#1
I've owned a Bugera 333XL for just over a year and up until about a month ago i've loved it. I blew a fuse a while back and although I know it's not a massive problem it started to get me worried about the whole Bugera reliability issue..

This week I had a gig and used it; for some reason on the lead channel even with a Boss NS2 in front of it had a horrible squeal (and this persisted for the majority of the set). A ridiculously loud noise that didn't even sound like feedback. I've got it home now and have been testing it out again and it seem to be that if you turn the master up above 3 (even with the gain and channel volume low) you get an ear piercing squeal. I have tried different guitars through it.

Does anybody have any idea why it is doing this or what I can do to prevent it?

Thanks again,

Liam
#2
sounds like a microphonic tube.
Quote by kangaxxter
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Quote by Blompcube

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#4
Yeah, power tubes. Swap em out before you blow more fuses, or worse.
WTLTL 2011
#5
Quote by Lr-Mtb
I've owned a Bugera 333XL for just over a year and up until about a month ago i've loved it. I blew a fuse a while back and although I know it's not a massive problem it started to get me worried about the whole Bugera reliability issue..

This week I had a gig and used it; for some reason on the lead channel even with a Boss NS2 in front of it had a horrible squeal (and this persisted for the majority of the set). A ridiculously loud noise that didn't even sound like feedback. I've got it home now and have been testing it out again and it seem to be that if you turn the master up above 3 (even with the gain and channel volume low) you get an ear piercing squeal. I have tried different guitars through it.

Does anybody have any idea why it is doing this or what I can do to prevent it?

Thanks again,

Liam


theres your problem.

but in all seriousness, to me sounds like a microphonic preamp tube too
#6
Thanks for the tube suggestions, I thought it may have been a tube problem but I don't actually really understand them so I couldn't judge. Would I need to replace all of the tubes or just the 'microphonic' one? How much would this cost/ link to tubes please? I've searched a bit but I can't find anything, there seems to be loads of different types of tubes :/
#7
2 minute google:

120-Watt amplifier driven by 4 x EL34 valves (convertible to 6L6)

Classic 3-channel preamp design (Clean, Crunch, Lead) featuring 4 x 12AX7 valves

If you can identify the faulty power tube, you can swap just that one. However, you would still have to rebias. Preamp tubes don't need biasing, are much cheaper, and you can just experiment with them freely.

Get a new set of 4x EL34s and 2-3 preamp tubes to experiment with.

http://thetubestore.com/teslael34l.html

http://thetubestore.com/tesla12ax7.html

Oh, you can also install 6L6 tubes if you prefer that. There's an internal switch, and you'd have to bias it differently. I suggest you let a tech swap the tubes and bias it for you.

http://thetubestore.com/tesla6l6gc.html
WTLTL 2011
Last edited by Mark G at Oct 4, 2011,
#8
its not your power tubes. when power tubes are bad the amp just sounds like shit, everythings weak, its not loud, just sounds bad it doesnt give squealing sound. I know this because i too own a 333xl and when my power tubes went bad it sounded like what i just described. I would focus more on the preamp tubes, in particular the microphonic one but it wouldnt be a bad idea to put new power tubes in to snice you've had it for a year now, as power tubes tend to life of around a year, atleast in my expreience.

People say you have to rebias when you change your power tubes but when mine when out on me i got the same el34's and just dropped them in and turned the amp and it worked just as it had before so i dont think you need to re bias as long as your using the same power tubes. The power tubes are'nt too bad as far price goes, go on guitar center and just type in el34, i bought the ruby tubes the quartet they sound pretty good. Ive never had any problems with my preamp tubes though but because they dont need biasing or anything and are cheaper it's pretty easy to swap them out. So start with the tubes if it doesnt slove your problem come back.
-Peavey 6505+
-Bugera 333xl(w/6l6 pt's) -dead
-412 X-pattern loaded w/ WGS veteran30s & HM75s
-Gibson Les Paul, SD Blackouts *being worked on back to stock*
-Jackson DR7, EMGs
-LTD MH417
-Peavey Vyper 75w
#9
If you have had it a year I would replace them all.

