Help me find this potentiometer (dual gang, double value)

Hi,

I need a 2-gang rev. log. pot.
The value should be 100K for a gang and the half (50K) for the other wafer,
or 50K/25K.

Does anyone know where to source it?

Thanks.

Don't expect to be able to find this off-the-shelf.

Omeg.co.uk is probably the only supplier that can make this at small quantities..

Depending on how you use of the pot, you can maybe parallel one section of a 2x100K with a 100K resistor?

Jakob E.

You could swap out one of the wafers for the proper size... check out aml, he's got both sizes:
http://www.audiomaintenance.com/acatalog/potentiometers_carbon_16mm_diameter_dual_gang.html

the math may not be perfect, but could you not source a 4 gang pot , connect 2 of the wafers in series and the third by itself, leaving the 4th blank?

if im insane and this makes no sense please disregard.

-Brock-

Not insane; an other possibility is to use a triple-gang and use two wafers in parallels or in series.
But I think, again, CONTEXT!
Why do you need these values? Maybe there is a possibility to modify the circuit in order to make it accept a dual pot?

Val_r said:

I need a 2-gang rev. log. pot. The value should be 100K for a gang and the half (50K) for the other wafer, or 50K/25K.

Click to expand...

mcfarlane_audio said:

but could you not source a 4 gang pot , connect 2 of the wafers in series and the third by itself, leaving the 4th blank?

Click to expand...

http://www.audiomaintenance.com/acatalog/potentiometers_carbon_16mm_diameter_triple_and_quad_gang.html

RU-01-003 (4x 47k rev log)

Connect two of the sections parallel and you get 47k / 23.5k. That is close enough 50k / 25k (think about potentiometer tolerances) and if I understood right the exact value was not important in your application but the ratio.

gyraf said:

Depending on how you use of the pot, you can maybe parallel one section of a 2x100K with a 100K resistor?

Click to expand...

No. It changes the curve.

The Sfernice P11 (cermet) or PA11 (conductive plastic) is a modular pot, with up to 7 gangs. Rev-log gangs are available.
http://www.datasheetcatalog.org/datasheet/vishay/p11pa11.pdf

Finding a distributor may be tricky, though...

Axel

mad.ax said:

The Sfernice P11 (cermet) or PA11 (conductive plastic) is a modular pot, with up to 7 gangs. Rev-log gangs are available.

Click to expand...

And the minimum order quantity is several hundred units if I remember correctly...

Right, last time I submitted them for a quotation, min qty was 500, and no sample orders.
Even Radiohm now want 500 min order.
I think Omeg are the last survivors. We should cherish them, as the day they go down, DIY will be only PIC's, GAL's and C-code...

abbey road d enfer said:

Even Radiohm now want 500 min order.

Click to expand...

And even worse, the company doesn't exist anymore.

Uh... I have a pending order with them. I haven't been informed they are not in a position to fulfill it. Do you have any specific info?

abbey road d enfer said:

Not insane; an other possibility is to use a triple-gang and use two wafers in parallels or in series.
But I think, again, CONTEXT!
Why do you need these values? Maybe there is a possibility to modify the circuit in order to make it accept a dual pot?

Click to expand...

I know about paralleling 4-gang pots, but I was looking to save space.
The app is an HPF in LR configuration.

Thank you.

gyraf said:

Don't expect to be able to find this off-the-shelf.

Omeg.co.uk is probably the only supplier that can make this at small quantities..

Jakob E.

Click to expand...

Thanks Jakob, I will check them.

abbey road d enfer said:

Do you have any specific info?

Click to expand...

That is what I was told some time ago. I haven't investigated it further since we don't use their products.

www.radiohm.com

Val_r said:

The app is an HPF in LR configuration.

Click to expand...

As abbey road d enfer said earlier, you should try to modify the circuit. Take the 2x 100k potentiometer for granted and change the other components.

As audiox suggested. That's the way SSL did it. Check attached schemo.

Thanks abbey road d enfer.
That solution looks pretty straightforward and hassle free.

abbey road d enfer said:

That's the way SSL did it.

Click to expand...

Where have they used it? The new 425 series eq?

Val_r said:

Where have they used it? The new 425 series eq?

Click to expand...

I don't know exactly. I suppose it's in the 4K. There's a bunch of schematics I got from a website. They are named 82E_XX and there are two preamp schematics, one seems to be the very early one, with a xfmr and a 5534 and the other may be a 9K. There are 3 different EQ's. The dates on the dwgs are 84-86.

It is widely used. Studer 900 came into my mind first and there must be many others. I found also one version adjustable from 20 to 200 Hz used in a custom console. I can post the component values if you dont like doing the math yourself.

abbey road d enfer said:

I don't know exactly. I suppose it's in the 4K. There's a bunch of schematics I got from a website. They are named 82E_XX and there are two preamp schematics, one seems to be the very early one, with a xfmr and a 5534 and the other may be a 9K. There are 3 different EQ's. The dates on the dwgs are 84-86.

Click to expand...

I think you're referring to this link.
The channels EQ's from Solid State Logic 4000 are the 82e02, 82e242 and 292.

I'm more interested in the last one, they use 4-gang pots in the hpf, including all of the 2 stages (it's a 18dB/oct. design).

Interesting info in this thread.

Yes, it's that link.
The 18dB/oct version uses 3-gang pots of identical values (in the thread, Keith mentions 4-gang with one 100k wafer, I suspect it's for the Total Recall -or whatever they called it at SSL).