Tubes - Can someone explain?

[waylay00]

Hello, I am really just starting to get in the technical side of all of my gear. Now I'm concentrating on amps and whatnot. Well I am very confused about all of this tube talk. I know that there are two main types of tubes, preamp and poweramp. But that's about it.

Can someone give me a rundown on the different tube types and popular models used for them (like 12AX7, EL34, etc). What does each one do differently?

Also, do you yourself install the tubes? Or do you normally take them to someone and have them install them for you?

Reason being, I have a Crate VC50H (10 years old used), and it's never had the tubes changed. I was wondering if changing the tubes to new ones would improve the sound. It has 12AX7 Pre amp tubes. Do I have to replace them with 12AX7's? That's why I want to know which tubes are best for what.

Thanks

 

[thucydides]

Re: Tubes - Can someone explain?

Tube replacement after 10 years would be a good idea. Here is a very short rundown on tube types. Others on this site are more knowledgable, and can get into detail.

Power tubes: EL 34, EL84, 6550, 6L6, 5881, 6V6. The first three are commonly associated w/British or British Style amps (Marshall, Vox, Hiwatt, and others) the last three w/American, or American style amps (Fender and others). Of course, there are many different amps being made today; the amps I've named above are associations that were formed 40 years ago. Today, you will find tons of "British" style amps being made in the USA. There are other power tube types, but those are the main types. There are distinct sound characterictics to each type, and that sound can vary among different makers of a given tube.

Preamps tubes: 12ax7 is the main one being used (also called an ECC 83). There are some common alternatives, such as the 12au7, and 12ay7. There are a few others that see use these days also. I'll let someone else get into those. The 12ax7 is generally the tube with the highest gain, when it comes to driving your amp. If less gain is desired, and 12ay7, or a 12au7 might be the ticket.

As far as installation goes, when power tubes are replaced, you need to have a tech rebias the amp. You can replace preamp tubes w/o rebiasing.

You can also check the archives on this site. Lots of info out there that I know I'm not aware of! Another good resource is at vintageamps.com. Great forums there also. Good Luck!

 

[waylay00]

Re: Tubes - Can someone explain?

Thanks, that heped alot. So when replacing pre-amp tubes, how caurious do I need to be of voltages, electrical hazards, etc?

Also what are these Russian type names I keep hearing like Sovtek? Are these brands? If os, which are the best brands?

 

[thucydides]

Re: Tubes - Can someone explain?

You should always be cautious sticking your hand in the guts of your amp.
Changing preamp tubes isn't a big deal because they are usually right out there in the open, but I am reluctant to advise people on the net when it comes to sticking one's hand in an electrical device. At any rate, you probably should replace the power tubes also, so a tech should do that so that he can properly bias it. I don't know your amp; I'm assuming it has power tubes (there are hybrid amps that have preamp tubes, along with a solid state power section). Whatever the case is, I would try to hook up with someone in person to give you a quick rundown on pulling tubes. It isn't difficult, but I'm not confident in my direction giving!

Sovtek is a brand of tube. Best brand of tube? You could get a multiple page thread out of that question! I use a number of brands in different amps. I am fortunate to have a good tech to recomend whatever is out there at a given time. I couple his ideas with my own research. You can find lots of discussion in archives about this, on this and other sites. You will find wildly differing opinions on one particular brand or type of tube. When I see that, I just try to identify a trend in the opinions. It actually is quite a bit of fun digging through the info!

 

[waylay00]

Re: Tubes - Can someone explain?

Yeah, I'll take it to my local shop, they have some good techs there. They're always working on big Bogner's and Soldano's.

 

[lastwinj]

Re: Tubes - Can someone explain?

www.guitarnoise.com, has a couple of really good articles on how to buy a guitar amp that runs down the various types of tubes. of course, i'm biased since i wrote them.