[sdiy] now on to tubes

[anthony]

Talking about switching op amps around made me think about using different 
tubes in some of the circuits on Ken's site. For the simple fact that I have 
a whole bunch of tubes. Some of them are cool and are being put to good use, 
but I have a huge number of triode/pentode combos like 6GH8A, 6CM8, 6CB6A (I 
think that might be a twin triode tho it's hard to see into it). In addition 
to the nice high-mu twin-triode tubes I have I have a lot of medium-mu 
twin-triodes like 6BK7B, but I found a good use for those in a pretty cool 
headphone amp. And I haven't found a definitive answer for why the 6922 is 
popular in high-endish audio.

And then there's all the li'l 7-pin pentodes like 6AU6 and 6HZ6. The 6AQ5A's 
look pretty cool for a little amp (they seem like a 7-pin version of the 
EL84/6BQ5A - not as much puch but a lot for such a small tube.) or two and 
the 6GZ5 for a teeny amp. I have a funky chassis with 3 7-pin sockets on it 
waiting for an equally funky project to go on it. Probably the teeny amp. 
Unless one 6AU6 is good for a preamp then I'd use two 6AQ5A's.

I understand using the thyratron for an oscillator. And the sheet beam tube 
for the beam modulator I understand. But naturally I don't have any of 
those. I was pleased to see that they can be had for pretty cheap. I figure 
the tubes that I mentioned might work in synth circuits but they might not 
really sound great, but how about something like a VCF from a 
triode/pentode? I've heard of vertical deflection tubes being used for amps, 
but I don't think all of them would sound all that great. I thought those 
tubes weren't very linear.

I have a lot of solid state (and acoustic) stuff to work on first. I have 
too many half-done projects. (I spend too much time online looking at 
everyone else's stuff... And a lot of you have some spectacular stuff!)

But my EL84 guitar ampis coming along nicely. The tube rectifier is not big 
enough by a long shot tho so I'l be using 1N4007's. I'll keep the tube in 
with the heater hooked up. Same with the 1V2 that I wasn't planning on using 
at all for anything.

Trying to put 6V pentodes where 12V twin-triodes used to be is kind of a 
headache... I'm glad this thing only has 4 tubes (that'll be doing 
anything - I'm using a 5651 for show too since I have a free 7-pin socket. I 
hope it glows like an 0A2).