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Zap Sound out of Speakers when Powering Off

I've recently put together a new system from fellow Agoner's and I'm going through a shake down right now. I have two problems and I could use some advice.

First the System:

McCormack DNA-1 Deluxe Amp
Conrad Johnson PV10a (with phono) pre
B&W 805 Naut's with Monster XP cables
Homegrown IC's Silver Lace
VPI HW19 JR TT
Phillips DVD/CD (crappie plastic IC)
XM Radio

First problem:

When powering off the pre-amp system, I get a loud static like "pop" from my right speaker. Then when shutting off the Amp It get a wierd "zip-zip" sound, again out of the right speaker. Is this normal when shutting down a two channel Hi-Fi system?? (speaker was slighly damaged on delivery - see below). Why is it only coming out of the right?? I'm waiting for DH Labs Q10 speaker cables, but it sounds more like a speaker or amp problem.

Second problem:

The system runs great and when the volume is turned all the way down it is very "black". However, after about 30 minutes or so of operation, it develops a very noticable high pitch "whining" sound out of the speakers. This seems to alternate between one of the two each time the system is powered up. You can hear it clear across the room when music isn't playing and it is almost at painful levels. I've shut down and turned off everything except the amp the pre and it still keeps "weeeeeeeeenn" Arghh!! Please help!!!

Note: The right speaker mentioned had a pushed in Tweeter cone when it arrived, but seems to be playing very well. It has a cracked tweeter case (very hard to even see) which lead me to think this might be the cause of both sound issues.

I haven't tried to swap out the speakers with something else to see if this is the cause (I'll try that tonight). Anyone have any ideas of what might be causing these noises??
whyt_rabbit
mezmo
516 posts
 
Jeesh, don't sound normal to me. As a preliminary suggestion, it's a good idea to turn off the amp first when shutting down. That way, if any of the other gear discharges anything weird when shutting down it's not passed along (and amplified) on its way to the speakers.

That said, your gear shouldn't be discharging anything weird while shutting down. Nor should it be screaming at you when it's on. I had a preamp that was haunted, hissed and whined and literally made the lights pulse once. Never did figure out what was up and finally replaced it (though consensus suggests a reactance/impedance issue with the amp--not that I know what that means). Maybe you caught my poltergeist? (Yes, my best guess is no help at all).
disc
124 posts
 
Re the high-pitched whine, that sounds like a microphonics problem related to tubes, but I don't know your equipment well enough to know if that's a possibility--the CJ pre, perhaps?
scotty_910
119 posts
 
I have a similar, but slightly different problem. I have no sound issues when poweing off the preamp, however, when I power off my amp, regardless of whether the preamp is on or off, I get a popping sound out of one of the speakers. The amp is a levinson 331 and I don't remember it doing it when I first got it. It works just fine and sounds fine except for this powering off popping sound. Any thoughts?

- Scott
s23chang
620 posts
 
Whyt_rabbit, have you replace the tubes and CJ preamp?
It soundeds like a tube issue to me. You have this high pitch noise after the tube warm up.
whyt_rabbit OP
20 posts
 
Last night I switched speakers and the high pitched noise continued, so it definately isn't the speakers.

Additionally, I got the same "Poping Static" sound when shutting down the units with the other speakers.

This is definately a amp/pre-amp issue.

I'm getting a new set of tubes for the CJ and I'll see what difference these make in the "high pitched whine". I'm glad to hear that others think it is the tubes.

What about the shutdown noise, could this also be caused by the tubes???
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