Need 3 gang 25k Pot for Trem Circuit

[ivey]

Gentlemen:

I am seeking a 3 gang pot for the tremolo circuit in the Sunn Amp.
Can any one assist me? Or do any one have a mod on the circuit. I do not want to dream one up. Bad for vintage.

Take Care

Ivey

[Chuck H]

There are all kinds of criteria for a pot. Does the pot need to be of a certain size or do the lugs/pins need to accomodate the mounting conditions in some special way???

Mouser sells pots that would "work" elecronically but may not be what your after otherwise. Many pot MFG's will make triple gangs but with a ridiculous minimum order that prohibits individual projects.

Chuck

[ivey]

Chuck:

Mouser only sells dual pots of 1/2 watt size by 14mm. MFG has no 3 gang pots at all.
A store in Florida, has a 3 gang 50k pot, but it would be to touchy to work with.

Stackpole and Clairostat, wants big bucks to make one and I must order 500.

So I am out looking for help.

Any broken Sunns out there?

Take Care

Ivey

[Chuck H]

There are some "salvage" type sites around that do have odd parts. Good places to find ganged pots and rheostats. Sorry I don't hve the links (I just relaced my computer due to catastrophic failure of the (very) old one and lost my "favorites") but they're out there if you look for them. Of course with this kind of shopping there is no guarantee you'll find just what you want. IMHE special pots are the hardest thing to find.

[ivey]

Chuck:

Are you near Seattle? Near the Naval Station there.

I heard that there was numerous surplus places in that area.

When I was last in Seattle (1991) I went to this electronic store downtown. It is perhaps not there now. But I tried to purchase as much as I could get into a carry on and still have room for my wardrobe.

When I return to California, I will give it a go. I will be in an around San Diego, and Los Angles. So I will hit the surplus places HARD.

Take Care

Ivey

[pdf64]

Standard DualGang Potentiometers : Potentiometers : Maplin
Some dual pots, such as the omeg ones above, could be simply modified to a 3 gang (if you bought 2 x dual gangs).

[ivey]

PDF64:

I will look into Maplin. They are expensive, but I will investigate.

Most dual pots today are 10k, 50k, and 100k, for stereo.

But I will check it out.

Take Care

Ivey

[loudthud]

Just to keep things interesting, the pot should be Reverse Audio taper. Are you sure the one you have is bad?

[Chuck H]

Are you near Seattle? Near the Naval Station there.

Yes, and no. As the crow flies I'm pretty close. But for me it's a long drive around the Admiralty inlet and a ferry ride. About two hours with no traffic. I don't get over to Seattle much but I was just on another thread mentioning that I would like to scout the surplus and salvage electronic places there. Don't know when/if I'll ever get that onto the priority list though.

[Alex R]

PDF64:

I will look into Maplin. They are expensive, but I will investigate.

Most dual pots today are 10k, 50k, and 100k, for stereo.

But I will check it out.

Take Care

Ivey

Not sure they have Maplin over there in the USA Ivey. They do in Surrey. That's Surrey UK, not the one with the fringe on top.

[ivey]

No Sir, it is not bad, it is not there.

Not the transistors or the LDR. But the caps and resistors are there.

I can wire it backwards. No problem there.

Ivey

[Alex R]

[Gtr_tech]

I have one I could let go. My 100s is partially torn down for rebuild/redesign. I scrapped the SS stuff so I won't be needing the 3 gang pot for anything. PM me and we'll work something out.

I see you mentioned you were a tech at Carvin....cool. I gig a mid 80s X head (modded to sound right). That thing has not let me down once in 15 years and I always get compliments on my tone. I just finished up repairing/modding a X-60 1-12 combo a guy gave to me in basket case condition. Whatta little screamer that is now. I'm not real big on combos, but it may come in handy for jam nights and stuff like that.

Also, there's a place near me that I buy parts from that has a big cabinet full of CTS type pot elements, shafts, etc. Its always possible to get a ganged pot with incorrect values from a surplus seller and replace the elements with the right ones.

[J M Fahey]

I think they used a 3 gang pot because a standard phase shift oscillator has 3 RC stages in series, in the feedback loop to oscillate.
You don't *need* to vary all 3 in sync, although ideally that's the best configuration.
Good old Leo Fender (and countless others) varied just one, with a single pot, and I see nobody complaining.
Look at the schematic.
I would use a 2 gang pot, much easier to find, and if you can stand going "backwards" a common and cheap dual log pot will do.
You can replace the 3rd pot with a fixed resistor halfway max and min values.
If worried about the range, you can put 2 10:1 resistors in series, with a switch shorting the larger one and labelled "Range" or "Lo/Hi".
Just my 2 cents.
YMMV
Etc.

[ivey]

I like your two cents, because it make sense. I did not want to change the original design. Yet, parts availability will force me to do just that.

Take Care


Ivey