bias and stuff

Blue glow in power tubes is perfectly normal and doesn't mean a thing's wrong with your tubes. If the plates of the tubes start glowing red or orange, that's a bad thing. If the amp's still sounding good and putting out adequate volume, your tubes are fine. I don't recommend replacing good working tubes. Tubes are more likely to fail when they're new than at any other time, and generally have long happy lives and fade out slowly at the end if they make it through the first 100 hours.

I agree that Bob's website (Eurotubes) is a sales site with a lot of hype, and he's certainly a salesman of the highest order, but I've never heard anyone accuse him of any dishonesty in his business dealings, and he does seem to have a lot of hands on experience with guitar amps. The JJ tubes he sells are good tubes. His prices aren't bad.

You didn't say what kind of amp you're talking about, though I suspect it's in your "handle."

What kind of amp do you have? If you supply that information we'll be able to give the spec's you'll need to retube it and what the bias should be. If those folks at that store are having that much trouble figuring out what goes were then chances are they don't know how to check or set the bias. Take it somewhere that does know what their doing. when you buy tubes get them as a matched set or Quad. Since your retubing you should change all the tubes.

Joe

when you buy tubes get them as a matched set or Quad. Since your retubing you should change all the tubes.I disagree with Joe on both of those points.

Matching of tubes for guitar amps is unnecessary, though it causes no harm. It's a recent invention, nobody did it before about 20 years ago. The idea was borrowed from the hi-fi freaks. If tubes are severely mismatched as to their idle ("bias") current, they'll cause more hum. That's about it. They'll produce some second harmonic distortion, which most listeners find pleasing. Contrary to some dire-sounding warnings I've seen posted, using unmatched tubes that are in spec for their type can't hurt your amp.

I've already stated why it's a bad idea to replace tubes that are working satisfactorily. It gives you more opportunity to experience a catastrophic failure that's most likely to happen at an inopportune time, as when you're gigging. "Preamp" tubes can be expected to outlast several sets of "power tubes" and rectifier tubes.

Lots of folks do routinely change good tubes in a quest for "tone" or in the belief that they're heading off trouble. Most of the time it works out OK. Be sure to keep spares on hand, whether you change out the ones you have or not, and that you know how to change them. You may have to in a pinch. If you have an amp with adjustable bias, you should check it or get it checked as soon as possible if you ever have to do this. If you've taken Joe's advice and gotten matched tubes, go ahead and get a matched quartet, then the bias setting shouldn't have to be altered if you change out one set with another set matched to it. There's something good to say about the matching scheme.
:)

The issue of matching output tubes like most things everyone will have their own opinion. It used to be common wisdom to simply buy matched tubes. I'll leave the decision on how you want to proceed. The best answer to this question is to consult your owner's manual for the amplifier. Please remember working inside a guitar tube amplifier can be dangerous and you need to know some basic safety which can keep you from getting hurt. You really need to take the time and learn the right precautions in order to keep safe. If your not willing to learn some safety don't work on your own amp.

Not every amp does actually requires it. I recomend you do. Many amplifiers are designed to have similar cathode current. Power tubes should be matched or balanced because of the way they amplify sound waves and can create exceptionally bad sound if they are poorly matched. When you replace your power tubes, you should do so in pairs or quads. You usually can't buy one tube, most of the time they come in balanced pairs. When a tube is part of a balanced group, their power curves will closely match each other. If you don't use a balanced set of tubes in your amp the tubes can end up fighting against each other for power. The ones with a steeper curve will try to pull the other tubes with the less curve. This will reduce their life span and possibly even dammage your amp's circuits.

Once you've installed your tubes, you should check the bias and adjust if needed. If you know how and have the the equipment I recommend that you bias your amp every time you change power tubes. Biasing helps to extend the life of your tubes and prevent damage to your amp's circuits. Proper biasing also improves your tone. If your amp is biased too low or cold your tone will suffer. If your amp is biased to hot, you'll burn through tubes and possibly ruin your amp. It's not hard to learn and will keep your amp working perfectly.

