Hissing sound?

[Music4Life]

I own A21 for almost a year now and yesterday I noticed a hissing sound coming from my speaker (ATC scm7). It's not audible from the "king's chair" but when I put my ears closer to the speaker I can hear the unwanted sound which I'm sure wasn't there before. Is it coming from my other components (DAC, dvd transport, cable)? Is it the noise interferance from other cable? Help eliminate this noise.

[Peter Nielsen]

First step is to disconnect the inputs of the A21 and see if that changes anything.

If you're using balanced (XLR) between your A21 and Preamp, you should try unbalanced (RCA) instead.

If you have very efficient speakers, a certain amount of hiss is normal and really cannot be eliminated. (You would need to switch to a different amp technology like the TacT amps to combat this problem).

Peter

[Mike_Schmidt]

I have noticed a slight hum from my A21 and some is not normal IMO. All of the cyrus gear I owned never had a hum from the box or speakers. But this is maybe how the A21 is built.

Do you turn off your A21 everynight? I never shut my cyrus gear off ever, but they never run hot like my A21. I thought this was supposed to be hard shutting down and powering up

[Peter Nielsen]

Note the difference between HUM and HISS

HUM is a low frequency 50Hz (Europe) or 60Hz (America) hum from the power grid. There are a number of reasons for this. First step is to try to disconnect a cable box or subwoofers to see if that helps.

HISS is a high frequency noise that usually is caused by very efficient speakers that pick up the normal electron noise of a powerful amp. It could also be caused by a bad component in the chain... (Remember tape decks and the inherent hiss).

It is usually possible to eliminate all hum. Eliminating hiss can be much more troublesome, especially when the problem is a big amplifier that by nature outputs hiss that can be audible with certain speakers.

I recall that a few guys with very efficient speakers here on the forum have said that the unbalanced connectors are a bit quieter and need to be used if you have very sensitive speakers. So, if you're using XLRs with the A21 switching to RCAs may solve the problem. Another possibility is a mismatch between your A21 and preamp. In this case turning down the gain knobs on the A21 might help to minimize or eliminate the hiss. Try all this and you stand a good chance to solve the problem :T

Peter

[Peter Nielsen]

I have noticed a slight hum from my A21 and some is not normal IMO. All of the cyrus gear I owned never had a hum from the box or speakers. But this is maybe how the A21 is built.

No, it's not normal. If you hear hum, you have a ground loop! Have you tried to flip the ground lift switch on the back of the A21 ? If the ground lift switch does not help, then try a cheater plug.

Ideally you should search for the actual source of the problem. This is done by first only connecting the A21. Then add one component at a time preamp, cd, etc. until the problem appears. When you have found the problem, you address it at the offending component. For instance, if the offender is the cable box, the problem is usually solved by adding a cable isolator.

Peter

[Mike_Schmidt]

What about shut down Peter, do you shut them down at night or keep them on all the time. Is this hard on the power amp shutting down and powering up, I keep my pre amp on all the time (JC2)

Thanks Mike

[Peter Nielsen]

What about shut down Peter, do you shut them down at night or keep them on all the time. Is this hard on the power amp shutting down and powering up, I keep my pre amp on all the time (JC2)

That depends on how much listening you do. If you turn them on in the morning and off at night, then you might just leave them on all the time.

However, if you only listen a few hours a day, then I'd recommend turning off the amps when not in use.

Peter

[Music4Life]

Thank you. I've tried your suggestion, somehow the hiss is lesser this time but still a small amount is there. Maybe it's suppose to be there anyway. Can't do anything.