I have the 100w Badlander and it's a bad ass amp no doubt. Had it since new since inception, about 5 years now. Never had an issue till now. The other night experienced volume swells and thought it was a loose guitar lead. It wasn't. Thought it was a flat battery in the active guitar. It wasn't. Could it be one of the power valves EL34 is on it's way out? Any ideas? I do have spare 6L6 set, I could always swap em out then try. If it still happens, what else could it be? Appreciate your thoughts, suggestions and comments. Thanks folks! JJ
Badlander volume swell
- Thread starter Satchur8
- Start date
Help Support The Boogie Board:
- Joined
- Oct 8, 2018
- Messages
- 798
- Reaction score
- 470
Does it occur on either chan?
- Joined
- Oct 8, 2018
- Messages
- 798
- Reaction score
- 470
ok, perhaps try switching to the other chan with the same config and see if there is any change. The suggestion is just to hopefully narrow down the issue to a preamp or power amp tube. If there is no change with the chan switch then it may indicate the power tube.
Also try switching to different power levels, ie: 50W only uses 2 of the power tubes.
It could be a number of things. 5 years on the original tubes? Do you have one of the original samples that went out for demos? I was on the pre-order list to get the first one and that was 4 years and 2 months ago. Still, it is hard to believe it was that long ago when they were shipping them. My first has a SN that is below 100. Still has the stock tubes in it. Depends on how much use the amp gets as all tubes do age with use. Considering use of the amp, you are probably due for a full tube replacement. Mine is not an everyday grinder but does get plenty of use since I got the first one. I blame the reduction in usage on the pair of Mark VII I have gravitated too.
You could swap out with the 6L6GC tubes. Depending on what they are you may get some mixed results. Do expect a slight drop in output volume when moving to the 6L6 tubes and bias. That is normal. Since the BAD is a Class AB, I found that greens or grays in the 6L6GC family work best to maintain that same level of grind. I have only explored the STR448 and STR445. I do not remember if I tried the other tubes on hand. Reds or yellows will neuter the amp (more so with the reds than yellows). Yeah, there is plenty of power tube distortion with green and grey and did not realize it was that important with this amp until I tried a set of STR448 in red code. That was lame.
Since the BAD is based in part on the Mark Lead drive circuit in the front half of the preamp (V1+V3). There are two cathode follower tube positions V2 and V4. Since all channels run through the same DC coupled cathode follower tone stack driver, I would at least replace V2. Volume swells were a common issue with the Rectifiers relative to the tone stack driver circuit. The other would be the FX loop tube V4 but that is not as much of an issue with preamp tube degradation but can sill occur as not all preamp tubes are identical even if they are the same.
If it was a power tube issue, you could just look into the front grill to see if one of the power tubes has become overloaded. It will be red plating and may not take out the fuse. I had a similar issue when I wanted to try out the Mesa STR442 (SED =C= EL34) tubes in one of the BAD100. They were near EOL but figured I would get a chance to hear them before I retire them. One red plated on me but the amp kept going. It was not pulling any of the other tubes into overload though and probably why the main fuse did not give out. The amp sounded more compressed and not as loud as normal. I did not hear any volume swells with that failure mode but that can be common if one tube overloads and swamps out the output transformer with more DC current as that has a saturable reactor effect, meaning it cuts out the AC signal transfer from the primary side to the secondary side (output). I would not rule out power tube issue, but you can see that if one tube is overloaded or ready to give out. Typically when one craps out it will effect one of the others on the opposing side.
You could swap out with the 6L6GC tubes. Depending on what they are you may get some mixed results. Do expect a slight drop in output volume when moving to the 6L6 tubes and bias. That is normal. Since the BAD is a Class AB, I found that greens or grays in the 6L6GC family work best to maintain that same level of grind. I have only explored the STR448 and STR445. I do not remember if I tried the other tubes on hand. Reds or yellows will neuter the amp (more so with the reds than yellows). Yeah, there is plenty of power tube distortion with green and grey and did not realize it was that important with this amp until I tried a set of STR448 in red code. That was lame.
Since the BAD is based in part on the Mark Lead drive circuit in the front half of the preamp (V1+V3). There are two cathode follower tube positions V2 and V4. Since all channels run through the same DC coupled cathode follower tone stack driver, I would at least replace V2. Volume swells were a common issue with the Rectifiers relative to the tone stack driver circuit. The other would be the FX loop tube V4 but that is not as much of an issue with preamp tube degradation but can sill occur as not all preamp tubes are identical even if they are the same.
If it was a power tube issue, you could just look into the front grill to see if one of the power tubes has become overloaded. It will be red plating and may not take out the fuse. I had a similar issue when I wanted to try out the Mesa STR442 (SED =C= EL34) tubes in one of the BAD100. They were near EOL but figured I would get a chance to hear them before I retire them. One red plated on me but the amp kept going. It was not pulling any of the other tubes into overload though and probably why the main fuse did not give out. The amp sounded more compressed and not as loud as normal. I did not hear any volume swells with that failure mode but that can be common if one tube overloads and swamps out the output transformer with more DC current as that has a saturable reactor effect, meaning it cuts out the AC signal transfer from the primary side to the secondary side (output). I would not rule out power tube issue, but you can see that if one tube is overloaded or ready to give out. Typically when one craps out it will effect one of the others on the opposing side.
