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GZ-34 in the SE84UFO? (Read 652 times)
DanG
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GZ-34 in the SE84UFO?
09/11/20 at 03:07:02
 
I have a Mullard GZ-34 from my old ST-70. Can you use this to replace the stock rectifier tube in the SE84UFO?

I think I remember seeing that you can use a GZ-33, but I have the GZ-34.

Thanks.
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CAJames
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Re: GZ-34 in the SE84UFO?
Reply #1 - 09/11/20 at 03:43:12
 
It will work great!
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alper_yilmaz
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Re: GZ-34 in the SE84UFO?
Reply #2 - 09/14/20 at 11:07:44
 
It works fine.  Joman, one of the forum members, has picked a make of GZ-34 as his favorite, but I do not remember what it was exactly (a search should direct you to his detailed review).  His was quite an expensive one, but he might have reviewed the one you are talking about as well.

Best,

Alper
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DanG
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Re: GZ-34 in the SE84UFO?
Reply #3 - 09/14/20 at 19:28:55
 
Thank you for your replies. I appreciate it.

More to the story. I realized the Mullard GZ-34 I have is from my original Dynaco ST-70 and is probably no longer any good.

I replaced the Dynaco with a Vacuum Tube Audio ST-70. Rather than going all in on an NOS Mullard GZ-34 I purchased a NOS Mullard GZ-33 rectifier tube. I felt it did very nicely. It's this tube that I'm considering swapping into my SE84UFO.

So I had it exactly reversed in my initial post. NOT a GZ-34, but a GZ-33, will this safely replace the stock rectifier tube in the SE84UFO?

Thanks.
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Lon
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Re: GZ-34 in the SE84UFO?
Reply #4 - 09/14/20 at 19:59:39
 
Will certainly work fine.
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DanG
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Re: GZ-34 in the SE84UFO?
Reply #5 - 09/18/20 at 13:16:39
 
Lon, I appreciate the reply.

The threads seem to mention the GZ-32 mostly for the SE84UFO. Bob Latino of VTA posted on the Dynaco Tube Audio Forum that the GZ-33 "is not an exact replacement for the GZ-34 as it draws a little more current". Does this make the other tubes run hotter?

Bob also notes that the rectifier tube does not affect sound quality for his push-pull model ST-120 unless played loudly or with inefficient speakers, which is not me.

It's either roll the GZ-33, or try the input tube first, and roll a Mullard Philco 6DJ8. I'm leaning towards the input tube first.
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Lon
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Re: GZ-34 in the SE84UFO?
Reply #6 - 09/18/20 at 14:13:25
 
Actually Dan, I'm sorry I was confused about your post. I had thought you were asking about the GZ34 and that will definitely work. As does a GZ32. I'm less certain about GZ33. . . looking about on the internet it appears it should work but I'm less positive.

I'd recommend trying that input tubes . . . should give you a nice change. In my amps rectifier tubes make a significant sonic difference, but it may not be true with other amps and a manufacturer should know!
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JOMAN
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Re: GZ-34 in the SE84UFO?
Reply #7 - 09/22/20 at 23:11:45
 
Dan have a look at the GZ34 that you pulled from your ST70.  If the bottle goes straight into the base and the base is wider than the bottle then itís a FAT Base.  The bottle must go straight into the base.  Next look at the plates. If there are no notches in the plates then you likely have a rare production GZ34 that was the first itineration after The Metal Base.  They did not make these for a long time and it was replaced by the FAT Base with 4 notches in the plates, which is not as refined.

The GZ34 Fat Base/no notch was also branded with the names of amplifiers it went into.  Mine was an EICO Branded GZ34.

This was the rectifier that for my tastes and set up bested all the others, until I got the itch and tried a Miniwatt GZ34 1958 Metal Base.  What a mistake that was -:)!  Of the GZ34ís that I have tried those are the only two that I liked.  The other variations arenít even close.

The rectifier makes a huge difference in the sound of the amp if the amp is transparent, and the UFO25 most certainly is.  I also found that my SE84UFO2 was very transparent, and I believe that yours is as well.

So if you have a GZ34 Fat Base no notches on the plates... by all means try it.  Then as Lon suggested try rolling the input tube.  I think youíll have a lot of fun.
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DanG
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Re: GZ-34 in the SE84UFO?
Reply #8 - 09/23/20 at 13:49:45
 
Joman, great minds think alike. I tried the GZ34 two nights ago.

