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Distortion from speakers - amp?

Friends, I have a new amp (Halcro MC20) and preamp (Atma sphere R13) that I have mated to my beloved Newform Research speakers. My previous set up was a Pass Aleph 5 and Blue Circle 21 preamp. While the new configuration sounds wonderful, I am hearing very audible distortion, greater with one channel. With the ribbons, it is a buzzing sound, and in the bass drivers like a feedback hum. Again, when I change the channel cable connections between the pre and amp, the sound changes sides as well. It does not seem to be dependent on volume setting. Turning it up does not increase the distortion. The preamp is stone quite but the amp has a bit of a buzz when it is on. Ideas? Thanks much.
deliberate1
9 responses Add your response
deliberate1 OP
33 posts
 
Atmasphere, since the distortion happens with both amp/pre configurations, could the problem be with the speakers - or perhaps the power supply. I am listening to this in a new location and I am not using any sort of power treatment. Thanks for your continued interest.
atmasphere's avatar
atmasphere
11,841 posts
 
Try swapping the input cables for your source and see if the problem moves. I was thinking the preamp because you mentioned that the volume control did not affect it, but if other gear behaves the same way there is something different afoot.

I've seen malfunctioning digital gear inject lots of RF noise into the rest of the system, but I would expect slightly different symptoms. You never know though...
deliberate1 OP
33 posts
 
Atmasphere, thanks for the suggestion. I will give that a go. I have some other tubes which I have can roll as well. Frankly, I do not think that it is the amp or your baby. I hooked up my old componants (Pass Aleph 5/ Blue Circle 21)to the speakers and heard similar distortion - just less pronounced perhpas because less juice. Is it possible that it is the power supply or are the speakers the source?
By the way, the R13 thing is really code for all of us owners who would have a hard time explaining to our wives how much we paid for that "MP-3" player.
atmasphere's avatar
atmasphere
11,841 posts
 
OK :) I would try a set of shielded cables just to be safe. Unshielded cables, even balanced, can sometimes pick up noise.

Otherwise I would guess that its in the preamp. If that's the case I would try moving the 6SN7 tubes from one channel to the other and see if the problem moves.
deliberate1 OP
33 posts
 
"What's an Atma-Sphere R13?? You'd think I should ought to know that one but I don't."

Shhhh. You of all people should know that it is a secret version of the MP-3 for people who can not remember what the hell they have.
atmasphere's avatar
atmasphere
11,841 posts
 
What's an Atma-Sphere R13?? You'd think I should ought to know that one but I don't.
swampwalker's avatar
swampwalker
5,138 posts
 
I do not believe that Anti-cables have any shielding at all.
deliberate1 OP
33 posts
 
Plato,
Thanks for your insight. The cables are Anticable balanced IC's. Not sure if they are shielded or not (do not even know what that mean to be honest). Is there a way to replicate the shielded function? Since they are XLR ends, they can not be reversed. I will try moving the AC cords as far away from the interconnects as well. Thanks again.
plato
1,543 posts
 
If the distortion changes sides when you swap the cables between the preamp and amp then the problem lies before the amp... It could be in the preamp, but what kind of cables are you using? Are they shielded? If not, you could try using shielded cables. If so, maybe the shield of one cable is connected to the wrong side, in which case reversing the direction of the cable between the preamp and amp (on the distorted side) might solve the problem.

If trying shielded cables or reversing the distorted side cable does not solve the problem then the problem could be in one channel of the preamp. Also make sure that the interconnects are not lying on top of any AC cords.
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