Hoffman Amplifiers Tube Amplifier Forum

Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: Stuff4bikes on March 11, 2022, 12:10:14 am

Title: Hoffman princeton reverb, tremelo speed
Post by: Stuff4bikes on March 11, 2022, 12:10:14 am

Tremelo speed is way to fast. 1 on mine is like 10 on a normal circuit, half way is like a machine gun.
I tried the .02 on the middle and first cap separately and it just kills the tremelo completely.
Also I think my new blackface style footswitch is faulty...

Title: Re: Hoffman princeton reverb, tremelo speed
Post by: tubeswell on March 11, 2022, 12:50:11 am

Somewhere between 0.02uF and 0.03uF on the first C/R filter should slow the trem down

Title: Re: Hoffman princeton reverb, tremelo speed
Post by: ac427v on March 11, 2022, 07:10:53 am

Check to verify that the Speed pot value is 3 meg ohms Reverse Audio (3MRA).

Title: Re: Hoffman princeton reverb, tremelo speed
Post by: Stuff4bikes on March 11, 2022, 08:12:32 pm

Definitely the correct pot....straight off the AES website.

Title: Re: Hoffman princeton reverb, tremelo speed
Post by: sluckey on March 11, 2022, 08:23:10 pm

Your footswitch is not a factor. You don't need it for reverb or tremolo to work. So, unplug it until your issue is resolved.

Try a different 12AX7. Measure voltages on the trem tube. Post some hi-rez pics. Compare your wiring and component values to the layout.

Title: Re: Hoffman princeton reverb, tremelo speed
Post by: Stuff4bikes on March 11, 2022, 08:32:51 pm

Quote from: sluckey on March 11, 2022, 08:23:10 pm

Your footswitch is not a factor. You don't need it for reverb or tremolo to work. So, unplug it until your issue is resolved.

Try a different 12AX7. Measure voltages on the trem tube. Post some hi-rez pics. Compare your wiring and component values to the layout.

I have been doing all that to no avail......deep down inside I know you are right though...I will get some voltage specs for you.....I am not good at pictures.

V4.......1-250.   2-0.   3-2.24.  6-200.  7-20.  8-60.

Title: Re: Hoffman princeton reverb, tremelo speed
Post by: sluckey on March 11, 2022, 08:47:05 pm

Quote from: Stuff4bikes on March 11, 2022, 08:32:51 pm

I am not good at pictures.

Hoffman's PR is a proven design. You will most likely find that your amp ain't wired just like his layout, or you have used a wrong value component somewhere, or your solder skills and workmanship are lacking. On a rare occasion you will find a faulty new component. Hi-rez pics are very helpful in solving new build issues. Not much left to say if we can't see the amp. Kinda like throwing darts in the dark.

Title: Re: Hoffman princeton reverb, tremelo speed
Post by: Stuff4bikes on March 11, 2022, 08:48:36 pm

Did you see the numbers I posted.

Title: Re: Hoffman princeton reverb, tremelo speed
Post by: sluckey on March 11, 2022, 08:51:01 pm

Voltages do not look suspect.

Title: Re: Hoffman princeton reverb, tremelo speed
Post by: Stuff4bikes on March 11, 2022, 08:53:22 pm

Quote from: sluckey on March 11, 2022, 08:51:01 pm

Voltages do not look suspect.

Dang it.....was hoping that was it.........what resistors should I look at for value verification.....

I will get some pics when the sun comes out tomorrow.....

Title: Re: Hoffman princeton reverb, tremelo speed
Post by: sluckey on March 11, 2022, 09:16:04 pm

Check all components in this pic. Verify proper values and that they are connected according to the layout.