Posted by Poindexter [ 4.63.6.102 ] on January 11, 2005 at 10:54:14:
In Reply to: Re: Holy Toledo! posted by Wayne Parham on January 11, 2005 at 07:24:48:
Yes, they're out there, but there seem to be two flavors:
Little peanut cheapos that sound like sh, ah, not so good.
Great bloody whacking things the size and expense of output transformers.
TC, my first try in the circuit above was the Hammond 124B. I really wanted to like it, but it sounds just like the 10K outputs I tried in the 6V6 amp; dry, opaque. I even tried Amveco power toroids (115+115 : 44), which Bench liked, but they were rolled off too much on both ends, and sort of wiry sounding. The Lundahls and Sowters and Tangos are all these ten watt monsters that cost $100-200 and won't even fit in the chassis. It seems impossible to get the quality without the huge capacity. Don't know why they feel that a component that's transforming a few milliwatts has to be rated at ten watts; maybe a traditional use for them is driving big transmitter tubes like 845's in A2.
I'm still looking, and also talking to some OEM winders who may be willing to wind to spec, but so far no joy. I'm not giving up because I have a long affectionate history with the singly-driven diff-amp (thus my original Holy Toledo!). The high PSRR of diff amps makes them a natural for low level signal use; don't have to use huge music-sucking caps in the power supply final stage.
Poinz
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