#1
Well...to be specific I think my amp needed regular valve replacements for the last few years of it's life!

I've only owned the amp for about 9 months, but I got it used and it's a few years old (I think about 4) and throughout that period I'm fairly certain the valves are still stock.

Anyway, the amp in question is a Cornford Roadhouse 30 (head) and while my current speaker cab is pretty bad, the tone I'm getting can't be completely down to the bad speaker I'm using, I know that the Cornford Roadhouse 30 is a pretty damn good amp, the tone I'm getting doesn't follow it's reputation!

Anyway! I'm sorry I get incredibly wordy even on the mildest of subjects.

What I need to know is, what valves are good but still decently priced (a quick google search suggests that JJ Tubes are pretty good and they seem decently priced, but I dunno!) the valves that are used in the R30 are two 6L6s for the power amp and three 12ax7s for the preamp if that helps.

Also, the process of replacing valves is confusing for me!
I've read and heard that it's a simple case of just taking one out and putting the new one in.
But then I read somewhere that you need to bias it every time you change valves, which involves taking resistors out while it's plugged in or something...

Anyway, my question on replacing valves is, do I need to take it to a professional or can I do it myself?

If anyone can help that'd be great, thanks.
#2
replacing the tubes isnt too difficult if you know how

just reaplce them
and biasing doesnt involve removing resistors if you hvae a fixed bias amp you just have to find the bias pot in the back and turn it til you find the bias is correct
too hot you burn throught tubes faster
too cold and it sound like crap is the usuall way it works
also watch out for redplating(usually means its too hot)
im not sure about that particular amp or biasing too much so you would want to do some more research on biainsg your amp
#3
That amp has cathode biased 6L6's so it doesn't need rebiasing. The 12AX7 preamp tubes don't need biasing either. It's all just plug and play.

JJ 6L6's are a fine choice, either that or SED =C=.

For preamp tubes it is best to find some NOS tubes. A general guide to goodness:
German (Telefunken, RFT)
Dutch (Amperex/Bugle Boy)
British (Mullard, Brimar)
Hungarian (Tungsram)
Australian (Miniwatt/Phillips, Mullard)
Indian (BEL)
American (Phillips, RCA, Sylvania, GE, Raytheon)
Japanese (Raytheon)

Stay away from Russian preamp tubes, even the old ones. I have listed those in pretty much order of goodness more or less. I'd probably rate American Phillips a bit higher than the other American ones (JAN Phillips are quite easy to find cheap) That also translates into price pretty much although you can often pick up RFT's quite cheap. They are a darker sounding tube in the NOS world so if you feel you amp is a bit bright they are a good choice.
Some patient haunting of Ebay will score you most of these valves for around $20 apart from Telefunkens and Bugle Boys which always seem to go for outrageous prices.
Those old tubes last for four or five times longer than a modern valve so even if they are half worn out you stlll come out in front. NOS power tubes are a bit more hit and miss. Unless you can find genuine NOS 6L6's you may as well go for JJ or SED.
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#4
Ah, thank you so much, very helpful post!

I'm also very relieved that I won't have to spend extra on getting it re-biased!
I'll take a look into all those. I'll probably (in terms of the pre-amp tubes) go for what's most affordable right now, just to get my amp back into full swing!
Then when I can afford better I'll grab some that are nicer when the next change comes along.

Thanks again!
#5
I have JJ 6L6's in my JCM 900 and they sound sick. Actually have JJ's in the preamp too. Extra dark to balance out the brightness.
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#6
Google searches show very few NOS 12ax7 valves available in the UK from any shops (and even if I went from like, thetubestore.com I'd be spending $80 on each valve then postage).
I think Ebay's the way forward for me!

And acdclandon, thanks for the input! Good to know the JJ 6l6's are good to go for!
#7
Sorry for the double post, but after some looking around I think for now I'll go for new Valves and maybe spring for NOS valves a bit later on when I have a more defined idea of what I'm wanting from pre-amp valves. Also when I have some more cash! Jesus they get expensive!

So, are there any suggestions for good 12ax7 valves which are probably under £20ish?
In terms of sound I'm not looking for high gain (I've seen a few potential valves advertised as high gain which has put me right off), I'm looking mainly for clarity and brightness (but not too bright of course!).

If anyone has any suggestions it'd be great. Of course if nothing fits what I want then just some good quality 12AX7 Valve suggestions would be good!