Eurotubes has kits for cheap $. Sound better then the stock ones that shipped with your amp.
#10
just take a pencil with an eraser, and tap all the preamp tubes one at a time when the amp is on. if you hear the tapping through the speaker or if it starts squealing then thats the bad tube. replace it with another preamp tube and your good.

online, 12ax7 preamp tubes can go as low as 7 or 8$ but normally around 10. and in stores near m, theyre around 15$ each.
#11
Quote by Seanthesheep
just take a pencil with an eraser, and tap all the preamp tubes one at a time when the amp is on. if you hear the tapping through the speaker or if it starts squealing then thats the bad tube. replace it with another preamp tube and your good.

online, 12ax7 preamp tubes can go as low as 7 or 8$ but normally around 10. and in stores near m, theyre around 15$ each.



this really works? ive never heard of this method, ill have to try it some time.
-Peavey 6505+
-Bugera 333xl(w/6l6 pt's) -dead
-412 X-pattern loaded w/ WGS veteran30s & HM75s
-Gibson Les Paul, SD Blackouts *being worked on back to stock*
-Jackson DR7, EMGs
-LTD MH417
-Peavey Vyper 75w
#12
That's pretty much the only way to test if a tube is microphonic.

Anyway, since it's just happening on the lead channel, and since it sounds like it may be microphonic, it's going to be a preamp tube and not a power tube. If the basic sound of the clean channel hasn't changed then it's definitely not a power tube problem. You can get one new 12AX7 and swap it out one by one with the preamp tubes to see which one was bad.
#13
Quote by OurRequiem
this really works? ive never heard of this method, ill have to try it some time.

yep - it works.

http://s545.photobucket.com/albums/hh384/buckethead_311/Amp%20stuff/?action=view&current=Microphonicpreamptube.mp4

I took a suspect microphonic tube out of my Valveking once and put it in my Splawn (because it is easier to test that way) and it was pretty apparent. I've found it is a great way to test tubes.

Not sure this would make a tube 'squeal' but if you can hear the tapping through the speaker then it is overly microphonic.

I also agree with Roc that it is most like a preamp tube problem and not a power tube problem but checking the amps bias at the power section and following others recommendations on the care and feeding of this amp would wise.
#14
Would it be possible for all four pre amp tubes to go at once? Because when I tap the small tubes on my amp, all of them come through the speaker :/ What is likely to have caused it?
#15
The preamp tubes usually all make some sound. A microphonic one will be exceptionally loud.
#16
Ok, I think there was one that was a bit louder, and one seemed dimmer but it didn't make more noise? They also have different names on the tubes like A,B, C on the end, would I need the right letter to replace it?

Sorry I really am clueless on tubes.
#17
Quote by Lr-Mtb
Ok, I think there was one that was a bit louder, and one seemed dimmer but it didn't make more noise? They also have different names on the tubes like A,B, C on the end, would I need the right letter to replace it?

Sorry I really am clueless on tubes.


No, those letters are probably referring to the position of the tube in the pre-amp circuit.

I.e. position 1 (usually called V1) is the first pre-amp tube, and so on.

Any pre-amp tube of the same type can go in any position, although you may want to read around that subject as there are some pros and cons of using certain tubes in certain positions etc but they are usually subtle differences in sound, mostly personal preference.

Buy your tubes here - http://www.hotroxuk.com/ best supplier in the UK
Last edited by Wesbanez at Oct 7, 2011,
#18
Actually, I thought the letters had more to do with designating where the tubes were made.

12AX7-C = China
ECC83-C same thing. These are just different ways of describing the same tube

The V1, V2 part is correct. I suppose it is possible that if V1 were microphonic then you 'might' hear the tapping in the other tubes (that follow) as well. Not sure. In my video it was pretty apparent which tube was overly microphonic.

I'd swap V1 with say V4 and try it again. Swapping the preamp tubes around like that is called tube rolling.

No, imo it is very unlikely that all the tubes would 'go' at once. Maybe 1 or 2 ECC83s and see what happens. I recommend JJ's. They are cheap and work great.


There are some good explanations in here
http://www.dougstubes.com/faq#g8

Yes - www.hotroxuk.com is where I would order from if I were in Europe.
#19
Quote by 311ZOSOVHJH
Actually, I thought the letters had more to do with designating where the tubes were made.


Good point, but I'd be surprised if ts' Bugera has tubes from any other country than China... providing he hasn't changed them since purchase.

If the suffixed letter indicates country, why is he seeing tubes with a, b, c appended?
#20
No, those letters are probably referring to the position of the tube in the pre-amp circuit.

