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Re: NEW GZ34!!!!!!!

2/17/2001 7:58 AM
Re: NEW GZ34!!!!!!!
Thats exactly it about the different rectifier tubes... some fo the 'softer' tubes give more compression or 'sag' when cranked, plus lower voltages=less high end. A GZ34 isn't all that much different than a solid state rectifier., whereas a 5y3 drops a LOT, and is very mushy (except the Sovtek 5y3, which is MUCH stiffer, more like a 5v4) You may want to get Duncan Amps power supply simulator to help you see the difference in voltages... I"m using the default power input ( a 333vac transformer, 20uF first stage cap, and a 1k5 ohm load to get these numbers)  
SS rectifire == about 460v  
5ar4/gz34 == about 445v  
5v4 == about 420v  
5u4g == about 410v  
5y3 == about 370v (the Sovtek 5y3 would put about 380-400v, and is quite a bit stiffer.. i'ts not a TRUE 5y3)  
there are some 6v rectifier tubes (great for amps that dont have a 5v rect. tap ;), that are an option as well... with the same parameters, hers' what they put out  
6ca4 == 430v  
6ax4 == 425v  
6x4 == 406v  
6x5 == 406v  
There are many others, and there are also other things to consider, such as current draw etc, but this is an example of hwo much difference in plate voltages will be with different rectifiers.
2/17/2001 9:50 AM
John Kelley Brown

Good info. But I get the sense that there's the opinion that a GZ34 of this brand makes an amp sound different than a GZ34 of that brand. I can understand what you are talking about with the differences between at GZ34 and a 5U4G, but can you hear a tonal differences if you switched from one brand of GZ34 to another in the same way that you can certainly hear the difference between one brand of 6L6 and another? I wouldn't think so but it's the feeling i get when I hear the things people say about these tubes. If brand X GZ34 puts out 445v and brand Y, though constructed differently, also puts out 445v, I would think there would be no difference in the tone of the amp regardless of which of those tubes you used.  
2/17/2001 11:13 AM
Here's another option that I'm working on.  
Will be available in about a month.  
Coppper Cap Rectifier  
2/17/2001 12:10 PM
Pierre Debs

I think the big thing with GZ34 rectifier, in addition to all that is mentioned above is reliablity. The Russian GZ34ęs donęt last long and I have a friend who goes through alot of them . They donęt last. I have three old mullards, pulled from three old amps , all over 25 years old, all are as strong as new, donęt rattle, and function properly. If the JJęs are anywhere near as goos as their other tubes, it saves alot from having to buy a NOS Mullard for 100 US dollars.
2/17/2001 2:38 PM
Well hey, at least someone is making tubes!  
I'll have to stick with my stash of old re-branded TungSol & Dynaco-labeled 5AR4/GZ34's...but that's more of an economics issue than a technical one. Could be you might prefer the sound of different brands.
2/17/2001 2:49 PM

FWIW, I tried to different GZ34's in the BF princeton that has a little noise(buzz) when you start to crank it. We tried swapping the recto to see if it would help. The one we took out was an old GE very small tube compared to the large RCA gray plate we put in.. There was absolutely no difference in sound or noise at all. Maybe a Mullard is different, don't know but this difference was null.,  
2/17/2001 9:59 PM

Well, New Sensor is selling a new-design russian GZ34, it seems to be pretty good. I just got some and started trying them out.  
I dunno about old Mullards - I've seen plenty of them that had reduced efficiency after years of use. Many of what is being traded as NOS now for darn sure AIN'T!  
Glad to hear that JJ is making one now too. They have a pretty good record.

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