Hi all
you're all very helpful folks when it comes to guild amps... and I don't really know where else to turn!
Here's a little problem I'm having with my Quantum:
Inside the amp at the moment are 9 tubes. 2 power tubes (6650/6550A), one 7591A (???), and 6 preamp tubes: 5 12AX7's, and 1 12AU7A.
It's a two channel amp, of course, and it would seem to make sense that there would be 3 tubes per channel.
What I'm getting at here, is that I'd like to replace the single 12Au7 tube with a 12AX7. The 12AU7 is a much lower gain tube compared to the 12AX7, which is basically the highest (see the chart: http://thetubestore.com/gainfactor.html )
Now normally numbers alone would not be enough to convince me to use the wrong type of tube, especially one of higher instead of lower gain.
But here's the kicker: the first channel is SIGNIFICANTLY quieter than the other. This channel needs to turned to 9 or 10 on the gain to get the proper volume. The other channel only needs 3 - 5 to get up to speed.
This seems to be in line with the gain characteristics of the two types of tubes.
Also, the layout of the amp puts the one 12AU7 right next to a 12AX7 in a pair of sockets*.
So, do you think I will be ok using a 12AX7 in there instead of the 12AU7A?
* it looks something like this: 3 12AX7's spaced evenly through the "preamp section" of the amp, ie, the faceplate where the knobs etc are.
moving into the power section, there's a 12AX7 right next to the 7591A.
Then next up is the 12AX7 and 12AU7A pair.
Then finally the power tubes.
you're all very helpful folks when it comes to guild amps... and I don't really know where else to turn!
Here's a little problem I'm having with my Quantum:
Inside the amp at the moment are 9 tubes. 2 power tubes (6650/6550A), one 7591A (???), and 6 preamp tubes: 5 12AX7's, and 1 12AU7A.
It's a two channel amp, of course, and it would seem to make sense that there would be 3 tubes per channel.
What I'm getting at here, is that I'd like to replace the single 12Au7 tube with a 12AX7. The 12AU7 is a much lower gain tube compared to the 12AX7, which is basically the highest (see the chart: http://thetubestore.com/gainfactor.html )
Now normally numbers alone would not be enough to convince me to use the wrong type of tube, especially one of higher instead of lower gain.
But here's the kicker: the first channel is SIGNIFICANTLY quieter than the other. This channel needs to turned to 9 or 10 on the gain to get the proper volume. The other channel only needs 3 - 5 to get up to speed.
This seems to be in line with the gain characteristics of the two types of tubes.
Also, the layout of the amp puts the one 12AU7 right next to a 12AX7 in a pair of sockets*.
So, do you think I will be ok using a 12AX7 in there instead of the 12AU7A?
* it looks something like this: 3 12AX7's spaced evenly through the "preamp section" of the amp, ie, the faceplate where the knobs etc are.
moving into the power section, there's a 12AX7 right next to the 7591A.
Then next up is the 12AX7 and 12AU7A pair.
Then finally the power tubes.