#1
I've been playing with the idea of retubing my JetCity JCA50 ever since i got it, and now i found a site that actually sells a shitload of different tubes for a reasonable price. It's actually a company (if its even a company, or just one guy), that makes high end custom hifi amplifiers and sound systems, and they have all this differnet tubes for sale. To top it of, the thing is like 30minutes away from my house, so i can go pick them up if i want. Here's the link if anyone cares to check it out. Its not in english, but there isnt much written anyway, except tube types:
http://www.trm-audio.si/elektronke.htm

Anyway, now, it turns out, i have a few questions.

First of all, im guessing that if I just replace the power tubes with another pair of 6L6's, i dont have to rebias the amp? Because that is one thing i dont feel comfortable doing.

Second, i belive i can just mix and mach the preamp tubes as i see fit, as long as they are all 12AX7 or ECC 83 type?

Third, there seem to be a lot of different subtypes of each tube, for example, Sovtek 12AX7 tubes have aditional designations like 12AX7LP, 12AX7LPS, 12AX7WA, 12AX7WB, 12AX7WC... Its the same for pretty much all the other makes. Does this make any difference? Or can i just use anyone i want? Also, some are listed as "balanced" and some are not. And all of them have listed things like "double triode" and "output beam tetrode". I hav eno idea what that is, but it seems that the same types (e.g. 6L6's), have the same description, they only differ in the aditional designations (6L6, 6L6GC...). Im kinda lost here.

Fourth, are the 6L6 the same type as 6V6? Or do they have to be strictly 6L6 tubes?

Fifth, the store has tubes from JJ Electronics, Sovtek, Svetlana, Electro Hamonix, Tungsol, Mullard and also some others, including NOS tubes. I play hi gain metal, so what tubes would you recomend, preamp and amp ones. The amp has 5 12AX7 preamp tubes and 2 6L6 power tubes. I was thinking either Tungsol or EH 12ax7's and Tungsol or EH 6L6's.

Thanks a bunch for your advice, since this is way more complicated than i thought it would be.
Joža je kul. On ma sirove z dodatki pa hambije.
#2
1. Not true in general. Using the same power tube does not mean that you don't have to rebias. On the other hand, the Jet City probably is set for very cold bias so you don't have to rebias. It would still be optimal, and might improve the tone, but if you really don't want to rebias you should be ok.

2. 12AX7 is the same thing as ECC83, and yes, you can mix and match brands.

3. The suffixes indicate a few different things - LP stands for Long Plate, for instance. Mostly, though, they're just to denote slightly different models. You can use any of them. You do not need a balanced tube in a guitar amp. All 12AX7s are twin triode, it's just a description of how the tube is constructed. You don't need to worry about it.

4. Hell no. Do not confuse the two, you will be very sad at the results.

5. EH 6L6s are not good. I'd suggest Tung Sol or JJ, both are nice. Tung sol are a bit brighter but they're both reasonably balanced. In the preamp, just the first two tubes (V1 and V2) are the ones I would consider using a nicer tube. As you go farther down the gain stages the tube makes less of a difference. So to save a few bucks you could just get JJs for V3-5, and then get a few different ones to try out in V1 and V2. You'll want a few spare preamp tubes anyway, so I'd suggest just getting a Tung-Sol, a Svetlana, and a Sovtek LPS to try out. Get an oven mitt and swap out the preamp tubes with the amp in standby, see what you like!
#3
^^ +1

One more thing re point 3 if it wasn't already clear: the different suffixes will make a difference to the sound of the amp. A 'W' or 'LP' tube is often employed in concert with the other standard high gain 12AX7s to reign in gain, noise & fizz and restore clarity and harmonic richness to your tone. With 5 of the buggers to play with I'd definitely find a spot for a Sovtek LPS if I were you.
Charvel DX-1 FR / DS-1 ST / DC-1 FR / Custom Strat / La Patrie Hybrid CW / Vypyr 30 / VK100 / 1960A
#4
Well i guess ill get 3 or 4 JJ 12ax7's and then one of each others and kinda swap them out. I already have a Mesa Boogie, Ruby and an EH 12ax7 at home, so ill test those out. And ill make sure to get the Sovtek LPS, since the amp is pretty noisy right now.

I just have to figure out which power tubes to get. It doesnt help that all the reviews on the "thetubestore" say that every tube is great Altough some people say that JetCity's go way to dark and warm with JJ's, so im probably gonna go with Tungsols. And of course there are two types of those, the 6L6G and 6L6GC-STR...
Joža je kul. On ma sirove z dodatki pa hambije.
#5
6l6g is a regular 6l6 with a glass casing, 25W. 6l6GC is a 30W version that can handle higher voltages. the str just means that its based on the old syvania str series tubes, eg they use fancier materials to make them. For the most part, you wont notice any difference whatsoever between 6l6 and 6l6gc(or any power tube for that matter) until you reach clipping which is at ear bleeding volumes on a jca50h. I dont know if 6l6gc and 6l6g will have many if any tonal difference at clipping though.

I dont know what power tube the JCA50H has, but it will mmuch less a pain in the ass if you switch them out for the same exact tube type. If it has 6l6, switch to 6l6, if it has 6l6gc, the same. If the amp uses 6l6 tubes and you put in 6l6gc, you will have to rebias the amp and the bias voltage might not be able to reach the required voltage for class ab. If you put in 6l6 in place of 6l6gc, the bias voltage might not reach low enough.
Marty Friedman is GOD!

curently in a SEX MACHINEGUNS and X JAPAN phase AND Galneryus AND Anthem phase

damn J-Metal, why you so awesome

My Gear:

Schecter Hellraiser V-1 fr
Ibanez RG321mh
Fender GDC-200sce
Peavey Vypyr 30 w/ sanpera 1
#6
Damn. Well apparently i have to rebias it anyway, since the magical internet tells me that they are not really well biased when coming from factory. Also, i cant find any info on what type of 6l6 are in it. im asuming regular 6l6's since they are suposed to be some random chinese cheap tubes. Apparently not even their customer support is completely sure what they put in...
Joža je kul. On ma sirove z dodatki pa hambije.
#7
Id imagine the tubes mounted on the amp right now have a model number on them somewhere. if not, then jet city must be far worse off than I thought.
Marty Friedman is GOD!

curently in a SEX MACHINEGUNS and X JAPAN phase AND Galneryus AND Anthem phase

damn J-Metal, why you so awesome

My Gear:

Schecter Hellraiser V-1 fr
Ibanez RG321mh
Fender GDC-200sce
Peavey Vypyr 30 w/ sanpera 1
#8
Well guess i have to open it up. Wanted to save that for the day i get the actual tubes.
Joža je kul. On ma sirove z dodatki pa hambije.