Hoffman Amplifiers Tube Amplifier Forum

Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: kagliostro on April 06, 2015, 04:04:50 am

Title: Fender Pawnshop Excelsior tremolo question
Post by: kagliostro on April 06, 2015, 04:04:50 am

Looking for the Marshall 1959T tremolo schematic, casually I've find the Fender Pawnshop schem

(http://www.diyitalia.eu/forum/download/file.php?id=10939&mode=view)

Whole schematic
http://www.diyitalia.eu/forum/download/file.php?id=10940 (http://www.diyitalia.eu/forum/download/file.php?id=10940)

in this tread PRR explained the function of the 2g374 on the 1959T circuit

http://el34world.com/Forum/index.php?topic=7261.msg64156#msg64156 (http://el34world.com/Forum/index.php?topic=7261.msg64156#msg64156)

(http://i26.tinypic.com/33lgm4w.gif)

but as I have poor knowledge of SS I'm not able to understand the tremolo circuit on the Pawnshop Excelsior on which there is an IRF820

Someone can explain how the Fender Pawnshop tremolo uses the mosfet ?

Is it there only as a Source Follower and if it is, why they used a SF in a tremolo that usually hasn't one ?

Thanks

K

Title: Re: Fender Pawnshop Excelsior tremolo question
Post by: VMS on April 06, 2015, 09:03:05 am

There is a cathode follower in older fender tremolos (tweed and blonde era), for example in vibro champ or tremolux:

http://ampwares.com/schematics/tremolux_6g9b.pdf (http://ampwares.com/schematics/tremolux_6g9b.pdf)

I'm not good at explaining the reason for this but maybe someone will chime in.

Title: Re: Fender Pawnshop Excelsior tremolo question
Post by: kagliostro on April 06, 2015, 03:23:56 pm

Thanks VMS

Franco