"Roger D Johnson" wrote in message
...
Don wrote:
Thanks for the response. Will I run the risk the damaging
other
components if I try an audio transformer with a 10,000
ohm primary and
an 8 ohm secondary?
Hi Don...

My tube manual lists the load impedance as 7600 ohms for a
6K6 with
250 volts on the plate. The 10k transformer will not
provide full
output from the tube but should be substantially more than
the
original transformer. No risk of damage to anything but
your ears
if you plug headphones in with the volume turned up!

73, Roger

There is some variation from manual to manual depending on
the exact operating conditions specified. For instance the
6K6 page from the RCA Tube Handbook at
http://www.pmillett.com/tubedata/HB-...t_2/6K6-GT.PDF

Shows three values of transformer load impedance:
For 100V on plate and screen grid, 12,000 Ohms for 0.35 Watt
at 11% THD
For 250V on plate and screen, 7600 Ohms for 3.4 Watts at 11%
THD
For 315V on plate and 250V on screen (maximum ratings), 9000
Ohms for 4x5 Watts at 11% THD

I don't see any voltages in the on-line handbook but they
should be easy enough to measure. In any case the
transformer impedance does not seem too critical. Check the
bias voltage to see what it is. You may want to change the
cathode resistor. The handbook gives the recommended bias
value.

Since the headphone jack is just paralleled across the
speaker terminals it might be useful to put a load resistor
across it when using high impedance phones.


--
---
Richard Knoppow
Los Angeles, CA, USA