Bugera v55 need advice

[Braddi]

Hi there i am new here and i need some advise about bugera v55.
I like the clean sound from this amp and gain channel to but i have one problome
I know this is not a 5150 amp but i still am looking for advice
when playing solos on the gain channel ( gain cranked up to 10) it sounds good,
and damped single note rithm fine to, but when playing deep powercords
then its like the amp is suffocating
I tried using the clean channel just using a overdrive pedal an the amp acts the same.
any advise is helpfull.
I know this is not a heavy rock amp and i am not buying 100w stack to play at my home
Thanks

[olddawg]

Hi there i am new here and i need some advise about bugera v55.
I like the clean sound from this amp and gain channel to but i have one problome
I know this is not a 5150 amp but i still am looking for advice
when playing solos on the gain channel ( gain cranked up to 10) it sounds good,
and damped single note rithm fine to, but when playing deep powercords
then its like the amp is suffocating
I tried using the clean channel just using a overdrive pedal an the amp acts the same.
any advise is helpfull.
I know this is not a heavy rock amp and i am not buying 100w stack to play at my home
Thanks

Try a compressor pedal.

[Chuck H]

How loud are you playing it? Is this the combo?

[Jazz P Bass]

Bugera V55 Schematic

As it is only a 50 watt amp, I would expect it to 'suffocate' on 'deep power chords'.

[Chuck H]

As it is only a 50 watt amp, I would expect it to 'suffocate' on 'deep power chords'.

Unless he's just using it for bedroom V-notch ubergain Munky tone (no offense-one of my favorite activities ) in which case it could be preamp muck. There are a lot of options on how to structure the gain on that amp, but it only has the one gain channel that must act as a do all. OP also reports the same thing with a pedal in the clean channel. Based on this alone I think the four most likely possibilities are:

Braddi is using the amp loud and the power amp can't keep up.

The bottom end is flatulent because Braddi is expecting too much of it. Especially if it's a combo. I don't expect the Bugera hand made speaker is going to win any prizes. Just keeping it real.

Braddi is dialing in a fat single note tone that just doesn't work well for big chords. Anyone who's used a single channel amp (or an amp with one dirty channel when you need two dirty tones) knows how it is to compromise with a tweener tone that's not great for lead or rhythm. And trying to use one tone that's right for one thing is frustrating for the other. A tough spot we've all had to find our way around until the advent of the three channel amp... Unless you still just have a one or two channel amp. Tough luck.

Looking at the provided schematic (thanks Jazz!) I can see a half dozen changes that could improve preamp clarity for big chords and possibly even raise gain too. So it could just be the way the preamp sounds, period. I don't know how easy these amps are to work on. The lit says "hand made" so that at least implies the components are soldered into a board and not SMD. Should be mod-able. Whether Braddi want's to go there or not I can't say.

[g1]

If I'm guessing right about the sound you are trying to achieve, you won't get it with an open back cab.

[frus]

looking at the schematic, if you crank the gain knob to 10 then there's no resistance at all between the plate of the first gain stage and the grid of the second (in gain channel). This kind of thing always results with "choking" sound because the coupling capacitor(s) charge up and pull the bias of the second stage, especially if there's a lot of low frequency content (I guess it's less pronounced here because C51 is so small, otherwise you would get it on single notes also) . If you set the gain knob to 9, the effect disappears and the amp sounds fine. I'd put a resistor instead of C57 (which it doesn't need anyway), and ditch C22, just because

Also I hope the schematic Jazz P Bass has attached may be wrong, I don't see any NFB resistor from any speaker tap to junction of R78/R39

[Chuck H]

The schematic is at least wrong in that regard. If there's no NFB that vintage style presence circuit isn't doing much

I did mention a half dozen things that could be changed. There's certainly even more if I had it on the bench. But we haven't even solved for what's actually wrong with Braddi's tone yet. If it's just that the preamp needs to be more do-all friendly then this option applies. If it's just the power amp compressing balls then maybe a cooler bias and some strident tubes. If it's a weak power supply or OT the solution is no solution at all WRT that amp. Unless Mercury has come out with their Bugera series transformers that invariably cost as much as the amp itself . If the problem is the open back cab and marginal speaker the solution is to plug the amp into a 4x12 and turn the bass down some. I don't doubt that part of the problem could be that Braddi wants "correctness" of tone but spent less that $500 for the tool to get it. Probably a great amp... For the price. I don't think many pro's are using them but I don't honestly know anymore.

[Mick Bailey]

The first thing that strikes me is the coupling caps are maybe on the large side (47n) and this can contribute to intermodulation distortion and a flabby bass. Sometimes a reduction in cap size can clean up the bass and give better definition. One of the problems with playing at home is the overall EQ can be very different to what you may use at stage volume. Many players turn the bass right up at home, but because the symptoms have already manifested themselves within the gain stages and the tone stack is post-gain, then it makes the problem worse. This can be compounded with a 'possibly-less-than-sub-optimal' speaker for the intended use. Maybe reducing the coupling caps to 22n may help.

