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05-08-12
Are you familiar with tube hiss? that would be my first gue ... Uru975
05-09-12
Mark, have you tried unhooking everything from the amp excep ... Mofimadness
05-09-12
Hi mark, if you can hear hiss at the listening position whi ... Almarg
05-09-12
Excellent suggestions guys. let me work through some of your ... Dodgealum
05-10-12
I played around a little last night and here is where we are ... Dodgealum
05-10-12
Hi mark, before finalizing any further suggestions, i'd sti ... Almarg
05-10-12
Sorry, al, i forgot to include answers to 2 and 3 in my repl ... Dodgealum
05-10-12
Hi mark, so my understanding is that: (a)amp on + preamp o ... Almarg
05-10-12: Bombaywalla
05-10-12: Dodgealum
I played around a little last night and here is where we are:
I confirmed that the noise is ONLY present when the amp is on. I can turn on any/all other components and don't hear the hissing sound.
.....
According to me, you'll only hear the hiss/noise once the amplifier is on 'cuz the amp is the only piece of electronics driving the speaker. Amp not on, no noise from the speakers.
Of course, this does not necessarily mean that the amp itself has a problem. Merely saying that unless the amp is on, the speakers are not driven thus any noise generated in the electronics will not be heard.
This is obvious to me but no one else including Almarg stated it so, what am I missing here?
So, this morning I moved the power cables around as much as possible to get them away from the IC in question and things improved--somewhat (I'm still not happy). .... to me this points to unshielded interconnect cables & to the preamp (since Dodgealum is not fully satisfied with the reduction in noise indicating that the interconnects are not the full source of the problem).
I believe that Almarg already stated this in his latest post.
One more thing to try, if you haven't already, would be to disconnect the balanced interconnects at the preamp end, while leaving them connected to the amp, and then turning on all of the components so that they are generating whatever noise or interference they normally generate. If that results in a similar amount of noise through the speakers it would pretty much confirm that noise being picked up by the cables is the problem.
yeah, this would be a good test to see if the cables are acting like antenna picking up RF noise.
My gut feeling is that balanced interconnects should not be the issue. Afterall balanced cables are used for the very fact that they are balanced hence noise cancelling. They perform remarkably well in (RF) noisy environments such as pro studios. If a balanced interconnect (even tho' unshielded) is being a noise antenna, something does not smell right to me.....
My brother once had a similar issue - the single-ended cables in his system were picking up signals from a FM station & creating a low level signal output from his speakers. Once he switched to balanced interconnects (I forgot shielded or not) the problem was fixed. Here Dodgealum is already using balanced cables.....
I have a strong hunch that it's the preamp. To me all fingers point to that device. As Almarg wrote: a)Amp on + preamp off = no noise.
(b)Amp on + amp inputs disconnected = no noise.
(c)Amp on + preamp on and muted = no noise.
(d)Amp on + preamp on and unmuted = noise. The noise level is independent of the volume control setting.
each time the preamp signal is not allowed to reach the power amp, there is no noise.
IMHO. FWIW.
Bombaywalla (System | Reviews | Threads | Answers | This Thread)
05-10-12
yes, i noticed that too, and you're not missing anything :-) ... Almarg
05-10-12
Mark, it could also be something coming into the preamp. i ... Mofimadness
05-10-12
Mofi, note that mark indicated that "the level of nois ... Almarg
05-10-12
Guys: i may have been unclear and so driven the discussion ... Dodgealum
05-10-12
ok. so that rules out the preamp as the source of the noise ... Almarg
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