Just finished this JTM 45. I decided to build it point-to-point and it came
out really well for a first try on this type of Marshall. Most everyone wants
a Plexi or a 2204. It's good to do something different every once in awhile.
This is the small chassis version, Thanks to Metro Amps for the chassis;
saved me some time not having to punch it my-self.
out really well for a first try on this type of Marshall. Most everyone wants
a Plexi or a 2204. It's good to do something different every once in awhile.
This is the small chassis version, Thanks to Metro Amps for the chassis;
saved me some time not having to punch it my-self.
I used Hoveland and Auracap capacitors as well as F&T caps. The output
transformer and choke are Mercury Magnetics, the power tansformer is a
Mojo Tone JTM45HV. The tubes are, 1x Electro Harmonix 5U4GB
Rectifier, 2x JJ EL34 Blues, 2x JJ 12AX7, and 1x JAN 5751. Sounds great
through my test cab. The amp required about 12 hours total to build and
adjust. I got a bad 100K resistor and a bad 1Meg pot, it took about an hour
to track down both failed components. Quality control is becoming a sad
state of affairs. Infant mortality on new parts is becoming increasingly
noticeable. However, Alessandro has some new mil-spec pots and foil in
oil caps they just released for sale on their web site. I am going to try both
new components out in my next build, I'll post a blurb after the build is
complete. This amp biased at 19.4 Watts per tube, 38.8 watts total
dissipation. I also added a bias pot, output transformer protection diodes,
and 1 Ohm cathode bias measurement resistors.
transformer and choke are Mercury Magnetics, the power tansformer is a
Mojo Tone JTM45HV. The tubes are, 1x Electro Harmonix 5U4GB
Rectifier, 2x JJ EL34 Blues, 2x JJ 12AX7, and 1x JAN 5751. Sounds great
through my test cab. The amp required about 12 hours total to build and
adjust. I got a bad 100K resistor and a bad 1Meg pot, it took about an hour
to track down both failed components. Quality control is becoming a sad
state of affairs. Infant mortality on new parts is becoming increasingly
noticeable. However, Alessandro has some new mil-spec pots and foil in
oil caps they just released for sale on their web site. I am going to try both
new components out in my next build, I'll post a blurb after the build is
complete. This amp biased at 19.4 Watts per tube, 38.8 watts total
dissipation. I also added a bias pot, output transformer protection diodes,
and 1 Ohm cathode bias measurement resistors.
I received a request to build this Marshall JCM 800 model 2204 for David, a guy
who's pair of Mig 50 heads desperately need a rest. I decided to repeat the JTM45
P-T-P concept and build a completely point-to-point high gain JCM 800. I also
decided to wire the first tube as a parallel single input channel which will give the
amp significantly higher distortion capabilities. I used the 1970's master pre-amp
layout sans the low gain input. The components I used are Alessandro mil-spec
potentiometers and Alessandro foil-in-oil capacitors in the tone circuit; along with
silver mica capacitors, orange drop capacitors, and Hoveland-Auracap capacitors.
About 90% of the resistors are 1% metal film resistors. I also used F&T filter
capacitors, Mercury Magnetics Tone Clone Transformers, and I added a 25K Bias
pot on top. The Alessandro pots and caps are very well made, the pots feel so tight,
the quality is excellant. The amp sounds terrific and the tube distortion is crushing.
who's pair of Mig 50 heads desperately need a rest. I decided to repeat the JTM45
P-T-P concept and build a completely point-to-point high gain JCM 800. I also
decided to wire the first tube as a parallel single input channel which will give the
amp significantly higher distortion capabilities. I used the 1970's master pre-amp
layout sans the low gain input. The components I used are Alessandro mil-spec
potentiometers and Alessandro foil-in-oil capacitors in the tone circuit; along with
silver mica capacitors, orange drop capacitors, and Hoveland-Auracap capacitors.
About 90% of the resistors are 1% metal film resistors. I also used F&T filter
capacitors, Mercury Magnetics Tone Clone Transformers, and I added a 25K Bias
pot on top. The Alessandro pots and caps are very well made, the pots feel so tight,
the quality is excellant. The amp sounds terrific and the tube distortion is crushing.
HIGH GAIN HEAD
