Possible mod to ch 2 of F50?
- Thread starter mikejc
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Plus one.
I love the clean/green channel, and that gain control is SOOOO powerful, just like the manual said it would be. The clean channel is real chimera, and the crunch sounds are the best I've ever played. Compared to that the Red channel is not nearly as dynamic or versatile, and I can get better distortion from my Robot Factor Ubber Rat.
What about just replacing V2 with tube like a 12AY7 or 12AU7 with MUCH lower gain? (Actually, I've got a JAN 6072A at home, maybe I should just try it!)
I love the clean/green channel, and that gain control is SOOOO powerful, just like the manual said it would be. The clean channel is real chimera, and the crunch sounds are the best I've ever played. Compared to that the Red channel is not nearly as dynamic or versatile, and I can get better distortion from my Robot Factor Ubber Rat.
What about just replacing V2 with tube like a 12AY7 or 12AU7 with MUCH lower gain? (Actually, I've got a JAN 6072A at home, maybe I should just try it!)
I have an f100 combo and the clean channel is as different as night and day to the dirty channel. I don't think and eq in the loop could compensate. The eq characteristics are so different for each channel. I have a tonelab running into the front of the amp right now, I use the clean channel. Have an MXR 10 band in the loop. Kinda tinkered around with crunch channel instead of the clean channel....didn't have much luck but then again, I didn't fiddle with it too much.
scandoslav
Member
greyblooz, please try the 6072A and let us know how it goes! 
Scando, I tried the 6072A in V2 last night for a while and really enjoyed it. Compared to the stock tube, there seemed to be less gain, less sustain, more clarity but I think the tube was only a very small part of the equation. Read on if you dare...
The rig I used to test was my '93 G&L Legacy which has been modded with a Callaham tremblock and Vintage Vibe pickups with a 5% overwind. The guitar sounds clear and chimey like a vintage STRATOCASTER. Since it was late at night, I used a pair of AKG K141 headphones with the speaker mute. My power tubes are SED Winged Cs, but I wonder how much effect that really had on the tone with headphones. No booster/compressors/overdrives before the preamp.
Basically, I found that if you look at the gain control in quadrants like four pieces of pie, you get four different characters of gain with subtle nuances within the quadrant. It started with some dry overdrive for blues or early rock'n roll and moves into some smother, juicier drive good for rock'n roll from the 70s. Pushing it past noon adds an extra layer of dirt onto the sound for single-note soloing, but you can still clean up pretty well with your volume control. Close to max gain, it sounds fuzzy but still sounded like a strat, though it wouldn't totally clean up. This is the area that would still be unusable for me, but maybe good for weaker pickups or maniacs.
Interestingly, I found the MID control has a HUGE effect on the amount of the character of the gain, just like it says in the manual. Keeping it almost all the way down open the sound up tremendously, and turning it up past noon gives the sound a nasal honk that dominates everything else. Treble and Bass have much less effect on the character of the gain. Treble just adds edge. So if you are looking for less gain, I suggested starting with the MID at the minimum and dial in from there. Of course, I played with the Contour on/off, and liked the sound a lot for solo boosts. With the gain at about noon, I found a good balance for rhythm and lead.
BTW, I was also able to find low-gain tones I liked at less than 3 o'clock with the stock tube in V2, too. So I think that the guitar you're using and the MID control has a lot to do with the amount of gain you're going to get out of this amp. I don't think the LEAD/red channel will every really do a "grainy" sounding overdrive. It's a Mesa/Boogie, and will give you that Mesa/Boogie sound that made Santana famous. For grainy crunch, stick with the Clean/green channel with the gain cranked, hot pickups, the stock tubes, and maybe a nice overdrive like an Adrock Ol'Yeller.
Incidentally, it is harder to get good crunch sounds from the Clean/green channel with a lower gain preamp tube in ANY socket from V1~4 because they're all shared by both channels. If you look at the manual, you'll know what I mean. I asked Boogie tech support whether V1 or V2 would be better for reducing the gain, but they said they hadn't tested the amp with lower gain tubes, but we should feel free to try a Boogie 12AT7 and listen. If you don't like what you hear, use a high end 5-knob pedal as a second channel.
