I've got a surplus stash of 6GM8 / ECC86 tubes and thought a re-working of the attached circuit might make a decent junk box linestage.
Can anyone assist with changing resistor & capacitor values if we were to have 24vDC B+ and 6.3v DC H+?
Can anyone assist with changing resistor & capacitor values if we were to have 24vDC B+ and 6.3v DC H+?
Thx, I've built the Aikido using the 6GM8 / ECC86, great sound but too much gain! This circuit should give less gain but the plate voltage is well beyond what the 6GM8 can tolerate.
This circuit may in fact be better - unity gain, low output impedance and appears to work perfectly with the 6GM8 without any changes whatsoever (unless I am mistaken)?
John Broske posted this scheme for reducing the Aikido circuit gain. I've use it to good effect.
https://tubecad.com/2020/08/blog0510.htm
The two 200k resistors are effectively in parallel and equal 100k of resistance, which then forms a two-resistor voltage divider with the 124k resistor. The result is a gain 4 (+12dB) with 6SN7s. If we use a 6DJ8 instead, we will need to impose greater attenuation.
https://tubecad.com/2020/08/blog0510.htm
The two 200k resistors are effectively in parallel and equal 100k of resistance, which then forms a two-resistor voltage divider with the 124k resistor. The result is a gain 4 (+12dB) with 6SN7s. If we use a 6DJ8 instead, we will need to impose greater attenuation.