I'd like a crash course on tubes please from the experts!

[hareek]

Background: A while back I got my dad's old Marshall Club and Country 4140. It hasn't had new tubes since like '94 so I want to get it re-tubed amongst other things. Anyway I was doing some research and found that the original tubes this amp was designed for are KT77's, whatever that means. From there I was introduced to biasing and basically determined that is something I can not and will not be doing. There's a local shop here that will do that and I can just bring them the amp and new tubes.

But then I see people talk about different makes like JJ and Sovtek. Of course everyone has an opinion, but I was wondering what those opinions are? Are there certain attributes I should be aware of? What other tube manufacturers should I consider?

Anyway I was hoping to try to get some kind of a crash course on this as I'm looking to make a purchase in the next week or so and get this item off of my to-do list and start enjoying this amp again.

Thanks in advance guys!

[Toe-Knee]

Re: I'd like a crash course on tubes please from the experts!

You cant really go wrong with JJs as a starting point. Especially in a marshall.

I prefer JJ's over most valves with the odd exception here and there. However I have never tried the JJ KT77

[hareek]

Re: I'd like a crash course on tubes please from the experts!

I prefer JJ's over most valves with the odd exception here and there. However I have never tried the JJ KT77

From what I can gather KT77 seem to be a less common tube maybe? I think my TSL 100 uses EL84's. That seems to be the most popular used tube from my limited and very brief internet searches. I could be way off on that one though.

[Toe-Knee]

Re: I'd like a crash course on tubes please from the experts!

From what I can gather KT77 seem to be a less common tube maybe? I think my TSL 100 uses EL84's. That seems to be the most popular used tube from my limited and very brief internet searches. I could be way off on that one though.

The TSL uses EL34s.

I haven't really looked into KT77's but from what I can see from a quick googling is that they are pin compatible with EL34 and are interchangeable and just require biasing correctly and don't require any mods to the actual amp.

It's just different flavours of tone really!

[hareek]

Re: I'd like a crash course on tubes please from the experts!

The TSL uses EL34s.

Oh yeah that's right.

I haven't really looked into KT77's but from what I can see from a quick googling is that they are pin compatible with EL34 and are interchangeable and just require biasing correctly and don't require any mods to the actual amp.

It's just different flavours of tone really!

Ok so besides tonal differences, are tubes in general classified by their pin layout? Or are there power requirements to be aware of? I'm really a novice in this area.

[Toe-Knee]

Re: I'd like a crash course on tubes please from the experts!

Oh yeah that's right.



Ok so besides tonal differences, are tubes in general classified by their pin layout? Or are there power requirements to be aware of? I'm really a novice in this area.

There are various types that all produce different power outputs,

In your amp you could safely use EL34/KT77/6CA7 which all produce ~25w

There are other deciding factors too but getting into that right now will probably confuse matters further as it's diving more into technical data.

One of the biggest deciding factors is whether the amp circuit allows for the correct bias to be set but you should be absolutely fine with any of the types I listed.

[hareek]

Re: I'd like a crash course on tubes please from the experts!

One of the biggest deciding factors is whether the amp circuit allows for the correct bias to be set but you should be absolutely fine with any of the types I listed.

Ok I'll stick with those products then.

But prying further into this statement for my own knowledge, how do you know if the amp circuit has the right particular bias for a tube?

In other words, when I go to replace the EL34's in my TSL 100, are there different EL34's to look for based on the amp's bias capabilities or is an EL34 an EL34 and that's it?

[Toe-Knee]

Re: I'd like a crash course on tubes please from the experts!

Ok I'll stick with those products then.

But prying further into this statement for my own knowledge, how do you know if the amp circuit has the right particular bias for a tube?

In other words, when I go to replace the EL34's in my TSL 100, are there different EL34's to look for based on the amp's bias capabilities or is an EL34 an EL34 and that's it?

Just so long as you stick to the same valve type the bias range will be absolutely fine as it is what the amp was designed for.

Now say if you were to use KT88s in an amp that was designed for EL34 most likely the bias control would not go high enough to get the KT88s within their ideal running range as that amp wasn't designed to run that hot.

[hareek]

Re: I'd like a crash course on tubes please from the experts!

Just so long as you stick to the same valve type the bias range will be absolutely fine as it is what the amp was designed for.

Now say if you were to use KT88s in an amp that was designed for EL34 most likely the bias control would not go high enough to get the KT88s within their ideal running range as that amp wasn't designed to run that hot.

Ok cool thanks for the help.

[Toe-Knee]

Re: I'd like a crash course on tubes please from the experts!

Ok cool thanks for the help.

It's not a problem. if you have any more questions don't hesitate to ask.