So I am in need of some advice/thoughts.
My Carver M1.0t has been connected up to my system for a couple days now and I have been having some slight issues. It appears that its got something to do with my electrical in the aparment I live in.
Now this is my first M1.0t which is a unique design and a much higher power amp than my other Carver (which is plugged into my APC H15) so some of this may be normal so let me know if what I am hearing is to be expected.
When I first turn on my M1.0t their is some humming from the transformer that is pretty low level but it stays constant when the amp is on. It kinda sounds like a toned down bug zapper.
When my M1.0t is on and I have the music paused on my computer and the Audio GD has the volume turned all the way down there is a VERY low hiss from the tweeters you can only hear when your literally on top of them. If I crank the volume the hiss gets worse, but how loud it is or isnt is dependent upon the volume level. Once the source is playing the hiss goes away and does not come over the top of the music.
When I turn it off there is about a 5 second pause and then a thump that comes through the speakers. Sometimes its a small one, sometimes its friggin loud.
Now according to the shop (who I trust) these issues were not present when they got the amp, or at any point before, during or after their testing/upgrading of the amp. I believe them as the seller also told me that (minus the thump which was there) the hissing issues present when I first got the amp were not there for him.
So this all points to something in my system/wiring generating the noise. On top of this we had some trouble a while back with our Uverse reciever freezing up downstairs watching On Demand movies. When the tech came out he told me his tests indicated there was some electrical interference that he thought could be the source of the issue. He thought it was related to my APC H15 as when he unplugged it his tests indicated the noise levels dropped. We then as a result went from a wired reciever downstairs to a wireless one and have not had any issues since then.
I should mention that at no point have we heard/noticed any noise or signal degredation with any of our other source gear including my Carver 705x (which has been plugged direct into the wall and also into the APC H15 with no difference in sound).
When these issues first arose I simply assumed that the tech was right and for giggles disconnected the APC H15 downstairs. The issues were still there.
Right now I have the amp connected upstairs to my Audio GD NFB-5 dac/pre via RCA which is connected to my computer. The amp is plugged directly into the wall on the top outlet. The bottom outlet has a Belkin cheap little surge protector strip on it that has my computer, the Audio GD and my Mini-ITX compter connected to it.
In the same room I have 2 long 2 plug extension cords used to connect the jack the wall switch controlls to 2 different lights. One of these cords runs right underneath where all this gear is tucked behind the baseboard where it is next to the Network cable for the desktop computer in the room. I also have on another outlet under my computer desk, my computer monitor, a printer and the charger for my wireless keyboard attached to another belking surge protector.
Here is what I have tried so far to get rid of the hiss that has not worked.
1. Switched from a cheap powercord to a PS Audio Premier cord
2. Tried a different set of RCA's (Audioquest G-Snakes to cheap Rat Shack)
3. Disconnected the RCA's and just had the amp on with no source music (hiss was only there if your on top the tweeter)
Here is what I have tried to solve the turn off thump:
1. Ensure pre has volume all the way down then turn off the amp first, then the pre
2. Ensure pre has volume all the way down then turn off pre first, then amp
Here are my thoughts on what I plan on trying next.
1. Take amp to my parents and test it out there to see if hiss still exists. If not it could be either my USB DAC/Pre or the wiring causing the noise
2. Use a "cheater" plug which as I understand it is a 2 prong to 3 prong adaptor (see pic below) to see if that eliminate the noise.
3. Use my Integra 5.9 downstairs to ensure its not the Audio GD adding the noise to the system.
Other than that, do any of you have any suggestions for what I might try to narrow down what might be causing the issue, or any possible solutions to fix it I havent listed?