I.e. position 1 (usually called V1) is the first pre-amp tube, and so on.
QUOTE]

If I recall, Bugera label their valves with A,B & C to assist where you put them in the 333XL. Of course the fact that Bugera test and rate their valves so accurately and can decide this is quite amazing really...... The soul of valves indeed

The 333XL is 'based' on the Peavey JSX so the valve positions should be -

V1 is the input tube and is shared by all channels.
V2 is only used in the lead/crunch channel
V3A is the active EQ section for the lead/crunch only
V3B is the preamp output tube.

Note - Peavey have no need for a balanced tube in this amp, so the same goes for the 333XL IMO
Quote by fly135
Just because one has tone suck it doesn't mean one's tone sucks.
Last edited by Dilberto at Oct 8, 2011,
#21
Quote by Wesbanez
Good point, but I'd be surprised if ts' Bugera has tubes from any other country than China... providing he hasn't changed them since purchase.

If the suffixed letter indicates country, why is he seeing tubes with a, b, c appended?

Can't speak to A and B - but it looks like Dilberto has an answer. I stand corrected.
#22
So if I was to buy one of these :http://www.hotroxuk.com/bugera-12ax7b-1.html or http://www.hotroxuk.com/tung-sol-re-issue-12ax7-set-of-5-mesa-boogie-triaxis.html and I swapped it out with the one I think is bad it should all be ok? Can you put all pre amp tubes in all of the positions or do you have to buy different ones for the different positions? :/

Is it likely that a local shop would have a 12AX7 tube for sale or are they just things that you buy online?
Last edited by Lr-Mtb at Oct 9, 2011,
#23
I wouldn't buy either of those personally.

Bugera doesn't make their own tubes so that would just be rebranded junk.

The Tung Sol will sound super bright in a 333X - I wouldn't buy that either UNLESS you feel your amp is super dark sounding which I doubt.

I also wouldn't get hung up on all the 12AX7 variants. Evidently, that lettering stuff is just a Bugera thing. That said - C is often used to designate tubes made in China, I do know that.

The only thing I would consider would be a 'Balanced' preamp tube for your Phase Inverter slot but I don't even think that is necessary.

I've been very happy over the years with both JJs and JAN Phillips 5751 preamp tubes. Think of that latter one as a New Old Stock military spec 12AX7 alternative.

Bottom line. Get a couple of JJs
#24
Don't bother with a balanced tube. As previously stated it's a copy of a Peavey JSX and there is no circuit in either amp that can make any use of a balanced tube so it's a total waste of money - there is no phase inverter.

Just get a JJ ECC83 or two from wherever. Put them in carefully and see what you think.
Quote by fly135
Just because one has tone suck it doesn't mean one's tone sucks.
#26
Quote by Dilberto
Don't bother with a balanced tube. As previously stated it's a copy of a Peavey JSX and there is no circuit in either amp that can make any use of a balanced tube so it's a total waste of money - there is no phase inverter.

Just get a JJ ECC83 or two from wherever. Put them in carefully and see what you think.

Yes there is, it is the 12ax7 next to the power tubes on the back side of the amp.
The Bugera 333/333xl, JSX/XXX only use 3 12ax7's for the pre-amp section, the 4th is the PI.

I know I own a Bugera 333
2002 PRS CE22
2013 G&L ASAT Deluxe
2009 Epiphone G-400 (SH-4)
Marshall JCM2000 DSL100
Krank 1980 Jr 20watt
Krank Rev 4x12 (eminence V12)
GFS Greenie/Digitech Bad Monkey
Morley Bad Horsie 2
MXR Smart Gate
#27
Sorry, my bad. V4 is indeed a phase inverter. However, there's still no need for a balanced tube in it. Peavey state themselves that there is no circuit in the amp that will benefit from it.
Quote by fly135
Just because one has tone suck it doesn't mean one's tone sucks.
#28
Ok back again. I've been talking to the guy at my local shop and bought a Marshall tube that is an equivalent to the 12AX7 that I have in mine. I replaced the one I thought was faulty but i'm still getting the problem.

The sound I am getting can be heard at about 55 seconds in this video (which isn't mine).
http://www.youtube.com/watch?v=EOl_8HaQlpM
#29
Did u try all the other ones? Also might be more than 1
Quote by kangaxxter
The only real answer to the SG vs Les Paul debate is to get a Flying V and laugh at all the suckers who don't have one.


Quote by Blompcube

if you embrace inaccurate intonation it can be quite arousing.


I <3 TWEED