Joe

Joe, I agree with everything you said there except for the "exceptionally bad tone" of tubes that aren't matched. To get a really bad sound out of tubes that haven't been specially matched, one of them has to be so out of spec that it's a defective tube. Any random pair of in-spec tubes should work together satisfactorily. Defective tubes do occur, of course, and matching is one way of catching and culling those out. In the early '60s I watched the local TV shop owner's teenage daughter check all of the brand new American made tubes (the ones that are sold at inflated prices as "NOS" now) as they arrived at the store, and a lot of them failed to pass the test new out of the box. Perhaps you've had some bad experiences with defective tubes. But normal variations within nondefective tubes won't produce "exceptionally bad tones." They'll produce a little second harmonic distortion that sounds good. Lots of guitarists have a special favorite set of tubes they keep for recording or use on important occasions because they sound so good. Check 'em and you're likely to find they're significantly mismatched. Mismatching within the normal variation of tube types won't cause any harm to the tubes or the circuitry unless you're running the amp biased on the ragged edge of what's allowable on the "hot" side of bias current, measuring the current flow to both tubes together, in which case one of the tubes could run a little hotter than the other. If one's running so hot that you fry something in your amp, though, you've got a bad tube (or some other defect in your amp that causes a severe bias mismatch.)

Tube matching was originated for hi-fi amps that were expected to faithfully reproduce sound exactly as it was recorded, when any distortion was considered a serious problem. Matched sets of tubes were developed primarily as a sales gimmick, and they continue to serve that purpose well.

For that matter, adjustable bias was uncommon in the '50s and early '60s, and when it started appearing in the mid '60s or so (another idea borrowed from the hi-fi set), it was adjusted to a fixed voltage value specified in the service manual. Biasing to particular current or plate dissipation levels is a recent idea. Formerly, the bias was set "cold" enough that any in-spec tube of the type the amp was designed for would operate safely.

I believe that these new ideas of tube matching and biasing to achieve particular tonal results were popularized primarily by Kevin O'Connor, whose books some regard as gospel. I'll admit that I've never read them. My background with tube equipment goes back to the '60s, and most of my references are older than that. I don't think the operating principles of tube circuitry have changed in the last half century, and I think a lot of the new ideas being foisted off on guitarists about tubes and tube amps are silly.

Since tubes have been replaced in most electronic equipment with solid state devices, most people are rather unfamiliar with them. Lots of students majoring in electronics have either had no training about tube circuitry, or got a very brief, oversimplified version as historical background on what was used before the transistor was discovered. I heard somebody say that he was taught that tubes were "big, inefficient transistors in glass bottles" or some such. Such a state of ignorance about how they function makes fertile ground for the growth of mythology, and that's what guitarists largely are being fed about tubes. Even worse, with the retirement and death of the old (mostly military-trained) radio and TV technicians, and the disappearance of "ham" radio operators who studied and built their own tube radio equipment, knowledgeable and practical tube amp techs are mighty hard to find these days.

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i have a peavey ultra 112, i read the manual online and it said it came with 6l6gc and 4 ecc83 i believe, but i dont understand what the problem was

Honestly, it sounds like the problem is that the folks in that shop don't have a clue what to do with an amp.

peaveywolfgang5150

To answer your question, I have ordered tubes from Eurotubes several times and have been very pleased with the quality of the tubes I received, and the exceptional service.

Don't let the website fool you. I agree, the site could be a little more professional. But Bob is simply a distributor for JJ tubes. You can buy JJ's at other sites.

I will tell you this. Anytime I have had a question on tubes, Bob has taken the time to answer my questions quickly. And everytime I have ordered tubes I have received them within 3 days of making the order. And check around, you'll see that Bob's prices are some of the lowest you'll find anywhere. So, while the website might not be so great, Bob's service is. I find him to be completely honest and trustworthy, I have and will continue to recommend him.

If your amp is operating fine, use the tubes in it. Tubes are not so fragile as many believe. In the old days, TV's with tubes often lasted 10 years or more before needing new tubes. And TVs get played for many hours each day. My 1958 Premier amplifier has the original tubes in it and it is still going strong. That's 48 years. :shock:

It is a good idea to have spare tubes on hand though. I carry a spare set in the back of both of my tube amps, just in case I have a problem at a gig. I have not had a problem, but you never know. I also agree with Ricochet in that usually if a tube is defective you will know it from the start. They tend to be simply good or bad. A good tube will last for many years unless you really push your amp all the time. If you use an attenuator and crank the amp to max, then this will shorten tube life. But you should expect to get at least 5 years out of any tube.