[gibosi]

Question on a certain rectifier. This page lists a GZ34 5690 RCA, but I can't find anywhere else which says this tube is a GZ34 which I know would work in my GlennOTL.
Was able to find this page on the 5690, and another on the GZ34 and even with my very limited understanding of tubes, looks like the specs are very different.

I don't want to try the 5690 if there's any chance of damaging the amp or other installed tubes, but I actually bought it based on the GZ34 description and it literally being the first thing in the ad. Can't get any info from the seller. Anyone know anything about using this 5690 tube? Thanks!

You are wise to hesitate.

Note that the heater voltage, Vf, is 12.6 Volts. The GZ34 is 5 volts. And except for the 3DG4, the only rectifiers you can use in your GOTL, without a special adapter, are 5 volt rectifiers. So the 5690 cannot be used in your GOTL.

And also note, from this example, vendors' descriptions cannot be trusted.

 

[hpamdr]

Since the 6J5 tube supposedly was developed from the 6J7 tube I decided to try the 6J7 metal and 6J7G glass tubes. (The 6J7 family of tubes have a top anode cap.) My GOTL has sockets for C3g which is a pentode, and Glenn said that it is better to use pentode to pentode sockets than a dual socket to 6SN7.
Deyan made two 6J7 to C3g adapters for me (also work for EL32 and some other tubes). The sound from the 6J7 tubes was good, but I had a persistent problem with hum and no matter what I tried, I could not get rid of the hum, and gave up on these tubes.
If you can find a way to eliminate the hum, the 6J7G tubes are a viable and very inexpensive alternative.

Tthe 6J7 familly do have Top Cap connected to grid and not to anode. Same pin out as EL32 or 6U7 so if you have 6J5 or C3g adapter for EL32, 6J7 can be used with Same Adapter.
6SJ7 need a specific adapter to be connected to 6J5 or C3g adapter:
For 6J5 : Pinout to base
1 -
2 - 2
3 - 8
4 - 5
5 - 8
6 - 3 (with 100R)
7 - 7
8 - 3

For C3g you need specific Loatal base
1 -
2 - 1
3 - 2
4 - 6
5 - 8
6 - 4
7 - 8
8 - 3

 

[robo24]

You are wise to hesitate.

Note that the heater voltage, Vf, is 12.6 Volts. The GZ34 is 5 volts. And except for the 3DG4, the only rectifiers you can use in your GOTL, without a special adapter, are 5 volt rectifiers. So the 5690 cannot be used in your GOTL.

And also note, from this example, vendors' descriptions cannot be trusted.

Some good news, finally heard back from the vendor who admitted his mistake and fully refunded me without having to send the tube back! So an honest mistake it seems and just glad it got resolved.

 

[Monsterzero]

Some good news, finally heard back from the vendor who admitted his mistake and fully refunded me without having to send the tube back! So an honest mistake it seems and just glad it got resolved.

Didnt I send you a GZ32 and GZ34?
Tired of the GEC U18/20? Have you tried that other 4v rectifier I sent you?

 

[robo24]

Didnt I send you a GZ32 and GZ34?
Tired of the GEC U18/20? Have you tried that other 4v rectifier I sent you?

I've tried them all! Been using the Tungsram lately which I really like but not sure exactly why. So now since this not-GZ34 won't work I still just have the ones you've included. There's no rhyme or reason for any of it for me honestly, and I've been on a tube buying binge. I think I remember saying to you that I planned not to buy more since you were including so many, but that I was probably lying to myself, and sure enough, lol. I just like the constant variety and I'd read some about their line of red-based tubes. Also got a red 5691 for the 6SN7 slot so at least that will work and have read good things about it. Problem is now I have way more tubes than time to even really be able to compare them well.

The thing is I've still yet to find a roll I strongly dislike and even all these cheap, black metal 6C5s and such have just been amazing!

 

[mordy]

I've tried them all! Been using the Tungsram lately which I really like but not sure exactly why. So now since this not-GZ34 won't work I still just have the ones you've included. There's no rhyme or reason for any of it for me honestly, and I've been on a tube buying binge. I think I remember saying to you that I planned not to buy more since you were including so many, but that I was probably lying to myself, and sure enough, lol. I just like the constant variety and I'd read some about their line of red-based tubes. Also got a red 5691 for the 6SN7 slot so at least that will work and have read good things about it. Problem is now I have way more tubes than time to even really be able to compare them well.

The thing is I've still yet to find a roll I strongly dislike and even all these cheap, black metal 6C5s and such have just been amazing!

When you have a good amp almost everything sounds good. As time goes by it is possible to find those tube combinations that are still better than others, and even outstanding ones.

 

[whirlwind]

I've tried them all! Been using the Tungsram lately which I really like but not sure exactly why. So now since this not-GZ34 won't work I still just have the ones you've included. There's no rhyme or reason for any of it for me honestly, and I've been on a tube buying binge. I think I remember saying to you that I planned not to buy more since you were including so many, but that I was probably lying to myself, and sure enough, lol. I just like the constant variety and I'd read some about their line of red-based tubes. Also got a red 5691 for the 6SN7 slot so at least that will work and have read good things about it. Problem is now I have way more tubes than time to even really be able to compare them well.

The thing is I've still yet to find a roll I strongly dislike and even all these cheap, black metal 6C5s and such have just been amazing!

Nice to hear you are enjoying the amp so much.

There are a lot of nice sounding 6/12SN7 tubes, but the 6/12J5 tubes and the 6C5 tubes are much cheaper and easier to find if looking for NOS tubes.

 

[Monsterzero]

Nice to hear you are enjoying the amp so much.

There are a lot of nice sounding 6/12SN7 tubes, but the 6/12J5 tubes and the 6C5 tubes are much cheaper and easier to find if looking for NOS tubes.

