2. amps-preamps
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Buzz originating from amp...please help ?

I bought a Pass X250 through Audiogon and when hooked up to my system, a hum or buzz is coming out of the tweeters and midrange speakers on both channels. After exhaustive trial and error, I find that the buzz does not exist when the amp is not hooked up to any other component. It is of course connected to the speakers. If I attach a pair of interconnects to the amp (whether or not these interconnects are connected to the preamp), the buzz comes back. Does anybody have any ideas what I should try, or what the problem may be? Thanks for any imput.
jcambron
9 responses Add your response
tpsonic
1,092 posts
 
Jcambron, You may have a ground loop. Is it possible to use a cheater plug on the AC line cord{convert 3 to 2 prongs}. You can also take a small gauge wire and try connecting the chassis of the amp to different components to see if the level or frequency changes. My system had a similar problem and this seems to help. Good Luck! Tom
jcambron OP
21 posts
 
I have tried using a cheater plug on the amp as well as all other components in the system with the same result. I have also used an ungrounded cord on this amp which I borrowed from a subwoofer and got the same buzz as before.

Thanks.
aaronm's avatar
aaronm
99 posts
 
Jcambron,

While you didn't say either way- hopefully you've tried different interconnects between your amp and preamp. If that doesn't work or you don't receive other info here that solves your problem, I would suggest emailing or calling Peter or Wayne at Pass Labs. They are both very concerned with ownership satisfaction and have a great deal of knowledge. Their website should have all needed contact info. www.passlabs.com Best Regards, Aaron
jcambron55c3
2 posts
 
Thanks Aaron. As a matter of fact, I wrote Peter @ Pass last night and will look for a reply early next week. I may just call them on Monday. I tried every combination of interconnects I can think of and still it buzzes. I am going to look in the Audioasylum archives on ground loops today to see if I can find any good ideas.
neroalo
1 posts
 
Is this part of a home theater set up? I had a similar problem and all I needed to get rid of it was to unplug my cable tv cable from the wall. I know this sounds strange but it worked. You can test just by simply unplugging the cable from the wall. If this solves your problem you can get a ground loup isolator for your cable.

Good Luck,

Nels
ljgj
955 posts
 
If your system is near your Cable TV connection it could be the culprit and creating the noise via a ground problem which can usually be solved by adding a MAGIC ground loop isolator to the tv cable connection right before it enters the tv set.
Audioadvisor has them about 100.
jcambron OP
21 posts
 
Thanks Nels and Ligi for the response. My audio room is located where my home theatre used to be. The only remnants of the home theatre are the double coax cables that were attached to my DSS/Tivo receiver. While the cables are no longer attached to the satellite dish, they are still grounded. These coax cables are lying within 5 feet of my amp. I will move these right away and see if that helps any.

Jim
alexanderj
139 posts
 
Single ended or balanced interconnects? Many amps require shorting pins for the unused balanced inputs when going single ended. I'm not familiar with Pass's requirements but the topic should be addressed in the owner's manual.
jcambron OP
21 posts
 
Alexanderj...I am using single ended IC's with the shorting pins in place in the unused balanced imputs. I am going to borrow some balanced interconnects one day next week and see if that helps anything at all.

Thanks
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