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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
ericd74
18 posts
 
i recently had the same "popping" problem with my set up - plinius amp / CJ pre / cary CD / thiel 2.3...

this problem is often referred to as "motorboating" and is most likely the result of bad tubes in the pre amp (search for "motor boating" and "motorboating" in the tube section of audioasylum.com for more on this problem and possible solutions...

often times, replacing the tubes fixes the problem...i replaced my tubes, which fixed the problem for a few weeks, but then it came back. my pre amp is actually at the CJ factory now getting checked out.
mejames
986 posts
 
have any idea how old the tubes are?
whyt_rabbit OP
20 posts
 
Well, I'm at home now and I'v had just the amp powered on for almost 1 hour (and nothing else - per Kr4 suggestion). NOTHING!! Pure silent blissful darkness.

Good, it's not the speakers and it's not the amp. That leave ole' Connie J in the hot seat on the high pitched "whinning". I'll have to get some new tubes first, but hopefully that will solve both issues.

However, I still get a "zipping" sound when I shut down the amp (with nothing else on). Could this still be caused by bad tubes even with the pre-amp powered off??

I have two distinct sounds on shut down. The amp makes a zipping sound and the pre-amp makes a "popping" sound. Each are separate sounds and independant of each other and other components or what is on or off when turning these components off. Both sounds only come out of the right channel.

I'll try to roll the tubes and see if the sounds switch sides. Stay tuned and thanks for your help so far.
swampwalker's avatar
swampwalker
5,138 posts
 
After you get the new tubes, if you still have a problem you might drop an email to Steve McCormack at SMcAudio (get the address under manufacturers. He's usually pretty generous with his time, although sometimes when he's travelling it takes a while to get a response.
kr4's avatar
kr4
3,689 posts
 
Also try swapping the ICs. And I second the suggestion to call Steve at SMc.
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