Rectifier tube list?

Hi Everyone,
possible stupid question......

Have done some searching but cannot find a comprehensive list of recommended rectifier tubes.
I have a couple of Sophia Princess Mesh Plate 274B's and was wondering if they could be used in my MKIII's.
The 274's are supposed to be a replacement for the 5AR4.
Figured I could use the extra heat this winter.
thx!

Ernstmach wrote:Hi Everyone,
possible stupid question......

Have done some searching but cannot find a comprehensive list of recommended rectifier tubes.
I have a couple of Sophia Princess Mesh Plate 274B's and was wondering if they could be used in my MKIII's.
The 274's are supposed to be a replacement for the 5AR4.
Figured I could use the extra heat this winter.
thx!

5AR4 or it's european equivalent GZ34 is what is needed.

"5AR4 or it's european equivalent GZ34 is what is needed."

Thanks for your response but it doesn't answer my question....
I'm currently using the GZ34 and have used the 5AR4.

Ernstmach wrote:"5AR4 or it's european equivalent GZ34 is what is needed."

Thanks for your response but it doesn't answer my question....
I'm currently using the GZ34 and have used the 5AR4.

GZ34 IS same as 5AR4. Only another name.

Other tubes differ in properties, they might have larger voltage losses or they might have
other demands on filament current.

"Other tubes differ in properties, they might have larger voltage losses or they might have
other demands on filament current. "

Thanks again. The 274 is supposed to be a direct replacement for the 5AR4 based on what I have read on other sites.
I was hoping that someone here may have some experience with the 274.
Thanks!

Ernstmach wrote:"Other tubes differ in properties, they might have larger voltage losses or they might have
other demands on filament current. "

Thanks again. The 274 is supposed to be a direct replacement for the 5AR4 based on what I have read on other sites.
I was hoping that someone here may have some experience with the 274.
Thanks!

It is probably not usable, it mimics a 5U4 ( that has a larger voltage drop) but the
most importent difference is that the first CAP in VTA is to large.
Snippet from emissionlabs webpage (http://www.emissionlabs.com/datasheets/EML274.htm) :

Just to give the classical warning once more, when you see more than 33uF on a 5U4G, or more than 4uF on a 274B tube, such a schematic is questionable

"Just to give the classical warning once more, when you see more than 33uF on a 5U4G, or more than 4uF on a 274B tube, such a schematic is questionable"

Well, that does help!
Thank  you!
have a great day!

Writing only for myself, I am a fan of the 5U4 as a simple means to de-rate (de-stress/increase tube life) for any amp using the 5AR4. In most (emphatically not all) cases, the listener will detect no difference for most signal played at reasonable volume. That they are readily available at a reasonable cost (so far) is also appealing.

Peter W. wrote:Writing only for myself, I am a fan of the 5U4 as a simple means to de-rate (de-stress/increase tube life) for any amp using the 5AR4. In most (emphatically not all) cases, the listener will detect no difference for most signal played at reasonable volume.  That they are readily available at a reasonable cost (so far) is also appealing.

I second your opinion. Also, the 5U4GB is MUCH more reliable.

Bob Latino has posted somewhere on this site a very comprehensive listing of tube rectifiers, use the search function (and hopefully it works) or maybe Bob will check this thread

"use the search function "
I did try that with a couple of different search phrases but nothing came up.
Thanks for the reminder though!

Bob,
thanks for posting that.
The photobucket thing really messed things up!
I have printed that and added it to my tube folder for future reference.
Thanks for all of your effort.

Where would the GZ33 and GZ37 fit in there?

Does anyone know the equivelent to the GZ33 or GZ37??

Just curious since I hear so much about them and they aren't really much more $ than nice GZ34s.

Dave_in_Va wrote:Does anyone know the equivelent to the GZ33 or GZ37??

Just curious since I hear so much about them and they aren't really much more $ than nice GZ34s.

I measured the voltage drop of a new GZ37 and it was close to what you get with a 5U4GB.
You get the benefit of a slow startup and they seem to be much more reliable than a GZ34. Plus they look REALLY nice!

Dave_in_Va wrote:Does anyone know the equivelent to the GZ33 or GZ37??

Just curious since I hear so much about them and they aren't really much more $ than nice GZ34s.

There is no equivalent to the old Mullard GZ-33s. They are tough birds. If you do Roy's "yellow-sheet" mod on the socket they'll outlive your grand-kids.

Dave_in_Va wrote:Where would the GZ33 and GZ37 fit in there?

I installed a NOS GZ33 today in my ST-70 and discovered that I didn't need to change the bias at all. I had been using a GZ34. It acted just like a GZ34 as far as voltage drop. As others have noted, it is apparently pretty much bullet proof. And much better looking!

Folks, I was wondering after you have more than a few years of running these GZ33s and GZ37s I had a few questions.

1. Is the Yellow Sheet Mod REQUIRED to use the GZ33?
2. Are all of those tubes in the image from Photobucket actually a list of all of the tubes that can be used in a ST-70 that has the VTA-70 board in it?

I have the original Dynaco transformers in my 70 and I like how the 5U4GBs work to slowly bring everything up. They don't have the slam of the 5AR4s or even my Bugle Boy GZ34s, but they do the job. Wanted to see what everyone's experience is. I have a line on both GZ33 and GZ37s and I may just pick them up...but if there are mods that need to be done....I would have to make them.

Thanks,

FG.

No. The yellow sheet mod is not required. It has been added solely to extend the life of the crappy modern day 5AR4/GZ34 tubes that can't handle the reverse voltage for very long. If you like your 5u4GB, keep using it. I found the GZ33 to be a drop in replacement for the 5AR4 tube. The GZ37 had a drop more like a 5U4GB.
As far as the rectifier list, if the tube has a pinout like a 5u4 or 5AR4 then it will work. It will just have a different voltage drop than a 5AR4. The original ST70 transformer was rated at 3 amps on the 5 V winding. So keep that in mind.

Tubes4ever wrote:No.  The yellow sheet mod is not required.  It has been added solely to extend the life of the crappy modern day 5AR4/GZ34 tubes that can't handle the reverse voltage for very long.  If you like your 5u4GB, keep using it.  I found the GZ33 to be a drop in replacement for the 5AR4 tube.  The GZ37 had a drop more like a 5U4GB.
As far as the rectifier list, if the tube has a pinout like a 5u4 or 5AR4 then it will work.  It will just have a different voltage drop than a 5AR4.  The original ST70 transformer was rated at 3 amps on the 5 V winding.  So keep that in mind.

Thank you so much for this. I was thinking that no one was going to reply back to this thread because it was very old. My config is a ST-70 with the original iron, with a new quad cap, and the VTA-70 Octal board which I adore. I am concerned about the original PA060 and have been toying with the idea of replacing it. I am going to get a GZ37 and GZ34, but right now I am using a 5U4G and sometimes 5U4GB as they are plentiful. Will I be completely wearing out my PA060 and the OPT if I continue using the 5U4/5U4GB or GZ37? I would really like to know what @Bob and @Roy think. I am hoping that they will see this.

Thank you again!

Regards,

FG.