Upgraded MP-1 transformer

[trader144]

Just wondering.
I know the mdrt is the upgraded transformer of choice, but it is expensive.

Is there an upgraded transformer mod that takes the transformer out of the rack, similar to a wall wart, so that there are options other than the mdrt?

David

[rnolan]

Hey David, there a post on here somewhere that discusses what you are suggesting, the consensus was it's doable although I suspect it would need to be a custom job ? to have the right taps for the tubes.
I'm the opposite, I'd like to get rid of the wall warts in my rack (quadverb, midiverb) as they are a hassle and get loose etc particularly the quadverb, the transformer is half way along and it's big and it's come off it's Velcro.....
I don't know of any other transformer mods apart from the original replacement (on MJMPs site) and the MDRT, not to say someone else may have tinkered with this ?
As I understand it, the MDRTs are a custom run/make so very low volume which will make them more expensive

[trader144]

True but the thought is I can get the transformer farther away from the board, and, maybe I can use standard production parts instead of a custom run.

I don't like wall warts either but given heat, buzz, and custom wind they are looking pretty good.

[MarshallJMP]

You will never find a wall wart with the voltages the mp-1 needs,you need 2 x 13Vac,2 x 18Vac and 1 x 240Vac.So you need something that's custom made again.Also an MDRT weights around 800 grams,that's a heavy wal wart.

[trader144]

Ok got it

[trader144]

Feast thine eyes on the M......D......R.......Teeeeeeee

time to join the club

"Speaking generally, higher voltage stages are cleaner, punchier, and have more headroom (ability swing more signal before the point of clipping), while lower voltage stages tend to be flatter in response, smoother, and distort earlier."---Joey Voltage

this could be just what I have been looking for to get better sound out of my mp-1 at lower OD1 and OD2 settings.

found a guy who hadn't installed his kit and bought it from him

[rnolan]

Hey David, cool  :thumb-up: :whoohoo!:

[MarshallJMP]

Wow that's an early version of the MDRT

[trader144]

Is that good or bad?

[MarshallJMP]

The transformers are all the same,it's just the way they are build.So no worries  ;D

[trader144]

As everyone knows the MDRT transformer puts higher voltage to the tubes.
It think it basically doubles the voltage and the 300k resistor increases the voltage to the heater to
240 volts.

Has anyone experimented with higher voltage?

I think this might be the limit for the 12ax7.

David

[MarshallJMP]

The heater voltge is 12.6V vs 9V from the original tranny,HT is 240V vs 190V for the tubes.(if you change R9 with a 300k resistor).

The limit according to the datasheet is 300V.(plate voltage)

[trader144]

Just installed the MDRT. Impressive custom piece of equipment and MJMP's instructions could not be easier.
Great improvement in sound and really brings the guitar out close and in 3D.

As expected the lower gain stages are much more useful now and there is more punch.
Had to dial back the master by 1.0 on clean tube and 0.5 on tube distortion as the additional power increased the clipping but that is not a problem.

A few questions please:
Why limit the voltage to 240 instead to 300v ? Is that the max for the transformer ?

Why do I only need to change the tube board resistor when the voltage increased and there are other components?

Why increase the capacitor from 4700uf to 10000uf? I know this allows for more charge to be stored but is it basically just 2x due to the new transformer?

The original transformer looks very weak and cheap compared to this work of art.

Great stuff MJMP thank you.

[rnolan]

Ultimate thanks go to Machinator, (Machinator Designed Replacement Transformer (MDRT)), but many thanks to MJMP  :bow: for keeping them coming  :thumb-up:

[MarshallJMP]

Why limit the voltage to 240 instead to 300v ? Is that the max for the transformer ?

==>i could go a bit higher but the caps on the tubeboard are only rated for 250V,so i need to stay below that voltage.

Why do I only need to change the tube board resistor when the voltage increased and there are other components?

==>if you don't replace it the voltage will stay at 190V even with the MDRT.The tubeboard has a voltage regulator onboard.

Why increase the capacitor from 4700uf to 10000uf? I know this allows for more charge to be stored but is it basically just 2x due to the new transformer?

==>this way you will have less ripple on the 12.6V rail for the tube heaters which results in less hum.