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Discussion in 'Amps/Cabs Tech Corner: Amplifier, Cab & Speakers' started by muddy, Apr 21, 2008.
Thanks for the link, Blue Strat.
Amen to that!! I just threw some in my Peters Halo last week and they sound fantastic, esp. compared to the JJ E34L's that were in there previously. More clarity, less upper-mid punch (was a bit much w/ the JJ's), tighter and simply better sounding low end, and different guitars sound even more different than one another as their nuances are more clearly presented.
I can't believe you can still find a matched quad of these for "only" $150. I always figured you could do 'good enough' with new production, but I took the leap and really dig these NOS Siemens EL34's...
Blue Glow -- what causes it?
There are TWO causes for this glow in audio power tubes; one of them is normal and harmless, the other occurs only in a bad audio tube.
Most Svetlana glass power tubes show FLUORESCENCE GLOW. This is a very deep blue color. It can appear wherever the electrons from the cathode can strike a solid object. It is caused by minor impurities, such as cobalt, in the object. The fast-moving electrons strike the impurity molecules, excite them, and produce photons of light of a characteristic color. This is usually observed on the interior of the plate, on the surface of the mica spacers, or on the inside of the glass envelope. THIS GLOW IS HARMLESS. It is normal and does not indicate a tube failure. Enjoy it. Many people feel it improves the appearance of the tube while in operation.
Occasionally a tube will develop a small leak. When air gets into the tube, AND when the high plate voltage is applied, the air molecules can ionize. The glow of ionized air is quite different from the fluorescence glow above--ionized air is a strong purple color, almost pink. This color usually appears INSIDE the plate of the tube (though not always). It does not cling to surfaces, like fluorescence, but appears in the spaces BETWEEN elements. A tube showing this glow should be replaced right away, since the gas can cause the plate current to run away and (possibly) damage the amplifier.
the above from www.vacuumtubes.net & Svetlana
The second case is what I am referring to.
Thanks for the interesting read FYI this link is dead at the bottom of your reference
Of course, you might have a serious situation if the blue glow looks like this.
©1996-1999 Larry Barras, all rights reserved. May not be reproduced without permission.
Last Modified: 12/31/1999
Oh well, I don't control all the links.
Woops sorry Mike I thought this was your WebSite Your WebPage Your Business.
That particular link doesn't belong to me. Any more sarcastic statements you'd like me to address?
I wonder if you'd also like JJ KT77. What you describe sounds like it could be the JJ KT77, from what I've experienced.
NICE to hear from you James! Hope things are well with you! I'm still in love with my Halo... as is everyone else who hears it. Thank you again.
Funny you should mention the JJ KT77 - I was looking at them, but decided to give another EL34 type a shot before I tried those out. Got lucky with the Siemens for sure! But I'll definitely pick up a pair of the KT77's from Bob @ Eurotubes soon and give them a shot. With your amp it only takes me a few minutes to install and rebias
You're welcome! I'm very glad you like the amp. I'm doing well, thanks.
The JJ KT77 won't sound quite like Siemens EL34 but in their own way they might provide the sonic qualities you're after. I used to include them with my amps, but I found they were too "polarizing" of a tube...not quite "EL34 enough" for some and not quite "6L6 enough" for others. Nowadays I'm actually including EH EL34 with my amps, since they seem to be appreciated by everyone for a "normal EL34 sound".
Thanks for the info James - I've tried a few different types and brands in the Halo, but not the KT77's. Might as well - never know 'till you try. Thanks again!
I just installed a set of Groove Tube EL34m in my Emplexador. Running three NOS world globe Amperex 7025's in the preamp. The tech said this setup's tone was of very impressive quality. Running an old Tung Sol 12AX7 in the first position gave it a tad more clarity and chime so will also use that one.
These are the ones I would recommend for the tone you're after.
I've had good luck with the JJ's. I think they sound great and haven't had any problems with reliability so far though one preamp tube arrived DOA but that's out of about 35 tubes so far. The price is cheap enough that you can buy a few pairs and have some for backup.
i currently have ARS el 34 in my bogner shiva.
picked up a pair of gt el 34m a while ago for back ups.
where should the Gt be biased in 25-30 ma?
i know bogner recommend svetlanas .
Would a set of KT77's benefit an amp like the Bogner Ecstasy or Shiva? I'm thinking these tubes would improve the clean channel while still maintaining the punch and saturation in the dirt channels.
Chinese EL34's wont last long in the Bogner. JJ's and St Petersburg winged =C='s are about the only ones that will take the plate voltage.
I like the sound of JJ EL34's but have had a 50% failure rate out the box lately. I hear that Eurotubes burns theirs in for a bit to weed out bad ones so I may try ordering from them in the future. Would like to try the E34L too.
I'm pretty sure Doug and Mike burn theirs in as well. I have never hesitated to order from either of them and never had any issues. :BEER
What's also interesting is how I've found that I prefer one tube over another depending on speaker used.
With an Emi Wizard I preferred a KT77's robustness, but with a Greenback type speaker I prefer an EL34 for more clarity over the KT77.