Hoffman Amplifiers Tube Amplifier Forum

Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: dude on July 15, 2024, 12:58:23 pm

Title: Correct LaMar Pot
Post by: dude on July 15, 2024, 12:58:23 pm
In a 6V6 Plexi model1987, adding a LaMar master, would a dual pot replacing the grids that are 100k and using 2.2M safety R’s, be Liner or Audio taper?
Using 220k grids, l assume dual 250k is good,  can’t remember if A or B taper. Doing a google search, it’s six to one, half dozen to the other..?
Mark Huss’s original 6V6 Plexi he used 100 grids to 6V6s, just wondering opinions.
Any info on this much appreciated.


EDIT: use KL pots, for best results, more gradual cut.
 

Title: Re: Correct LaMar Pot
Post by: Latole on July 16, 2024, 03:25:18 am
I use 500 k dual A ( audio ) pots
Title: Re: Correct LaMar Pot
Post by: dude on July 16, 2024, 10:25:15 am
A while back the the guys talked about Liner vs Audio Pots for a La Mar MV at the Metro forum, half said KL, half KA...?
One other question, I have built a 6V6 Plexi from an AO-43 chassis, Sluckey's schematic basically.  Mark Huss who I think was first to try this this used 100K ohms grids to power tube, most other use 220K, what is the difference in tone or the like?
Second, I added a switch to change to Cathode Bias on one of my 6V6 Plexi's, I like the two choices. Can I install a La Mar Master in this 6V6 Plexi without any issues when switch to the cathode Bias mode..?
 
Title: Re: Correct LaMar Pot
Post by: dude on July 16, 2024, 02:52:24 pm
I can’t see any reason that cathode bias would cause an issue. Just was making sure l was thinking correctly.
Title: Re: Correct LaMar Pot
Post by: Latole on July 16, 2024, 03:00:50 pm
I can’t see any reason that cathode bias would cause an issue. Just was making sure l was thinking correctly.

Master Volume work as well  in cathode or fixed bias