For instance, I know on some amps, v2 is the gain stage. I have a Bugera V22 and I want to get some new tubes, and I am wondering which tube position does what. For those that don't know, the V22 has 3 12ax7s and 2 el84s. I am probably going to go with JJs on all spots, but I may get some other tubes to swap into the clean and gain positions to see what changes I can get.
Do most amps have the same tube positions?
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Funkfingers
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Re: Do most amps have the same tube positions?
In a three valve pre-amplifier, each ECC83/12AX7 has two stages within its glass envelope. Each of these could be performing one of several functions.
v1 is gain.
v2 could be gain, EQ or reverb. (The latter is highly unlikely on your Bugera.)
v3 could be reverb or the phase inverter / driver.
If v1 and v2 are cascaded for high gain, there are various changes that can be achieved through your valve choices for each position. For instance, a ECC82/12AY7 would increase clean headroom but at the expense of maximum possible gain.
In a three valve pre-amplifier, each ECC83/12AX7 has two stages within its glass envelope. Each of these could be performing one of several functions.
v1 is gain.
v2 could be gain, EQ or reverb. (The latter is highly unlikely on your Bugera.)
v3 could be reverb or the phase inverter / driver.
If v1 and v2 are cascaded for high gain, there are various changes that can be achieved through your valve choices for each position. For instance, a ECC82/12AY7 would increase clean headroom but at the expense of maximum possible gain.
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Edgecrusher
New member
Re: Do most amps have the same tube positions?
In MOST amps but definitely not all V1 is going to be the position where swapping tubes will have the strongest effect. Without seeing the schematic there are dozens of configurations that each tube slot could be.
Swapping tubes in the eq network, reverb driver, effects loop will have little effect.
The PI or cathode follower CAN have a great effect but again it depends on the circuit.
Your best bet is to just try em out. Swapping the tubes around wont hurt anything.
In MOST amps but definitely not all V1 is going to be the position where swapping tubes will have the strongest effect. Without seeing the schematic there are dozens of configurations that each tube slot could be.
Swapping tubes in the eq network, reverb driver, effects loop will have little effect.
The PI or cathode follower CAN have a great effect but again it depends on the circuit.
Your best bet is to just try em out. Swapping the tubes around wont hurt anything.
Re: Do most amps have the same tube positions?
I'm pretty sure that V1 and V2 are cascaded for gain. V3 is phase inverter. Reverb is digital but it's pretty damned good. At any rate, V1 and V2 both worth experimenting with. I have the head version, had it for a while. Aside from pulling the rattling tube cage, I haven't done any tube rolling. I don't know how gainy the current production JJ's are but I have some that I got a dozen or more years ago that are on the cooler side. I may have to try one in V1 or V2. Aside from some current production tubes and some NOS, I also have Svetlana (winged C) and EI from about the same time. Other than the preamp being a little hot, whatever Chinese (probably) tubes Bugera has in there, the amp sounds fricken great. Right now, I'm not inclined to do anything to it other than knocking the gain down a notch.
I'm pretty sure that V1 and V2 are cascaded for gain. V3 is phase inverter. Reverb is digital but it's pretty damned good. At any rate, V1 and V2 both worth experimenting with. I have the head version, had it for a while. Aside from pulling the rattling tube cage, I haven't done any tube rolling. I don't know how gainy the current production JJ's are but I have some that I got a dozen or more years ago that are on the cooler side. I may have to try one in V1 or V2. Aside from some current production tubes and some NOS, I also have Svetlana (winged C) and EI from about the same time. Other than the preamp being a little hot, whatever Chinese (probably) tubes Bugera has in there, the amp sounds fricken great. Right now, I'm not inclined to do anything to it other than knocking the gain down a notch.
Edgecrusher
New member
Re: Do most amps have the same tube positions?
Doubt it, That would be 4 gain stages the V22 doesnt have that much gain. Maybe the 2nd half of V1 goes into the first half of V2 it might even have 3 stages but I doubt 4. Likely V1 is the cascaded stages with V2 being the tone network and cathode follower with V3 being the PI
Doubt it, That would be 4 gain stages the V22 doesnt have that much gain. Maybe the 2nd half of V1 goes into the first half of V2 it might even have 3 stages but I doubt 4. Likely V1 is the cascaded stages with V2 being the tone network and cathode follower with V3 being the PI
allbutromeo
New member
Re: Do most amps have the same tube positions?
