Hoffman Amplifiers Tube Amplifier Forum
Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: Diverted on April 18, 2021, 11:06:50 am
-
Havent built anything in a while so I'm getting the itch. I wanted to try matching a blackfave reverb circuit in to a Deluxe 5E3 circuit. With the reverb needing an extra gain stage, where would be the best place to put this on a Deluxe? Between the preamp and second gain stage, or between the second gain stage and phase inverter? Was thinking the latter, but I am not sure.
Reason why I'm doing this is I'd like to have reverb in a saggier cathode-biased amp w/a cathodyne phase inverter.
Thanks!
-
This may have already been done. Search the forums.
Also, you may consider the 6G15 standalone reverb unit or even a Revibe. Then you can have reverb in ANY amp you chose.
-
Between the preamp and second gain stage,
My vote
The pan output transducer signal is very weak, and the further along the dry signal path that you have the wet signal insertion point, the more (wet signal) gain (stages) you will need to compensate. (Or you’ll require more dry-signal attenuation to get enough wet in the mix). YMMV
-
Thanks for the responses.
I guess I was assuming I would put that extra gain stage right before the phase inverter because that's how it's done in the Princeton Reverb, which also has a cathodyne phase inverter. Only major difference in the power amp is the fixed bias vs. cathode in the Deluxe.
I'll try it both ways, see what works best, thank you.
-
Thanks for the responses.
I guess I was assuming I would put that extra gain stage right before the phase inverter because that's how it's done in the Princeton Reverb, which also has a cathodyne phase inverter. Only major difference in the power amp is the fixed bias vs. cathode in the Deluxe.
I'll try it both ways, see what works best, thank you.
The PR works well -and by all means copy it if you want reverb- but it’s a different dry-signal gain structure to a 5E3 (and even different to a BF Princeton).
-
Well , last November I did a add reverb mod to a friend's 5E3 clone , and it turned out well , though it took a few revisions before it was right . I took the signal from the wiper of the Bright vol pot , sent it to a 12AT7 driver as Fender does , return signal from the pan to a 12AX7 , like Fender , 100 K linear Rev pot to another 12AX7 section , and the output from this triode was coupled , through a .02 cap to the input of the split load phase inverter . By doing it this way , the front end remained very close to the original design , with interacting vol controls . Also reduced the value of the 6V6 screen supply decoupling resistor by half , to compensate for the extra current draw as this is where the rev transformer primary was connected . Wanted the 6V6 screen voltage to remain as it was . Tried to make the reverb add , as transparent as I could , leaving the 5E3 circuit as unaffected as possible . Turned out nice . Reverb on the Bright channel only .
-
This is Tubenit's one tube reverb, but perhaps it might still be helpful...
https://el34world.com/Forum/index.php?topic=19866.0
-
Both of these schematics are from proven reverb circuits in 2 amps that I've built. With both amps, I had all the reverb I wanted with the reverb pot at around 3-4. I don't use very much reverb and this doesn't come close to "surf reverb" at all.
Note there are some similarities in the Carolina Blues Special and a 5E3 regarding gain stages, cathode biased and cathodyne phase invertor.
with respect, Tubenit