I went a different route.
hammond/182e117/toroidal-transformer
The original Hamond transformer bobbin tranny did not show stress, according to tech. Since it was designed as a filament transformer, we decided to leave it be and supply only the filaments properly wired with it and to find a torroid that fits internally in the case to supply independent plate voltage. I was able to find a deal on the Hammond over 1/2 the price of catalog, so I thought what the heck--let's give it a try. I opted not to go blue, as well.
The torroid is 3.0" diameter, 1.6" tall. It fits in the Extreme case. The pics show it wired properly.
The data show 6.3V from Hammond and 180V out of the torroid. The external form factor is unchanged, only a single smallish bolt holds the torroid to case bottom, not visible unless unit is upside down.
Well, I turned it on and plugged in the the neural net distortion meter, cochlea-driven, pinna-modulated, HD600/cardas aided. RCA 6AS7G and WE 396A (ECC1 adapter). FYI.
The preponderant bass is gone, the unit is more transparent sounding, better balance. Still great bass, just not a 'tipped-down' sound anymore. Maybe I was hearing a bit of sag before--though it was not bad, just better now TME.
Notable is that the tranny case is now only warmish to touch. I estimate now 110 deg F, which is cool, I think. Before, it passed the the manly pinky test, now it could pass the Hot Lips Hoolihan test.
Listening volume out of Zapped Zahlou DAC into amp is 9 o'clock. Tube hiss sets in at 1-ish. ZERO HUM all the way up the dial, just like before. So it's true what they say about torroids not humming, I suppose.
What I call the OTL character (or others may believe it is the large cap character) is still there, and this is not bad, just different than some of the OT amps I own, like my favorites pictured below. I still own my Ear Max Pro, btw, still smitten by the warm clarity and goodness of prime hot gl-ass with pinched waists from Germany and Holland. Talk about cool running and tiny triode footprint. A classic.
The OTL amps I have owned are more fatigue free on over-extended loudish (85 db or so, db-A weighted, peak captured) listening, I have noted.
The extreme sounded great before, it sounds better now. I kept the external form factor, which I wanted to do, and I saved some bucks, which I also desired. I have seven or so tubed headamps (having sold around six others), and not all can live under one roof this coming (cold) winter, due to some changes I fear are coming. On the other hand, seven tube amps might be comfy on some days, when wolves start to howl. The problem is, each time I listen to these gals, I fall in love all over again with each. Clearly, I gots to get a life, and sell an amp or two. I may need to take extreme steps.
That's my story for now.
Thanks Kevin, Rob, Paul, Skylab, et al., for the great guidance. I found this particular thread the best I have experienced anywhere due to the above truly SUPREME, and not extreme, headfilies.
I'll listen for a bit more, let it run in overnight and tomorrow, and if all is well, I will post tech contact info. Might be useful to have a pro tech when needed.
P.L.H.
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