While this link is for the V55, I'm assuming that the preamp operate the same. So, V1a is the input gain stage common to both channels, when the clean channel is selected this is the only gain stage. When the OD channel is selected V1a is cascaded in to V1b and then V2a. V2b is the tone stack common to both channels and V3a & V3b are the 2 sides of the P. I.
https://musicgroup-prod.mindtouch.u...s_do_in_my_Bugera_V55_valve_guitar_amplifier?
While this link is for the V55, I'm assuming that the preamp operate the same. So, V1a is the input gain stage common to both channels, when the clean channel is selected this is the only gain stage. When the OD channel is selected V1a is cascaded in to V1b and then V2a. V2b is the tone stack common to both channels and V3a & V3b are the 2 sides of the P. I.
https://musicgroup-prod.mindtouch.u...s_do_in_my_Bugera_V55_valve_guitar_amplifier?
Re: Do most amps have the same tube positions?
So 3 gain stages. That makes sense. Excellent, thanks for posting this.
So 3 gain stages. That makes sense. Excellent, thanks for posting this.
Re: Do most amps have the same tube positions?
https://musicgroup-prod.mindtouch.us/04_BEHRINGER/Getting_started_-_V22_Pre_Amp_Tube_Signal_Flow
They have the signal path for the V22 as well it seems. Looks to be the same to me.
https://musicgroup-prod.mindtouch.us/04_BEHRINGER/Getting_started_-_V22_Pre_Amp_Tube_Signal_Flow
They have the signal path for the V22 as well it seems. Looks to be the same to me.
Re: Do most amps have the same tube positions?
According to that link, it's not the same. For V22 lead channel, signal goes through both halves of both V1 and V2. 4 gain stages ... if that's accurate anyway.
According to that link, it's not the same. For V22 lead channel, signal goes through both halves of both V1 and V2. 4 gain stages ... if that's accurate anyway.
Re: Do most amps have the same tube positions?
I guess I read it wrong. Bugera is owned by music group, and that is where the support link on their website goes, so hopefully it is accurate.
Edgecrusher
New member
Re: Do most amps have the same tube positions?
Looking at the schematics no its not accurate V2B is the tone stack. V1A is a gain stage but a pretty weak one which makes sense that way the clean channel really is "clean" V1B and V2A are where the heavy lifting is done. You might even get some mileage out of using a 5751 for V1 if you want pristine cleans way up loud.
You can find the schematic here http://www.acousticguitarforum.com/forums/showthread.php?t=346568
Looking at the schematics no its not accurate V2B is the tone stack. V1A is a gain stage but a pretty weak one which makes sense that way the clean channel really is "clean" V1B and V2A are where the heavy lifting is done. You might even get some mileage out of using a 5751 for V1 if you want pristine cleans way up loud.
You can find the schematic here http://www.acousticguitarforum.com/forums/showthread.php?t=346568
Re: Do most amps have the same tube positions?
I've been pretty happy with the stock tube compliment aside from the amp being a little gainy. Swapped out V1 for a Svetlana yesterday. Not quite as bright. But not much change in gain which was a little unexpected because this tube really lowers gain in the Valveking and V1 in both the Valveking and the Bugera appear to be the same, Chinese tube. It still could be a relative difference between the tube in both amps but may be more the circuit. I have some JJ ECC803's that are even less gainy than the Svetlana (in the Valveking anyway). I may try one. Haven't tried swapping V2, will get around to trying that as well. Really don't want to resort to a 5751 but I probably will end up trying one if I can find them in my stash. I do have some NOS and good, used 12AX7's. Use them in tube audio gear. They could be microphonic as hell in guitar amps but I should roll some in. I forgot the Svetlana 12AX7 history but these tubes were bought probably early 2000's. Not winged C's so I don't recall if they are St. Petersburg made tubes or not. They do tend to hum in circuits with AC on the filaments. DC to the filaments for the preamp tubes so no hum in the Bugera.
Thankfully, Bugera recessed that area of the chassis so there is enough tube exposed to get a decent grip to pretty easily pull the preamp tubes. Sockets don't feel super tight though, which could be a problem down the road with too much tube rolling.
