What’s happening. Today I want to talk a bit about tubes in tube based amplifiers. We’ll save the solid state vs tube amp choice topic for another post, but today, I’ll let you know what I know about tubes.
I have been using tube amps for a long time because I like the way they sound and react to my playing. For my live rig and recording I always go to the main tube driven set-ups.
Now, we have two main type of tubes. (1) Pre-amp tubes and (2) Power-amp tubes. And, sometimes you have tubes used as a (3) Phase inverter tubes. Those are also smaller tubes (actually same tubes and size as pre-amp tubes), but are used as last in line in your pre-amp section before going into the power-amp. The pre-amp tubes are ones that are much smaller in size compared to the power tubes. Both tubes glow in the dark when warmed up in that beautiful warm, amber light.
Most popular Pre-amp tube for metal players is 12AX7. It’s a model name and many companies make them such as Mesa/Boogie, Groove Tubes, etc. There are other tube models such as 12AT7 and the only difference between them all is the amount of gain you get. 12AX7 are hot. Their distortion rating is 100. I like those. 12AT7 are rated at 60. Less hot, but might work fantastic for a blues sound. There is also a Pre-amp tube named ECC83, but guess what? It is exactly the same tube as 12AX7, just named differently for an European market. In some on my pre-amps I have 12AX7s and one has an ECC83, but they are exactly the same tube. If my Marshall pre-amp has the original tubes and the amp was made in England, then yep – it probably has the ECC83 in there.
Power tubes are the bigger ones that also glow nicely in the dark. Usually it is that big glassy tube you see when you look in the back of the amp. You tube amp at least has 2 of them. More on that shortly. Several options exist there such as EL34, 6L6, KT88. For Metal, EL34s work perfect. It’s my favorite tube. It’s punchy and warm.
You usually have 2 power tubes per 50 Watts of power, so if you have a 50 Watt amp, you’ll have 2 tubes. If you have a 100 Watt amp you would have 4. Some guys who have 100 Watt amps remove the two tubes and make them 50 Watters. Cool trick that works fine, you just have to know which tubes to remove.
What is my favorite brand of tubes? So, far I have been familiar with 3 brands: Groove Tubes, Mesa/Boogie and Russian made Svietlana. They are all excellent. There are others from Electro Harmonix, Slovenia. Eastern block is famous for making tubes because so much stuff used to run on them before Western digital revolution showed up there. I remember as a kid growing up in Poland I would turn on our TV and we’d have to wait until it warmed up. We were essentially waiting until the tubes warmed up just like with tube guitar amps. By the way, guitar players take notice – if you take off the stand-by switch off too soon on your tube head you are asking a lot of the tubes. Don’t do that, let them warm up first. So, to finish the TV story, if the TV broke, the repair man usually showed up with a bunch of vacuum tubes. I actually suspect the Eastern block makes most of the tubes for the world since they still have the old technology on hand left over.
I have 4 Svietlanas in one of my power amps and they are very warm and rich. Nice. Mesa/Boogie tubes are excellent and realiable. Pricey though, but they sound great. One thing that Mesa does is “match” tubes together in a package of 2. This is important. I’m not sure what other comapnies do, although I suspect they do this as well. Having tubes matched in pairs saves you from having you amp having to be biased.
Replacing tubes in your amp is something most can do themselves. You remove any retainer ring for a pre-amp tube and they go out. Power tubes simply pull out and pop-in. Works good. I never had an issue replacing tubes, although I do not do that task too often. I run tubes for a long time until they start sounding bad or I think something is off with them. Life span depends on how much time the tube worked for and how loud/hot you run your amps. I run my power amp hot in order to get a well defined sound, so I am sure it’s not the best for the poor tubes. Sometimes the tube starts glowing red (instead of amber) and it can be a sign it’s getting old. But, I have used tubes for years without anything happening to them. It might sound like it’s a lot to think off, but in reality it is really not. I never think about the tubes after they get installed.
And, of course, I have to tell you to always have spare fuses for your amp when playing live, they do pop on rare occasion.