alexg wrote:SNZ, I have a couple of amps that the input/driver is a bit short in driving the amp into full power (EL84 into 2A3,for example), my phonostage (12at7 into 12at7) also have lowish gain) the 12sl7/12sn7 aikido helps. I also liked the sound of the 12sl7/12sn7 aikido over the other combinations I have tried, 12au7/12au7, 6dj8/6dj8/6n1p, 7n7/6sn7,12sn7/12sn7 (yun lang yung tubes sa stash ko eh...
Alexg,
Good observations. I know that the gain needed is dependent on multiple factors. My Aikido in service for some time has 6cg7 input and 5687 output. So, it has 10 db gain, which is at the moment more than enough. I was going to try 6gu7s for input to drop the gain a few dbs. The octal Aikido is for trying different tubes for different sound. I have 6sn7s, a pile of 6f8gs, 7n7s, 7af7s and 12sn7 and 6sl7s to roll around. The Aikido phono has a lot of gain with 12ax7s for input , so somewhere in the high 40s for gain. Will try some 5751s for lower gain later. It would yield somewhere in the low 30s. I was even thinking of using some 6C8gs in the octal linestage that have a mu of 36, so they sit somewhere roughly half way between the 6sn7 and 6sl7. I will be running two separate systems with the same sources, so all this gets a little interesting, if not complicated.
By the way, the Janus in Rene's build is a shunt regulator that should work well with the Aikido. Will use the same topology for the Aikido phono power supply. Glad to know that you like your Aikido. I have been really delighted with it, but would like to experiment more now. I guess that will happen soon enough!