What could I build around this output transformer?

[disorder]

Got my hands on one of these Mojo Music Man 130 output transformers and have no real use for it. The leads have been trimmed so I can't return it. It's rated up to 130 watts, 5.5k primary, 4 and 8 ohm secondaries.

Mojo Transformers » Music Man 4-130 Output Transformer

Obviously I can build any of those compatible Music Mans but I was hoping there was a comparable Fender build I can use this on. I'm not sure which tube type would work well with the 5.5k primary. Any suggestions?

[trevorus]

They either had a quad of 6L6's or EL34s... There are a lot of things you could do with that.

[tubeswell]

BF Twin Reverb or Shaman Reverb

[disorder]

I thought so but the output transformer that Fender used for the Twin and Showman had a 2k primary. Would this throw the sound enough to not bother?

[loudthud]

It's going to take a very high B+ to get 130W out of that OT. So high you can't run the screens at near the same voltage. Plan on some kind of split supply, a voltage doubler like MM used or a solid state regulated screen supply.

[disorder]

not looking to squeeze 130w out of it. will it sound off if i build something in the 50w range off this ot?

[disorder]

sorry still trying to understanding transformer design. is the wattage rating on an output transformer simply a "max capacity, do no exceed!" type of rating? or does it involve something else as well?

what im trying to say is, should a 130w output transformer be used close to to its potential for best sound? or could you build a 50w design around it and just take those extra 80w as a safety buffer

[imaradiostar]

Sounds like it's ideally suited for a pair of KT88's or 6550's with a high voltage supply- should be able to use an antec inc toroid and run it with with the screens at half the voltage of the plate supply.

[Ronsonic]

not looking to squeeze 130w out of it. will it sound off if i build something in the 50w range off this ot?

With that primary Z you could definitely run a pair of EL34 or 6L6 with it.

[loudthud]

In general, this OT will have lots of clean bass if run at say, 60W. That's not a bad thing, but it won't sound like a Marshall. Maybe more of a Hiwatt vibe depending on what tubes you use. You can see the trend here is away from a Fender type sound, cleaner and more HiFi. Overdrive might be a little clanky, not as warm as a Fender. I could be wrong so experiment and have fun.

[imaradiostar]

I have a music man output from one of the "65" watt amps- I've watched it produce clean 40 Hz sine waves in excess of its rated 65 watts on a test bench with EL34's at around 550 volts. There isn't anything wrong with using your transformer for something lower powered but to me it would be a shame to waste the excellent bass response on say...a 35 watt open back 6l6 powered amp. On the other hand a twin reverb or plexi power transformer (check out triode electronics) matched to that output would make an excellent and very loud amp. There are about a billion different preamp designs to pick from but with nice output iron like that I would tend to favor clean amps or amps that rely almost entirely on preamp distortion. It wouldn't be my choice for a Trainwreck or JTM45 clone, that's for sure!

Jamie

[imaradiostar]

Wait a sec, I just did a little research. You have the mojo version of the actual music man TF I have. Pretty nice transformer! Pretty much anything in the 50-60 watt range will be great. You might wanna shoot for slightly high plate voltages and slightly large screen resistors. There are quite a few PT's that'll work great. For the money I'd probably go with an Antek, assuming you're OK with a toroid.

jamie

[Tom Phillips]

Disorder,
Just out of curiosity. What is the weight of the transformer?
Tom

[Prairie Dawg]

All that metal would sound pretty good in a 50w something or other. I've got a Fender Bantam and the last owner replaced the 30w output with a Twin Reverb output and changed the speaker impedance to match, kinda like what Leo did with the Vibrasonic. It adds a lot to the bottom end.