Volume Drop-outs on JCM 800?

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I was playing last night and I would get these random(not consistant)volume drop-outs on the dirty channel, playing about 4 on the master volume, gain on 8, channel volume 5. Any thoughts as to what might be the problem?

Thanks,
JK

[Cleveland Metal]

Re: Volume Drop-outs on JCM 800?

I'd be contemplating retubing it about now. A likely problem and at the least will give you a strong set of tubes to eliminate them from the troubleshooting process.....

[ April 23, 2003, 03:18 PM: Message edited by: Cleveland Metal ]

[ColdVayne]

Re: Volume Drop-outs on JCM 800?

Yeah i had that do that when i had a jcm 800 and when i retubed it , it stoped .

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Re: Volume Drop-outs on JCM 800?

If that is the case, do I have to take it in and have it re-biased at the same time, or can I just change the tubes as long as they are the same and matched?

JK

[Cleveland Metal]

Re: Volume Drop-outs on JCM 800?

When you change power tubes, you have to get it biased (unless it's a MESA and you use their bogus tubes in it).

Preamp tubes don't require biasing. But the power tubes do. Should not be too expensive. $15-40 bucks depending on your location.

Personally, I would replace all the tubes, preamp and power. But, at the least, do the power tubes and see if it helps your problems. You'd do well to do them all, just for the sake of good tone.

I'd use either Svetlana or Tesla Power tubes from like the tubestore.com in that. NO sovtech or Groove tube crap.

Then, snag some NOS cheese grater getter Chinese preamp tubes off ebay and not the current tubestore ones that are useable, but aren't as nice sounding and are more expensive.

I could refer you to a good seller that usually has them for $6 each, he's a great reliable guy. If they aren't up for auction, he prolly still has them....

http://cgi6.ebay.com/ws/eBayISAPI.dl...ort=3&since=-1

[thenine]

Re: Volume Drop-outs on JCM 800?

yep, hes a cool dude with fast shipping. I grabbed 6 of those bad boys for my XTC. Brand new, excellent.


JOHN

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Re: Volume Drop-outs on JCM 800?

Great - thanks guys.
Interesting though that last night I was playing it again and no probs?
Also, I found out my brother was over weeks ago messing around and left the thing on standby for about 10 hours - which I'm assuming may the reason for the earlier problems. So, would 10 hours on standby almost kill somewhat new tubes?

[ColdVayne]

Re: Volume Drop-outs on JCM 800?

No it wouldnt kill it , but it did take some time away from the tubes . Depending how long you play your amp , you should change your tubes every 6 to 8 months.

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Re: Volume Drop-outs on JCM 800?

Thanks again for the info - much appreciated!