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Amp gave me a nice light show tonight

WopOnTour

WopOnTour

Hoarder Extraordinaire
So I've been recapping my old Harmon Kardon A260 over the last couple of weekends. Fired her up tonight and after a bit of burn in and voltage check, I decided to throw in the quad of RCA black-plates (6L6GC) I've been saving for this old girl (had some Chinese JJs in her during the testing phases of the upgrades)

After listening for about an hour in total amazement, I decided to turn out the lights and see how the good ol' tube glow lit up the room. To our surprise we received quite the light show from the bright blue haze that had formed and danced within each envelope.

I've seen this before, but never witnessed it with this level of royal blue intensity in any of my tube amps through the years- not even in my JEL 300Bs operating at much higher plate voltage
Took some pics and thought I'd share.
Hard to believe but I think it made even Steely Dan sound even better and added a totally surreal ambiance to our listening session.

Enjoy
Wop
 

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I've always thought tubes had a "living, breating" quality to them - like there is real magic happening inside those glass envelopes.

We may never see the end to the argument of "tube sound" vs. "solid state" but watching transistors is nowhere near as cool as that!
 
Yeah ! Tubes in the night are a kind of magic.
This is the first reason for serious audiophile to listen in the night.
The second reason is because you do not want your wife understand you bought something else...
 
My quad of GrooveTubes EL34's glow like that, but not as intense. Still very noticeable and cool to look at.......
 
6L6GCs have always done this the most of any output tube I have ever used. Some 6550s and KT88s do the purple glow also, just not quite as dramatically as can 6L6GCs. Unfortunately most EL34s generally dont have much of this cool glow. :sigh:

I'm not certain what causes it though. All of the amps that I have owned that did this had Pentode output stages, and used "beam-power tubes". I've read some people say that this is the result of a tube getting gassy, but I don't know if this is correct or not. :scratch2:
 
goldear said:
6L6GCs have always done this the most of any output tube I have ever used. Some 6550s and KT88s do the purple glow also, just not quite as dramatically as can 6L6GCs. Unfortunately most EL34s generally dont have much of this cool glow. :sigh:

I'm not certain what causes it though. All of the amps that I have owned that did this had Pentode output stages, and used "beam-power tubes". I've read some people say that this is the result of a tube getting gassy, but I don't know if this is correct or not. :scratch2:
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Yep, has been my experience as well.
 
I used to have a Soldano 50 watt tube guitar head. They are designed so that you can see the tubes through expanded metal grills on the front and back.

It was cool to hit a power cord and watch those tubes go purple and blue.

Nice pics!
 
It is fluorescence caused by electrons striking elements in the glass envelope. Doesn't mean that the tube is bad or gassy.
 
It is fluorescence caused by electrons striking elements in the glass envelope. Doesn't mean that the tube is bad or gassy.
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Agreed, it's my understanding that the "blue glow" on the inside of the glass envelope is normal in many power tubes. However, when the glow is coming from within the plate or grid area this can indicate a "gassy" condition.
 
junkaudio said:
strange thing i found tubes without lightshow sound better
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Well these sound great, but I did notice they wernt putting quite as much ooommmff as some of my other quads for this amp.(and some of them dont glow at all!) So maybe they're a bit tired? Perhaps this contributes to the effect?
I dunno- but I like it :D
Wop
 
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