[Phantaminum]

@2359glenn

Good luck tomorrow.

Glenn’s going to be up to his neck in orders with all of the Verite and Aeolus reviews coming out. If he’s not already there.

 

[JazzVinyl]

Hi JV,
You mean 75 year old tubes, right?

Goodness! Yes!!

75 year old FDD20’s!!

Thats crazy!!

And still freeing electrons from random atoms!!

 

[2359glenn]

Glenn’s going to be up to his neck in orders with all of the Verite and Aeolus reviews coming out. If he’s not already there.

Swamped with amp builds.

 

[JazzVinyl]

See!!! Same number and date!!!!

 

[JazzVinyl]

Due to the large gain from FDD20, I like them best with 6AS7G, 6080 or 5998, as powers...



They are a superb driver. Do an excellent job of freeing electrons, some 75 years after being manufactured...(almost 76 years, now)...


.

 

[leftside]

5998 have high gain....

 

[JazzVinyl]

5998 have high gain....

Yes, a gain of 5 isn't it? Higher than 6080 or 6AS7G at 2x...for some reason, my FDD20's suffer from noises when using the six pack of BX/BL's...

 

[leftside]

I get slight noise with 2 ECC35 if I use them with 2 5998 in the WA22. They are fine with the GEC 6AS7G.

 

[mordy]

I get slight noise with 2 ECC35 if I use them with 2 5998 in the WA22. They are fine with the GEC 6AS7G.

Tube proverb: If they make it, it hums.

 

[leftside]

Tube proverb: If they make it, it hums.

Not in this case Humming because they are in pain (too much gain).

Generally, if I have tubes that hum I try the following:
1) Use some very fine grit sandpaper to clean the pins
2) Try with a different combo of other tubes
3) Try running for a few hours. Perhaps they need to settle down. Perhaps they haven't been used for 75 years....

If they still hum after that, then they head for the trash.

 

[mordy]

Not in this case Humming because they are in pain (too much gain).

Generally, if I have tubes that hum I try the following:
1) Use some very fine grit sandpaper to clean the pins
2) Try with a different combo of other tubes
3) Try running for a few hours. Perhaps they need to settle down. Perhaps they haven't been used for 75 years....

If they still hum after that, then they head for the trash.

Hi leftside,
Let me know when you are throwing something out - was able to tame hum with high temperature silicon tape tightly wrapped around the glass.....
(Makes the tube look like a TS BGRP lol)

 

[Xcalibur255]

I finally switched the 5pin sockets to 8 pin and switched filament voltage from 2.5 to 6.3. Going from #27s to GEC L63
So the amp is all GEC now the beauty o these tubes they are perfectly quiet. I had a hard time finding quiet 27s.
I went nuts with filtering and run the filaments ob DC just to have noisy tubes.
If you can find a pair of L63s cheep get them they sound great. You will need a dual 6J5 to 6SN7 adapter though.
Pic of the amp had to clean allot of dust of o it as it was buried in the back of a cabinet just had to turn on the switch.
Went crazy building this amp in 2006 all wires carrying audio are DH labs 18 ga 99.999% pure silver. And I used
giant Solan output coupling capacitors. Would never do this today craziness.

Glenn what is the single Jupiter PIO cap that is sitting between the Solen caps for? I'm assuming the Solens are the output coupling caps so is the Jupiter some kind of a bypass?

 

[UntilThen]

25 May 1942

 

[2359glenn]

Glenn what is the single Jupiter PIO cap that is sitting between the Solen caps for? I'm assuming the Solens are the output coupling caps so is the Jupiter some kind of a bypass?

The Jupiter is coupling between the L63 and 6AS7 the other one is under the two blue bypass capacitors.

 

[gibosi]

Yes, those 75 year-old FDD20 are pretty old, but if you want old, try some 90 year-old #27's. As Glenn points out, it's hard to find quiet pairs, but when you do, they sound glorious.