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best new production GZ34 ??
Posted: Sun Sep 23, 2012 9:07 am
by antosimoni
Hi
Im in need of a new GZ34 for my JTM45, Im searching for maximum voltage and long life, what do you recommend me guys?? I need the best if NOS isnt avoidable can you please help me understand know how can I score a great one ??
Many Thanks
Re: best new production GZ34 ??
Posted: Sun Sep 23, 2012 9:39 am
by HTH
JJ GZ34
Re: best new production GZ34 ??
Posted: Sun Sep 23, 2012 10:44 am
by demonufo
Value for money wise, and for long life, you're better off looking at NOS rectifiers IMO.
Re: best new production GZ34 ??
Posted: Sun Sep 23, 2012 12:40 pm
by antosimoni
I know but my concern is to spot a real one in great condition and I dont know how, should I go to Mullard or I can go to something else ?
Re: best new production GZ34 ??
Posted: Sun Sep 23, 2012 4:03 pm
by demonufo
Usually see other Philips tubes cheaper than Mullard branded ones. And Mazda's too.
And the Japanese tubes are a lot cheaper still, and yet still a huge improvement over CP GZ34's.
I nearly bought a batch of 24 jap tubes a while back, but I rarely ever see valve rectified stuff, and don't have a JTM45 myself, and I was quite hard up (still am), so I passed.

Would've worked out at just over £20 a tube.

Re: best new production GZ34 ??
Posted: Sun Sep 23, 2012 9:14 pm
by Coot Boy
I've had JJ before and had one die, I think I've read somewhere that Sovtek is the best CP GZ34, who knows, I have two amps that take that tube n I bought old used ones pretty cheap n figure that's a better way to go than CP.
Re: best new production GZ34 ??
Posted: Mon Sep 24, 2012 5:11 am
by demonufo
Could well be. Sovtek make some very 'meh' tubes, but then they used to make some incredibly rugged tubes as well. They certainly knew a trick or two about making them last.
I've got a set of Sovtek 5881's somewhere that had a good 10 years of strong abuse, and still won't give up.
Re: best new production GZ34 ??
Posted: Mon Sep 24, 2012 5:47 pm
by Coot Boy
What do you think of the diodes and cap that Nik at Ceriatone is putting on the recto socket, I emailed him and he said the tube will not fail with them on there, I have them on both of mine and so far so good

Re: best new production GZ34 ??
Posted: Thu Sep 27, 2012 8:37 pm
by johniss0001
I am probably chiming in a bit late here Sovteks Imo are no good they are prone to flash over and failure my guru tried them when he was using them in the chiswick reach valve compressor and they were just dieing left right and center. I use chinese rectifiers and valves I have not had a single problem with a failure yet and I have had 1 of them in my marshall jtm45 reissue and modded reissue for about a year with no problems or flash over.
JJ had too many bad experiences with, until i start seeing some good stuff i am not going to hold my breath from my experience
Re: best new production GZ34 ??
Posted: Thu Sep 27, 2012 8:55 pm
by Coot Boy
johniss0001 wrote:I am probably chiming in a bit late here Sovteks Imo are no good they are prone to flash over and failure my guru tried them when he was using them in the chiswick reach valve compressor and they were just dieing left right and center. I use chinese rectifiers and valves I have not had a single problem with a failure yet and I have had 1 of them in my marshall jtm45 reissue and modded reissue for about a year with no problems or flash over.
JJ had too many bad experiences with, until i start seeing some good stuff i am not going to hold my breath from my experience
Hey John, I've been using the chinese EL34b since I read your endorsement of them. Really great value for money, just the other day I was using some old xf2s in a 50w bandmaster clone I built, Bandmaster pre n Marshall power section, then the amp acquired a hum that was one of the xf2s going bad, I swapped them out for another set of old rfts, I thought the amp still wasn't great so I put in a new pair of the 34Bs, the amp is glorious once more. The price of these tubes means you can have copious spares and if you reckon the recto tubes are good too then I believe.

Re: best new production GZ34 ??
Posted: Thu Sep 27, 2012 9:20 pm
by johniss0001
thanks cootboy I am glad you are digging them. and they can take a pounding i have them in my laney supergroup with 600VDC on the HT and they are loving it no signs of breakdown or nothing and they start to hit that spot around the 20-30hr mark. did you check out the matching tolerance when you were biasing? mine are biased in with 1milivolt of difference.
I have some chinese kt66 in the amp with the chinese rectifier and i couldn't be happier although... I do have some nos rca in there and they sound fantastic, i put some 12ax7bs in and they had a similar feel as well
Re: best new production GZ34 ??
Posted: Thu Sep 27, 2012 10:21 pm
by Coot Boy
Bias was pretty good but in a couple of quads I have in my 100s they weren't brilliant but still close enough . I've got 3 12ax7bs, had em for a few years now, I thought they were a bit bright at the time n haven't used em for ages, all my 8 Marshall clones have old pres in there and I've got quite a few more in reserve. Also bought a pretty cheap pair of used GEC KT66s for the JTM45, they sound just a tad better than the shuggy 66s but not by a lot IMO. Cheers mate.