Drive Channel Volume Problem (Bugera V55)

[MartyVega]

I picked up a used Bugera V55 a couple weeks back. This one has an amber light, so second generation manufacture.

I love the amp -- well, the Clean channel anyway. I mostly play on the Clean channel, and use the Drive channel only as a boost.

But now there's a big volume drop in the Drive channel. I'm pretty sure that, while practicing a couple days ago, I heard a very quick whistle-like sound. I thought it odd, but as I wasn't using the Drive channel at the time, I don't know if the problem with the channel started there.

Yesterday during sound-check, however, the Drive channel just wasn't giving me any volume at all. I was pretty stressed out, and didn't have time to fuss around, so I just did the show entirely on the clean channel (I used an FX processor anyway).

Am I right in thinking one of the pre-amp tubes blew, or could this be something more serious? Since it's a used amp, I have no idea how old/used the tubes are, of course. I do have a guarantee on the amp.

I will say that I didn't like the sound of the Drive channel anyway -- the Clean channel is great, really rich, thick sound. The Drive channel becomes really thin in comparison, and especially loses the bottom end -- maybe this is a symptom?

Thanks for your help! I've had tube amps in the past, but never had any problems with them - I guess I was just lucky.

[Usable Thought]

The Drive channel becomes really thin in comparison, and especially loses the bottom end -- maybe this is a symptom?

I don't know that amp and can't help at all with your question (sorry) but I'm sure others can. I only wanted to say that it doesn't seem surprising that a drive channel would be designed to have less bottom end. The same logic also sees amp companies taking some bottom end out of high-gain inputs, etc. As Laney puts it in the owner's manual for the little Cub 10 tube amp I have:

HI INPUT: ‘Hi’ stands for high gain. This input is designed to enable the amplifier to be overdriven more easily and has a restricted low frequency range to avoid a “mushy” sound from high output guitar.

Similarly, from the "features" web page for the BIAS amp emulation software sold by Positive Grid:

For a metal tone, cut the LOW SHELF control quite a lot to prevent too much bass signal from going into overdrive (which might cause too much saturation or a boomy bass response).

And so on. So your Drive channel may have been thin without bottom end on purpose, not as a symptom.

[MartyVega]

Yes, that does make sense.

In the meantime, I figured out the problem with the amp -- I'm pretty sure one of the stage techs fiddled with the knobs! They were a very inexperienced crew, more used to running bingo events than working with a band. I think he was trying to lower the volume on the amp, and ended up sabotaging the drive channel. And when I went to perform, it was too late to try to figure it out - I just assumed I'd blown a tube or something.

Still don't know what the "whistle" like sound was. Could have been some random noise from my pedal too.

Playing around with the amp this morning, I figured out that if I turned the Drive channel's gain extremely low - around 2 -- and its volume up pretty far, I get a nice-sounding boost. There's still a slight drop in low end, but not much. So it really does sound like a louder, slightly grainier Clean channel.

Maybe we should just get a bass player, that would solve the low end problem too. Of course, then we'd have to deal with a bass player....

[Usable Thought]

Playing around with the amp this morning, I figured out that if I turned the Drive channel's gain extremely low - around 2 -- and its volume up pretty far, I get a nice-sounding boost. There's still a slight drop in low end, but not much.

A little off topic, but personally, I find this tendency (cutting bass response) on the parts of amps & also pedals to be a bit irksome. I play mostly jazz, often solo, pretty clean with just a little of what I've heard called "bloom," meaning some gain - enough to add extra harmonics when playing chords or a loud run - but not a lot. And I really like a good bass response on the bottom end of the guitar & pick my speakers to help with this.

So for example, I have a clean boost pedal that I use a lot, built from a DIY design by Jack Orman over on his AMZ site. It doesn't cut the bottom end at all. And I often put it after a tone pedal that I built, also from the AMZ site, & that I like for the way it softens the upper registers. HOWEVER . . . I finally figured out a couple of weeks ago that the tone pedal is cutting the bass even when supposedly set not to do so! I started Googling & came across what is claimed to be an easy way to fix many such pedals that cut the bass too much: replace the typically small input cap (e.g. 0.01uF) with a larger value cap, say 0.1uF, to let more bass come through. I am going to try this on the AMZ tone pedal as soon as I get time & am hoping it will turn a "pretty good" tone into exactly what I'm looking for.

[MartyVega]

I didn't have much luck with the two DIY pedals kits I tried. Nothing terrible, just nothing spectacular either.

Actually, the V55 has a really great mid-boost. It would be all I need really. Unfortunately, they didn't think about making it footswitchable. And it affects both channels, otherwise I'd be able to still use the amp's footswitch to change channels. Seems like a silly oversight. I believe there's a mod for it, but that's beyond my capabilities, and I doubt there's a capable amp tech anywhere near me.