WTB: GZ34/5AR4 tubes

Hi all,
Just wondering if anyone has a used GZ34 a.k.a. 5AR4 valve that they would
to sell off.Also some 6L6GC valves.
I would really prefer vintage stuff, would'nt mind used,but still with some good life left in it.
This is because the new ones cannot handle the voltages in my valve guitar amp.They keep turning red immediately.

So, if any of the brothers out there has 1 or 2 that you would would like to sell,
please PM me or send me a text message @ 012-3980810.

But at reasonable prices lah.


Cheers.
teleman51

I think it is time for an overhaul if your amp had run for 10 or 20 yrs.
You may need to check the supply voltage and the bias voltage. Your e-cap may had dry out. Eventhough it is new tube, it wont turn red for no reason.

Thanks Akita,

Had my amp tech check out caps and bias and he confirmed all
okay and in fine order.
However, according to him the new valves being sold just can't
cut it.Waste of time according to him.
Recommended that I look out for NOS valves.
The new 6L6s' are just fine but not the Sovtek GZ34 that I've tried so far.
Am going to order the (TAD) Tube Amp Doctor brand next to try out
Wonder how well this brand will handle the voltages that my all valve
guitar amp puts out.
Hope this works out.

Cheers.
teleman51

Its true Sovtek GZ34 don't last very long and they somehow built with smaller glass tube and run hotter than other good rectifiers, worse if ventilation is a problem.
I'm been using JJ brand GZ34 at 450VDC and does last many years in my tube monoblocks. They're best bang for the buck as I'm not into wasting money for NOS rectifiers. They easily withstand at 400 to 500VDC easily, AFAI experienced.
Tubes turning red is almost definitely because of signal, bypass caps leaky and bias resistors changed value at operating voltages and when the bias shoots up unusually and possibly after some time in operation. Leaky caps or bias resistors are not easily diagnosed with normal ohm meter and they should be replaced anyhow after many years. Caps or bias resistors are cheaper then the tubes, so replace them all anyhow.
Its not always the manufacturer install best quality parts either and a risk to damaging tubes or the transformers in many occasions.
My 2 sen.

Thanks cmboy,

Man, a big thank you from me for letting me know that the new valve from JJ is worth trying.
Didn't realise that the NOS ones cost thaaaaaaat much!!!!
So the ones from JJ are a way out for someone( El Cheapo!) like me.

Will inform my amp tech to go through all the caps & resistors once again, like you suggested.

Then order one GZ34 from tubesandmore.com
Have it installed & then play my vintage Fender telecaster through the amp.
Looking for that cool vintage sound that only vintage valve amps produce.

Was always suspicious of the new ones after my experience with Sovtek!
And then the hype or vodoo about NOS valves.

cmboy, your 2 sen worth will be most in the future.

kind regards & cheers.

teleman51

I'm quite an avid user of JJ tubes and so far my experience is no complaint. This include a very recent experience a new batch of JJ 6L6GC to renew someone's Class A tube amp. Another affordable make of tubes are from Electro Harmonix. I reckon both these makes are quite suitable for guitar amps, as some audiophiles may disagree. Its entirely one's own choice where price may be a primary concern.
As long as I see the amp circuitry and parts in excellent condition, I don't expect new tubes to fail or go haywire for no just reason. Its usual if I see the output tube biased a bit too high, I'd bias it down for longevity as a priority with least compromise on sound quality. Its not like the old days to go to electronic shop and you buy replacement tubes easily and on the cheap. Now most desirable tubes have to be gotten from abroad on the internet for affordable prices. Having said that, I can't say all new tubes are perfect, if unlucky a lemon may turn up once a while. If you're familiar buying things from Ebay, there's lots of tube sellers there but look carefully at shipping prices and if they ship worldwide or not. EMAIL the seller 1st to price and shipping before commiting to the purchase. Good luck!

P.S. If you can afford it, maybe try new KT66 from JJ, as I think I've heard many Fender folks putting this in instead of 6L6 tubes. You may get a better tone.

Yeah cmboy,
heard about that too. I've never tried KT66s' but always had doubts
regarding that valve in place of 6L6s'.
I mean the pin configuration may be the same but what about the current draw, plate voltages,etc.
I'm no amp tech but heard somewhere that all these must be considered before swapping one type of valve for another similar one.
What say you on this matter? Like maybe your 2 sen worth again.
What about other issues like is there any strain on the power & output transformers?
Us guitar guys come into this from a different direction, so I beg your patience on these questions.

