Neumann W492 equalizer DIY project (PCB docs added)

[audiophreak]

yes selco has them and they take small quantity orders.  check back in the thread i posted a link

http://catalog.selcoproducts.com/viewitems/collet-knobs/basic-collet-knob?&forward=1

  I got these, haven't tried them yet, I can mount a couple tomorrow and post back...but they look real nice  ;D

 

[Minotaurus]

Hi,

is there a part list for Germany (Reichelt) ?? The Links on the First Page dont work for me, and i didnt read the whole thread yet, so if anyone has one, it would be nice to have.

thx.

Klaus

 

[audiophreak]

I mounted the Selco knobs and they fit nice, first time using collet knobs. 
  Question.. this is only the second project I've done with Opamps, the first being the GSSL, was wondering if I should fire it up the first time without the Opamps in ?  test voltages, as with the GSSL.
  Thanks 

 

[audiophreak]

 Question.. this is only the second project I've done with Opamps, the first being the GSSL, was wondering if I should fire it up the first time without the Opamps in ?  test voltages, as with the GSSL.
 Thanks  

 I ask because i dont know if it will damage anything else if I leave them out to check voltages.
getting close to the power up  

 

[audiox]

was wondering if I should fire it up the first time without the Opamps in ?  test voltages, as with the GSSL.

That is a good idea. Also check the op-amp output voltages after inserting the chips (a few millivolts or few tens of millivolts when working properly).

I ask because i dont know if it will damage anything else if I leave them out to check voltages.

It could be possible in a circuit where the op-amp outputs are used to bias the surrounding active circuitry. I have seen a few examples, mostly in power electronics. But in this case, no reason to worry.

 

[audiophreak]

Thanks audiox !   

  if everything goes well, I should be powering up four channels by the end of the week.

 

[conleycd]

Could be a flaw on my computer but it seems the Google links to the documents are not up any more.  The documents are listed as 0kb? 

Any thoughts?

CC

 

[Spendor]

Hi All - just back from touring and want to start this project. I've got the pots and boards, but can't download the schematic or BOM from the start of this thread - can anyone help out here?
Cheers!

 

[audiox]

it seems the Google links to the documents are not up any more.

I checked that all the documents are still in Google docs and "shared to everyone".

A few weeks ago some of the files disappeared the same way but returned next day.

 

[envelope]

yes selco has them and they take small quantity orders.  check back in the thread i posted a link
http://catalog.selcoproducts.com/viewitems/collet-knobs/basic-collet-knob?&forward=1

  I got these, haven't tried them yet, I can mount a couple tomorrow and post back...but they look real nice  ;D

Hi Audiophreak, how have these knobs worked out for you cosmetically and quality wise? I am searching for 32 4mm shaft 11mm diameter collets.

 

[audiophreak]

Hi envelope,
                I got a burst of work recently, so haven't gotten back to this project in a week or so. I have the panels from " Dans front panels ", mounted the pots and have put a couple of these knobs on to see how it fit and how it looked, and both are good, they fit fine, quality seems good and they feel and look good too IMO.
                I'm building four of these in a 2U rack case, its been challenging, but I think I've got it. Will post pix as soon as possible.

  Hope this helps.

 

[envelope]

Thank You, I just got a great quote from Selco, so I'm going to try them. The HWBP relay array (will install in the blank area in front of XLR's, on the substrate panel). finding the 4mm collet knobs and final wiring/assembly/shielding are all I have left to do.

 

[audiophreak]

Looks great, clean work !

I'm very much a Newb, what is - (HWBP Relay array will be installed in the blank space area in front of the XLR's.)

  and why not WIMA's ?  I thought most people here preferred them ?

I should have mine up and running in a week or so, wil post pix soon.

 

[envelope]

what is - (HWBP Relay array will be installed in the blank space area in front of the XLR's.)
and why not WIMA's ?  I thought most people here preferred them ?
I should have mine up and running in a week or so, wil post pix soon.

