Neumann W492 equalizer DIY project (PCB docs added)

[backstreets]

Hi,

I have two W492 equalizers that I use for as an M-S EQ setup in my mastering chain. I've been thinking about the idea of modding them from +-15 dB gain range to +- 7.5 dB.

I would also like to change the low cut from being 80, 20, 140 Hz to 80, 20, 40 Hz. As the 140 Hz is too high and I could use a 40Hz cut in-between 20 and 80.

I talked with Mazz (www.vintagecity.de) and he suggested that I'd check with you guys who have DIYed the W492 and see if you could help me out. From what he wrote to me I understand that I would need to change both pot's and resistors as well as caps and resistors in the Rc low-cut section.

It would be super if you could help me out on what I need to do and what to change to what to pull this off!

I attached the original W492 schematic as well.

Thanks in advance,
L

 

[Harpo]

.. I've been thinking about the idea of modding them from +-15 dB gain range to +- 7.5 dB.
I would also like to change the low cut from being 80, 20, 140 Hz to 80, 20, 40 Hz. As the 140 Hz is too high and I could use a 40Hz cut in-between 20 and 80.

Different from DIY-project, but for HPF 40Hz instead of 140Hz I'd try R6=28K, R10=182K, R13=36K5.
For your reduced boost/cut range I'd increase R19+R68 to 1K91 2K43 and R42+R61 to 2K2 3K01 to get this voltage divider level down.
Good luck


edit: prev.values missing dB2AV-conversion.

 

[backstreets]

Very nice, thanks a lot!

Would getting the voltage divider down be sufficient to reduce boost/cut range, no need for new pots? (That would be fantastic  )

/L

 

[backstreets]

.. I've been thinking about the idea of modding them from +-15 dB gain range to +- 7.5 dB.
I would also like to change the low cut from being 80, 20, 140 Hz to 80, 20, 40 Hz. As the 140 Hz is too high and I could use a 40Hz cut in-between 20 and 80.

Different from DIY-project, but for HPF 40Hz instead of 140Hz I'd try R6=28K, R10=182K, R13=36K5.
For your reduced boost/cut range I'd increase R19+R68 to 1K91 2K43 and R42+R61 to 2K2 3K01 to get this voltage divider level down.
Good luck


edit: prev.values missing dB2AV-conversion.

Thanks for the corrections! Will go to the local component store now, then the soldering will being. I'll report back on how it goes!

 

[superslaukey]

Hi,

I`m not sure if this was already addressed here: i`m thinking of having stepped frequencys for band 2 and 3. as a first approach for calculating resistor values and frequencys i did the following. since linar pots are used here, I made a graph in open office using 0 - 10000 R and 60 hz to 1000 hz (band 2). The resulting linear function can give any frequenzy from 60 to 1000 hz and the corresponding resister values by interpolation. I know, it`s not the most sophisticated approach. But is it WRONG to do it that way?

Thanks in advance and a happy new year.

 

[colonelmot]

Interested in building this eq but a bit confused by the pot situation.....

Which pots (vishay or omeg) fit both Gyrafs PCBS and Dan Frontpanels?
Is there a an affordable source for the vishay pots listed in the BOM?

Thanks

Tom

 

[spase]

you can get those pots from TAWElectonics.

 

[SKJGProject]

i bought an almost finished kit from outoftune some time ago, but i just realized after checking all my unfinished stuff,
that i have the sfernice pot pcb version but omeg pots...can i use them together?

 

[kante1603]

i bought an almost finished kit from outoftune some time ago, but i just realized after checking all my unfinished stuff,
that i have the sfernice pot pcb version but omeg pots...can i use them together?

Hi,
there is only the sfernice version pcb existing.It was never made for omegs so they won´t fit directly.You can mount them off-board with some short wires.
The sfernice pots are very hard to source and very expensive.
So use what you have,the omegs are o.k. for this.Check them for right values and remember that they must be conductive plastic types!As far as I remember you need 6 single and 2 duals per channel.

Hope to have helped,

Udo.

 

[signalflow]

i bought an almost finished kit from outoftune some time ago, but i just realized after checking all my unfinished stuff,
that i have the sfernice pot pcb version but omeg pots...can i use them together?

From what i remember people just bent the back pins of the pot into place on the PCB for the omegs.

-Casey

 

[dekelm8]

Hi Everyone.
I built this eq, but it not working...
I need check it that all is work good...
So my question is:
i can check the circuit band by band (connect only the first section and check if it's working) or i must soldering all the components?
The circuits (splits by pages on the pdf) can working alone or for get any response i must all the circuit togther???
Please Help ASAP
Thanks All

 

[audiox]

So my question is:
i can check the circuit band by band (connect only the first section and check if it's working) or i must soldering all the

You can build and test one section at a time if you want.

 

[rmaier]

I'd like to build a pair of these using stepped switches. For the gain switches, I'd like to limit them to +/-5dB in 1 dB increments using 11-position rotaries. Since the circuit calls for a 10k lin. pot, I plan on making up some series-type stepped attenuators using 340r resistors (x10) for a total resistance of 3.4K. I'll then add a 3.3K resistor on either side of the switch for a total resistance of 10K. Can someone tell me if this will work? Or is there an easier/better way to do it?

Thanks!

Ralph

 

[audiox]

Can someone tell me if this will work? Or is there an easier/better way to do it?

That is probably the easiest way because you can leave the rest of the circuit as it is.

Circuit simulator will help you with the resistor values.

 

[rmaier]

Great. In that case, do I connect my 3.3K resistors to the outside terminals of the rotary switch (pins 1 and 12) and leave the wiper connection as is? Sorry for the newbie questions - still struggling to understand how this works  .

When it comes time to adjusting the trim pots, can I simply follow the same procedure outlined in the build docs, substituting 5dB for the regular 15dB range? Also, how would one recalculate the trimmer values for the alternate method using no test equipment?

Thanks!

Ralph

 

[dryman]

i finished my new W492. I have to do some tricks, to connect the OMEG-Pots(https://www.buerklin.com/default.asp?event=ShowArtikel%2875E730%29&l=e&jump=ArtNr_75E730&ch=59533, that i use. They are a little bit bigger, so i can't mount them on the PCB.
The construction is very solid and the PCBs don't need to be mounted on the case. Sounds nice.

 

[dryman]

Another Picture

 

[sr1200]

I know this is an old thread, but figured I'd ask since I only recently picked up some boards from the BM.
The original had a HPF  of like 20-80-140 i think (but were out of order if memory serves) has anyone built a little HPF to go along with this.  I've been playing with some simulations, but nothing is really getting me close to the desired result.  Would be quite helpful for mixdown.

 

[wolfgang]

I am selling 2 fully assembled PCB´s!
If some one is interested check out this:

http://www.groupdiy.com/index.php?topic=51135.0


regards,
Wolfgang

 

[firfe]

hi everybody
i've finished my W492.
but i've a problem with the P1 and P2 ( bass potentiometre)
there no action with this 2 pots.
and the P1 cut all the sound of the machine when i 'm around the middle position (zero-)
there 's sound before 0 and no after (0 to 15) and no action.
and P2 do nothing when i turn it.
i've changed the 2 potentiometre and the NE5532 ut nothing change.

all looks good and the pcb came from pcbgrinder.
the other pots work  good

i'm completly lost...

maybe someone have an idea to help me.

hope you can understand my beautiful english (sorry about that)
best

JF