Little more reverb?

[dcribbs1412]

Revisted a 2 el84 rocket build from a while back...
https://tubeamparchive.com/viewtopic.ph ... erb+rocket
I really like this circuit, its very quiet no humming, reverb is very subtle...maybe too subtle. I have to crank dwell and reverb. I did some searching wondering if there is a way to get a little more reverb out of it. Or just get a different tank?, using a MOD 8ab2a1b
Wondering if you guys might have some suggestions
Any are greatly appreciated

Darin

[ampgeek]

I do that by any one or combination of the following:

Increasing the value of the pots. I always seem to end up in the 500K to 2M range. YYMV depending on what plan you are using.

Increasing the gain of the tubes by lowering cathode resistors and/or increasing plate resistor values. You can also bypass the cathode caps but that will also impact the reverberation's tone. Listen carefully to the "waves" to determine what, if any, change you would like. Select the bypass cap accordingly (e.g., higher values=more bass, lower=less bass).

I couldn't seem to find a circuit diagram in the thread at the provided link. Could you post one here?

Good luck,
Dave O.

[dcribbs1412]

Thanks Dave
Here's a link to the layout I used
https://tubeamparchive.com/files/2xel84 ... et_462.pdf
I did not use the MV in my build

I'm using a 1M for dwell and a 100k for reverb..may try a 250k or 500k
as you suggest.I did change the 820 bypass to 470 not much of change

Thanks
Darin

[ampgeek]

My pleasure mate!

Looks like two triodes in parallel driving the pan through the R-transformer and a single triode recovery stage. Is that correct? I can get lost quick without a schematic.

IME, one of the keys to a great reverb is driving the R-transformer current to the hilt. What tube are you using for that? Consider a 12AT7 for more current if you are using a 12AX7 there.

Consider lashing a resistor between the 100K reverb pot and the ground buss. Maybe start with ~10K and work up in 10K increments until you have more reverb than you like (or the non-inverting side of the PI gets overdriven). The 100 K pot wont get you down to zero reverb any more. But....you will at least know what resistance area code you want be in to size a replacement pot if this approach brings joy.

You could also play around with the 220K to ground on the grid of the recovery tube. Increasing that will drive the recovery tube more to give a bit more oomph. I would try a 500K just to see what happens. The worst that could happen would be a distorted signal at the PI non-inverting stage from being overdriven.

First things first though....jot down all of the tube pin voltages if you haven't already. That will give you a base line if you happen to wander too far off the beaten trail and need to find your way back home.

Cheers,
Dave O.

[dcribbs1412]

My pleasure mate!

Looks like two triodes in parallel driving the pan through the R-transformer and a single triode recovery stage. Is that correct? I can get lost quick without a schematic.

IME, one of the keys to a great reverb is driving the R-transformer current to the hilt. What tube are you using for that? Consider a 12AT7 for more current if you are using a 12AX7 there.

Consider lashing a resistor between the 100K reverb pot and the ground buss. Maybe start with ~10K and work up in 10K increments until you have more reverb than you like (or the non-inverting side of the PI gets overdriven). The 100 K pot wont get you down to zero reverb any more. But....you will at least know what resistance area code you want be in to size a replacement pot if this approach brings joy.

You could also play around with the 220K to ground on the grid of the recovery tube. Increasing that will drive the recovery tube more to give a bit more oomph. I would try a 500K just to see what happens. The worst that could happen would be a distorted signal at the PI non-inverting stage from being overdriven.

First things first though....jot down all of the tube pin voltages if you haven't already. That will give you a base line if you happen to wander too far off the beaten trail and need to find your way back home.

Cheers,
Dave O.

Thanks Dave
here's a schem I was using for reverb(courtesy of TAG members). I believe you are right about the reverb circuit. I replaced the 100k reverb pot with a 500k, I'll try upping the recovery grid next.
really appreciate your time

Thanks
Darin