Hoffman Amplifiers Tube Amplifier Forum

Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: dragonbat13 on September 24, 2021, 10:36:35 pm

Title: My Princeton Reverb Build. Too much reverb, Too fast tremolo
Post by: dragonbat13 on September 24, 2021, 10:36:35 pm

How do I go about slowing down the bias vary vibrato?
also what are the different methods for reducing the heavy reverb? Mine is just too surfy!

Title: Re: My Princeton Reverb Build. Too much reverb, Too fast tremolo
Post by: Latole on September 25, 2021, 03:41:53 am

Show us schematic as built.

Is it a kit ? Or from scratch ?
Did you use the right Power Transformer ?

Give us more information

Title: Re: My Princeton Reverb Build. Too much reverb, Too fast tremolo
Post by: sluckey on September 25, 2021, 07:07:32 am

See attached for tremolo speed. The easiest thing to do for the reverb is change the reverb pot to a 100K audio taper pot. You'll still have the same amount of reverb but you will have much better control and can easily set a small amount of reverb. For even more control, replace the 1M resistor on the driver tube grid with a 1M-A dwell pot.

Title: Re: My Princeton Reverb Build. Too much reverb, Too fast tremolo
Post by: jordan86 on September 25, 2021, 08:24:45 am

Yes, what Sluckey said on the 100ka pot for the Princeton. I’ve tried swapping the 1m grid leak into the reverb circuit and it was less helpful than I expected it to be. You could try it though. It changes the vibe of the reverb more than I preferred. I think a audio taper pot is a better approach.

As for the trem, simple fixes. See Rob Robinette’s two component swaps. Another .02 cap and 470k resistor. I used a 433k (470k measured low) and I wouldn’t go any lower. This makes it real slow and swampy. Very brownface Princeton. Almost swallows the attack of the note. The cap change slows it down. The resistor makes it deeper. If you just want it slower the .02 cap is all you need. If you don’t have a .02 and can parallel a second .01 in with the “middle” cap of those three on the layout.

https://robrobinette.com/images/Guitar/AA1164/AA1164_Tremolo_Depth_Mod.png

Title: Re: My Princeton Reverb Build. Too much reverb, Too fast tremolo
Post by: dragonbat13 on September 25, 2021, 02:32:38 pm

Just to try, I put a RCA blackplate into the reverb driver socket and it tamed the reverb alot.  Not sure how long that tube is gonna last though.

Ill try the  tremolo speed mods .  Thanks

Title: Re: My Princeton Reverb Build. Too much reverb, Too fast tremolo
Post by: Latole on September 25, 2021, 02:38:05 pm

Did you use those tubes models ?

Title: Re: My Princeton Reverb Build. Too much reverb, Too fast tremolo
Post by: dragonbat13 on September 25, 2021, 05:56:19 pm

Quote from: Latole on September 25, 2021, 02:38:05 pm

Did you use those tubes models ?

For the most part yes.  I used dougs schematics and layout.

https://el34world.com/Hoffman/files/Hoffman_PrincetonReverb.pdf

Title: Re: My Princeton Reverb Build. Too much reverb, Too fast tremolo
Post by: dragonbat13 on September 25, 2021, 05:58:32 pm

Quote from: Latole on September 25, 2021, 03:41:53 am

Show us schematic as built.

Is it a kit ? Or from scratch ?
Did you use the right Power Transformer ?

Give us more information

It was parts sourced from different places.  Doug supplied most of the components.  PT is a princeton reverb PT from Classic Tone, Output is also from classic tone.  Everything was correct application for the amp.

used dougs schematic and layout.
https://el34world.com/Hoffman/files/Hoffman_PrincetonReverb.pdf

Title: Re: My Princeton Reverb Build. Too much reverb, Too fast tremolo
Post by: jordan86 on September 25, 2021, 06:17:34 pm

Here are the two components for that layout.