds I'd guesstimate 85 sans pcb's?