Hi, HWPB is hard wire bypass, using relays. The boards are made by [silent:arts]

I should (I now have) retract the negative WIMA comment. They are fine, and can be exceptional. (if the right series in used). My reasons are based on the lack of a well stocked WIMA suppliers that is located and ships from within  Canada. 'regards

EDIT: will try TAW for Wima capacitors, they seem like good folk. 

 

[conleycd]

Hey there,

Here is a good WIMA supplier http://www.tawelectronics.com/ - I've always found them to be very helpful and I think they might offer a Prodigy-pro.com/diy discount.

Now... I have a question wondering if someone can answer.  I am planning to use this as the last stop in a channel strip in a rack.  I have some EA 2623-1 output transformers from classicapi.com and I was planning to strap one onto the 'end of line' to the output of the W492 eq.

Now, the primary is rated at 75 ohms secondary at 75ohm or 300ohm if in 1:2 ratio.  Do the NE5532s have enough juice to drive this transformer?  Would I just strap + to + and - to -?

In front of the eq I'll have a microphone preamp (discrete opamp), compressor (with a discrete opamp for output makeup), and then the eq.

Thanks.

CC

 

[audiophreak]

  Well .... I just fired up four channels in a 2U case.. no smoke and and everything seems to be working.. However ... I  wired the pots off board and soldered all the  jumpers from the top of the PCBs , so when I connected the pots, all the pots that would have been on the bottom of the PCBs are wired backwards .. DUH.. :

  Could I have damaged anything by this Newb mistake ?

  Over the next couple days I will correct the wiring try and calibrate, and post some pix

 

 

[audiox]

all the pots that would have been on the bottom of the PCBs are wired backwards .. DUH.. :

Could I have damaged anything by this Newb mistake ?

Check the rotating direction of the planet Earth. If it has changed, please correct your wiring as soon as possible.

The circuit itself is not damaged, no reason to worry.

 

[audiophreak]

Thanks audiox 

  after I powered it up and was just messin with the controls, I noticed that a few of the frequency sweeps seemed " backwards " after thinking on it for a few min. realized what I had done, so just have to swap the outer pin leads on the pots that would have been mounted upside down / on the bottom of the PCB.  ;D

 

[audiophreak]

Hello again  ;D

  OK, I have the pot wiring straitened out. Now that I've had the unit on for a while and testing each channel, I got to the 4th channel and " pop "  audio went out, checked voltages and the pos dropped to 14.1vdc from 14.91vdc when I turned it on  :'(

  The PT is .500 amp at 30v and I am powering an LED in the mains switch from the NEG side - with no load the NEG side was -15.3vdc and POS side was 14.97vdc, with all four channels on I get +14.91vdc and -14.97vdc. The heat sinks dont seem to get too hot, so I dont think its thermal shut down, but after I let it sit for 15min. channel four was up and good, POS was +14.43vdc and NEG was -14.98vdc

  anyone have an idea whats happening ?  PT too weak ?  maybe thermal shut down ? 

  Thanks in advance 

 

[audiophreak]

Hello,
        Well, I fired this unit up and left my meter on it and checked it every 5-10 min. and everything seams O.K. now - POS voltage starts at +14.97 and after 10-15 min. slowly drops to +14.84 , NEG starts out at -15.03 and slowly drops to -14.78, both stabilized there for 2 1/2 hours. 
 
      Should I be concerned about this ?

  I Have an Mnats PSU with trimmers, would that be better, then I could set it right at 15v or 15.5

Here is a link to pix, only used it on my own voice so far, but sounds good and think it will be very useful.

https://goo.gl/photos/rdyaKt2qo9feE95k6

I cant say enough about TAW electronics for the WIMAs, I got them from TAW for this project and SSL 9k and G-Pultec, they have great customer service, great prices, and shipping is reasonable. also the Selco knobs for the same reasons.

  Thanks audiox and everyone for your invaluable help and knowledge, I am very pleased with this project.