Shuguang, Sovtek or JJ Tesla, which GZ34 is best??

tubeboob

tubeboob

Super Member
I just got back my Scott 299A integrated, and alls very well except that I need a new GZ34. The output tubes, all original Scott 7189's tested over 11,000 and were deemed by my tech to be as good as new.

Vintage GZ's are too costly, but GZ's from Shuguang, Sovtek and JJ Tesla are all available for a little over $20.00, so I want to choose one in this price range.

Wanted to know if any of you had experience with the respective rectifier tubes, and could you give me your thoughts.:scratch2:

Thanks in advance.
 
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My opinion:

I have a Sovtek in my Heathkit AA-100 since two years without problems.

I don't know the other ones though.

Patrice
 
I have had one failure with Sovtec in about 3 yrs worth of use in various amps. I know they are expensive but a Mullard is really the way to go. I have never seen a Mullard fail or have any friends report of one doing so. Way in folks, ever have a Mullard die out on you. Very curious!
 
Shuguang, I had problems with Sovtek and Tesla in my Dynaco MKIIIs. BTW the filter caps were replaced with 550vt so it could not be blamed on that.
 
Just another angle but you might try looking for a device that uses the GZ34 and buy it for the tube, or look for tube or tube lots containing one or more GZ34`s.
By parts I mean many people sell trashed heathkits with no tubes but for some reason the rectifier tube is there.
The sovtek sounds like a good replacement though.
 
I'd suggest doing one of two things...

1) Buy a known good testing likely used Mullard. Pricey but fairly safe purchase... they do fail so there is a gamble involved with used tubes.

2) Buy a couple modern production GZ34's and save the cash. I usually use Sovteks. They tend to last a couple years if you get a good one right out of the gate. The spare will help ease the pain when it does let go.

One thing that will help with the modern production jobs is to always let your amp cool down before turning it on again if you shut it off hot. They really hate the slam they get if turned on with all tubes hot and ready to draw current. Doing so even with a Mullard is not wise.
 
tubeboob said:
I just got back my Scott 299A integrated, and alls very well except that I need a new GZ34. The output tubes, all original Scott 7189's tested over 11,000 and were deemed by my tech to be as good as new.

Vintage GZ's are too costly, but GZ's from Shuguang, Sovtek and JJ Tesla are all available for a little over $20.00, so I want to choose one in this price range.

Wanted to know if any of you had experience with the respective rectifier tubes, and could you give me your thoughts.:scratch2:

Thanks in advance.
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Unfortunately, that's what/how most people think.

However, since the modern day production GZ34/5AR4 may not be as robust as you need it to be, you could go through several of them in a very short period of time. I blew through six of them in less than nine months!

One of those I killed by turning the amp off then right back on within about 10 seconds. Another of them was killed by the utility company when the power went off, on, off, on, off, on one day for no reason. Both of those puppies arc'd. . .big time!. . dead.

But, the other four failed (arc'd) all on their own.

So after realizing that I could have actually saved between $50 to $75 (over $100 if you include shipping costs) by purchasing a used vintage Mullard GZ34 that tested really well; that's exactly what I did. As soon as I plugged in the Mullard all anomalous behavior with my amp ceased.

Now, I only purchase fat-based vintage Mullards dated between July 1958 and the 4th week of January, 1962.

* * * EDIT * * * Actually, I've also purchased NOS vintage 1959 Mullards from the Sittard manufacturing facility in Holland. Another excellent GZ34!

I don't splurge, and refuse to pay outrageous prices. So, you need to be patient to find one at a reasonable price ($40-$70). Remember, it doesn't HAVE to say 'Mullard' on it; just be sure it has the etched Philips/Mullard codes on the glass envelope, or is printed on the base. From time to time you can find them for $25-$30, especially if the person doesn't know what they're selling and/or the photo is fuzzy. Most people wouldn't take a chance on an auction like that, but I would if it's really cheap.

Some of the companies that labeled Mullard GZ34's with their own brand were:

Amperex, Miniwatt, Sylvania, RCA, GE, Philips, BEL, Philco, DuMont, Zenith, Genalex, Telefunken, Brimar, Tungsram, Raytheon, Valvo, Daystrom, IEC, Siemens, Marconi, Sonotone, Adzam, Mazda, Heath, Motorola, Webcor, International Servicemaster, Hammond, Conn, Lowrey, Dario, Fisher, HH Scott, Eico, Dynaco, Bogen, AeroSound, Zaerix, RSD, Pope, Trigon, and Ediswan.

