Hoffman Amplifiers Tube Amplifier Forum

Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: Leevi on September 25, 2011, 03:13:07 am

Title: Tremolo question
Post by: Leevi on September 25, 2011, 03:13:07 am

What are the differences in behavior of the tremolos where only one triode is used
and the tremolos where two triodes are used? Is one of these somehow better or is the solution dependent on
where it will be used?

At least Fender is using both versions:

http://www.webphix.com/schematic%20heaven/www.schematicheaven.com/fenderamps/deluxe_6g3_schem.pdf (http://www.webphix.com/schematic%20heaven/www.schematicheaven.com/fenderamps/deluxe_6g3_schem.pdf)

http://www.webphix.com/schematic%20heaven/www.schematicheaven.com/fenderamps/champ_vibro_aa764_schem.pdf (http://www.webphix.com/schematic%20heaven/www.schematicheaven.com/fenderamps/champ_vibro_aa764_schem.pdf)

/Leevi

Title: Re: Tremolo question
Post by: sluckey on September 25, 2011, 07:31:07 am

In the Fender circuit, the second triode is always a cathode follower. The CF is usually used when you need to provide more drive current (not more voltage) to the circuit you will be modulating, such as a low impedance cathode rather than a high impedance grid. The CF also provides a lot of isolation between the oscillator and the load. This means that the load or changes in the load will have very little effect on the operation of the oscillator.

So basically, higher drive current, lower impedance, and isolation are the benefits of using the second tube.

Title: Re: Tremolo question
Post by: Tiny_Daddy on September 25, 2011, 08:31:06 am

I have added a follower to some one-triode circuits with good results. I used a 500V mosfet transistor on a terminal strip.