diytube.com

I finally came up with a good test strategy to measure max output power for these single ended triodes, so now I can go back and more accurately test the get*set*go and Darling Clementine, too. Previously, I thought I would select 5%THD for the measurements, but this didn't reflect max output swing into the power triode or pseudo-triode. Instead of a fancy test setup monitoring the voltage swing and cathode bias, I am just increasing the input signal until the cathode bias peaks and then starts to decline. This can be done quickly with one DMM and a hand on the signal generator adjust. I adjust upward in 10mV increments and then do fine adjustments of 1mV to get the exact peak. Note that the preponderance of the distortion is second harmonic. Noise was extremely low, too.

-3dB bandwidth is around 15Hz to 31kHz. Not bad for a simple 6SL7 driver and budget Edcor iron. I used a Russian 6L6GA that I pulled randomly from the tube vault - I think Ed Brown sent me these a few years ago. Note that '11' is a junk number. The distortion data here was garbage due to my automatic data collection method.

Tests at 1W (adjusted for a 2.828V output at 1kHz):
http://www.diytube.com/clementine/russ6l6_383mv.pdf

Tests for max output power (adjusted at 1kHz as described above):
http://www.diytube.com/clementine/russ6l6_695mv.pdf

Shannon

Really good info. Did you post the same for the Darling, and I missed it?

Great data,thanks!

/ed B

So what is the expected power output of a triode strapped/ pentode 807 in this configuration?
Thanks,
Al

apurcell22 wrote:So what is the expected power output of a triode strapped/ pentode 807 in this configuration?
Thanks,
Al

It will be around the same. The 807 can be run at a higher current than these 19W 6L6s, but the result will be linearity vs output power. I remember hitting 4W exactly with my 807 tests earlier in very limited testing. The mu and gm and B+ are all a factor on exactly where you end up. Thermion is testing his 1625 Chubby Clementine this week and he is getting the same numbers.

I had stolen the Darling's output transformers for the Chubby. I have it put back together for the same testing ASAP.

Shannon

Here's the Darling Clementine using some National Union 1626s:

Tests at 1/8W (adjusted for a 1V output at 1kHz):
http://www.diytube.com/clementine/darling_200mv.pdf

Tests for max output power (adjusted at 1kHz as described above):
http://www.diytube.com/clementine/darling_535mv.pdf

Shannon

Is 5k the best load? I don't really care about power. I have jame 6113hs opt's
Al

apurcell22 wrote:Is 5k the best load? I don't really care about power. I have jame 6113hs opt's
Al

Yes - use the 5K tap on your James. The 3.5K tap would be too much distortion.

Shannon