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GZ-34 in the SE84UFO? (Read 282 times)
DanG
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Posts: 14
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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Marantz SA-8005 SACD
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Don Sachs PH16 Phono Stage
Decware SE84UFO Beeswax Bypass Cap Mod
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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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Mac Mini with Roon, Rega RP6, Rotel RCD-1070 & Marantz CD6005; Hegel HD30 & Copland DAC215; Decware SE84UFO25, Decware SE34I.2+ & Copland CTA405; ProAc D28, B&W DM630 & Rega RS1; Stein and BlackNoise filters; DH Labs power, interconnect and speaker cables
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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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Marantz SA-8005 SACD
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Don Sachs PH16 Phono Stage
Decware SE84UFO Beeswax Bypass Cap Mod
Caintuck Audio Betsy Open Baffles
Dayton Audio Sub-800
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Herbie's tube dampers, tenderfeet
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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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Marantz SA-8005 SACD
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Don Sachs PH16 Phono Stage
Decware SE84UFO Beeswax Bypass Cap Mod
Caintuck Audio Betsy Open Baffles
Dayton Audio Sub-800
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Herbie's tube dampers, tenderfeet
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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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HR-1,ZTPRE,ZBIT,ZROCK2,SE84UFO3-25th x2, CSP3-25th.Taboo Mk IV; Rega RP3 w/25th mods PS Audio: DMP+DSD,P15,NPC,PowerBases,AC-12 pwr cbls, Statement spkr cbls;Mapleshade:Samson V3; Oppo UDP-205; VooDoo:Cremona+Amati intrcncts, Iso-Pods;headphones:PM1,HD800S,ZMF Ori
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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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Marantz SA-8005 SACD
Mission 775 Turntable, Mission 774LC Tone Arm, Audio Note IQ3 cart
Don Sachs PH16 Phono Stage
Decware SE84UFO Beeswax Bypass Cap Mod
Caintuck Audio Betsy Open Baffles
Dayton Audio Sub-800
(3) DHC-1
Herbie's tube dampers, tenderfeet
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JOMAN
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Posts: 405
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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