Just curious ... did you pull that P.O.S. tube cage yet? I have the V22 head and the cage rattled at anything approaching moderate volume and above. That think must buzz and rattle like crazy in the combo. The tubes are tucked in there a ways so there isn't much chance of damage. But they don't have shields so I guess they used a cage for extra caution. But it couldn't be made much cheaper. The ends aren't welded to the long sides and that's what causes the rattle.
At any rate, post back with an update when you swap tubes.
I've been pretty happy with the stock tube compliment aside from the amp being a little gainy. Swapped out V1 for a Svetlana yesterday. Not quite as bright. But not much change in gain which was a little unexpected because this tube really lowers gain in the Valveking and V1 in both the Valveking and the Bugera appear to be the same, Chinese tube. It still could be a relative difference between the tube in both amps but may be more the circuit. I have some JJ ECC803's that are even less gainy than the Svetlana (in the Valveking anyway). I may try one. Haven't tried swapping V2, will get around to trying that as well. Really don't want to resort to a 5751 but I probably will end up trying one if I can find them in my stash. I do have some NOS and good, used 12AX7's. Use them in tube audio gear. They could be microphonic as hell in guitar amps but I should roll some in. I forgot the Svetlana 12AX7 history but these tubes were bought probably early 2000's. Not winged C's so I don't recall if they are St. Petersburg made tubes or not. They do tend to hum in circuits with AC on the filaments. DC to the filaments for the preamp tubes so no hum in the Bugera.
Thankfully, Bugera recessed that area of the chassis so there is enough tube exposed to get a decent grip to pretty easily pull the preamp tubes. Sockets don't feel super tight though, which could be a problem down the road with too much tube rolling.
Just curious ... did you pull that P.O.S. tube cage yet? I have the V22 head and the cage rattled at anything approaching moderate volume and above. That think must buzz and rattle like crazy in the combo. The tubes are tucked in there a ways so there isn't much chance of damage. But they don't have shields so I guess they used a cage for extra caution. But it couldn't be made much cheaper. The ends aren't welded to the long sides and that's what causes the rattle.
At any rate, post back with an update when you swap tubes.
Ascension
New member
Re: Do most amps have the same tube positions?
In my Boogie .50 cal + V-1 is the gain stage. It's not set in stone from manufacturer to manufacturer which slot does what so best to get an actual tube function chart if you can on a particular amp.
Re: Do most amps have the same tube positions?
I actually thought about pulling the tube cage, but mine has about 6-8 screws in it, on every corner and on the sides, and I haven't had any problem with rattle. This is with the head version, sitting directly on the 1x12 cab. Another point worth mentioning, it is EXTREMELY easy to just unmount the chassis from the cab. IIRC its only 4 screws on top, and 3-4 on the back. Don't get me wrong, it feels very solid, just worth mentioning. It made it very easy to pull everything apart to see how well the amp was built, and also to get to the screws on the front of the tube cage.
Re: Do most amps have the same tube positions?
Yeah. I pulled the chassis out already. To remove the cage. I also checked out the construction. Basic Chinese fare. Only thing I didn't really like was that the OT wires were pulled tight but I didn't mess with them. My V22HD sits on an open back 2 x 12. Cage buzzed so cage is gone. It's not necessary to pull the chassis to swap tubes, unless you have to remove the cage of course. I'm a thin, old guy and can get my arms in there with ample room, even without removing the small bottom panel section. But even if the cage didn't buzz, I wouldn't have replaced it after I did any tube swapping. I couldn't see having to pull the chassis to remove the cage to be able to check or replace tubes.
Yeah. I pulled the chassis out already. To remove the cage. I also checked out the construction. Basic Chinese fare. Only thing I didn't really like was that the OT wires were pulled tight but I didn't mess with them. My V22HD sits on an open back 2 x 12. Cage buzzed so cage is gone. It's not necessary to pull the chassis to swap tubes, unless you have to remove the cage of course. I'm a thin, old guy and can get my arms in there with ample room, even without removing the small bottom panel section. But even if the cage didn't buzz, I wouldn't have replaced it after I did any tube swapping. I couldn't see having to pull the chassis to remove the cage to be able to check or replace tubes.