Chickenwings
Alnico 6/8
cos another harp player told him it was a good idea....
was it?
was it?
my friend put a 12DW7 in the PI in his super....
- Thread starter Chickenwings
- Start date
glassman
Electron Herder
Re: my friend put a 12DW7 in the PI in his super....
I do work for a few harp players and 12DW7s are very popular. It doesn't hurt anything. The PI isn't the only place they use them but it is the most popular position to start with. It's one of the "kinder" things I've seen done to some harp amps...speakers cut to shreds and extra cone material glued to them to make it sound as distorted as possible.
I do work for a few harp players and 12DW7s are very popular. It doesn't hurt anything. The PI isn't the only place they use them but it is the most popular position to start with. It's one of the "kinder" things I've seen done to some harp amps...speakers cut to shreds and extra cone material glued to them to make it sound as distorted as possible.
ItsaBass
New member
Re: my friend put a 12DW7 in the PI in his super....
I use a 12DW7 in the V2 spot of my Ampeg Jet, which I consider my main amp. That came about by accident. I had a tube go bad, so I did some digging and found some old tubes sitting around from years ago when I completely retubed my old V4. It had a piece of tape on it that I had marked "87 percent," so I did some research, and then stuck it into the little Ampeg. I tried it in the V1 and the V2 spot, and settled on keeping it in V2. It made the amp cleaner, which was a great benefit, as I was running into an overly gainey sound when trying to keep up with my bandmate's half stack. As I understand it, they drop right in with no issues, and the one half of the tube makes for about 20 percent of the gain of the other half. As V1, it sounded good, but lost too much volume. As V2, it just added a little clarity without sacrificing a lot of volume.
I use a 12DW7 in the V2 spot of my Ampeg Jet, which I consider my main amp. That came about by accident. I had a tube go bad, so I did some digging and found some old tubes sitting around from years ago when I completely retubed my old V4. It had a piece of tape on it that I had marked "87 percent," so I did some research, and then stuck it into the little Ampeg. I tried it in the V1 and the V2 spot, and settled on keeping it in V2. It made the amp cleaner, which was a great benefit, as I was running into an overly gainey sound when trying to keep up with my bandmate's half stack. As I understand it, they drop right in with no issues, and the one half of the tube makes for about 20 percent of the gain of the other half. As V1, it sounded good, but lost too much volume. As V2, it just added a little clarity without sacrificing a lot of volume.
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Chickenwings
Alnico 6/8
Re: my friend put a 12DW7 in the PI in his super....
Thanks fellas!
Thanks fellas!
glassman
Electron Herder
Re: my friend put a 12DW7 in the PI in his super....
I feel the need to interject here and clear up HOW a long tail phase inverter works and WHY using a dissimilar dual triode like a 12DW7 doesn't drive the tubes at different levels in a push-pull circuit. This also ought to clear up why a "balanced output" dual triode has no actual effect.
Lets start with a typical long tail PI like in a Fender...the input section (drawn on top in a schematic) sets the gain of the PI. The lower half has no gain; it is cathode driven and simply mimics the inverse of the signal on the upper section regardless of the gain factor of the tube itself. The signal itself is the same coming from both sides, only inverted on one side. The biggest tonal difference in the case of a 12DW7 is from the very dissimilar plate impedences; this changes the frequency response of the two sides but not the amplitude of the signals. If you want to drive one side of a push pull circuit harder than the other, you have to do it in the power section or, to a limited degree, in the preamp by adjusting the duty cycle of the signal.
I feel the need to interject here and clear up HOW a long tail phase inverter works and WHY using a dissimilar dual triode like a 12DW7 doesn't drive the tubes at different levels in a push-pull circuit. This also ought to clear up why a "balanced output" dual triode has no actual effect.
Lets start with a typical long tail PI like in a Fender...the input section (drawn on top in a schematic) sets the gain of the PI. The lower half has no gain; it is cathode driven and simply mimics the inverse of the signal on the upper section regardless of the gain factor of the tube itself. The signal itself is the same coming from both sides, only inverted on one side. The biggest tonal difference in the case of a 12DW7 is from the very dissimilar plate impedences; this changes the frequency response of the two sides but not the amplitude of the signals. If you want to drive one side of a push pull circuit harder than the other, you have to do it in the power section or, to a limited degree, in the preamp by adjusting the duty cycle of the signal.
