my 5150....HELP!

Freak Guitar · #1 08-04-2004, 09:25 AM

Hello, I bought a mint condition (1992?) Peavey 5150 EVH block style head. I, of course, am in love with it, however I am having some problems. I didn't have anything wrong with it until my band played live. The thing had SO many problems with buzzing, that it came through the sound system. And, of course, back at the rehearsal studio, it's all silent. Is all my buzzing caused by all the electric things going on in the room?

Another thing, when I am just playing, usually soon after, the thing makes a weird noise buzzing noise(different than the other one, I can hear this WHILE I play). The only way to stop it is to bump the amp a bit or move the head around. I went to my old coworkers at Guitar Center and they said it was a power tube problem. Considering that the tubes were the ORIGINAL ones from when the previous owner bought the head 10 years ago, I just bought a FULL set of JJ/Tesla tubes online.

I guess my question is, how do I take care of the first problem?

And will the new set of tubes most likely take care of the second problem?

Thanks guys.

Drew · #2 08-04-2004, 10:01 AM

The new tubes will almost definitely help the amp overall, altough personally I can't confirm if old tubes on their way out would give you the second problem you were experiencing. Anyone out there able to say one oway or the other?

As for the first... Number of possibilities. What kind of guitar do you play? Single coils or humbuckers? If you play a single-coil equipped guitar and there were a number of neon lights in the place, then 60-cycle hum could be at the root of this. Also, was it just one club, or a number of different ones you've had this problem at? It could be a club with poorly groudned wiring... Have you played there before with another amp, and did it cause problems then?

-D

frethack · #3 08-04-2004, 10:35 AM

If its clean at rehearsal, but sounds dirty at this particular club, it sounds like the club is having problems with dirty power and your amp is picking up on it. There are certain power conditioners you can buy that are actually line regulators that might work to correct the problem. (IF thats what it is) Youll have to look at something akin to a Furman AR1215 Voltage Regulator. That MIGHT change the problem. Do you play there often, and does it do this every time? I had almost the same experience and it worked for me, though you might want to do some research and ask the other bands that play there if theyve had the same problems. High gain amps seem especially sensitive to these things.

Did changing your power tubes correct the second problem?

JerryP · #4 08-04-2004, 12:14 PM

Are you running any kind of rack gear in the effects loop? If bumping the amp is fixing the buzz you could have a tube problem or a poor connection. The 5150's are rock solid and there's not much that goes wrong with them.
Jerry

tobe · #5 08-04-2004, 03:58 PM

Problem at the club: As Drew said depends on your gear, and are you plugged into the same circuit as the bass player, another guitar player, keyboard player, PA? If you are and if the amps are different on polarities this will cause problems. Most amps have a switch to change polarity. That might only minimize the problem. The club could have poor wiring, ie not up to code, or even more so up to the sensitive nature of some musical gear. A power conditioner may or may not help with these kind of problems. Unfortunately it could be a ton of different things, and if you only play this club once in a while it could take a long time, ie might not be worth figuring it out...Other things that could cause it, is are your line cables running on top of mike cables, power strips, extension cords? All these things could cause problems as well. Cables running at certain angles are more prone to pick up RF and other electrical disruptions, flourescent lights etc.....Finally are you sure its coming from your amp and not through the PA mains/monitors....smaller, heck even mid size venues have problems like yours all the time. One time a sound engineer was complaining about a buzz from my amp, and it was really coming from a faulty mike cable.

Problem 2) Sure sounds like a power amp tube. I used to have that year of 5150, and it did the same thing when its power amp tubes started to die...Remember to have the amp re biased...if it has the original tubes in it, I would take it in and have thorough overhaul done on it. Yes they are pretty basic and bullet proof, but with tube amps its always good to do routine maintanence...saves you from gettin' a big bite in the posterior down the road

Hope you figure it out and good luck! Tobe

Freak Guitar · #6 08-04-2004, 04:42 PM

Quote:

Originally Posted by tobe

Remember to have the amp re biased

I talked to Bob at Eurotubes.com(the guy who makes JJ/Tesla), and he told me I don't need to rebias my amp in order to put these new tubes in. What would be the advantage of doing so.

I was playing through my Caparison TAT with EMG's. I played my friends guitar through it, and the buzz was still prominent. We played at this same place twice, and both times have had the problem. Depending on where I stand onstage, the buzz decreasesa LITTLE bit.

I haven't gotten the new tubes yet, they should arrive today. I will update after I install them.

Thanks for all the help!

tobe · #7 08-04-2004, 04:59 PM

Quote:

I talked to Bob at Eurotubes.com(the guy who makes JJ/Tesla), and he told me I don't need to rebias my amp in order to put these new tubes in. What would be the advantage of doing so.

Its been so long since I owned the 5150, that I could be wrong, but I don't think it has the feature of not needing to be rebiased. Biasing is kinda like "setting" the new tubes to work within the electrical structure of your amp...different makes and models have different specs which require "dialing" in. Sometimes even if you replace tubes with the same brand, model, etc you still need to do it. On some amps, not rebiasing will result in a HUGE change in sound and response...almost always for the worse. harshness, etc.. Even though I only use tube amps for guit stuff, I must admit that I have forgotten much more than I remember about 'em. Some one like micromitry, I believe that is his/her post name, knows alot about tube amps....

JerryP · #8 08-04-2004, 05:02 PM

Eurotubes sells the JJ's, he doesn't make them. He sold you a set that will have a higher current draw so they will run warmer in the cold biased 5150. When ever you change power tubes in an amp you need to have the bias checked and adjusted if needed. You have no way of knowing the condition of your amp without having a tech stick his head in it every once in a while. Most techs will clean jacks and pots and give the amp a general check over while they bias it. I can't tell you how many times I find amp problems when I'm biasing an amp. Your ear can't always tell when there's a problem. I've found several 5150's with open screen grid resistors that wouldn't have been found had I not been in there checking the bias. When that happens the amp runs on 3 tubes. The owners never knew the amps had problems. Prolonged use like that will take out other parts like output transformers.
Bottom line, have the bias checked unless you have money to burn.
Jerry

Freak Guitar · #9 08-04-2004, 05:25 PM

Quote:

Originally Posted by JerryP

Eurotubes sells the JJ's, he doesn't make them.

Sorry, I didn't know.

Does it usually cost anything to have it checked? I have NO money after I bought those tubes.

tobe · #10 08-04-2004, 06:20 PM

Quote:

Originally Posted by Freak Guitar

Does it usually cost anything to have it checked? I have NO money after I bought those tubes.

Yup...a good electrical service (for musical instruments) is at least 40-50/hr if not more up to the 75 range. Usually want a deposit before starting work. If you do not know about biasis...do not attmept it yourself! There is enough amperage stored in a tube amp to kill-or to severly ruin your day, even with it turned off and unplugged.....

JerryP · #11 08-04-2004, 06:24 PM

It depends on the shop as for how much they charge. I charge $40 here. If your 5150 is stock and has never had the bias modded then you should be safe to put them in and play, but you should have a tech check it when you have the cash. Peavey sets the bias extremely cold so you don't have to have it biased but that defeats the whole purpose of having a tech give it the once over and get a clean bill of health. On top of that, biasing is the only way to get the most out of the tubes you just spent your hard earned cash on.
Jerry