AudioNervosa
Systemic Development => Amplification and Preamplification => Tubes => Topic started by: Bob in St. Louis on March 26, 2010, 02:39:58 PM
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Hello folks,
Quick question for you:
Recently, I installed a new set of tubes in a Jolida 202a amp. The sound is wonderful, no complaints there. However, the instant I turned the amp on, one tube (12AX7) has the lumens of a 50 watt light bulb. An extremely bright white light that lasts about two seconds as it gradually dims to its normal orange glow. It's rather pretty, but scares the Hell out of me.
Is this safe for the amp? Should I worry about it?
Thanks guys! :thumb:
Bob
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Amperex? Pray tell?
It's normal for some tubes.
I think you need some hell scared outta you anyway/./
I didn't know you had tube amps, dude. I have newfound respect. :-P
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Sovtek I think. :-k
I got 'em from McShane a few weeks ago. If memory serves, he directed me to the Russian jobbies. I can check when I get home.
I scare the Hell out of myself on a regular basis anyway Rich. With the system being full active and requiring six channels to listen to two channel music, it never fails that I'll forget a setting (muting one of the channels) and I'll search for a hour thinking I've blown an amp. :duh
Anyway, yea. I've been much cooler than you've know about for quite some time Rich. 8)
So suffice it to say that it's normal and I shouldn't worry about it?
Thanks for the speedy reply!
Bob
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BOB :roll: :wtf: Run for cover, hug the kids, kiss the wife , put your head between your knees andkiss your arse goodbye. :rofl: :thumb:
charles
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I always thought you were cooler than you acted online. :thumb: Glad to know I was right.
It's the filament drawing too much juice because its resistance is too low. You could check it with a meter if you knew which pins and the spec. It will wear itself out a little quicker that way. If there is a fuse on the filament circuit it is safe to use it without stressing the circuit. If not, make sure it always goes dim quickly. If it stays bright more than a few seconds, shut it off and ditch the tube. If it always did that since you got it new it's just a defective tube, email Jim and ask for a replacement, or put your old ones back in.
All of the 4 tubes have the same filament voltage (nominally 6.3VDC) and same filament part (if they are all new sensor tubes) so they should all behave the same. But as long as it dims down quickly it is OK to keep for a spare.
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hehe... My Ecc801S Mullards do the same thing. They both light up then dim to the appropriate level. Its been running fine.
M
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My sex tube does it too. Amperex 12AU7. I wonder if they are from same factory as your Mullards?
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Bob,
That is normal, do NOT worry about it, some Euro tubes do that, especially Amperex,some Mullards, a few more. Just don't have any amplifiers on or the signal going to the amp, tubes need to dissipate their start up energy down for at least 30 seconds, that is why we put in a 30 second time delay output in all of our products. You would not want that start up energy to be passed thru your source,to the preamp and then to your speakers. Tubes need to settle down upon first start up. The flash which is definetly scary is the way it is and you should not be alarmed.
Now, if it was a power tube then there is a problem but that little 9 pin minature was built to do that. As Arnold would say "no problemo"
The golden rule for tube components when first turning on your system is source first, let it settle down for a minute or so, then tube preamp, let that settle down for at least a minute maybe two, then power amps.
When your done with your listening session, power down the amps first, then the preamp, then the source. The exact opposite of the turn on sequence.
Later,
Bill
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Bob,
As the others mentioned, most tubes from Amperex and Mullard will flash upon startup but I have never heard or seen a Sovtek do that. The only other brand that I've seen flash is some Tungsrams. Confirm with Jim Mac to verify.
Cheers,
Paul
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Hello men. Sorry for the delay.
Thank you very much for the information. Much appreciated.
I checked the brand, it a Tung Sol. Not sure if that matters, but it doesn't sound like it would.
BOB :roll: :wtf: Run for cover, hug the kids, kiss the wife , put your head between your knees andkiss your arse goodbye. :rofl: :thumb:
charles
Charles,
Actually, you don't know how correct you are.
I sent myfamily out to the driveway for about 30 minutes in the cold and rain when it happened.
Also, how do you get Halon out of audio equipment?
Bob ;)
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Hello men. Sorry for the delay.
Thank you very much for the information. Much appreciated.
I checked the brand, it a Tung Sol. Not sure if that matters, but it doesn't sound like it would.
BOB :roll: :wtf: Run for cover, hug the kids, kiss the wife , put your head between your knees andkiss your arse goodbye. :rofl: :thumb:
charles
Charles,
Actually, you don't know how correct you are.
I sent my family out to the driveway for about 30 minutes in the cold and rain when it happened.
Also, how do you get Halon out of audio equipment?
Bob ;)
I think a Halon fire suppression system is in order. Hey if all fails you can open a restaurant. No worry as the posters have said.
Here is some tube law. Always turn on source first. preamp second and amp last. The reverse in turning off. With one cravat leave the music playing when turning off the system. drains the power supply caps leaving no residual current. After turn on let the tubes warm up for 15 minutes before playing. About an hour later when all is up to operating temp. your in like Flynn. If you have a bias adj. try a lower bias setting [ 20% less] it will extend tube life. Have fun. :thumb:
charles
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Lower bias may extend tube life, but higher/normal bias will usually give you a crisper, punchier, better sound. Trade off's.
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All good points, thanks men! :D
Also, thanks for the reminder about biasing. I've been meaning to do that for a while now.
Bob