Cheers & have a great day

If you care to name the exact model of your amp, I could try to look for the schematic and analyse if its entirely compatible. But in most cases a swap won't pose any major problems. KT66 is actually a tougher tube than 6L6GC but if any circuitry parts are questionable, remature failure can occur anyhow.

Hi cmboy,
the amp that would be requiring that good GZ34 valve is the Fender
Tremolux amp with the 6G9B circuit.(from the early part of the 60s'
Fairly simple amp.These are the classics from Fender.
Another would be the Fender Super Reverb.
And of not forgetting my vintage Leak Stereo 20 hifi amp from 1958.

Cheers
teleman51

teleman51 wrote:Hi cmboy,
the amp that would be requiring that good GZ34 valve is the Fender
Tremolux amp with the 6G9B circuit.(from the early part of the 60s'
Fairly simple amp.These are the classics from Fender.
Another would be the Fender Super Reverb.
And of not forgetting my vintage Leak Stereo 20 hifi amp from 1958.

Cheers
teleman51

Looking at the circuit, I hope the Tremolux (assuming thats yours) hasn't been replaced with filter caps of bigger capacitance as that would boost up the B+ more than it was designed for. The B+ should be no more than 365VDC after the rectifier. 365VDC B+ is no problem for most GZ34 or 6L6GC or KT66 and comptible here. I hope the adjustable bias setting at the grid (minus voltage) are correct as misadjustment will turn the tubes red. Higher B+ may be good for hifi but not good for guitar amps and change its sonic character. Again, if your tubes turn red, I'm sure there's faulty components in the circuitry. The Tremolux circuit is nothing more than a classic fixed bias tube amplifier. No rocket science here.

Thanks cmboy,

I willl take into account all your comments above before I meet up with my guitar amp tech next weekend.Need to take special note of the grid bias issue.
Yes, Leo Fender used very basic circuits and worked on them
to create his own legendary amps & guitars.
They've become world famous and some like the '59 Bassman amp have become the "Holy Grail" of guitar amps.Marshall more or less copied Leo's circuit and came up with the legedary Marhshall JTM45.
Mine is a 1963 Fender Tremolux which puts out about 35 wattsrms.
Rich, warm vintage tone to die for.
Again I'll have to agree with you that there are different requirements
between the guitar player & hifi community.
Howver, that said, we all fight over most all the same valves.
Rich hifi dudes can afford them, but poor musicians can only dream
of getting good NOS varieties of GZ34,6L6,5U4GB,5Y3, and of course the entire range of the common preamp valves like ECC83.ECC82.
I'm also glad that the hifi guys havent taken a shine for the
lovely sounding 6V6.They rather prefer the EL84 amps.

I have a Leak Stereo 20 using these but it's still waiting for a proper
preamp match before I can fire her up.
All the valves are with me except the GZ34, which I'm think i'll
try getting from JJ online.
Hope that you good word about this brand holds out though.
Well, you never know.May receive a dud valve in the mail

Cheers & have a great weekend cmboy.

regards,
teleman51

I think the US-made General Electric (GE) 5AR4 rectifier tube is the best. I've got four on my Quicksilver monoblocks (2 per channel) and they have never failed me. I've seen my GE 8417 power tubes turn red (from setting too high bias — itchy fingers!) and hundreds of fuses blow, but the 5AR4 is steady as a rock.

Good tubes may be costly, but you save money in the long run by not having to replace them often.

Yeah razwill,
I guess you're right about those GE valves.
Those were stuff from the good old days when companys really were competing to come out with the best.Then transistor technology went and spoilt it all.All of the American,British & most all Europen plants started shutting down one by one.Sigh!!!!!!!!!!!!!!!
Bought a TAD( Tube Amp Doctor) 5AR4 recently to put into my Fender
guitar amp.
Wasn't expecting much but it turned out well.
Now I'm happy with the amp.No need to go out looking for NOS stuff.

Anyway I managed to score a couple of NOS recently too.
1 was a Siemens (a real beauty) and the other a big bottle Mullard.
saving these 2 for my Leak System.
Anyway I think I'm done looking for NOS valves for now.

Cheers,
teleman51