Hoffman Amplifiers Tube Amplifier Forum

Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: Rockranger on November 30, 2018, 04:44:18 pm

Title: AB763 deluxe reverb pentode/triode
Post by: Rockranger on November 30, 2018, 04:44:18 pm

Just wondering if anyone could tell me how to install a pentode/triode switch in this amp?
https://el34world.com/Hoffman/files/Hoffman_AB763_2.pdf

I am aware this may not be a desirable addition to this amp just wanted to try it out, any help would be appreciated!

Title: Re: AB763 deluxe reverb pentode/triode
Post by: sluckey on November 30, 2018, 04:54:26 pm

Look at page 3...

     http://sluckeyamps.com/misc/Amp_Scrapbook.pdf

Title: Re: AB763 deluxe reverb pentode/triode
Post by: Rockranger on December 01, 2018, 03:12:57 am

Perfect, Thanks

Title: Re: AB763 deluxe reverb pentode/triode
Post by: tubenit on December 01, 2018, 05:26:49 am

I have found the pentode/triode switch to be a useful mod with 6V6's giving two distinct tone/vol changes.  Not so much with 6L6's where I couldn't hear that much of a difference.  Just an FYI, IMO.

With respect, Tubenit

Title: Re: AB763 deluxe reverb pentode/triode
Post by: davidwpack on December 01, 2018, 01:33:07 pm

I tried it with KT66 and thought it sounded completely awful... muddy. I removed it.

Title: Re: AB763 deluxe reverb pentode/triode
Post by: Rockranger on December 02, 2018, 10:28:38 am

What would be the appropriate voltage rating for the dpdt switch? I have a mini switch here but I believe the DC rating on it is quite low.

Title: Re: AB763 deluxe reverb pentode/triode
Post by: sluckey on December 02, 2018, 10:36:05 am

Use the same rating you would use for a typical standby switch. I definitely would not use a mini switch of any rating. That DPDT Long bat switch that Hoffman sells looks good to me.

     https://hoffmanamps.com/MyStore/catalog/parts7.htm

Title: Re: AB763 deluxe reverb pentode/triode
Post by: Rockranger on December 02, 2018, 10:58:08 am

Yeah thanks sluckey, I will order some!