A Note on The Service and Repair of Valve Amplifiers

I am always very happy to repair valve amplifier repairs as I believe these are the best amps for guitars. But I do understand that some people want the lower maintenance, lower purchase cost and reduced weight of a solid state amp.

There are a few things to say about the repair and alignment of valve amps and it would be worth reading these notes if you are considering having me look at your valve amp.

The 'Simple' Repair

I have never had a valve amp brought in for repair which had a single, simple fault.

Here's why...

When a valve amp goes faulty (so that you actually notice 'a problem') that is usually the final straw or the weakest link failing in an amp which has needed attention for some time.

The fault as presented may be relatively straightforward to fix, but please be aware there are likely to be other areas which need attention. The older the amp, the more likely this is to be true.

The analogy is an old car. Eventually it 'goes wrong' but on lifting the bonnet you find there are several other things which also need attention such as the hoses are cracked, the fan belt is worn etc.

Do I need my Valve Amplifier Servicing?

The short answer is 'yes'. Here's why:

Valves have a finite life and eventually need replacing. That is one major area of service. You may be amazed at the difference a new set of valves can make to your amp sound.

Valve amplifiers are also 'biased' to work in their correct range. This can have a dramatic affect on the sound if the bias is not set up correctly.

Volume and tone pots become noisy and crackly. Sometimes cleaning works, other times you need to replace the pot(s).

Finally, these amplifiers have various capacitors in them. Many of these will be 'electrolytic' types and they have a finite life. In very old amps, other types of capacitors can become leaky. At some point, if your amp is over 20 years old, you will need to 're-cap' the amplifier.

I will discuss all of this with you when I have had a look at your amp.

Conclusion: A valve amp needs regular maintenance to ensure it is working correctly. The harder the amp is used, the more often maintenance is needed. The older the amp, the more maintenance is likely to be needed.

Can I Service my Own Amp?

Yes - if you know what you are doing. No, if you have no electronics knowledge.

Valve amps contain potentially fatal DC voltages in excess of 400V. You don't get many second chances touching that kind of voltage!

If you are not an engineer, do not even take the 'lid' off your amp! A little knowledge is a very dangerous thing with valve amps. Those voltages can be present even with the power switched off and the lead disconnected from the wall!

Can You Supply Spare Parts Such as Valves Etc?

Yes, just ask me.

A good supplier of valves is AmpValves.

Can You Refurbish my Valve Amp and What is Involved?

Definitely and this is something I specialise in, particularly for the older and more collectible equipment.

Unless you have had a new set of valves recently, this is the first thing to replace.

If the amplifier has a valve rectifier I will suggest I change this to solid state (it will not affect the sound of the amp as it is not in the signal chain.)

The high voltage electrolytic caps in the mains filter stage also usually need replacing as these have a finite life.

Other, older types of caps which are known to be leaky should be replaced.

Some of the carbon composite resistors will also need replacing with more modern types.

All control pots will either need cleaning or replacing, depending on condition.

Finally, the cabinet might require some attention.

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