Three nights ago I tried the Philco Mullard 6DJ8 in the input. Less bass, mids and highs veiled. Same for a Russian 6922 that had worked well in my phono stage. So I put the 6H1N red tip that came with the amp back in, and the bass, mids, and highs were restored.

This gave me renewed respect for the stock tubes that came in the SE84UFO. 6H1N input, the SV83 output, and the Valve Art 274B.

I was hesitant to try my NOS Mullard GZ33, as it is not listed as a replacement. So I pulled the Dynaco branded Mullard GZ34 from the ST70 and tested it on my Eico 625. It tested as well as my new issue Mullard GZ34. So I thought why not give it a try.

I have to say that I had just rolled some Amperex Philips 7308 into my phono stage. This was a great improvement. I've really been enjoying it . So I was in a good place. But it put the tube rolling bug into me, I thought, what can I do with the SE84UFO, it's still stock.

I didn't know what to expect with the NOS Mullard GZ34, same, worse, better. I was not prepared for what happened.

The bass is a tad better, fuller. I may be getting more color, the Mullard GZ34 may be imparting its own 'flavor', the stock Valve Art 274B may be cleaner. But everything is now organic. The soundstage is more cohesive, everything relates better to each other and the whole. I'm struggling to comprehend it.

I play fairly low volume, 9 o'clock on the dial, peaking at 80+ dBA. But I can't handle loud volume. It doesn't matter, the NOS Mullard GZ34 is now giving me this organic whole where I hear everything, and hear new things in music I know well, and the timbre of everything is enhanced in a wonderful way.

So I'm playing all my vinyl favorites to hear them anew, as I struggle to comprehend how the NOS Mullard GZ34 has changed the amp.

I'm having a good time. Yesterday I thought, "my stereo is having a breakthrough." And, I thought, the people at the office wouldn't even understand that statement. "What do you mean your stereo is having a breakthrough, doesn't it just play the music?" Yeah, but now, it plays it better!

Thanks for your help.
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JOMAN
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Re: GZ-34 in the SE84UFO?
Reply #9 - 09/24/20 at 03:41:31
 
Glad your enjoying the music, thatís what itís all about.

The organic nature that became evident after trying the GZ34ís that I mentioned in my earlier posts is one of the first things that I noticed as well as the other attributes that you mention.

The Metal base took that to an entirely different level in my UFO25.  In addition there was this decay and and detail that came across as it would in live music.  Not saying itís the same as live, rather theres enough enough of the live that it gives a sense of the real, itís quite disarming actually.

My conclusion after trying the specific GZ34ís that I mention in my earlier post isnít that it makes the component better.  Rather it allows the full potential of a component to come through.  It also allows the associated tubes to be at their best.

So in some amps it may make no difference because the amp is limited.  In other amps there will be a difference because the full potential of the amp is limited by the tubes.

These tubes will tell you just how capable your amp and system really is.  ENJOY!
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DanG
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Re: GZ-34 in the SE84UFO?
Reply #10 - 10/10/20 at 21:13:15
 
Joman, I have a Dynaco branded Mullard GZ34 4-notch, see photo.
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Lin
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Re: GZ-34 in the SE84UFO?
Reply #11 - 10/11/20 at 03:34:48
 
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piezoman
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Re: GZ-34 in the SE84UFO?
Reply #12 - 10/12/20 at 02:58:06
 
That is a standard, high production early-mid 1960's Mullard.
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JOMAN
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Re: GZ-34 in the SE84UFO?
Reply #13 - 10/13/20 at 01:12:27
 
Dan, Piezo is correct.  I did not try this particular version so I cannot comment.  However, take the time and look up Dub step Girls Massive Rectifier reviews.  In this review the GZ34 that you have is reviewed and compared to the  Metal Base version.  Based on my experience with the Metal base, I would say that this review is very accurate.

I did have the Fat Base, Smooth Plate version which is the one that came immediately after the Metal Base.  When I tried it, part way to my listening chair I stopped dead in my tracks, turned around and tried to process what I was hearing.

I started to wonder ďhow much better could a Metal Base GZ34 be?  Is the review on target?Ē  There was only one way to find out.  This was a somewhat painful process as at one time I felt that I would never spend the kind of money that the Metal Base were getting and here I was looking for one (I now have two, amp and preamp).  As I looked for a reasonably priced Metal Base I came across ads that would claim that certain ďGZ34 were equal to the Metal Base or very close to.Ē  So I picked up a couple of later release, used GZ34 smooth plate versions as well (skinnier black base).

