Case,
I have been waiting for someone to try this fantastic tube in a TP! I know Dan used one at the audio show in Germany and seemed to like it. I use one in my ModWright SWL 9.0 as well as in the PS for a ModWright Sony 9100. You have an early version with the welded plates. I have both versions and have not had the time to compared the welded plate to the folded plate version.
Here is a link to the Philips GZ34 versions:
http://www.tube-classics.de/TC/Tubes/Valvo%20GZ34/GZ34.htm
Enjoy your TP!
Interesting JG2, you having both versions of the metal base GZ34's. Have you already been able to compare both types?
Let me first introduce myself a bit. I live in the country which once produced these particular tubes: Holland. Last week we swapped tubes in a friends Modwright PS for his Modwright preamp (the dual mono one).
Being quite astonished about the effect of the different rectifiers we used, I wanted to check some other persons experiences. While doing this I came across this forum.
We replaced the standard Sylvania's GZ34's supplied by Modwright by Sovtek GZ34's. Sound improved significantly. The Sovteks were then replaced by Mullard 5U4G (big bottle, brown base, late 50's I guess, not the Wycombe). Wow, much better sound now! More musical (instruments sounded much more like the real thing) and more transparant. Then, a few days later, the 5U4G's made place for two Philips Metal Base GZ34's (1957, perforated plates) and... even more wow! The metal base GZ34's sounded much more balanced IMO. Base is much, much tighter and the treble more extended. The 5U4G's mids are extremely smooth, more so than the mids of the metal base, very seductive. However the metal base doesn't sound harsh or grainy when compared to the 5U4G. On the contrary, and the decay of tone is also similar. All in all I feel the mids of the 5U4G are a bit over the top, maybe they are to velvety smooth. Last but not least, soundstage/focusing: I thought the width and depth of stage increased significantly with the GZ34. Further the focusing of the single instruments was more precise with the metal base.
As my preamps rectifier in the separate PS is a GZ34 too (preamp: Silvaweld SWC1000) I lately bought two metal base GZ34's (one for spare). A 1957 version with perforated plates and a 1955 version with the more sturdy/welded non-perforated plates. As my system is under construction I haven't been able yet to hear the difference these tubes make with the National GZ34 that Silvaweld once used. No doubt they will blow away the National. Curious however to the difference between the two metal bases. I read on a Asian website that the first version with welded plates is the best ever made, but maybe you have been able to compare both metal bases already?
Kees
