Hoffman Amplifiers Tube Amplifier Forum

Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: dscottguitars on March 12, 2014, 06:57:04 pm

Title: bias pot
Post by: dscottguitars on March 12, 2014, 06:57:04 pm

what is the technical name for these type of pots?  Every search I try I get only 10K fender pots and I need a 25K.  Also, I think $9.99 is way too much to pay.

Title: Re: bias pot
Post by: firemedic on March 12, 2014, 07:04:19 pm

trim pot.

Title: Re: bias pot
Post by: dscottguitars on March 12, 2014, 07:14:35 pm

the only ones I see like that are PC mount or not the traditional pots.  Any suggestions on how to search for them?

Title: Re: bias pot
Post by: eleventeen on March 12, 2014, 10:12:26 pm

"screwdriver adjust"  (versus "shaft")

Title: Re: bias pot
Post by: Leevi on March 13, 2014, 12:19:02 am

or "trimmer pot".

A good choice is to use the following type of pots.
They have normally better quality than cheap trim pots.

http://www.ebay.com/itm/like/301098183505?lpid=82 (http://www.ebay.com/itm/like/301098183505?lpid=82)

/Leevi

Title: Re: bias pot
Post by: sluckey on March 13, 2014, 06:38:34 am

This is my preference for bias pots. I have these in all my fixed bias builds.

http://www.digikey.com/product-detail/en/RV6LAYSA103A/RV6L103C-ND/222821 (http://www.digikey.com/product-detail/en/RV6LAYSA103A/RV6L103C-ND/222821)

Here's a dual bias system in my Sunn amp...

(http://home.comcast.net/~seluckey/amps/sunn/mod_1.jpg)

(http://home.comcast.net/~seluckey/amps/sunn/mod_2.jpg)

Title: Re: bias pot
Post by: Ed_Chambley on March 13, 2014, 01:20:02 pm

Quote from: sluckey on March 13, 2014, 06:38:34 am

This is my preference for bias pots. I have these in all my fixed bias builds.

http://www.digikey.com/product-detail/en/RV6LAYSA103A/RV6L103C-ND/222821 (http://www.digikey.com/product-detail/en/RV6LAYSA103A/RV6L103C-ND/222821)

Here's a dual bias system in my Sunn amp...

(http://home.comcast.net/~seluckey/amps/sunn/mod_1.jpg)

(http://home.comcast.net/~seluckey/amps/sunn/mod_2.jpg)

Sluckey, where do you source those test points?

Title: Re: bias pot
Post by: sluckey on March 13, 2014, 03:02:56 pm

From surplus military equip.

Title: Re: bias pot
Post by: eleventeen on March 13, 2014, 03:37:15 pm

I like those too. Very expensive to buy new, free in old military-commercial junk. I won an auction for about 40 of them on ebay for $8 once. Allen-Bradleys, new.

Title: Re: bias pot
Post by: dscottguitars on March 13, 2014, 05:58:20 pm

The locking pots look perfect.  I found some at Weber Speakers for $1.80 too... thanks all...