Neumann W492 equalizer DIY project (PCB docs added)

[Andreas Pfeiffer]

What is the best spot for an attenuator in this EQ?
Should be easy to implant in a ready build EQ.
Maybe the best at the first OP amp output?

Somebody has an idea, please ?

 

[ArnoldLayne]

Ok, I think it was these:

http://tbaudiogear.com/?product=bi-10k-linear
http://tbaudiogear.com/?product=bi-2x-10k-linear

They're conductive plastic, have 10% tolerance, an way cheaper than P11's.
I saw that there is also a version with one, 11 or 21 detents... (http://bitechnologies.com/pdfs/p260.pdf)
Could this be an easy way of having some repeatability, without going into mastering requirements ?

I found these as an alternative to the expensive P11 pots. Would they be better than Omegs ?

Which ones does your question refer to?

Udo.

Oh no, I forgot the link 
Now I don't even know what I was talking about...

 

[late]

What kind power transformer i need if i use mnats psu board. Is 2x15V and 30VA good?

 

[kosty]

Ok, I think it was these:

http://tbaudiogear.com/?product=bi-10k-linear
http://tbaudiogear.com/?product=bi-2x-10k-linear

They're conductive plastic, have 10% tolerance, an way cheaper than P11's.
I saw that there is also a version with one, 11 or 21 detents... (http://bitechnologies.com/pdfs/p260.pdf)
Could this be an easy way of having some repeatability, without going into mastering requirements ?

Did anyone try these ?

 

[horvitz]

Hey, noticed you guys swinging by looking for pots.  Anything I can do to help out?

Looking at the the copper files, I think they might fit the Omeg version using those outside holes.  The spacing between decks is 7.6mm and the pins 2.5mm LS.  The Sfernice is only 5mm between decks so no go there.  I didn't get past the first post though, so I am probably missing something.

I think your front panel might change a little, too.  The centerline of the pot is 6.95mm over the PCB and it's a 1/4" bushing. 

  Brian

 

[ArnoldLayne]

Hi Brian,

I was planning on wiring them off-board personally, on Dan's (ddt) panels. The Omegs fit on them, and your pots are smaller so it works.
I'll definetely try them, but I'm also planning for a TBDD rack  Also intrigued by the TBFX platform...
Nice projects !

 

[horvitz]

I was planning on wiring them off-board personally, on Dan's (ddt) panels. The Omegs fit on them, and your pots are smaller so it works.
I'll definetely try them, but I'm also planning for a TBDD rack  Also intrigued by the TBFX platform...
Nice projects !

Thanks!  They are PC pins, so off-board  wiring will be a bit of work, but you should be able to make it work.  Bending a small hook at the end of the pin should help.

I've actually added a discount for you guys doing this project.  It's not published on the site but if you add 8 to your cart, it will automatically apply a 10% discount.

Brian

 

[kosty]

I was planning on wiring them off-board personally, on Dan's (ddt) panels. The Omegs fit on them, and your pots are smaller so it works.
I'll definetely try them, but I'm also planning for a TBDD rack  Also intrigued by the TBFX platform...
Nice projects !

Thanks!  They are PC pins, so off-board  wiring will be a bit of work, but you should be able to make it work.  Bending a small hook at the end of the pin should help.

I've actually added a discount for you guys doing this project.  It's not published on the site but if you add 8 to your cart, it will automatically apply a 10% discount.

Brian

This is a very nice gesture from you ! Thank you very much.
Regarding the spacing between decks, I think that it wouldn't be a big problem since the pots needed per board are 6x single decks and 2x dual decks.
For the 2 duals you can bend the pins from the rear deck and connect it with wires.
I was wondering if would also consider offering a discount for the single deck 10k pots
I guess this would be the perfect opportunity to finally order the TBDD rack kit
Thanks !

 

[horvitz]

OK.  I was misunderstanding the layout.  The PCB footprints all look like dual decks.  I can make a package for 6x single deck and 2x dual.  I'll post back when that's up.

