Tube amplifier poll
On Aug 10, 6:16 pm, Bret Ludwig wrote:
Slowly. I am loath to bend sheet-metal until I have a firm circuit.
Why? A genenric box accommodates many circuits.
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.
Build around whatever's handy, change later.
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.
Easy to fab a cover.
But all that is the easy part. It's the circuit that is taking the
time and making me waffle...
Bull****. You're stalling. Build something, any goddamned thing.
Anything actually built-even single ended triodes, as hard as it is to
believe-sounds better thatn the best idea not built.
If you want an amp to listen to build any of several known good
circuits. If you want to tinker, build a GOOD power supply for bench
or static use and then breadboard the circuits.
Known good basic designs include the Williamson, Marantz, several RCA
and MO/GEC tube manual designs, and many others. Build, listen, test,
rework, whatever suits your fancy. But don't spend a lot of time on
thinking without building.- Hide quoted text -
- Show quoted text -
Bret, with all due respect (none), eat **** and die.
Peter Wieck
Wyncote, PA
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