Replacing tubes needs often special attention. The combination of some specific designs, and users which are not qualified to service amplifiers, causes problems.

Contents

Introduction.

What to do in problem cases.

Amplifiers which need special attention

Introduction.

Actually, problems with Emission Labs tubes are very rare. With most defect cases, tubes were replaced blindly, and amplifier tube exchange instructions were kept unavailable by the manufacturer. The expectation of unexperienced users is, a replacement it ok, as long as the sound is good. Then, at a problem, the complaint is about tube quality, because the sound was good after the replacement, and the tubes appear to have broke down without reason.

Now many such amplifiers exist, where you can blindly replace tubes, and these are ideal products of course. Many other amplifiers are simply not like this. Manufacturers have sometimes the standpoint, users must send in or bring their amplifiers for a tube exchange. Needless to say, shipping tube the amplifier by post, every normal person will try to avoid it.

Yet, when no repair person can find be found near by, what shall the owner do?! Some amplifiers weigh 40kg, and need dedicated shipment crates. So the alternative is to drive it by car to a service location, at hours driving distance, and not even being able to wait for the repair. So people try the exchange themself. Then, the crying becomes loud when a tube defects error occurs only after half a year. Some require free replacements, with the only intention to repeat what they have been doing before.

Most of the time, if defects occur, it was a problem with the voltage or current at some point. Like when operating a light bulb at 10% too high voltage, it will work satisfactory for some time, and then say good-bye at a moment without warning.

If any problem occurs, it can be one of those:

Most errors occur in this order:

  1. Emission problems, due to wrong heater voltage
  2. Thermal overload of the whole tube
  3. Spark effects inside, due to in-rush current too high, by wrong design

In the following pages, we want to gives some background about how to prevent problems, by correct installation.

With power tubes, such as EML builds, any complications is rather loss of function, and once the tube has stopped working, the root cause can not be found easily. Yet if the root cause is indeed the amplifier, replacing the tubes will only repeat the problem. Even so, replace the tubes may seem to solve such a problem, though of course amplifier problems are not solved that way, just become not visible.

For instance, somebody has broken tubes in a 220V amplifier, which was connected to 230V mains, and he did now know this was important. In fact not know it at all, because there never was a problem. Until he replaced the tubes. Logically he will say, 220V or 230V, was never a problem, so why is it now?

When we analyze this, it means he expects tubes to work fine in a 220V amplifier, which he connects to 230V. He feels this should be possible because it never went wrong. At this moment, already the conclusion is wrong. The users says it never went wrong, but it fact it did go wrong, because that is what we were talking about.

In short, users expect from the tube Lifetime and Quality. If a blind replacement appears to be possible, does not mean this was a good thing to do. You would find out only after a defect, but it is too late then.

These pages just try to give some assistance. Good users manuals are rare. So at EML we try to help you out, when manufacturers play the usual a hide and seek game with manuals, but it is assistance only. We do not have responsibility for the amplifiers.

Part 1. What to do in problem cases.

Part 2. Amplifiers which need special attention