 

[horvitz]

OK, package is up here:
http://tbaudiogear.com/?product=neumann-w492-eq-diy-pot-package

That's 2x  P260P-D2AS3CB10K and 6x P260P-D1AS2AB10K.  Price is $31.95, which is 10% off buying them all individually.

  Brian

 

[kosty]

This is awesome !
The footprint is for dual decks to allow better stability, since the PCB doesn't have any mounting holes. But there are no traces to the pins on the second gang.

Will order soon

 

[noiseattitude]

Guys,
noob here
I have 3 question, I hope somebody could reply me.

1) For this project i have to use only SPDT Switches or fit also SPST ?

2) About the capacitors, i have to use (for 1 channel):
4 elcos, 4 ceramic and the rest is all poliester caps (like as wima) ?

3) A toroidal trafos 230v - 15v x 2 - 15VA  I think is good, can you confirm ?

Thanks in advance,

giovanni.

 

[horvitz]

So sorta good news and bad news.  Well it's the same news, just depends upon if it's for you or me.  You guys totally wiped me out on the single deck pots quickly!  I've ordered more but unfortunately, BI is a very long lead so it'll be 10-12 weeks before they are back in stock.  Thanks for your orders and sorry for those of you who didn't get any.

  Brian

 

[horvitz]

It's worth pointing out though that I have loads of the dual deck pots still in stock so if you want to use 8 of those for a unit, the 10% discount still applies.  That would make a mono unit $46.80 rather than $31.95, which is still not bad.

 

[kogstudio]

Does anyone have any links to history of the w492,
e.g. what years it was in production, desks used in, major uses etc?

For some reason my usually good research skills have eluded me on this one...

anything useful appreciated 

 

[mtw]

I bought these boards around 5 years ago  and am finally ready to start building them.

I took a 3 year break from doing DIY stuff, but I'm ready to get back into it.  So as a new newbie I could use some help the BoM.  I've put together this BoM from Mouser - what I'm mostly concerned about are the caps.  If someone could just give this a once over and make sure I did the right thing I'd greatly appreciate it.

https://www.mouser.com/ProjectManager/ProjectDetail.aspx?AccessID=8b0570daba

It looks like you need electrolytics for C5,C6,C11,C18 and ceramic for C19,C20,C21,C22. The rest I went with WIMA film caps.  I chose 100V (at random) or 63V if 100V wasn't available.

Anyway just a sanity check on this list would be greatly appreciated.

Cheers!

-mtw

 

[Emalot]

The link to buy some W492 boards, page 1, doesn't work.
Someone knows where i can buy these boards pleae?
Thank you

 

[haebbe58]

Hi,

here you are:

https://pcbgrinder.com/index.php?route=product/product&path=59_70&product_id=62

Regards
Herbie

 

[pvision]

I am just finishing a stereo W492 with Gustav's boards and Dan's front panels and have run into an unexpected problem.  After 60 seconds or so the psu shuts down and the negative rail drops to around 0.7 volts

The power supply is one of Gustav's PCB1518 psu boards with 7815 and 7915 regulators.  I did a bit of web searching, read the data sheets and modified the circuit to have a 10uF cap across each regulator output plus the original 100 nF decoupling caps.  This hasn't stopped the problem

I have two of these power supplies, built with the same components, and they exhibit the same symptoms.

The regulators are ON SEMICONDUCTOR MC7815CTG and MC7915CTG and they're fed from a 25-0-25 transformer

I'll try adding diodes as per the data sheet but wonder if I am missing something obvious? 

A couple of things I should mention: the psu ground is not connected to the chassis, just to the PCBs.  The mains incoming earth is not earthed to the chassis yet either

Nick Froome

 

[haebbe58]

with your transformer, you get about 35 or more volts DC after rectifying at the inputs of the regulators. But they cannot stand more than 30 volts DC at their input, some have their maximum at 35 volts, but tzhat is the absolute limit So maybe you have blown them or their safety mechnism does act and they shut down.

for that application you have to choose a transformer that doesn't deliver more than 30 volts dc after rectifying which means not more than appr 20-0-20 AC. E.g. a 15-0-15 or a 18-0-18 would be the best.

Regards
Herbert