6080 audio amp?
On Feb 17, 1:54 pm, "Engineer" wrote:
Hi, Vacuumlanders.
Just a speculation but has anyone built a P-P audio ampliifier with
the 6080 (6AS7) tube? (twin power triodes used as the series element
in voltage regulators)
Yes, I had a stereo amp breadboarded up with two 6AS7's in each
channel.
OK, why would you want to?... it's low voltage, high current, high
bias, likely difficult to drive, you don't need to since there are
plenty of better alternatives, etc...
My answer: I have several 6080's (mostly NOS); getting bored with
designing for 6V6, 6L6, EL84, EL34, etc (well, not really!); you get P-
P in one envelope; I have a couple of spare universal replacement
OPT's (the Hammond 125E) so a choice of plate-to-plate impedances from
3000 ohm up (low enough?)
3,000 ohms was the impedance I used.
is easily obtained; two O/P tubes for
stereo; and, finally, the 6080 sort of looks nice!
So, any opinions on this?... including don't bother! g
I used 270 volts on the plates and a twenty volt dropping
resistor common to both cathodes. The grids were directly coupled to
a negative bias supplied by a 6SN7, this was power by a 270 volt
negative power supply. The 6AS7's require alot of drive signal. The
pre-amp was a quad op amp(a LF347?) The adjustable bias was obtained
by a 5,000 ohm potentiometer between the cathode and the return of the
6SN7's. To get more power I had one triode in the same envolope
cooling as the other was heating.
I used a power transformer as an output transformer and it
sounded pretty
good if I recall correctly. Nice and bassy.
Cheers,
Roger
|