Speaking of that, is there a 6j5 equivelant to the Tung Sol BGRP? Photo please if you got it.

 

[mordy]

Speaking of that, is there a 6j5 equivelant to the Tung Sol BGRP? Photo please if you got it.

Not to the best of my recollection. But the Tung Sol 6J5GT clear glass pack a good bass punch.
I don’t have the 6J5G TS tubes but I read that it is a top tier tube.
Maybe time to explore the ugly duckling TS 6J5 metal tubes?

 

[Monsterzero]

Maybe time to explore the ugly duckling TS 6J5 metal tubes?

Already have a pair of black can TS. Yes, not beautiful looking, and while they sound decent enough, theyre def not BGRPs

 

[dminches]

What is the best way to fix a loose tube base? The tube works fine but the base moves. I assume I should use an epoxy or silicone? Can someone recommend something?

 

[mordy]

What is the best way to fix a loose tube base? The tube works fine but the base moves. I assume I should use an epoxy or silicone? Can someone recommend something?

I use crazy glue in a little bottle with a brush. Just put in a little bit (a drop or two) and brush it into the space between the tube glass and base. Then hold everything in place for 60 seconds; afterwards I let it sit and dry for 24 hours.
Gibosi likes to use nail polish in the same way - with nail polish you can reseat the glass using nail polish remover if something goes wrong.
Crazy glue is kind of final - I have a working tube that looks like the leaning tower of Pisa...

 

[mordy]

Already have a pair of black can TS. Yes, not beautiful looking, and while they sound decent enough, theyre def not BGRPs

Just put in a pair Tung Sol 6J5 - not bad at all. The problem I have is that I don't know if they are Tung Sol tubes - maybe they were made by RCA.
Some Tung Sol tubes have the regular military date codes (instead of number/letter combinations):

322 = Tung Sol EIA number
5652-3 = December 1956 factory #3.
The same tube pictured above has more designations on the rim of the tube with a dating system used by RCA:

RCA DATE OF SHIPMENT From 1-1-36 to 7-1-45 The shipping date code for RCA-brand tubes used a letter for the year, plus a number (1 to 6) for each two-month period within the year, plus "E" for OEM sales. Lack of "E" indicates a tube for distributor sale. Whether the letter is to the right or left of the year letter indicates which month of the two possibilities (only 6 numbers for the months). Here are the year designations:
1936 Z 1937 U 1938 T 1939 X 1940 R 1941 Y 1942 S 1943 K 1944 H
1945 V
According to the RCA system, the Tung Sol labeled tube above which has a TS date of Dec 1956 and a RCA code 3Y was made in 1943 May-June. (To clarify - if it had said Y3 it might be May 1943 and 3Y = June 1943).
We do know that the all metal tubes were abandoned by the US defense forces because glass tubes were cheaper to manufacture. I have seen all metal tubes dated 1973, and even an all metal tube dated 1956 seems out of place.

Don't know what to make out of this - maybe gibosi can weigh in?

Here is an interesting link explaining why all metal tubes are better than glass tubes (although no mention of sound quality):
https://www.rfcafe.com/references/radio-craft/now-metal-tubes-june-1935-radio-craft.htm

Here is another link to the "medical vacuum tube department" - an autopsy of a metal 6J5 tube - very interesting:
http://www.r-type.org/articles/art-018.htm

 

[gibosi]

Just put in a pair Tung Sol 6J5 - not bad at all. The problem I have is that I don't know if they are Tung Sol tubes - maybe they were made by RCA.
Some Tung Sol tubes have the regular military date codes (instead of number/letter combinations):

322 = Tung Sol EIA number
5652-3 = December 1956 factory #3.
The same tube pictured above has more designations on the rim of the tube with a dating system used by RCA:

RCA DATE OF SHIPMENT From 1-1-36 to 7-1-45 The shipping date code for RCA-brand tubes used a letter for the year, plus a number (1 to 6) for each two-month period within the year, plus "E" for OEM sales. Lack of "E" indicates a tube for distributor sale. Whether the letter is to the right or left of the year letter indicates which month of the two possibilities (only 6 numbers for the months). Here are the year designations:
1936 Z 1937 U 1938 T 1939 X 1940 R 1941 Y 1942 S 1943 K 1944 H
1945 V
According to the RCA system, the Tung Sol labeled tube above which has a TS date of Dec 1956 and a RCA code 3Y was made in 1943 May-June. (To clarify - if it had said Y3 it might be May 1943 and 3Y = June 1943).
We do know that the all metal tubes were abandoned by the US defense forces because glass tubes were cheaper to manufacture. I have seen all metal tubes dated 1973, and even an all metal tube dated 1956 seems out of place.

Don't know what to make out of this - maybe gibosi can weigh in?

Here is an interesting link explaining why all metal tubes are better than glass tubes (although no mention of sound quality):
https://www.rfcafe.com/references/radio-craft/now-metal-tubes-june-1935-radio-craft.htm

Here is another link to the "medical vacuum tube department" - an autopsy of a metal 6J5 tube - very interesting:
http://www.r-type.org/articles/art-018.htm

I don't believe that Tung-Sol ever made all-metal tubes. Given that they were more expensive to manufacture and required specialized factory equipment, many manufacturers, especially the smaller ones like Tung-Sol, passed. Although, some companies simply mounted a glass octal inside a metal shell.

So I'm inclined to believe that Mordy's Tung-Sol is a relabeled RCA.

 

[gibosi]

What is the best way to fix a loose tube base? The tube works fine but the base moves. I assume I should use an epoxy or silicone? Can someone recommend something?

Hard nail polish ("Hard as Nails") or crazy glue and a couple rubber bands. And a Cossor 53KU is good to go.