Hoffman Amplifiers Tube Amplifier Forum

Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: 67polara on September 25, 2010, 10:32:27 am

Title: Question about 250 dual pot on tos
Post by: 67polara on September 25, 2010, 10:32:27 am

Hello:

Having a problem finding a 250k dual pot for the master volume on the TOS.  Would it be OK to parallel 330K ohm resistors with the 1 Meg dual pots to bring it to the correct value?

Tony

Title: Re: Question about 250 dual pot on tos
Post by: tubenit on September 25, 2010, 11:05:55 am

Until I got both TOS amp switched over to VVR, I used a 500k dual gang pot with 470k resistors and that seemed to do fine. 

I also currently have that 500k dual pot/470k resistors on my Tweed OD lite & it works fine on there.

I'm thinking your plan with 1M and 330k should work fine. You could also use 270k instead of 330k.

With respect, Tubenit

Title: Re: Question about 250 dual pot on tos
Post by: 67polara on September 25, 2010, 11:18:34 am

Will do thank you.  Any wattage concerns with the resistor, 1/2 watt ok?  A 270k calcs out to 212.6k and a 330k is 248k. Are you sure I should use the 270K?  What about the Resistance not matching between the two pots due to tolerances?  Should I put a trimmer on one side to match them?

Tony

Title: Re: Question about 250 dual pot on tos
Post by: Geezer on September 25, 2010, 11:40:34 am

http://www.mouser.com/ProductDetail/Alpha-Taiwan/RV24BF-10-15R1-A250K/?qs=R1h7DEsyLZi9EhQqk47wow%3d%3d

That's what I use, on this page of the catalog>

http://www.mouser.com/catalog/catalogUSD/642/687.pdf

They are 1/4W, so no concerns there....

G

Title: Re: Question about 250 dual pot on tos
Post by: toobzilla on January 30, 2025, 09:12:43 am

Quote from: 67polara on September 25, 2010, 10:32:27 am

Hello:

Having a problem finding a 250k dual pot for the master volume on the TOS.  Would it be OK to parallel 330K ohm resistors with the 1 Meg dual pots to bring it to the correct value?

Tony

try hoffman amps.