Neumann W492 equalizer DIY project (PCB docs added)

[MartyMart]

anyone have the current draw for two channels? im trying to find out if i can use some smallish torroids i have laying around.

I can't remember where the post was but I'm 99% sure that a 7.5VA traffo will do 2 channels no problem.

MM.

 

[stereokillah]

i've build 4 dual for me and i used 15v 15va with the 9k psu, and work fine  you could add a CRCRC before this 9 psu to have a very good signal.

 

[mitsos]

quite a while ago:

Transformer can be quite small. Current consumption of the eq is about 70 mA per channel.

 

[iangomes]

so I took a walk around the internet, and I haven't been able to find any explanation as to how these filter curves/frequencies are set up. Everywhere I look it says the -3db point is the turnover frequency, but if that were true, the frequency's for the low filter, for example, would be 130 hz to 3k. The points which are specified are at -15 db, not -3... can anyone help me out with this?? what am I missing? ??? ???

 

[sirzodiac]

Hi folks,

i wanna share what i learned messing around quite a while with the potentiometer issue.
First of all: both pot brands are easily available, at least here in europe.
And: the price came down to exactly the same, because of high freight cost and toll taxes for shipping from england. I know because I ordered finally both (by mistake).
I first ordered all Omegs for a total of eight channels (2-gangs only where they are needed). Later on i decided to put four channels standing in a 4U rack, with space for four more & PSU, kinda my own lunch box. So i have a total widht of 4cm (1.55") per channel, which would just fit with the Omegs, but with a pretty silly design, because the pots are closer to the neighbour channel's pots than within it's own channel.
My buddy who's gonna build the other four channels bought cases from DIY-racked, which have a horizontal spacing between the two pot rows from 15.5mm, this is only to fit with the Vishay Sfernice ones.
So i had to look for the Vishay pots. On their website there are the sales contacts per region, or, even better, you browse through the product range to your desired pot meter (P11A in our case) and look unter the "i" icon ("Product Support") for "Sales contacts". This filters just the distributors who DO sell this product. So, for little Switzerland, i had a list of eleven distributors. I choosed three bigger ones out of all them, asked for an offer, and the next day i had three quotations, two with a MOQ of 50 and one with 25, lead time between 7 and 13 weeks, price between 6.5 and 7$ each (as suggested by Audiox, i only asked for the 2-gang type, to reach the MOQ).
By the way: the SAP Order Code from Marty Mart is absolutely correct, I went through again, never trust a stranger...  ;D
Thanx, Marty!

So, in short:
- Omegs have a much bigger horizontal distance than Vishay Sfernice (26.5mm for Omegs, 15.2mm for Vishay Sfernice)
- Both are easily available (at least in Western Europe)
- The price of the Omegs can become the same than for the Vishays (in Western Europe) because of shipping and toll taxes.
- If someone is looking for Omegs, I have. PM me.

I hope this can help.
May the DIY force destroy your budget and free time as well, we all know how much fun this is!... 

cheers,
benu

 

[goldvasser]

Hi !

A noob question : I have 10k A double gang Vishay pots with an indent position on center . My issue is when I am mesuring the values of the two gangs set on the indent, I have some differences between them (i.e. :track.1 : poles1-2 :4.75k, poles2-3: 4.58k - Track2ole1-2: 4.82k poles2-3: 5K)
Is there a way, trick or something to have a balanced value (5K on center) corresponding with this indent marker ?

Any suggestions really welcome !

thanks !
Bruno.

 

[stereokillah]

I think it's normal, i don't how to say this in english, entre la marge d'erreur du multi mettre et la marge d'erreur du pot

aLOT of 2 gang pot don't have the same value exactly.

 

[RedNoise]

10% de tolérance tes pots Vishay ??

 

[aprendiz]

Hi,

Looks perfect for my live rack. I have half rack space for an eq.

Boards still around?

