Hi Bill,
> I am not an amplifier expert- but, before retirement, I was recognized as
> a BS detection expert.- There is a lot of that going out about the DAF
>
> 1. I have seen NO-ONE detract the G2DAF who has actually built one
> according to the original circuits, and really TRIED to make it work. 1a.
I've built them Bill, and measured them, but not with the original
tubes used by G2DAF.
> I have seen several reports, all anecdotal, about people who say they
> sound good. Some of these sources are also experts. 2. ALL the bad reports
> I have seen were anecdotal, but refered to someone who said he was using a
> DAF, but- (the sinker) "my own improvements". 3. Rich, nor anyone else,
> can be honest in saying that the thing is bad, with any believability.
> This stems from the fact that he, or anyone else, can make it "not work"
> if he, or they, choose. Making it work is also hard to prove, because some
> peoples minds are made up, and they will find errors, real or imaginary.
> Sad to say, on this subject, Rich, like Chip on any subject, has lost
> credibility. 4. The BS content on both sides has been high- high enough
> that no further claims, either way, are really worth making. 5. the
> foregoing statement is worth very little, and wont stop anything.
Rather than have my "biased" opinion, what about the
measurements made by the K1 (a former G station) who designed
the VOMAX audio processor?
He submitted data on a Svetlana tube based G2DAF amplifier that
he "refined". He was trying to talk Martin Jue into building a DAF
design at MFJ, using the Svetlana tetrode. He measured IMD in the
range of -25 dB, using the dB below PEP method. That is on par
with what I measured on other tubes, and my own systems.
The sales pitch offered was the IMD "wasn't that much worse" than
that offered by many radios.
It isn't just Rich who has the opinion that applying time-varying dc
voltages to grids and deriving that voltage from the RF driving
source isn't a good idea. I would never try to load the driver with a
dc supply system, let alone use that system to control the
operating point of a tetrode tube. It's a very poor engineering
concept.
The argument offered was
73, Tom W8JI
w8ji@contesting.com
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