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Post by Ayton(e) on Mar 27, 2009 18:17:33 GMT -5
After replacing a speaker today, I bumped the amp pretty hard while it was on standby. Switched on, got about a minute of good sound, then some nasty barking and a bright (possibly blue?) flash from the power tubes. Turned off right away. Tried again after a few mins, got a little normal play then some scratching and volume loss while one power tube went supernova, glowing bright orange. Turned off fast.
My question: Could the new speaker have caused this, shorting something out? It's an old speaker and may have had a hard life before it came to me today. Sounded nice before the flash.
Or is it much more likely that giving the amp a good bump while on standby has hurt a tube? I think I read somewhere they are more prone to damage when hot.
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Post by joshsage on Mar 27, 2009 20:21:55 GMT -5
nah man, by bet is it just popped a power tube. Try on a diff cab, are you sure you wired it up correct??? Had an elmwood m90 with a bad power tube act like a strobe light, REAL SCARY! Worst case, you'll probably be out a pair of tubes, but hell you're on a comp, half price for power tubes!!  Good luck! |
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Post by Jammermatt on Mar 27, 2009 22:23:06 GMT -5
My bet's on a bad tube. i've never seen the flash, but when my tubes go out they supernova like that.
After stealing your sliding clip idea, i went and bought a cheapie multimeter to test my speaker cabinet while i was swapping speaks in and out. it was a good 20 dollar insurance policy.
Pray tell, what kind of speak are you abusing now?
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Post by Ayton(e) on Mar 28, 2009 10:10:07 GMT -5
Thanks guys, it must be the tube then. I was just sort of worried the speaker had caused the tube to blow, because the timing seemed so coincidental. I definitely wired it up right: one speaker, 8 ohms, not a lot you can get wrong! I put the speaker in another amp though and it operated fine. Jam, I got an old T75. I was curious already, but after hearing that clip on here of the QR through a 75 I needed one. It 'gave good Yngwie' in the minute I got to play the Splawn through it before the fireworks! Now to call Scott and get some toobz. Hope they ship fast.  |
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Post by Jammermatt on Mar 28, 2009 10:56:36 GMT -5
You'll have them probably in under a week. I have a very worn set of Mullards, but Scott's will get there first. My experience is the 75 will give you your bass knob back and pinch harmonics should be more prominent.
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Post by splatter on Mar 28, 2009 11:08:51 GMT -5
never heard of speakers hurting tubes . If the impedence isn't matched it will kill the out put trans not the tubes .
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Post by Ayton(e) on Mar 30, 2009 9:40:43 GMT -5
never heard of speakers hurting tubes . If the impedence isn't matched it will kill the out put trans not the tubes . This is the sort of grown up talk that puts my mind at ease. Thanks. New pair of Mullards ordered just now. I'm not going to get into the biasing just yet, so gave the shop my codes from the tubes that shipped with my amp when it was new. I think they might have changed testing machines; my old rating of 56 equates to a 37 on the new scale. I can't wait to have her singing again.  My only fallback is my old modeling amp, and although it's the easiest thing in the world to play, it just has no life or body to the tone like the real thing. |
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Post by Jammermatt on Mar 30, 2009 10:35:28 GMT -5
Ayt,
My tech/hairdresser told me that when a transformer goes it is unmistakeable because the smell is like no other - you would definitely know it. I hear you on the modeling amp thing. After playing the Comp for two years now, the modeling amp really makes me sound like I know what I'm doing. But, there's no dialing back the volume to get clean, and it sounds the same all the time.
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Post by splatter on Mar 30, 2009 12:05:39 GMT -5
I burned up a tranny in a plexi once . It was cause I was using a sholtz power soak . It started smoking like a smoke stack . Stank to high heven . If you burn up a transformer you will know it .
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Post by Jammermatt on Mar 30, 2009 12:31:17 GMT -5
Did it smell like death?
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Post by splatter on Mar 30, 2009 14:07:52 GMT -5
yea, plexi death.
actually it wasn't that expevsive to get it repaired
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Post by SonicExplorer on Mar 30, 2009 18:41:01 GMT -5
Check the resistance on the cab with an ohmeter to be sure you are still getting the proper impedence.
Yes, it's very possible the bump toasted your tube. I try to tell people all the time that heat and vibration are the death-blows to tube amps. The heat comes naturally from the tubes themselves, so throw in a good bump or excess vibration and you are taking life off the tubes.
DC will say this concern is as real as cone cry (even though it exists). ;D
Think about it...remember what happened to sparklers when you were a kid? They bent over as the steel center became red hot. So when you bump or shake hot tubes what do you think eventually happens to the internals?
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Post by Jammermatt on Mar 31, 2009 22:14:37 GMT -5
The Eurotubes guy swears by what Sonic says also.
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Post by Ayton(e) on Apr 1, 2009 10:40:01 GMT -5
Yep, I can totally believe that the bump killed my tubes while they were on, thanks to all for the peace of mind. Hopefully as I switched off fast I won't have harmed any other components... although I did turn the amp back on briefly. :/
Well, delivery works fast on the east coast it seems. Ordered the tubes Monday and today found a FedEx door tag! Tomorrow I will watch for that redelivery, don't know how I missed them today.
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Post by LooseCannon on Apr 1, 2009 19:37:37 GMT -5
Well, delivery works fast on the east coast it seems. Ordered the tubes Monday and today found a FedEx door tag! Tomorrow I will watch for that redelivery, don't know how I missed them today. You gotta stop masturbating man  |
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