Hoffman Amplifiers Tube Amplifier Forum
Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: tdvt on December 14, 2023, 03:07:28 pm
-
I have been wondering for a while about circuit mods to the both the typical AB783 reverb circuit (with added dwell) & Doug's 6g16 trem circuit to be able to use stacked or concentric pots, which are typically only available in equal value? The common exception is the 250K/500K Jazz bass pot.
I see several of the one-tube reverb designs use a 1M on each end, so that one likely seems doable, but the trems (bias as well as opto) have fairly different control values, not to mention the typical reverse taper speed pot.
At the moment, I don't have any available guinea pig amps that I can re-wire, so I thought I would ask if anyone has fooled with this already & might have some insights?
-
The Supro S6424 uses a 500K pot for speed and intensity.
https://el34world.com/charts/Schematics/files/Supro/Supro_s6424.pdf
-
I've thought about this too. You can use the 500k as the upper half of a voltage divider replacing the 1M grid leak at the driver. The 250k can take the place of the reverb level control with a coupling cap value tweak. You don't really need two controls both capable of going to 0.
-
Thank you both for the suggestions!
Steve, I am only just making the connection to your Supro project that I have looked several times on your page.
-
The Supro S6424 uses a 500K pot for speed and intensity.
https://el34world.com/charts/Schematics/files/Supro/Supro_s6424.pdf (https://el34world.com/charts/Schematics/files/Supro/Supro_s6424.pdf)
I have been comparing a bunch of Supro/Gretsch/Valco trem circuits, along with a few others used on SE amps & think that I will make up an add-on board of the circuit you linked to in your Supro project.
I read a note on one of your build docs that you liked having a slower speed, as do I, & I was wondering if this slower speed is attributed more to the dual 500K speed pot mod or to the larger cap values?