On Aug 10, 8:08 pm, John Byrns wrote:
In article om,
Peter Wieck wrote:
On Aug 10, 3:48 pm, Sander deWaal wrote:
How's your homebrew-tube amp project going, Peter?
Slowly. I am loath to bend sheet-metal until I have a firm circuit.
Each circuit I try has its advantages and disadvantages... right now,
I am investigating a PP 6L6/5881 configuration, each channel using a
single 12AX7 as driver w/a very simple SS power-supply. It sure takes
a load off the power-transformer, appears to be very stable while
breadboarded on the bench, makes nice sound and is quite simple.
Everything gets to be a little bit lazy, a good thing for stability
and longevity. My test speakers for this are the AR Athenas, the
satellites are tiny (1.5"dome mid & 3/4" dome tweet) and the sub ( 2
x 8" long-throw) makes a nice footrest under the bench. And those
speakers would likely be the permanent mates.
I also tried a near-duplicate of the Dynaco ST-35 circuit with a fixed-
bias circuit and based on 6BQ5 outputs, and I am tempted to try the
original 7591A output tubes as Fisher configured for the original
iron... So many things to try, so little time.
I think I rejected the 6BQ5 option as I want a bit more than 13 watts,
but I would settle for a reliable 20, well within the range of the
5881 in PP Class A. And I prefer to be able to use readily available
(to me) NOS; or vintage tubes already in hand.
I am contemplating a very simple black-box type cosmetic layout with
the transformers concealed and the tubes caged behind the front
panel. Just an LED or neon pilot on the front panel, the on/off switch
being a momentary-contact relay-system so that any interruption of
power would cause complete shut-down... no possibility of automatic re-
start.
Cats and grandkids preclude exposed tubes, but suchlike was never a
big thing of mine, eyewash does not sound much, good or bad.
But all that is the easy part. It's the circuit that is taking the
time and making me waffle...
I don't understand why you are waffling, reading between the lines you
wrote above it is clear you already have your circuit.
Regards,
John Byrns
--
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- Show quoted text -
John:
I have tried (breadboarded) two circuits. Both had their merits, but
the 6BQ5 circuit was just too 'little'. I am tempted to try one or two
more including one based on the 7591A, and one possibly with different
drivers before I bend and punch sheet metal.
That's really all there is to it. I am not in a hurry, and I am trying
to learn rather than assemble by rote.
Peter Wieck
Wyncote, PA