Hoffman Amplifiers Tube Amplifier Forum

Other Stuff => Solid State => Topic started by: tdvt on February 23, 2024, 02:18:36 pm

Title: 6G2 SS Trem draft
Post by: tdvt on February 23, 2024, 02:18:36 pm

I guess this would go in this forum...no tubes.



Anyway, THIS THREAD (https://el34world.com/Forum/index.php?topic=31336.0) got me pondering about adapting a power-tube bias trem design for use as a pre-amp tube trem, specifically the one-triode 6G2 trem mentioned in that thread.


Then taking it one step further, thinking to modify the circuit to SS as a potential add-on to an existing amp that has little room.


I gathered what information I could find out there & have drawn up a preliminary schematic that I thought I would try building.


BUT, I know next to nothing about SS & will have to bump into the walls for a while as I find my way. A major copy & paste, with a few gathered hints/suggestions mixed in.



Hoping some of the more savvy will check this out & offer some guidance.

Title: Re: 6G2 SS Trem draft
Post by: PRR on February 24, 2024, 01:46:52 pm

You "may" not need a 'cathode' cap; the MOSFET likely has way more voltage gain, and may climb to a distorted 'sine'.

You stray from the 6G2 plan between the LFO and the 6V6es. The first 0.1uFd cap is in the wrong place? do you want -35V or ground? and the three pot terminals are wired different.

Title: Re: 6G2 SS Trem draft
Post by: tdvt on February 25, 2024, 06:46:07 am

Quote from: PRR on February 24, 2024, 01:46:52 pm

You "may" not need a 'cathode' cap; the MOSFET likely has way more voltage gain, and may climb to a distorted 'sine'.

You stray from the 6G2 plan between the LFO and the 6V6es. The first 0.1uFd cap is in the wrong place? do you want -35V or ground? and the three pot terminals are wired different.

Thanks for looking this over, point noted on the bypass cap.


The straying is intentional as I would like to adapt this LFO circuit to land upstream on a pre-amp cathode & not the power tubes. It is the post-LFO section I am unsure of.

I am hoping to adjust the LFO voltage swing to an appropriate level (R TBD) to wiggle the bias (1.5V-ish) of V1 or V2 in the typical Fender pre, ala Champ, Valco, etc.


I added that .1 to ground as Sluckey mentions it smoothing the sine (as well as reducing the signal) in the referenced thread above.

Title: Re: 6G2 SS Trem draft
Post by: shooter on February 25, 2024, 07:05:21 am

FWIW
tried something similar, tried wiggling the 2nd gain-stage, got swamped out by anything but soft playing.  One of my crash-guitarists though I should leave it because the INT pot acted as "A pretty cool gain knob"

Title: Re: 6G2 SS Trem draft
Post by: tdvt on February 25, 2024, 07:18:06 am

Quote from: shooter on February 25, 2024, 07:05:21 am

FWIW
tried something similar, tried wiggling the 2nd gain-stage, got swamped out by anything but soft playing.  One of my crash-guitarists though I should leave it because the INT pot acted as "A pretty cool gain knob"

Thanks for the report, I'm going to give it a shot.

The Champ & various vintage budget amps seem to work with that approach, so I am hoping it is ultimately workable. None were SS however.

Some MOSFETs incoming...

PS: Champ used a follower stage, maybe that is part of the trick