Cary SA500.1 mono blocks

04-18-15: Mitch2
Is it mechanical hum of the transformers inside the amps, or a hum/buzz coming through the speakers?

Kwa69, you should clarify this. As Mitch2 indicated earlier, "Mechanical hum from the transformer is caused by DC on the line, which can result from many sources regardless of whether you have dedicated lines." But if the hum is coming from the speakers, I see no reason to conclude (as you have stated both here and in your system description thread) that the cause has anything to do with "bad power."

If the hum is heard through the speakers, and if I am correctly interpreting from your system description thread that you are driving Martin-Logan Odysseys with these amps, I'm thinking that the following statement in the SA-500.1 manual may have some relevance, even though you are apparently not connecting a sub to the amps:

Caution! Do not under any circumstances connect the amplifier to a subwoofer through its high level (speaker) inputs. There is a potential of damaging the amplifier using this type of connection due to differences in grounding schemes used by some subwoofer manufacturers.

Although the Odyssey does not incorporate a powered woofer or subwoofer, as a hybrid electrostatic it nevertheless receives AC power. I'm wondering if as a result there may be an incompatibility between the amp and how AC ground and signal ground are handled in the speaker, resulting in effects similar to what might happen if a powered sub were connected to the amp.

What I would suggest, assuming that the hum is coming through the speakers, is that you try the amps with different speakers, that do not require any AC power. Also, if you already haven't, try plugging the amps directly into the wall, without any of the power conditioners that are mentioned in your system description.

Regards,
-- Al

Al, good catch as usual. KWA should call Cary on this. If this is the issue, he could damage the amps. BTW, the first iteration of the manual did not have that warning. It was added after the issue was observed by owners.

Thanks for trying to help me .I think the amps are fine it must be a ground loop issue that I can't fix .I did lift the ground pin on my power cables with no effect.The hum is coming from the speakers not inside the amp itself.I don't have any other speakers they are all Martin Logan and need a power cable wow I never thought I could damage an amp buy hooking them up to Logans that would suck.I will try different speakers tomorrow. I just finished putting my system back together its been a frustrating couple of days I might take a day off .

Hello I just wanted to give yall an update. It's been a few months since I returned the amps . I gave up on buying amps for a few months but a couple of weeks ago I got the bug again and started looking again. So I called the same guy about some other amps he sells. He told me he just talked to Cary and they told him to open the amps and check for a loose connection. Well he said that was the problem . He asked me to come up to the store he would show me the problem so I did. I saw the connection that was the problem its was a quick connect that got loose when they got shipped back from Cary . So I took them home to try them again. Well they are not coming out of my system this time they sound great. He gave me a great deal that that couldn't say no to. So all is good they have been in my system for a few weeks and they sound fantastic with no problems and most important dead silent.

Kwa,
Glad this was something minor and you got it fixed. If you need tons of juice, these are good amps.