Thanks

 

[Whoops]

Hi,

Looks perfect for my live rack. I have half rack space for an eq.

Boards still around?

Thanks

you will find the boards here:

http://www.groupdiy.com/index.php?topic=10776.0;topicseen

 

[Whoops]

I would like to build a unit using the SSL 9K preamp and this EQ.

Could I run an unbalanced out of the SSL 9K board and bypass somehow the balanced input of the W492?
going unbalanced from one board to unbalanced in the other


also,
if the NE5532 IC's are capable, could I use this circuit with + an - 18V instead of +-15v ?

thanks

 

[audiox]

Could I run an unbalanced out of the SSL 9K board and bypass somehow the balanced input of the W492? going unbalanced from one board to unbalanced in the other

Use the inverting input pin. No modifications required (but remember that the polarity of the balanced output changes).

if the NE5532 IC's are capable, could I use this circuit with + an - 18V instead of +-15v ?

Yes

 

[sirzodiac]

@ Rednoise:

yes, even worse, it's 20%.
According Vishay's datasheet there is 20% standard (M as last letter of the SAP ordering code), and 10% and 5% only available for cermet (not for lead plastic), letters K and J...

 

[RedNoise]

@ Rednoise:

yes, even worse, it's 20%.
According Vishay's datasheet there is 20% standard (M as last letter of the SAP ordering code), and 10% and 5% only available for cermet (not for lead plastic), letters K and J...

So goldvasser mesures seem to be correct regarding the tolerance...

 

[Whoops]

Could I run an unbalanced out of the SSL 9K board and bypass somehow the balanced input of the W492? going unbalanced from one board to unbalanced in the other

Use the inverting input pin. No modifications required (but remember that the polarity of the balanced output changes).

What I would like is to have the balanced input parts removed and connect the unbalanced out of the SSL9k right after them

 

[gemini86]

Just a passing thought:

Has anyone looked into ordering a bunch of custom dual concentric pots from Omeg for this build? I was going to send in a quote request, but I feel silly doing that knowing there's no chance of me buying them. If they could be made for like 10-12 bucks a piece would that be worth it to anyone? That might make this project 51x-able?

http://omeg.com/p2c2bub2.htm

 

[kazper]

Just a passing thought:

Has anyone looked into ordering a bunch of custom dual concentric pots from Omeg for this build? I was going to send in a quote request, but I feel silly doing that knowing there's no chance of me buying them. If they could be made for like 10-12 bucks a piece would that be worth it to anyone? That might make this project 51x-able?

http://omeg.com/p2c2bub2.htm

Why not buy the ones that Colin is stocking at audiomaintenace?

 

[Harpo]

Could I run an unbalanced out of the SSL 9K board and bypass somehow the balanced input of the W492? going unbalanced from one board to unbalanced in the other

Use the inverting input pin. No modifications required (but remember that the polarity of the balanced output changes).

What I would like is to have the balanced input parts removed and connect the unbalanced out of the SSL9k right after them

Not that easy to get a single op-amp stage dremeled away from a dual op-amp without destroying the chip.

 

[gemini86]

Just a passing thought:

Has anyone looked into ordering a bunch of custom dual concentric pots from Omeg for this build? I was going to send in a quote request, but I feel silly doing that knowing there's no chance of me buying them. If they could be made for like 10-12 bucks a piece would that be worth it to anyone? That might make this project 51x-able?

http://omeg.com/p2c2bub2.htm

Why not buy the ones that Colin is stocking at audiomaintenace?

Simply because I didn't know he sold them... :-[

 

[goldvasser]

@ Rednoise:

yes, even worse, it's 20%.
According Vishay's datasheet there is 20% standard (M as last letter of the SAP ordering code), and 10% and 5% only available for cermet (not for lead plastic), letters K and J...

So goldvasser mesures seem to be correct regarding the tolerance...

Yep, They're 20%... Is there a way to correct the value mesured to match them when the axis is on the indent ?

Thx !!!