The valves that came installed in your combo amplifier or head aren't just there to make sure your amp actually functions, but dictate the quality of your sound. So if your valve amp has started to sound a bit dead or the quality has taken a dive, then it's probably time to replace the valves.
Combo Amplifier & Amplifier Head Valves
Before having a browse through our range of amp valves, it's essential that you know what kind of valve (also known as a tube in USA-speak) you actually need. Valves are like glass bulbs with a heating element inside (much like an old-school light bulb), and while they might all look the same - they're not. Basically, if you were more-than-happy with your amp sound before it conked out, then just look for the same model as the valves your amp came with and replace them with the same ones. If you want to change things up, then make sure to find valves with the same amount of pins as the originals - and with the same type of base - otherwise, they could actually damage your amplifier.
Everything Starts with Your Preamp Valves
The sound of any valve-driven guitar amplifier starts in the preamp. The most well-known and most-used preamp valves are the 12AX7 or ECC83. There are other preamp valves that offer a different character of sound, like the 12AT7, 12AU7 or 12AY7, and while all of these valves looks really similar, they're not identical, so only ever fit valves that have the same base as your old ones. If you're not sure, then have a chat with a local amplifier technician and maybe even get them to do the job for you, since messing around with electronic equipment you don't know much about is never a great idea.
Power Amp Valves: Singles to Quads & More
When it comes to the power amp section, you'll have more valves to choose from, but four particular models stick out. A lot of Marshall-style amps will have EL34 tubes in the power amp, while Vox-style amplifiers tend to have EL84 tubes. USA-style combo amplifiers and amp heads, like classic Fenders and similar models usually have one or more 6L6 or 6V6 valves in the power amp. You'll also find KT66 and KT88 valves in a lot of guitar amplifier heads and combo guitar amplifiers, but these are far less common than the others, simply because they're used far less by amp builders. The valves that sit in the power amp section of your amplifier and how this is combined with the type of speaker in your combo or cabinet is responsible for the lion's share of your amp sound. If you have more than one valve in your power amp and need to replace them, make sure you're replacing them with a 'matched set'. These matched sets of valves are often called duets, quartets, sextets or octets. Also, before you fit them, make sure that your amplifier is properly 'biased' for the new valves, which refers to how the power amp section is set up for the valves. While there are more and more self-biasing amps on the market (so they automatically adapt to the new valves), 95% of any older amplifiers will need biassing. If you're not sure how it's done, it's well worth getting the advice of an amp technician.
Rectifier Valves vs. Transistor-Rectifiers
Valve amplifiers also have something called a rectifier on board. In a nutshell, rectifiers make sure that the alternating current that comes from the mains power socket is converted into a direct current to feed all the components of the amplifier. Traditionally, this job was carried out by a rectifier tube, but these days, a lot of amplifiers will have a transistor-rectifier instead. A lot of guitarists still swear by rectifier valves because they tend to give the playability of the amp a more accurate and natural feel. But, while transistor-based rectifiers can't really do the same thing, they do take up far less space and make your amp far more reliable. Rectifier valves are also more common in high-power models, while lower-powered amps tend to use transistors.
Class A, B, AB and D Valve Amplifiers
Class-A amplifiers are known for having a high-quality, clean sound, but of all the possible amplifier classes, are also known for being the least efficient. Things get smoother with Class-B amplifiers, even if these amps have a little more bite and distortion to the sound. The Goldilocks-region comes in the form of Class-AB amplifiers, which have a nice dose of extra power to them as well. But, if you're looking for extreme efficiency and you're not so bothered about high-fidelity sound, then it's best to go for a Class-D amplifier.
Old Valves: New Old Stock
While you might come across New Old Stock models in our range, these are an exception rather than a rule. New Old Stock valves are basically old, vintage valves that were made a long time ago but still have yet to be used in an amplifier. Because production of these valves was halted quite a while back, left over stock is limited and getting smaller and smaller - in turn, these valves are also more expensive. If you're looking for a really specific New Old Stock valve and can't find it, then feel free to fill in our Special Order form and we'll be glad to see if we can get hold of it for you.
Valve-Driven Stereos & Microphone Preamps
If you need to replace the valves of an old-school valve-driven Hi-Fi stereo system or microphone preamp, you can actually use some of the same valves used to build guitar amplifiers. So, if you're looking for a high-fidelity valve for a sound system, amplifier, microphone preamp or even an old valve radio, you'll be able to find it in this section as well. If you need something really specific but can't find it, then feel free to fill in our Special Order form and make sure to include the make, model and kind of valve you're looking for as well as the number of pins it needs, and we'll be glad to see if we can get hold of it for you.
Valve Amplifier Parts: Replacement & Repair
If you have little idea of what you're looking at when you open up the back of your guitar amplifier, or you just lack the confidence to replace any valves or other parts yourself, then it's always recommended to seek out a good local amplifier technician or a good guitar shop that offers a repair service. They'll not only be able to advise you but get the job done for you. If you don't know what you're doing, working on any electrical equipment can be dangerous, so always get help from a qualified professional. Also, note that, since amplifier valves are considered consumables, they're not covered by any standard warranty.
Frequently Asked Questions About Amplifier Valves
Should I get a valve amplifier or a transistor amplifier?
Valve amplifiers tend to sound warmer and more natural than transistor amplifiers. However, transistor amplifiers tend to have a more consistent sound, so it's all down to personal preference.
What is a valve preamp?
With any valve amplifier, the preamp is the first part or section of the amplifier. So, the preamp section is what forms the core tone of your amplifier before it reaches the EQ section, where you've dialled in your custom sound. The effect of the preamp on the sound is less noticeable than the effect of the power amp section, until you push the volume up.
Why are valve amplifiers better?
If you want a more organic guitar sound with a little more life to it than the often tighter sound of a transistor amplifier, then a valve amplifier will probably suit you best. If you want consistent sound that comes as close as possible to valve-driven sound, then you might want to try a modelling amplifier.
How do valve amplifiers work?
With any guitar amplifier, the sound of your guitar is passed through various different components before it comes out of the speaker. With a valve amplifier, or similar audio gear, an electric current is passed through glass tubes (valves) instead of a transistor, to increase the power of the current before passing it on. Just as the valves literally heat up during the process, the sound is warmed up in the process as well.
How long do valves need to warm up?
While some guitarists will set their valve amplifier to standby to give it more time to warm up, you often don't need to let the valves warm up for any longer than two to five minutes. If you've just replaced the valves, then play for short periods of time to 'break them in', to make sure that they're burning properly and smoothly.