Bottom line... The Metal Base is in a completely different league!  Even the successor fat base, smooth plate was not itís equal.  But the immediate successor (Fat Base, Smooth plate) was extremely good in itís own right and had I not tried the Metal Base I would still have it.  I did not find it unrefined as the review commented on the notched plate version.  I suspect that the notched plate 60ís version has a lot of what the Fat Base, Smooth Plate does with less refinement and bass impact.

Based on your comments I feel that a lot of the early Fat Base, Smooth Plate GZ34 character is still ďinĒ the notched plate version.  I still have the two used GZ34ís that were supposed to be as good as the metal base so I decided to put one in my UFO25 before commenting.  NOT EVEN CLOSE to my Metal base or the successor Fat Base, Smooth Plate and likely not close to your notched plate GZ34.

I believe that you quite liked the notched plate GZ34 that you pulled from your ST70.  If that is the case Iím going to to do something that I rarely do... recommend that you try the Metal Base GZ34.

I came across the following, bidding started at $152.00 and there are 25 bids with 5 days to go:

https://www.ebay.ca/itm/1-vintage-1955-Amperex-metal-base-GZ34-5AR4-tube-tested-...

If you were to get it at a good price you can easily re sell it if you didnít like it.
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DanG
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Re: GZ-34 in the SE84UFO?
Reply #14 - 10/13/20 at 03:26:32
 
Joman, thank you for your comments and recommendation. Thank you for relating your experiences with these tubes.

The Dubstep Girl review is an eye-opener.

My experience is limited. I was fortunate to get a minty Dynakit ST-70 with Mullard EL34s and GZ34. I tried substitute EL34s when the Mullards finally failed, they did not do it. Only the Mullards did it, by far and away.

My takeaway is that my amps did one thing with other tubes, but, as you say, stunned me with the Mullards. To now understand there is even a further step up is a little shocking.

I haven't contemplated spending such silly money on a tube. But now I find myself contemplating it.

Do you have any experience with the other tubes in Dubstep Girl's top six? And her surprise pick the RCA 5U4G?

Thanks.

Dan
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JOMAN
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Re: GZ-34 in the SE84UFO?
Reply #15 - 10/13/20 at 13:55:21
 
Dan,
I have not had experience with the RCA5U4G.  I did have an Australian made 5U4G, the AWV Radiaotron version and liked it.  I did have the CV593 and the Philips 5R4GYS.  Preferred the CV593 to the Philips 5R4GYS.

None of these came close to the Mullard Fat Base, Smooth Plate and not even remotely close to the Metal Base Mullard/Phillips.  There in lies the problem... how close to is close to???  These are words that attempt to describe something that is very multi faceted.  Itís like trying to describe a painting or a fall scene, you would need a thousand words and still not be able to capture the feeling that one gets.

Last night before responding I wanted to check my memory so I subbed the Metal Base with an Amprex Smooth Plate GZ34 in my UFO25.  It was very nice but something was obviously missing.  I re installed the Philips Miniwatt Metal Base GZ34.  The best words that I can use to give an idea of the difference is that I started to get goose bumps with the Metal Base in place.  I could wax on about the sonic differences but that would not describe the ďfeelingĒ that I got.  I didnít have to think about it, it just happened.  

Thatís what music and song does to me, thatís what I pay for, unfortunately more than I would like at times.  Itís not just the tube or tubes, itís also the Decware components that I have.  If one appreciates music and is willing to pay hundreds of dollars for a watt, why stop short at the tubes, especially if the tubes allow the component to be at itís best?

Not trying to persuade or push you into spending your hard earned cash on the GZ34 Metal Base.  Just trying to help you understand why I did.  Be careful here... once you experience this, if it suits you, there will be no going back!
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CAJames
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Re: GZ-34 in the SE84UFO?
Reply #16 - 10/13/20 at 15:12:52
 
Quote:
...And her surprise pick the RCA 5U4G?


I can't comment on that specific tube, but I just wanted to point out that the 5Z3 is the same tube as the 5U4G but with a 4 pin base. With even the humble 5U4Gs getting expensive (at least for my Scottish heritage) I got a 5U4G to 5Z3 adapter and have been stocking up on 40's and 50's rectifiers, JAN RCAs, National Unions and Sylvanias, for like 10 bucks a tube. My current favorite (in my non-Decware amp) is a early 50s (I think) NU 5Z3 I got for 10 dollars. And I've got plenty more to try in my UFOs when they (finally) arrive.

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