[Jazz P Bass]

At the very least, I would suggest lowering the bypass cap values on the first input stages. (C13 & C27)
Fender goes with the 25uf capacitor on C13 & they always sound bad with the amp cranked (too much bass)
Marshall would use a 0.1uf capacitor on C27.

Edit: here is the V55HD schematic.
(that other one seems to be 'hand drawn'.)

[Chuck H]

hanks for the more accurate schem Jazz. That's a somewhat different amp, idn' it.?.

Since all the gain from the input triode is channeled through a 470p cap before reaching the distortion circuitry I'm not sure how much reducing the input triodes cathode bypass cap would help. That 470pf cap also negates any need to reduce the .047 coupling cap size. Some progress could probably be made by muntzing or altering one or both of the top treble bleed circuits. An even cooler bias on that third stage, an increase in gain to the recovery/summing stage (with a corresponding change to the reverb input circuit). Other stuff too, but I wouldn't know if it was worth it unless I could hear it in front of me.

Not sure what the diode arrangement just after the master volume is for.?. The schem markings show what I know to be a shield (even though they also show this as a connection elsewhere) on a voltage divider with two diodes isolating two opposing 15V supplies from the LV. If this is just where they chose to show the relay power circuit they didn't make it very clear at all and it sure doesn't look like any clipping circuit I've ever seen.

[JohnnyN]

Not to hijack this thread, but I have a hard time making good use of the OD channel on my V55 HD.
My problem is that the drive channel sounds more like a fuzz than overdrive. Now I play blues and classic rock, so I don't need a lot of preamp distortion.

It seems like the Gain (marked as Pre on Jazz's schematic) is putting too much load on either V1b or V2a. (btw V2a seems to run at very high voltage).
Also the OD channel lacks bottom end. Running the Master at 10 helps this to some degree.
I realize there will always be a disadvantage when having common EQ for both channels. However it appears to me, like it takes more than just a twist of the EQ knobs to make it right.

I would love to have a more useful range of the gain (Pre) and a bit more bottom on the OD channel.
Any input would be appreciated

Thanks to Braddi for starting this thread and thanks to Jazz for the schematic

[Enzo]

Chuck, do you mean after the channel relay just past the post control? D16,17?

I don't see any shielding indication, the junction of those diodes just goes to pin 7 of ribbon connector X33. X33 connects that board to the DFX board.

This is actually a very common circuit, at least on SS amps, anything with op amps. it is not clipping at all, and has nothing to do with relay power. That voltage divider is across the signal path. The output of the preamp stages, at relay contacts RL1C feeds into the tone stack driver, V2b. Note also that the reverb return mixes into that same V2b grid through R52 et al. That reverb has to come from somewhere. Thus our voltage divider. The signal level is way too high for op amp circuits at the relay contacts. R64 and R77 knock the level down to about a third of what it was. The output of the divider then goes through X33-7 to the DFX. The two diodes are just clamps. They are not isolating the 15v supplies, instead they are using them as sinks. The diodes are reverse biased until a signal peak exceeds the supply voltage, then they conduct, shunting the excess signal into the low impedance of the supply. Nothing fancy, it just keeps the signal hitting the op amp from going past the rails. That would damage the IC, since to the IC it appears as reverse voltage. Until the signal there exceeds the supply voltages, those diodes are invisible.


A quick and dirty line out can be added to the speaker out of most amps by just making a voltage divider. That is all the more this is, the diodes are added to protect where the signal is going. And if you look at the last page, the DFX circuit, the input to the card is upper right. The only thing I see unusual here is that the two diodes are on the send end at the main board rather than at the input of the DFX card.

[Chuck H]

Thanks Enzo. Then it is a clipping circuit. Of sorts. That makes perfect sense. It's funny I didn't pick it up because I used a similar circuit for an OT driven reverb once to protect the pan. The drive level is user adjustable with a meter to show when it's in the correct range but I included the clamps because, well, You know As it happened the guy I built it for was using the drive level control as a volume (with the knob labeled "volume" set too low) and complained of "distortion" before I saw what he was doing and corrected him. I really should write little user guides for these custom builds.

[km6xz]

All pretty standard stuff as Enzo correctly pointed out. The rush to mode a piece of gear without a clear idea of what is to be accomplished and whether the circuit designer's value selection is in error. I would have an experienced player in many genres come listen and make it sound as good as it can just with setup first. Cranking the gain to 10 is almost guaranteed NOT to be how to get the sound desired. So much depends on input level, signal content, eq etc. that rushing to mod a working amp is ill-advised. What about making everyone happier by just turning down so the speakers and power amp/supply are not internally hemorrhaging? It is not a top amp but when used well, does amazingly well. No changes of component values is going to make up for a power supply running on the ragged edge or a speaker designed for mids being pushed with bass. Turn down, and move the cabinet closer to a corner and turn the bass eq down and you might find that that open back cabinet generates more bass coupling to the room by backing off and using the room corner as a folded horn?
I suspect the amp is fine but the expectations and use are not.