Author Topic: A Question about tubes (Read 2846 times)

Kepu · « **on:** September 20, 2007, 07:03:38 PM »

Hello there!

I'm about to buy some new tubes for my Framus Cobra, I've already decided on the JJ 6L6GC power tubes and JJ ECC83S pre-amp tubes

there's 4 of ECC83S for sale for about 20 euros, in store they cost 9 per one
and 2 of those 4 are slightly used, does that matter?
but I don't know what that 'matched/selected set' thing means?

so should I buy those 4 and then get 1 new?
or should I get 5 new ones?

Thanks in advance

Elliot · « **Reply #1 on:** September 20, 2007, 07:10:02 PM »

Normally slightly used pre-amp tubes - i,e, the Ecc83 (same tube as its American title 12AX7) are ok as they last for ages. Power tubes are the one you want new.

When you change power tubes (the 6L6s) you want a 'Match set' as change of tube normally means re-biasing the amp. Having a match set makes re-biasing easier and more optimum as the tubes all sing from the same hymn sheet in terms of current. Even if you choose not to rebias match sets give you uniformity.

Kepu · « **Reply #2 on:** September 20, 2007, 07:29:29 PM »

oh sorry, I didn't explain detailed enough

I'm gonna buy the 6L6GC power tubes new, 4 of them

but it's just that Cobras have 5 pre-amp tubes and that guy is selling only 4, so I should buy those 4 and then 1 new and re-bias all of them?
would that be better than buying 5 new ECC83S tubes?

Twinfan · « **Reply #3 on:** September 20, 2007, 08:45:31 PM »

You don't have to bias pre-amp tubes, just power ones ;)

I'd buy a new set of 5 - less chance of a problem when gigging that way.

Elliot · « **Reply #4 on:** September 20, 2007, 08:58:09 PM »

sorry that's what I meant to say above

Kepu · « **Reply #5 on:** September 20, 2007, 09:02:06 PM »

oh alright, sorry for my tube n00biness :oops:

I don't think I'll be gigging in a few years tho
and remember that 2 of the set of 4 are new, so if I buy 1 new more, that'll make 3 new and 2 used
but by the time I'll be gigging I think those particular tubes are blown to dust already :lol:

so should I just get the cheaper set?

Twinfan · « **Reply #6 on:** September 20, 2007, 09:30:21 PM »

You have a Framus Cobra and you don't gig? :o

In that case, buy what you like!

fps_dean · « **Reply #7 on:** September 21, 2007, 12:06:48 AM »

Preamp tubes last a long time...

If it was me, I'd be looking at tubes a lot better than JJs especially for a quality amp like that.

For the power tubes, look for the Groove Tubes GT-6L6GE. They sound a little better than anything else on the market, much better than JJ and hold up much better than any of the competition.

For preamp tubes, look for some NOS RFTs. There were Russian RFTs made later which aren't quite as good as the German made tubes, but the German made tubes sound just like old Mullards and cost a fraction of the price.

Kepu · « **Reply #8 on:** September 21, 2007, 01:30:54 PM »

Quote from: Twinfan

You have a Framus Cobra and you don't gig? :o

Yep, but you really can't argue with the price I got it :lol:

I'm not really looking for the 'ultimate tubes' just ones that will get the buzzy/fizzy high-end of the amp away :P

gwEm · « **Reply #9 on:** September 21, 2007, 02:12:59 PM »

http://I'm not really looking for the 'ultimate tubes' just ones that will get the buzzy/fizzy high-end of the amp away

i think then you have the right idea getting JJ tubes. better tubes are available, but JJ certinally are damn fine sounding with the right price. like many here i use JJ tubes, very happy with them. in fact i think it was a someone here, along time ago, who suggested them to me.

Twinfan · « **Reply #10 on:** September 21, 2007, 02:16:14 PM »

Do you use an attenuator? If you're running it at low volumes with gain, it's always going to be buzzy...

Kepu · « **Reply #11 on:** September 21, 2007, 02:20:33 PM »

Nope not yet, but I don't really have a problem cranking it as the closest neighbours are about 200 metres away, still the high-end sounds kinda thin and ear pearcing
the rythm tone is excellent tho

so should I get those JJs?

Elliot · « **Reply #12 on:** September 21, 2007, 03:09:38 PM »

This may sound counter intuitive but I find a slightly lower gain pre amp tube in V1 such as a GE 5751 (as opposed to a 12AX7) gives you slightly more headroom and allows you to get the power amp going without loosing clarity from the first valve going into OD. It also, to my ears, allows the character of OD/distortion pedals to come through as V1 doesn't go into OD so quickly.

Kepu · « **Reply #13 on:** September 21, 2007, 03:15:05 PM »

so you think I should buy 4 of the JJs for V2 - V5 positions and then something lower gain for V1?

but I gotta decide on the 4 JJ tubes pretty soon cuz the auction ends tonight

Elliot · « **Reply #14 on:** September 21, 2007, 10:27:19 PM »

Probably one of my idiosyncracies - but its worth trying if you have a spare 5751 or a 12AT7 lying around :D