Bassling C3G 300b schematic
Hi
So after taking all the advice on this thread, and the very generous help of Andy Evans I now have this as Amp and PSU. I have moved away from a C3m and am now using a C3g. It is a much simpler layout than EBAs, and I wanted to ask for comments on this simpler triode driver approach before I built it.
Thank you so much for all your help and support so far.


Hi
So after taking all the advice on this thread, and the very generous help of Andy Evans I now have this as Amp and PSU. I have moved away from a C3m and am now using a C3g. It is a much simpler layout than EBAs, and I wanted to ask for comments on this simpler triode driver approach before I built it.
Thank you so much for all your help and support so far.


300V anode-cathode voltage is is in the lower side, and if you use 5k OPT the expected output power about 5W.
For 5k transformer I use 400V, 70mA operating point.
For 5k transformer I use 400V, 70mA operating point.
So on some further investigation 100k seems a more acceptable value and should have little impact sonically. Do you agree?
To drop 178 volt the 7k4 resistor should be 14k8.
The resistor feeds 2 channels.
Then better split the power supply and use two 14k8 resistors.
Yes it's possible too. Personally, I just use one PSU for both channels. Do you split the supply yourself, and what benefits have you found?
In fact, in my own system I have a separate PSU for the input section. I don't split between channels, though.
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I always would do it without asking myself.
In the schematic I don't see the second leg drawn for the other channel.
Benefits? Maybe a bit less cross talk.
In the schematic I don't see the second leg drawn for the other channel.
Benefits? Maybe a bit less cross talk.
That is my mistake. Sorry. I just assumed everyone would be stereo these days. I think that I will split off the PSU and then duplicate the channel with two 14k8 resistors.
And in that case should the PSUD load be 1k75? Bah - in whch case the PSU design doesnt work!
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And in that case should the PSUD load be 1k75? Bah - in whch case the PSU design doesnt work!
Not necessary when using a single supply for both channels.
OK, so using the constant current supply and a GZ34, I can get 360v, or if using a SS bridge I can get 378v. I have already got the transformer (300-0-300), so that seems to be the choices. What would people recommend?
Euro21...you are correct in your simulation. But 3.7 watt can be enough for someone who has sensitive speakers and low volume listening habit. No?
For my 2xmono 300b se B+ is 378 volt, cathode sits at 64 volt against 1270r resistor and that is plenty loud for my taste.
Regards
For my 2xmono 300b se B+ is 378 volt, cathode sits at 64 volt against 1270r resistor and that is plenty loud for my taste.
Regards
Bassling....since you already got your PT please go ahead and build it with GZ34. Afterwards, if you find you need more power you may change the PT not a big problem other than $$. By the way what speakers will be driven by this amp? Please note to increase power by three db you need to double wattage.
Regards
Regards
But 3.7 watt can be enough for someone who has sensitive speakers and low volume listening habit.
It's true, but this power is rather in the 2A3 region than 300B.
BTW now I use 96dB loudspeaker with 10W (A2 capable) 300B amp.
Is there a big difference in sound between gz34 and Diodes (am I opening myself up for some serious abuse here ;-))?
Thankyou, Minhaj. Still undecided over GZ34 or diodes. I guess I can try both and see which I prefer
Euro21...thank you. Yes this is a valid question why use 300b for 2A3 power level. For me the above biasing gives me right mellow tone which greatly satisfies my listening taste. I tried 2A3 se but I prefer 300b for this duty.
Regards
Regards
Bassling....since you already got your PT please go ahead and build it with GZ34. Afterwards, if you find you need more power you may change the PT not a big problem other than $$.
Regards
For more AC voltage you can just add a second transformer in series. Like 24+24v or whatever you need to raise the voltage.
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