avguytx Posted January 29, 2021 Share Posted January 29, 2021 I had sold my VTA ST-70 because I rarely ever used it and what happens? I come across a group of things that I couldn't pass up including a basically new, and mostly finished, Dynakit ST-70 with the upgraded transformers, etc. All that it needs is the power transformer wiring finished and a full set of tubes and it should be off to the races. Kevin, at Dynakit, recommended using some KT77's in it and I believe I have a pair of Stromberg Carlson labeled 7199's to go in, too. On the VTA ST-70 I had, the original GZ34 failed after a few months and I replaced it with a Genelex Gold Lion and also bought a JJ Tesla for backup. Is there any advantage to using a Solid State rectifier in place of the tube besides cost? Does it put more stress on the output tubes? I've also got a Scot 299-d integrated tube amp that I'll have to get 11 tubes for that was serviced by Terry Dewick maybe 15 years ago. But that's another story... Quote Link to comment Share on other sites More sharing options...
amped Posted January 29, 2021 Share Posted January 29, 2021 http://www.tubes4hifi.com/ST70.htm has a TDR board that may be helpful. You might have a look here: https://dynacotubeaudio.forumotion.com From what I understand the S/S rectifier uses 17 volts less because it doesn't need heater current. I use a Weber WS-1t in my Bob Latino VTA ST-120. Prior to this I was using a Re-issue TungSol 5AR4 with no problems (about 1 1/2 yrs) I got an auto bias board and this also has a delay so I got the S/S. I don't hear a difference. Both Kevin and Bob L are good guys to deal with in my experiences. Quote Link to comment Share on other sites More sharing options...
hogwylde09 Posted January 29, 2021 Share Posted January 29, 2021 Personally I believe a ST-70 is worth putting a good notched plate GZ-34 in. Sometimes can pick up a decent used Hammond labeled. Of course does not have to be notched plate. I have picked up some Valvo NOS a bit cheaper then Mullard, Amperex, etc. 1 Quote Link to comment Share on other sites More sharing options...
seti Posted January 30, 2021 Share Posted January 30, 2021 Vintage GZ34 don't risk one of the newer ones. For all the tube knowledge we have we can't make them like they did. Quote Link to comment Share on other sites More sharing options...
kevinmi Posted January 31, 2021 Share Posted January 31, 2021 I've run both in my Latino ST-120, and you will need some sort of time delay with the ss unless it has a built in delay. I found some cool Mullard GZ-33 rectifier tubes that not only look great, but have handled the load on the ST-120 for ten years now. I kept blowing new production GZ-34's. I prefer the look of glowing tubes! 1 Quote Link to comment Share on other sites More sharing options...
OO1 Posted January 31, 2021 Share Posted January 31, 2021 On 1/29/2021 at 9:35 PM, seti said: Vintage GZ34 don't risk one of the newer ones What do you think about the Telefunken GZ34 Quote Link to comment Share on other sites More sharing options...
seti Posted February 1, 2021 Share Posted February 1, 2021 4 hours ago, RandyH000 said: What do you think about the Telefunken GZ34 If it is new production it doesn't cut it. I'd save my penies for a vintage good GZ34... If you get a nos gz34 you won't need another for the lifetime of that amp. Quote Link to comment Share on other sites More sharing options...
OO1 Posted February 1, 2021 Share Posted February 1, 2021 20 minutes ago, seti said: If it is new production it doesn't cut it. I'd save my penies for a vintage good GZ34.. ok Quote Link to comment Share on other sites More sharing options...
avguytx Posted February 2, 2021 Author Share Posted February 2, 2021 I appreciate all the information on the GZ34 tubes. I know these have the ability to get pretty pricy pretty quick especially for the NOS models and even used. I guess I need to decide something soon and might spring for one of the better GZ34's as soon as I get a pair of JBL L50's sold off which will free up some "toy money". Quote Link to comment Share on other sites More sharing options...
Schu Posted February 2, 2021 Share Posted February 2, 2021 second on vintage GZ's... I use the copper lined GZ Mullard and I love it. 1 Quote Link to comment Share on other sites More sharing options...
seti Posted February 3, 2021 Share Posted February 3, 2021 23 hours ago, Schu said: second on vintage GZ's... I use the copper lined GZ Mullard and I love it. Yup I use Mullards and Amperex GZ34. I wish I had more. Quote Link to comment Share on other sites More sharing options...
EMRR Posted February 6, 2021 Share Posted February 6, 2021 I've had the same GZ34 in a 1966 Fender guitar amp since I got it in the mid-80's, still going strong. It may be the original tube for all I know. 1 Quote Link to comment Share on other sites More sharing options...
Schu Posted February 9, 2021 Share Posted February 9, 2021 Quote Link to comment Share on other sites More sharing options...
avguytx Posted March 11, 2021 Author Share Posted March 11, 2021 I just wish I new better on where to look for the GZ34's and which to go with. I'm not a tube guru so it's a shot in the dark for me and I ultimately go months before ever getting one. Like now. Quote Link to comment Share on other sites More sharing options...
seti Posted March 12, 2021 Share Posted March 12, 2021 11 hours ago, avguytx said: I just wish I new better on where to look for the GZ34's and which to go with. I'm not a tube guru so it's a shot in the dark for me and I ultimately go months before ever getting one. Like now. Just go to ebay and bid on a few tubes. You can't go wrong with any vintage gz34s. Something like these. https://www.ebay.com/itm/2-x-Mullard-GZ34-5AR4-Rectifier-Tubes-Very-Strong-Balanced/373483825952?hash=item56f55eeb20:g:6mcAAOSwnBdgQF9W 1 Quote Link to comment Share on other sites More sharing options...
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