Fender 013691 - 135W UL opt questions..

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Fender 013691 - 135W UL opt questions..

Postby Anticpunk on Mon Apr 15, 2013 1:36 am

Hey, does anybody know the primary impedance of this transformer? I want to use it with a pair of 6550's, but I want to make sure I'm in the ballpark.

Originally the secondaries would have been 4 and8 ohm taps, so with only a pair of power tubes I would need to use them at 8 and 16 ohms for the correct reflected impedance I think, but I can only guess at what the original impedance was....

I would be using a Twin Reverb power transformer and this output for the pair of 6550's. Is that a feasible thing?
I'm targeting 500VDC on the plates and in UL mode the screens are probably a 40% tap which will hopefully keep they happy and sound pretty decent......

I'm basically trying to build a ballsy amp out of my parts bin for a sludge band. My current amp is a modded Pro Reverb and I'm not getting the oomph I need for that style. It runs out of steam with all of the low-end signal and a distortion box pushing it. I don't want to mod that one anymore, and I'd like to be in a 60-100watt half stack without buying a head...... I'm planning the build along the lines of a Fender preamp/eq into a LTP PI, PPI MV and a Sunn style duet 6550 UL power section.....

Any guidance (aside from buying something else) is appreciated. If you think this OPT is really not worth it for what I'm wanting to do, I'm interested in the why's and why not's.....

Thanks so much!

Jay
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Re: Fender 013691 - 135W UL opt questions..

Postby pdf64 on Mon Apr 15, 2013 10:36 am

Easy to check it yourself http://www.marstran.com/Measuring%20Pri ... edance.htm
I read a thread somewhere which mentioned that the UL taps on these were at ~20% rather than 40%; 20% being optimal for power output, 40% being optimal for distortion.
Pete
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