I went to a friend's place today to pick up some tubes for my TL/12 to try out, and the first thing I noticed upon plugging in this mismatched set of 6L6's was the rather distinct blue glow! I'd seen it in photos from the same friend on different tubes, but his camera isn't all that great and couldn't really capture it well... So I took a few shots with my dSLR, and this is the best of the bunch.

Enjoy! :D :D :D

http://members.shaw.ca/Orcinus2/AV/LEAK_TL12/healthy_blue_glow.jpg

:music:

:cool:

Very nice, love that blue glow:thmbsp:

I went to a friend's place today to pick up some tubes for my TL/12 to try out, and the first thing I noticed upon plugging in this mismatched set of 6L6's was the rather distinct blue glow! I'd seen it in photos from the same friend on different tubes, but his camera isn't all that great and couldn't really capture it well... So I took a few shots with my dSLR, and this is the best of the bunch.

Enjoy! :D :D :D

http://members.shaw.ca/Orcinus2/AV/LEAK_TL12/healthy_blue_glow.jpg

:music:

Ya gotta love the "noise free" images those Canons deliver in low light. I love the warmth and glow of a kick a** tube amplifier.

Appears to be a some orange glow on the plate as well.....

The RCA 7591's in my MAC MA230 glow like that, beautiful. None of my other tube amps or even my other 7591's have such a wonderfull glow. I may try some 6L6's in my AES Superamp.

Appears to be a some orange glow on the plate as well.....

Yep and that isn't a good thing. Needs to be re-biased.
*EDIT* Very pretty pic BTW.

I thought the blue glow indicated tubes that had comprimised vacuum?

No,the blue glow represents a "hard" (very high) vacuum. The deep blue fluorescence is stuff (e.g., "rare earth" minerals) in the glass fluorescing.

I have a new desktop background for the day.

EDIT: which camera did you use?

Some of my chinese 6L6GCs have that blue glow when I'm using them in my Fisher 500. It does look sweet!

EDIT: which camera did you use?

My guess is that it was a Canon Digital Rebel XT, shot with a 20 second exposure at F8, with the ISO set at 400. The lens probably had a focal length of 100mm. Mind you, this is just a guess:)

crud, I didn't even notice the glowing plate in the one tube.
I must resign my tube-guy commission :-(

Do you know what kind of tubes they are?

No,the blue glow represents a "hard" (very high) vacuum. The deep blue fluorescence is stuff (e.g., "rare earth" minerals) in the glass fluorescing.

I have a new desktop background for the day.

EDIT: which camera did you use?

I used a Canon EOS Digital Rebel XT with an EF 28-135mm f/3.5-5.6 IS USM lens, at 20 seconds, f/8, ISO400. The image is un-edited aside from cropping and resizing.

Do you know what kind of tubes they are?

one is a Westinghouse 6L6GB, the other is a General Electric 6L6GB. the GE tube is the one with the glowing plate.

My guess is that it was a Canon Digital Rebel XT, shot with a 20 second exposure at F8, with the ISO set at 400. The lens probably had a focal length of 100mm. Mind you, this is just a guess:)

Someone knows how to read EXIF data. :thmbsp:

Yep and that isn't a good thing. Needs to be re-biased.
*EDIT* Very pretty pic BTW.

How do I rebias? There are no adjustment pots in the amp. Schematics are provided below.

http://home.mira.net/~kiewavly/Leak/tl12_cct.gif

(First and foremost) Match the tubes.
Check the 470k and 600 ohm resistors and make sure they match each other.
Replace those 35 uF electrolytics, while you're at it.

(First and foremost) Match the tubes.
Check the 470k and 600 ohm resistors and make sure they match each other.
Replace those 35 uF electrolytics, while you're at it.

Amplifier documentation specifically says matched tubes are not needed.

All capacitors (except those sealed inside steel can; those will come later) have been replaced. paper/oil ain't so great after 55 years of slow leakage.

Will check the resistors next time the amp is on the bench for tube rolling, probably later tonight. (Do I have that term right? tube rolling, i.e. the process of swapping tubes out to see how different ones sound? I admit I'm a bit of a n00b when it comes to tubes :D )

Speaking of capacitors, does anyone have any spare 500v caps they'd be willing to donate to a poor AK'ers first tube amp restoration? I only need two 4uF, one 8uF, and one 0.001uF.