Somewhere I saw a note that a dual rectifier mod was being considered to be offered for the M-125's. Anyone know if anything was ever developed for the 125's? I have the new style chassis layout if that makes any difference?
Thanks, Ed
Thanks, Ed
+5
Tubes4ever
Rec
mijohn
5/35
98indypacer
9 posters
VTA M-125 Dual Rectifier Tube Mod?
98indypacer- Posts : 23
Join date : 2022-01-12
5/35- Posts : 15
Join date : 2014-03-01
Location : Friday Harbor WA
I too was wondering if anyone has given this topic some thought. Bob??
mijohn- Posts : 119
Join date : 2013-06-19
The best person to know the answer to this question I would of thought is Dan at:
info@tubes4hifi.com
info@tubes4hifi.com
Rec- Posts : 77
Join date : 2020-03-11
Check this thread: https://dynacotubeaudio.forumotion.com/t5064-dual-rectifiers-for-st120-st70-amps
Also my understanding, although I could be wrong, new style m125 uses diodes for rectifier so probably don’t need the dual tube mod?
I like the idea of dual tube rectifiers, needed in the m125. in a pair of m125 world that would make 12 total tubes to monitor…. Lots of glass!
. I used solid state and a dropping resistor. I got tired of fireworks…
Also my understanding, although I could be wrong, new style m125 uses diodes for rectifier so probably don’t need the dual tube mod?
I like the idea of dual tube rectifiers, needed in the m125. in a pair of m125 world that would make 12 total tubes to monitor…. Lots of glass!
. I used solid state and a dropping resistor. I got tired of fireworks…98indypacer likes this post
98indypacer- Posts : 23
Join date : 2022-01-12
Rec wrote:Check this thread: https://dynacotubeaudio.forumotion.com/t5064-dual-rectifiers-for-st120-st70-amps
Also my understanding, although I could be wrong, new style m125 uses diodes for rectifier so probably don’t need the dual tube mod?
I like the idea of dual tube rectifiers, needed in the m125. in a pair of m125 world that would make 12 total tubes to monitor…. Lots of glass!
That's the link I was looking for. This was post #10 in that link:
the mod itself will work with M125s, but this board won't fit an M125. Anybody else want this mod for their M125s? If we can get maybe 6 people to say yes, we can go for it
There have been multiple recommendations for rectifiers for the M125's. I've seen 5AR4, the solid state option and now I think the 5U4 is the current recommendation. I think if you use the 5AR4 you would need two tubes but with the 5U4 you just need one. Maybe someone can confirm!
Tubes4ever- Posts : 167
Join date : 2015-07-14
Location : Star, Idaho
Yes. Just one 5U4GB.
Bob Latino- Admin
- Posts : 3273
Join date : 2008-11-26
Location : Massachusetts
Tubes4ever wrote:Yes. Just one 5U4GB.
You can use a 5U4 in place of a 5AR4/GZ34 in any of the VTA amps BUT > a 5U4 has a higher voltage drop than a 5AR4 and will provide a slightly lower B+ DC voltage. Using a 5U4 in place of a 5AR4 will work fine in a VTA M-125 but instead of 125 watt per channel you will have an amp of maybe 110 watts. Consider this though > You probably won't even notice the difference in power of your amp(s) between using a 5AR4 and a 5U4 rectifier under normal playing conditions.
Bob
Dave_in_Va, Tubes4ever and 98indypacer like this post
98indypacer- Posts : 23
Join date : 2022-01-12
Bob, thanks for the reply. I’ll them both a try.
lavane- Posts : 4
Join date : 2015-10-14
What about 5V3A's? This last version of this rectifier has a 3 amp heater current draw and only has 17 volts more drop over a 5AR4. They're pretty stout rectifiers used in TV's. The earlier versions of this rectifier had a 3.5 to 3.8 amp current draw for the heaters, so you would want to make sure its a 5V3"A", NOT the 5V3, 5AU4, or tubes marked 5V4/5AU4.Bob Latino wrote:Tubes4ever wrote:Yes. Just one 5U4GB.
You can use a 5U4 in place of a 5AR4/GZ34 in any of the VTA amps BUT > a 5U4 has a higher voltage drop than a 5AR4 and will provide a slightly lower B+ DC voltage. Using a 5U4 in place of a 5AR4 will work fine in a VTA M-125 but instead of 125 watt per channel you will have an amp of maybe 110 watts. Consider this though > You probably won't even notice the difference in power of your amp(s) between using a 5AR4 and a 5U4 rectifier under normal playing conditions.
Bob
I tried a 5V3A in my VTA ST-70. The 5v winding is rated for 3 amps, but it did cause the power transformer to run hot so I put the 5AR4 back in it.
Seamus- Posts : 92
Join date : 2020-03-17
Tube rectifiers have NO PLACE in a HiFi amplifier.
OEMs dumped them as soon as solid state was available.
Tube rectifiers are nice in MI amps where their sag adds to the tone.
Not so much in HiFi
OEMs dumped them as soon as solid state was available.
Tube rectifiers are nice in MI amps where their sag adds to the tone.
Not so much in HiFi
mijohn and lavane like this post
lavane- Posts : 4
Join date : 2015-10-14
Most of my tube amps and preamps do have SS rectifiers. The 5V3A's should be more reliable than a 5AR4 in the ST-70. I do use SS rectifiers now in my M-125's. But for those that prefere a tube rectifier. The 5V3A is much cheaper than a GZ-37, but isn't a soft stert rectifier though. The 5U4 is rated for 3 amps also, so if people have been using them, I would think the 5V3A would be a good sub for those using 5U4's since it has a lower voltage drop over the 5U4. Personally, I just didn't like that the power transformer ran hotter in my ST-70.
rebellovw- Posts : 78
Join date : 2022-01-23
Thankfully my GZ37's have lasted for some time. I only run two output tubes, independent bias at .5 and a bucking transformer - I'll never run more than 2 tubes as that was just crazy and resulted in many blown tubes. I wish quads of KT88s were cheaper (and of Sovtek quality) like they used to be.
Anyhow - I have gobs of power with my two 6550's, KT88s or KT120s.
Anyhow - I have gobs of power with my two 6550's, KT88s or KT120s.
LeGrace likes this post