#1
When I power off the amp or put it on Standby there is this huge crackle for about 2 seconds and it's loud. Turning the volume down when powering it off or when putting it on Standby does nothing. It still crackles real loud. It does this bout 90% of the time.
I'm new to tube amps and I couldn't really turn up much on Google. I read that it could be the preamp tubes, but I'm not too sure..
It's a Peavey 6505+ 112 Combo Amp

Any help is appreciated.

I looked at the power tubes of the amp when I switched it to standby mode and noticed one of the tubes doing this when the amp crackled (more specifically the one on the right):

(Actual vid of my tubes)
http://www.youtube.com/watch?v=XZO9VjaEODE&feature=youtu.be

I was able to "recreate" the crackling by turing up the volume on the amp a bit.

Diagnosis?
Last edited by IbanezGSA at Mar 8, 2012,
#2
If you can crack it open, tap the tubes, one by one, if the tap isn't amplified (should heard like either a ping or a louder tapping sound), the tubes too microphonic and it will need replacing
#3
I took a pencil and gave the power tubes a couple slight taps and there wasn't any sound.
Is that a bad thing?
#4
No, that's a good thing. It means your tubes aren't microphonic and should be fine. I don't know what else could be causing your noise, though. Maybe the outlet you're plugged in to doesn't provide good, clean current? Are you using a power conditioner?
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#5
Quote by barden1069
No, that's a good thing. It means your tubes aren't microphonic and should be fine. I don't know what else could be causing your noise, though. Maybe the outlet you're plugged in to doesn't provide good, clean current? Are you using a power conditioner?

Alright, cool.
I'm not using a power conditioner.
I recorded what the tubes to when the amp crackles does that say anything?
It's linked on the first post.

I thought it was interesting that only one of the tubes flashes blue..
Last edited by IbanezGSA at Mar 8, 2012,
#6
Sorry, I didn't see that (or maybe I did and my brain just didn't register it). Blue tubes are usually fine - I've heard it's actually a sign of a better gas content in the tube itself. It's caused by electrons interacting with the gas near the glass, I believe (although I'm no expert, so if I'm wrong, by all means someone correct me). The flashing therefore means that there's spikes in the current (and therefore electrons) going through the tube. If you turn it up really loud and strum hard, the tube should flash blue too.

Based on that, I'd say it's something to do with your power source, but I'd really like a second opinion as this is mostly anecdotal...
Gear
Highway One Tele (w/Custom Shop 51 Nocaster pickups)
Standard Tele (modded to Nashville specs)
Reverend Roundhouse

Orange Rockerverb 50 MKI
Vox AC4c1
Jet City JCA20H

And pedals!



"Shiva opens her arms now..
...to make sure I don't get too far"
Last edited by barden1069 at Mar 8, 2012,
#7
Quote by barden1069
Sorry, I didn't see that (or maybe I did and my brain just didn't register it). Blue tubes are usually fine - I've heard it's actually a sign of a better gas content in the tube itself. It's caused by electrons interacting with the gas near the glass, I believe (although I'm no expert, so if I'm wrong, by all means someone correct me). The flashing therefore means that there's spikes in the current (and therefore electrons) going through the tube. If you turn it up really loud and strum hard, the tube should flash blue too.

Based on that, I'd say it's something to do with your power source, but I'd really like a second opinion as this is mostly anecdotal...

What I've researched so far about blue tubes matches what you've said.
Normally my tubes brighten and dim the neon blue color depending on how loud or hard I'm playing and both tubes lighten up and dim in unison. What I'm confused about is why only the right tube is flashing so bright of a neon blue. It makes sense that it's flashing due to a peak in current, but what's causing the peak and the crackling sound?
Last edited by IbanezGSA at Mar 8, 2012,
#10
It almost sounds like a bad voice coil in the speaker. Can you plug in another speaker and check that?
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#11
Tried a different Cable?
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#12
Quote by barden1069
Blue tubes are usually fine - I've heard it's actually a sign of a better gas content in the tube itself. It's caused by electrons interacting with the gas near the glass, I believe (although I'm no expert, so if I'm wrong, by all means someone correct me).

Allow me to correct you. Blue is impurities on the plate flourescing. If you look closely you'll see the blue is nowhere near the glass.

The crackling is as the filter capacitors discharge through the tubes. Some tubes will crackle, some don't. I wouldn't worry about it. If it was crackling after it is all charged up and ready to go I'd be concerned (I'd start by cleaning the sockets) but what you are describing is no cause for alarm.
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#13
It never hurts to re-seat the tubes and get some contact cleaner in there.

Other than that, possibly a dirty power source.
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#14
Quote by Cathbard
Allow me to correct you. Blue is impurities on the plate flourescing. If you look closely you'll see the blue is nowhere near the glass.

The crackling is as the filter capacitors discharge through the tubes. Some tubes will crackle, some don't. I wouldn't worry about it. If it was crackling after it is all charged up and ready to go I'd be concerned (I'd start by cleaning the sockets) but what you are describing is no cause for alarm.



Thanks, now I know the proper reason from someone who is very knowledgeable about this subject!
Gear
Highway One Tele (w/Custom Shop 51 Nocaster pickups)
Standard Tele (modded to Nashville specs)
Reverend Roundhouse

Orange Rockerverb 50 MKI
Vox AC4c1
Jet City JCA20H

And pedals!



"Shiva opens her arms now..
...to make sure I don't get too far"