Hoffman Amplifiers Tube Amplifier Forum

Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: Gareth81 on June 27, 2012, 02:13:07 am

Title: Marshall 1959u vs 1959t (no choke!?)
Post by: Gareth81 on June 27, 2012, 02:13:07 am
These two amps a pretty much identical except for the tremolo circuit in the 1959t.... and the 1959t doesn;t seem to have a choke!?  :w2:

See the attached schematics, this must just be a mistake, yes?
Title: Re: Marshall 1959u vs 1959t (no choke!?)
Post by: fdesalvo on June 27, 2012, 06:21:12 pm
If the 1959T is from the late 80's, then it will have a resistor in place of the choke.
Title: Re: Marshall 1959u vs 1959t (no choke!?)
Post by: Gareth81 on June 27, 2012, 09:05:52 pm
According to these schematics, there is no extra resistor in the place of the choke.

Would not having a choke raise the voltage levels on the B+, to accommodate for the extra tube?
Title: Re: Marshall 1959u vs 1959t (no choke!?)
Post by: HotBluePlates on June 27, 2012, 09:29:40 pm
According to this thread (http://www.lespaulforum.com/forum/showthread.php?t=157668), the 1959T does have a choke (you can see it in the chassis pictures).

So it must be an error on the schematic.
Title: Re: Marshall 1959u vs 1959t (no choke!?)
Post by: fdesalvo on June 28, 2012, 09:27:13 am
From what I read, they ran chokes up until 1987 and the reissues were built with chokes, however.  :dontknow:
Title: Re: Marshall 1959u vs 1959t (no choke!?)
Post by: HotBluePlates on June 28, 2012, 06:27:01 pm
What I was saying is that thread has pictures of an original 1959T. The original amp has a choke on the chassis (and it's the proper, original style with what appears to be authentic age). Therefore, the best guess is the 1959T included a choke and the schematic is in error.
Title: Re: Marshall 1959u vs 1959t (no choke!?)
Post by: fdesalvo on June 28, 2012, 06:37:09 pm
Roger.