Here's a '63 Vibroverb Reissue with some Dumble Hybrid modifications.
For those that love the AB763 style circuit with the clean channel capability of the ODS.
This amp sounds amazing with the mods!
The normal channel is set up with a little extra drive for nice pushed singing driven tones. Feel free to add a 120pF bright cap on its volume control if you don't like the 50pF bright cap.
The bright channel is more tamed for cleaner tones but still has a nice pushed drive tone with great sustain after 8 on the dial. I installed a 68k resistor after the volume control for the bright channel before V2B's grid, this cleans up the channel a little bit and sounds smoother to me.
I left the Vibrato circuit alone since I don't use it at all. You may wish to restore that circuit to the AB763 version or just leave it as is if you want Vibrato on both channels like the RI has.
I use JJ 6L6GC power tubes with the mod along with a pair of Celestion G10-Creambacks.
Vibroverb RI Dumble Hybrid Mod
Moderators: pompeiisneaks, Colossal
Vibroverb RI Dumble Hybrid Mod
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Last edited by xenrelic on Tue Feb 06, 2024 6:09 am, edited 2 times in total.
Re: Vibroverb RI Dumble Hybrid Mod
Posted some updates to the schematic in the original post attachment if anyone wants the latest schematic of the Vibroverb Dumble Hybrid.