I built these amplifiers and would like to get a little bit more gain as my DAC will put 3 volts output with balanced inputs on the amps. The first stage in this amp i believe is doing the phase splitting.
Any leads would be greatly appreciated.
Any leads would be greatly appreciated.
The best thing you can do to increase gain is to destroy the parallel in the first section and use the first triode as voltage gain stage (cathode grounded for signal) while retaining the second one as the phase splitter. Only need a couple of passive elements and rewire first socket. 6SL7 has a mu of 70, so you can add a 50 times gain doing what I suggest.
Thanks for the suggestion Osvaldo.
I really like the sound of this amplifier and didn't want to change the circuit that much plus on Pete's website there is another circuit which increases the gain as well. I don't know enough to say your suggestions will improve or hinder the sound.
I really like the sound of this amplifier and didn't want to change the circuit that much plus on Pete's website there is another circuit which increases the gain as well. I don't know enough to say your suggestions will improve or hinder the sound.
Do you need more gain or more power? It appears that you built Pete’s version 2 design with lower gain, requiring 3.1 V RMS for full output. Have you considered converting it to the version 1 design? Version 1 requires only 300 mv for full output and is essentially what Osvaldo is suggesting.
If I understand version 2 design that you currently have correctly, there are two 6SL7 triodes in parallel, functioning as one phase splitter. So, “adding balanced inputs” will required some redesign and conversion to a differential amplifier to accept the balanced inputs. Something like Pete’s Engineers Amp front-end with CCS in the tail, or a transformer input that will result in something like Pete’s “Universal driver” PCB with input transformers. Google should find you a few designs of tube amps with balanced inputs to start with.
Also, take a look at this thread and the schematic in post #1 and #9 here: https://www.diyaudio.com/community/threads/6n13s-6as7g-pp-amplifier-schematic.393969/#post-7221084
Good luck.
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Thanks Francois, that answers my question.
When I am streaming music some content has lower volume than others. Most content has plenty volume. I will leave the amps as is.
They sound to good to change.
O.B.
Another way is taking the 6SL7 stage out from the circuit if your line amplifier has sufficient output to drive the low gain power amplifier.
Johnny
Johnny
