Neumann W492 equalizer DIY project (PCB docs added)

[sr1200]

2nd bottom and 3rd bottom if i remember correctly, its the mid bands freq adjust, i think... i have 4 that im still putting together.  If i ever get a night off.

 

[Siegfried Meier]

Just found a pic online that confirms your post.  Thanks so much!

Too bad these omeg pots need to be wired off board with the Purusha case...

 

[sr1200]

There IS a way to do it with them connected to the board, but it's a LOT of work
If you're interested i can explain.
I just decided to wire them now, as this is the 3rd time im re-doing this project.

 

[sr1200]

Actually, here i have a pic of how to do it using leads i cut from diodes and caps n stuff.

 

[Siegfried Meier]

Oh lookit you fancy pants!

Thanks, very cool idea.

 

[kante1603]

Actually, here i have a pic of how to do it using leads i cut from diodes and caps n stuff.

That's excellent!

Udo

 

[sr1200]

Having an issue with my pair of 492s.  On both 3 of the 4 filters work fine.  Filter 3 doesnt seem to turn on or function on both channels. Im seeing 14v on the switch which im thinking isnt correct. There are no voltages on the schematic which is making things a little more difficult for my nubbliness.

 

[kante1603]

Hello everybody,

started this project early 2011,then it went to the shelf,now I did it finally ;D

Nothing special,but a lot of work.....and now fully working,hahaha......
Panel is from NRG Recording,4RU,engraved(,thanks Frank!),pcbs from Gustav.
Pots (Omeg from Laura at TAW) and switches are held on a mounting plate,pcbs are attached by solid core bus wires (partly),holds up easy.
Knobs are SIFAM.
Case is from Modushop,Italy (as always).
PSU is a JLM AC/DC,modded to 12vdc on the former phantom power rail for the LEDs (low current types,2mA).
Made some grounding stuff to have the choice of connecting pin 1(XLRs) to chassis,psu/audio ground or leave it open.Was highly influenced by the 51x racks,I really can recommend it to do.Easy job,just some perfboard stripes,headers and jumpers,done.
Have these options on all i/os,great,it´s running in AES/EBU configuration now and dead quiet.
Transformer is from Schuro Elektronik,Germany,fully sealed with extra shield going to chassis ground.

Thanks to AUDIOX of course for making it possible!

Thought I should show some pics of it,here we go:






PSU & Distribution:




Audio wiring:



Grounding/Jumpers:



Inside pics:





Thanks for watching,

best regards,

Udo.

 

[kosty]

http://www.mouser.com/ProductDetail/Bourns/91A2A-B28-B15-B15L/?qs=sGAEpiMZZMtC25l1F4XBU0lMC8qKAKdNb%2fFsrRH3ibQ%3d

still hunting down pots... will these bourns work?

Has anyone tried these pots ?

edit: I just noticed that some users mentioned Omegs being available at rapidonline for us Europeans !
Dual pots are 65-1442 and singles are 65-1404.

@Udo : Your build looks amazing ! You just convinced me to build 8 channels

 

[kante1603]

@Udo : Your build looks amazing ! You just convinced me to build 8 channels

Thank you for the kind words.
As said a lot of work to do,especially when mounting the pots off-board,but doable.
I made the pot connections with 1mm bus wire on the most outward pins on the lower row (gain pots) and adjusted the boards,then proceeded with thinner bus wires for the inner connections.Also one solid wire per pot on the opposite side made the construction very sturdy,absolutely no need to mount the boards anywhere else.
The easiest and fastest part was populating the boards,the big part is thinking about the project and designing the frontpanel.
The grounding options are working perfect.

Didn't want to convince you,hahaha ,but the result is a really nice eq,a very good expansion to my existing EQs,so why not?
I like the mid bands btw.

Happy designing and building of course,

Pfüati,

Udo.

 

[sr1200]

Udo, thats beautiful... wish i could get mine working. lol.

 

[kante1603]

Udo, thats beautiful... wish i could get mine working. lol.

Thank you very much.
About your issue,looks like a series build error.
Do the gain pots work on the faulty bands?
You can compare the schematics of the mid bands,they're identical concerning topology,just some values are different.Do you have the same reading on the switch on the working mid band?
ICs all in correct orientation?Lytic too?
Band three,that's the high mid band,right?
I would check all parts around the area at ic5 as a starting point.
Maybe a good picture of it might help.

Good luck,

Udo.

 

[sr1200]

Ill get a pic thanks.  The funny thing is it was working fine, calibrated fine.  I re-wired it to fit into a 1u instead of a 2u and all hell broke loose only on that upper mid band (on both channels... so maybe i just did the same thing wrong on both...  thanks, and you mentioned sifam knobs.  Got a link to those?

 

[kante1603]

Hi,

I sourced the knobs here in germany:
http://www.sibalco.de/produkte/drehknoepfe/spannzangenknoepfe.html
Don't know who sells them in the usa,have only seen them at canford,uk.
I would google it.
But be aware that they are quite expensive.

About your issue,what was changed when you say you rewired them?
Still looks like a series build error to me,and if you say they worked and calibrated fine before rewirering it should be something simple.

Cheers,

Udo.

 

[sr1200]

I had the pots connected directly to the board previously.  Now they are wired.  Thanks for the link, the part number will be quite helpful.

 

[kante1603]

I had the pots connected directly to the board previously.  Now they are wired.  Thanks for the link, the part number will be quite helpful.

Wires swapped?Wires for boost/gain in the correct position (1st row)?

Anyway,it's 2,5 years ago when I ordered the Sifams.
I think they are these:

Typ SP- 11mm - niedere Bauform / low profile (13,5mm high)  Serie: K010005 ,grey no line,4mm shaft

You'll need coloured caps too.
I'll look for the bill if you want.

Best,

Udo.

 

[sr1200]

Naa thats cool.  Thank you I can find em from there, i just wanted to see what you did about the shaft size and find a model that actually FITS lol.  I wound up having to put little collets on each pot to make em 1/4".

 

[audiophreak]

some VERY nice work there Udo 

 

[kante1603]

Naa thats cool.  Thank you I can find em from there, i just wanted to see what you did about the shaft size and find a model that actually FITS lol.  I wound up having to put little collets on each pot to make em 1/4".

My Omegs were 4mm,Sifam has nearly all sizes both metric and imperial.
Pot sizes from 10 to 13mm diameter are for 2/3/4 mm and 1/8" shafts,the bigger ones go to 6mm and 1/4".

Best,

Udo.

 

[Markus_Krippner]

Potentiometers: I just found these very cheap ones:

http://www.voelkner.de/products/288619/Leitplastikpotentiometer-9mm-P092s-10-Kr-20-Lin.html

Well...they won't fit into the PCB... and they are 6mm. But the are 2Gang 10k linear conductive plastic.... for Eur 2.82 only.

Should I try them ?  ;-)


...markus