. . Falcon
 
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I have a 299A and have used a Sovtek in it without any problem. You might also check out the small bottle GE 5AR4 with the copper side plates which also sounds good and can sell for less $$$ than a Mullard. I think Scott used these as OEM rectifiers as well in some models.

The 299A is probably a milder working environment for a 5AR4 than some other amps.....365V B+ and a first cap of 30uf in stock form.....if cost is an issue I would go Sovtek.
 
I too have been down the JJ, etc. road. After several premature failures I looked for a Mullard and found one at a "reasonable" price. It's been in use for a couple of years now without a problem. Still tests like new. I figure I have saved money in the long run.
 
Check out the Weber Copper Cap rectifiers. I use one in my SET amp, its a drop-in replacement. Mind you, my SET uses a 6AX5, but Weber does make the equivalent of the GZ34. I used to use NOS GE 6AX5s in my amp before, but this copper cap has made a marked improvement on the sound. http://www.webervst.com/ccap.html
 
Hi,
I've been using a JJ CZ34 in my Scott LK48 and it's been suffering from
a Buzz, low in volume but there none the less, So I went on ebay and won
a $47.00 bid on a Amperex/ Mullard 5AR4/CZ34 when I put it in the buzz
went away and the amp got much cleaner with less noise. So there you go.
I will try the Sovteks one day but I'll see how this one works out.

Thanks
tube-a-lou
 
Normally I'm using a Valvo GZ34 in my Fisher X-100, but I decided to give the Shuguang tubes a try since they are available for next to nothing....so heres my experience so far:

I bought a pair directly from Hongkong (a factory outlet it seems to be) off ebay for $28 incl. shipping! and the tubes arrived in less than a week. :)

The first tube I put in worked fine, sound was surprisingly good...not quite Mullard, Valvo etc. quality but definitely very good sounding even though it had not yet been thoroughly burned in.

Ok :) so after 4-5 hours I put the second tube in...but sadly after around 5 hours that tube stopped working. :(
However these tubes are same as the TAD GZ34, so if you're lucky and get a sample that works, they're actually very fine tubes

How they will hold up in the long run I cannot say: the one tube that is working I'll let stay in my Fisher x-100 and then we'll see how long it'll last ....

So where does this leave the verdict ? well these tubes sounds fine, but with such a failure rate it just might not be worth the effort even if they're dead-cheap...or buy them from a seller that put them through a test before selling them. ;)

The NOS tubes might be more expensive and are definitely getting more difficult to find, but they will last 30 years or more, so in the long run they still are the best value for money buy imho.
 
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I've seen the Shuguang recommended a few times, if you want to stick with tube.

FWIW, if the Mullard 5AR4/GZ34 rectifier ever goes out in my amp I'll probably be trying one of the Weber Copper Caps.
 
Sylvania fat bottle from around 1970. Saw one sell for 11 bucks on that auction site. Very sturdy well made 5AR4.
 
(update to my previous post)

I've contacted seller about the failing tube: in short: he want's the failing tube returned before sending me a replacement.

Well fair enough, but that is heavily subtracting to the "dead-cheap / great deal" part...hopefully he'll put the replacement tube through a test before sending it to me...;)
But fair enough: hopefully they will dissect the failing tube and learn from it, so they can improve on the future production.

Regarding the tube that works:...now that it has a few more hours on it I must say that the sound is impressively good. :music:

When they get the failure rate down these Shuguang tubes really is a worthy alternative to the increasingly expensive NOS tubes imho. :thmbsp:
 
This and That

tubeboob said:
Vintage GZ's are too costly, but GZ's from Shuguang, Sovtek and JJ Tesla are all available for a little over $20.00, so I want to choose one in this price range.

Wanted to know if any of you had experience with the respective rectifier tubes, and could you give me your thoughts.:scratch2:

Thanks in advance.
Click to expand...

Have a JJ GZ34 that is still going strong. Bought a GZ34 from an outfit and I thought I had ordered a Shuguang but it was a cheap Sino knock off and arced within days of installing it. Purchased a pair of genuine tested Shuguangs from Jim McShane and they are the real deal. Visually, a night and day difference. Have had absolutely zero problems.
 
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