The rig I used to test was my '93 G&L Legacy which has been modded with a Callaham tremblock and Vintage Vibe pickups with a 5% overwind. The guitar sounds clear and chimey like a vintage STRATOCASTER. Since it was late at night, I used a pair of AKG K141 headphones with the speaker mute. My power tubes are SED Winged Cs, but I wonder how much effect that really had on the tone with headphones. No booster/compressors/overdrives before the preamp.
Basically, I found that if you look at the gain control in quadrants like four pieces of pie, you get four different characters of gain with subtle nuances within the quadrant. It started with some dry overdrive for blues or early rock'n roll and moves into some smother, juicier drive good for rock'n roll from the 70s. Pushing it past noon adds an extra layer of dirt onto the sound for single-note soloing, but you can still clean up pretty well with your volume control. Close to max gain, it sounds fuzzy but still sounded like a strat, though it wouldn't totally clean up. This is the area that would still be unusable for me, but maybe good for weaker pickups or maniacs.
Interestingly, I found the MID control has a HUGE effect on the amount of the character of the gain, just like it says in the manual. Keeping it almost all the way down open the sound up tremendously, and turning it up past noon gives the sound a nasal honk that dominates everything else. Treble and Bass have much less effect on the character of the gain. Treble just adds edge. So if you are looking for less gain, I suggested starting with the MID at the minimum and dial in from there. Of course, I played with the Contour on/off, and liked the sound a lot for solo boosts. With the gain at about noon, I found a good balance for rhythm and lead.
BTW, I was also able to find low-gain tones I liked at less than 3 o'clock with the stock tube in V2, too. So I think that the guitar you're using and the MID control has a lot to do with the amount of gain you're going to get out of this amp. I don't think the LEAD/red channel will every really do a "grainy" sounding overdrive. It's a Mesa/Boogie, and will give you that Mesa/Boogie sound that made Santana famous. For grainy crunch, stick with the Clean/green channel with the gain cranked, hot pickups, the stock tubes, and maybe a nice overdrive like an Adrock Ol'Yeller.
Incidentally, it is harder to get good crunch sounds from the Clean/green channel with a lower gain preamp tube in ANY socket from V1~4 because they're all shared by both channels. If you look at the manual, you'll know what I mean. I asked Boogie tech support whether V1 or V2 would be better for reducing the gain, but they said they hadn't tested the amp with lower gain tubes, but we should feel free to try a Boogie 12AT7 and listen. If you don't like what you hear, use a high end 5-knob pedal as a second channel.
scandoslav
Member
Excellent post! Thank you very much, that's some great info. Yeah, the tube diagram is slightly baffling to me; is there any particular reason that they'd have the green channel also use V2?
Well, it's only HALF of V2 really. My limited understanding is that each preamp tube "contains two separate triodes" (according to the manual), and that a triode is something like the predecessor to a transistor. In other words, each tube is amplifying the signal twice. So the first half of that tube is amplifying the clean a bit further, and the second half only when the Lead channel is engaged.
I am at a total loss to explain why they would do it this way. Anybody?
I am at a total loss to explain why they would do it this way. Anybody?
elvis
Well-known member
The amp uses 6 gain stages. Each 12ax7 has 2 completely separate gain stages (triodes) in it. They are used as if there were 6 separate tubes. This is common usage dual triode tubes. The choice of which tube is used for which stage is partly for wiring convenience and partly for stability (the two halves do have a little crosstalk).
For the original question: there is an extra gain stage that is switched in for the gain channel. The component values are a bit different in the controls as well (I think...). So you COULD mod the amp to be a dual clean amp. Just disconnect the extra gain stage and alter the components a bit.
For the original question: there is an extra gain stage that is switched in for the gain channel. The component values are a bit different in the controls as well (I think...). So you COULD mod the amp to be a dual clean amp. Just disconnect the extra gain stage and alter the components a bit.
scandoslav
Member
elvis said:
How would I go about doing that? I don't intend to mod my amp anytime in the foreseeable future (if at all), but I'm curious.
elvis
Well-known member
When switching the amp, there are FET switches that switch in the extra tube. Wire out the switches so that the extra tube is not added to the circuit.
As for the components, you would have to study the schematic to figure out where the changes are. It may not be necessary, as they are probably slight differences.
As for the components, you would have to study the schematic to figure out where the changes are. It may not be necessary, as they are probably slight differences.
