Hoffman Amplifiers Tube Amplifier Forum

Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: octal on January 18, 2015, 05:56:38 pm

Title: Does anyone make dual concentric friction coupled pots?
Post by: octal on January 18, 2015, 05:56:38 pm

Does anyone remember those dual concentric pots used for tone controls on old stereo receivers like Marantzes? The inner and outer rings/knobs would turn together as a unit, then if you wanted, you could hold one of the rings stationary and offset the other ring relative to the other.

I was thinking such a pot would be a cool feature to incorporate into a plexi build with internally jumpered channels. You could set your bright and normal volumes to where you wanted to get the tone you wanted, and then could turn both channels up and down as a unit with a single knob without disturbing your EQ.  (Yes, if the channel volumes were offset, you couldn't turn the volume completely down, but you could have a pretty wide range of adjustment.)


Does anyone sell something like that "off the shelf" nowadays? Is this a stupid idea?

Title: Re: Does anyone make dual concentric friction coupled pots?
Post by: Ed_Chambley on January 19, 2015, 08:49:37 am

Mouser has them.
http://www.mouser.com/ProductDetail/Bourns/PTJ902-030F-105B2/?qs=sGAEpiMZZMtC25l1F4XBU0MJhHSqaKlcU%252btEK1%2fDJQU%3d (http://www.mouser.com/ProductDetail/Bourns/PTJ902-030F-105B2/?qs=sGAEpiMZZMtC25l1F4XBU0MJhHSqaKlcU%252btEK1%2fDJQU%3d)

Not stupid at all.  Knobs will be different, but that could be cool.

Title: Re: Does anyone make dual concentric friction coupled pots?
Post by: kagliostro on January 19, 2015, 09:40:49 am

CTS has some in their catalogue

http://www.ebay.com/itm/CTS-500k-500k-STACKED-CONCENTRIC-Potentiometer-Solid-Shaft-Jazz-Bass-Pot-/290964023139 (http://www.ebay.com/itm/CTS-500k-500k-STACKED-CONCENTRIC-Potentiometer-Solid-Shaft-Jazz-Bass-Pot-/290964023139)

http://www.warmoth.com/Concentric-Pot-500k-By-CTS-P720.aspx (http://www.warmoth.com/Concentric-Pot-500k-By-CTS-P720.aspx)

http://www.angela.com/jazzbassdual500k250kpot.aspx (http://www.angela.com/jazzbassdual500k250kpot.aspx)

also here you can find something

http://www.guitarpartsresource.com/electrical_concentricpots.htm (http://www.guitarpartsresource.com/electrical_concentricpots.htm)

K

Title: Re: Does anyone make dual concentric friction coupled pots?
Post by: shooter on January 19, 2015, 10:36:58 am

My current prototype has the gain and tone pots ganged on 2 channels, only the caps for each TS are different.  works good.

Title: Re: Does anyone make dual concentric friction coupled pots?
Post by: octal on January 19, 2015, 12:15:30 pm

Thanks, guys. I see those concentric pot listings, but are they friction coupled? (i.e. the inner and outer parts will turn together as one, unless you hold one stationary while turning the other.)


I guess you could maybe put a felt washer under the smaller knob and push the knob in far enough that it couples to the larger knob and they turn together?


Anyway, thanks for the info!


Nathan

Title: Re: Does anyone make dual concentric friction coupled pots?
Post by: Ed_Chambley on January 19, 2015, 12:40:49 pm

Check with these guys.

http://www.state-elec.com/ (http://www.state-elec.com/)