I got this little SE amp that has a 6L6 for power tube and 6SL7 for driver tube. Wired 100% parallel with the 6SL7 tube however is a 12AX7A. When I say 100% parallel I mean just that. All pins on the 6SL7 socket are directly connected to the corresponding pins on the 12AX7 socket.
What could be the purpose of this? I know that the 6SL7 and 12AX7 are almost identical electrically but what is the benefit/consequence of running in this configuration? Could it just have been to easily swap driver tubes between the 2 types?
The amp works fine and sounds great with just one of either driver tube at a time. When I plug in both drivers at the same time it sounds about the same but just a tad more open...maybe thats just me though.
Throw in your 2 cents I'd be delighted to hear it.
What could be the purpose of this? I know that the 6SL7 and 12AX7 are almost identical electrically but what is the benefit/consequence of running in this configuration? Could it just have been to easily swap driver tubes between the 2 types?
The amp works fine and sounds great with just one of either driver tube at a time. When I plug in both drivers at the same time it sounds about the same but just a tad more open...maybe thats just me though.
Throw in your 2 cents I'd be delighted to hear it.
If one tube has a different gain curve to the other you might some distortion.
Its quite common to parallel tubes in the pre amp/driver stages but usually with same type of tube.
Its quite common to parallel tubes in the pre amp/driver stages but usually with same type of tube.
AFAIK, 6SL7 and 12AX7 are different enough that putting one section of a 6SL7 in parallel with one section of a 12AX7 could be a mismatch. The published data sheets for 6SL7 and 12AX7 have different spec for mu, or amplification factor: 70 for 6SL7, 100 for 12AX7. That right there would be enough to make me think they're different enough that you wouldn't want to do that.
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Sockets may have been wired in parallel so that you can use either 6SL7 or 12AX7 but not at the same time?
Either that, or a peculiar fashion statement. 6SL7 and ECC83/12AX7 are sufficiently different that there is no good reason for paralleling them. If you want to parallel an octal and Noval use 6SL7 and 5751 - but there is still no reason to do it!
Good points by all. Thanks. I think I will just run a single driver.
However having dual sockets sure makes tube rolling easier!
However having dual sockets sure makes tube rolling easier!
Remarkably there is almost none of any of those. There is a slight hum when I turn on the neon lights in the garage but they are also running 15kV @ 60Hz with no shielding!
Now if I could just get that 1.21 Gigawatts into the flux capacitor!
Now if I could just get that 1.21 Gigawatts into the flux capacitor!
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