Hoffman Amplifiers Tube Amplifier Forum

Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: g-man on April 23, 2019, 12:33:52 pm

Title: Tube substitution
Post by: g-man on April 23, 2019, 12:33:52 pm

Deleted

Title: Re: Tube substitution
Post by: kagliostro on April 23, 2019, 02:27:00 pm

Ciao g-man

I know, I didn't did a good job, but this way the schematic seems more readable

(https://i.imgur.com/JiPEGSr.jpg)

Franco

Title: Re: Tube substitution
Post by: 2deaf on April 23, 2019, 04:57:09 pm

OK, so here'e what I think.  The 300V (Vp3?) is in the wrong place.  It should be on the other side of R11 (10K), where Cnnn (XXXpF) and R11 (10K) meet.  Now if R10 (10KD?) is 100K, the voltages could be made to work and it would make sense for a 12AX7.  It just goes to show that you shouldn't draw schematics with crayons.

A 12AY7 will draw more current in the FX Loop and have less gain for the recovery.  A 12AT7 will draw a whole lot more current in the FX Loop and also have less gain for the recovery.  They should work in the FX Loop, though.  Try it.   

Title: Re: Tube substitution
Post by: g-man on April 23, 2019, 06:22:25 pm

Deleted

Title: Re: Tube substitution
Post by: PRR on April 24, 2019, 02:46:55 pm

Just try it. I don't see that it can smoke. I don't think it will make a large difference of gain or overload.

Title: Re: Tube substitution
Post by: g-man on April 24, 2019, 03:06:20 pm

Deleted