Neumann W492 equalizer DIY project (PCB docs added)

[audiox]

All potentiometers are dual 10K linear. Only two of them needs to be duals, but the dual type is used in all positions because it is mechanically more stable than single and buying only one type is cheaper than buying two types. Pin spacing is 5.08mm.

to sinestaraudio:
Conductive plastic pots must be used because the circuit is DC coupled. Normal pots start to scratch quite soon.

 

[MartyMart]

EDIT _ Sorry Audiox , we crossed posts there !

I almost have the full 18 digit code down but just need the spacing between
the two sets of pin connections, front to back on the board.

Is it also 5.08mm or 7.62mm or 10.16mm

Many thanks,
Marty.






Yes there's two pots in the schem that seem to be "dual" and the image of
the pots are all the same, It looks like 8 dual pots required, judging by the
front to back pot image size in the project doc's ( compared to data sheet images )

I'm trying to get a group buy together and have PM'd about the details.
I can get a decent price break @ 250 units.

The Sfernice data sheet needs an 18 digit SAP code for an accurate order,
so the PA11QXF is not enough detail.

Lets see when Audiox gets back about the pots.

Cheers,
Marty.

 

[audiox]

Length between the two rows of pins is 5 mm. Please note that standard tracking between the elements is quite poor in this potentiometer. So you must order the pots with interlinearity option. I think that option is mentioned somewhere in the datasheet.

 

[dustbro]

[quote author="audiox"] I have about 100 knobs more than I need because of the minimum order quantity. I am going to make them available too.[/quote]
:thumb:
I would definitely go for the knobs and pots

 

[cannikin]

[quote author="dustbro"][quote author="audiox"] I have about 100 knobs more than I need because of the minimum order quantity. I am going to make them available too.[/quote]
:thumb:
I would definitely go for the knobs and pots[/quote]

ME too

 

[king-rb]

...

 

[MartyMart]

Here's the exact 18 digit code for ordering the correct pots, though I find out
on monday about a group buy price for over 250 pots !!

P11A2Q0EJSX00103K that's 17 digits and the final 18th is the special request
for interlinearity, which doesn't have a "number".

Marty.

 

[audiox]

Potentiometers and knobs available:

http://www.groupdiy.com/index.php?topic=28431

 

[lofi]

think a gb might be preferable though, with 8 pots a board its going to get quite expensive, plus your freind only has 250 before restocking or 31 boards worth.

its the exclusivity of these pots thats making me hold back from joining in the fun

love and kisses

Iain

 

[MartyMart]

Iain, let me see what the suplier says on monday, but audiox price is about
right to be fair.

If there's interest in over 250 pieces and the price is under 8 euros then I'll
put up a feeler thread.
I can't possibly fund that kind of number, so payment would be up-front of
the order, which will take approx 4-6 weeks.

The other option , if you are going to put 2 boards in a 1u rack, is to use off
board pots, there's some others with conductive plastic and similar spec for
around £3.50 each ..... I'm still searching !!
( that's a lot of off-board wiring though ! )

Marty.

 

[lofi]

i have no doubt that the price is about right sir, it was the small supply available that worried me.

i am also looking to make a summing/mixer box for my DAW so thinking about 24 EQ's. i am tossing between this and the ts80 available and cost/performance would be a factor.

Iain

 

[mitsos]

Hey Marty,

It looks as if there is a huge interest in pots in the BM.. In case Audiox runs out... did you get an answer from your distributor?


EDIT:
ALSO, is the only reason to use these pots cuz of DC? Do they "sound" better? Could I put some type of blocking caps, and then use regular carbon pots? Ok, maybe stupid question... but I am a total noob here. and cheap.

thanks

 

[cannikin]

Hey Audiox

Can you post some pictures of your unit? trying to figure out the layout of parts on the chassis.

 

[MartyMart]

They are still thinking about it !
He came back to me on tuesday just to check the final "correct" pot details
and I've heard nothing more.
I asked for a quote for 250 and 500 !!!!

I'll chase them up.

MM.

 

[mitsos]

Thanks Marty!

I also thought of the off-board pots, been looking like crazy at all the distributors. Makes the front panel easier to do in my opinion... No worry about the wires, no one is going to see it but me!

What do you guys think about the DC blocking caps to be able to use carbon pots? Stupid idea??

 

[audiox]

To mitsos:
Carbon pots and DC blocking caps doesn't work because potentiometers provide also DC path for the op-amp inputs.

 

[audiox]

I added a new drawing about potentiometer assembly and front panel drilling:

http://audioxxx.googlepages.com/potentiometer_assembly.pdf

 

[cannikin]

Thanks Audiox

Now I can visualize how this thing lays out on the front panel ... thanks very cool very excited.

 

[Purusha]

I have two questions.

1. What kind of PSU can we use with these?
Will there be any PSU boards available?

2. What kind of miniature toggles can we use here?

 

[audiox]

Any psu type giving +/- 12 to 18V will do the job. I guess there are number of designs available that have been succesfully used with other diy projects.

There are generally two types of small toggle switches: miniature and subminiature. Most common is the miniature like C&K 7101 (the standard toggle switch). Subminiature has smaller body (for example Farnell 957-5715. For those living in Northern Europe Elfa 35-355-31 is much cheaper).

If you want that the switches are in the same line with the potentiometers, it is better use the subminiature because there is not much space. If you mount the switch so that the lever moves horizontally, them miniature switch fits too. But it is better looking when it moves vertically. See the face drawing in the first message of this thread.