Maintenance, Repair & Tone Restoration

Maintenance, Repair & Restoration

Is it time to get those tubes changed? Or do you have a classic amp sitting in your basement just waiting for a little TLC? Onyx Amplification can help. Also, since we provide free estimates, it makes sense to have your amp checked out for whatever your concerns may be.

Most amps require a little work from time to time. The following are some indications that your amp might need maintenance or repair...

   The amp:

This list is by no means exhaustive. So, if your amp does not sound right, please contact us by phone, email or in person.

See the following sections for more on Maintenance, Repair and Tone Restoration.


Here are some important services that we provide in order to keep your amp running optimally and safely:

power tubes

Although power tubes can fail gracefully, I would recommend having them replaced at regular intervals (before they fail) to prevent other components from being destroyed. If you play often, you might need to have them replaced every six months or sooner. If you play a few hours a week, your tubes could last many years. Tube quality and life depends on various factors such as how they were manufactured and when. It is also important to minimize the shock tubes are subjected to, especially when they are still warm.

"Why not just use them until they die," you might ask? Here are a few reasons not to:


Power tubes should be changed by a qualified technician. Depending upon the amp, biasing may or may not be required. Even if the amp is "self-biasing", it is important to make sure that new tubes are working correctly within the circuit and at an optimum level. If something is not right and needs correcting, we are qualified to make that assessment.

If you look up the subject of biasing, you are likely to find quite a few different opinions. Some are based upon a thorough understanding of electronics, whether acquired through theory and/or practice and others tend to be more subjective. Some techs bias only by listening to the amplifier's response while making the necessary adjustments. Ideally it would be great if this was all that was needed. However, great tone can be in conflict with tube life and amplifier health. Therefore, it is important to know the limits for each amplifier and power tube combination, and to bias for the "best" tone while keeping the amplifier running safely and with acceptable tube life.

There are also amps that use fixed biasing (no adjustment needed). In this case, one must rely on the manufacturer (or other company that can grade tubes) to provide the properly graded tubes for their amp. According to some manufacturers, users should be able to order their own tubes, install them, and then have them work as originally specified. As long as the biasing circuit is functioning properly, and as long as the manufacturer is careful about providing the correctly graded tubes, the amp should operate properly and the tubes should last a normal life.

preamp tubes

Since preamp tubes are not usually too destructive when they fail, and since they typically last longer than power tubes, you won't normally need to change them as often. In some amps, the phase-splitter might be an exception as it can be worked quite heavily.


Is your amp all dead or mostly dead? Does it make irritating sounds or noises? Does it have problems that other techs have not been able to fix?

Although various things can go wrong with an amp, most problems are relatively easy to find and repair. For example, burnt-out resistors and capacitors are common conditions and are usually inexpensive to replace. However, some components such as speakers and transformers can be fairly expensive to replace. Fortunately, serious problems can usually be avoided with proper maintenance, handling, and by changing worn out tubes before they get a chance to fail.

In order to find most problems, we test the system at various points (as the signal progresses from input to output) until we find the place were the signal fails or is abnormal. A few simple tests at this point will then indicate the specific cause and the problem can then be fixed.

In contrast, there are other problems which are not so easy to diagnose and remedy without an advanced understanding of electronics. This is when you need our help: we have been able to solve many of the problems that other techs and even larger companies could or would not touch. We know the theory behind why these problems occur and can troubleshoot and almost always solve the problem (we will always give you an estimate before we start the work, so you will know what to expect).

Tone Restoration

Check back later for more information on our Tone Restoration philosophy...

Hourly Rate

Our hourly rate is $50.