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#94678 - 05/16/05 11:25 PM Hum &/or hiss from speaker
winterpeg Offline
old hand

Registered: 03/17/05
Posts: 88
Loc: Manitoba, Canada
I tried different speakers first, same hum and/or hiss from drivers and tweeter. I changed source from amp to receiver only. I tried everything turned off except source powering speakers, both receiver and amp. I disconnected everything, right down the the bus bar/surge protector and powered only the power source and the speakers with the same low level hiss and hum. It can be heard up to 6 or 7 feet away when there is no actual sound being produced.

Is this maybe normal to get some sound coming from the speakers when no input is selected?

It isn't noticeable when even the lowest sounds are being produced.

Any thoughts??

Troy
_________________________
M80 VP150 4-QS8 EP600 Monitor Audio S8 NAD T 773 Anthem MCA3 II Hitachi 57" projection

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#94679 - 05/17/05 02:44 AM Re: Hum &/or hiss from speaker
Haoleb Offline
connoisseur

Registered: 09/25/02
Posts: 1488
Loc: Maine
Well. Does depend if your getting a humm or a hiss. We havent established that yet

Usually a hiss is a trademark of cheap amplifiers. However looking at your list of gear i dont see anything "cheap" there. Hum on the other hand is common with a grounding problem or physical transformer noise from the amps. not speakers.

Although Hums and hisses are both somewhat common with tubes depending on the individual tube itself. But you dont have any tubes i guess.

Dunno what to tell you really. If its not noticable from your listening seat. which I assume is farther back then 6 or 7 feet then i woudlnt worry about it.
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Haoleb's Audio/DIY Website

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#94680 - 05/17/05 11:57 AM Re: Hum &/or hiss from speaker
ravi_singh Offline
connoisseur

Registered: 03/14/02
Posts: 1351
Loc: Montreal
if it's a hiss and the volume on your amp is turned all the way up, then that's likely normal.

i have a denon 1602, if i turn the volume way up, i hear some hiss, even 6-7 feet away.

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#94681 - 05/17/05 10:52 PM Re: Hum &/or hiss from speaker
michael_d Offline
connoisseur

Registered: 07/23/04
Posts: 3915
Loc: Up yonder
i hear absolutely nothing from mine with no source playing, volume pegged.

I doubt if this could actually cause a hiss or hum, but how's your speaker wire conections - just to rule that out?
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#94682 - 05/18/05 06:04 PM Re: Hum &/or hiss from speaker
winterpeg Offline
old hand

Registered: 03/17/05
Posts: 88
Loc: Manitoba, Canada
I used banana plugs, but removed them on the speaker side.
I didn't try removing them on the receiver or amp side though. The hum is the sound from the drivers and the hiss type sound is from the tweeters. I tried to move power cords as far apart as possible, but read somewhere to try seperating the digitol/audio cables from the speaker wires as well. Don't know how it is possible to seperate them all but I'll try anything. It would be a perfect world if as you stated they would be silent when not playing anything. I'm sure that it must distort the sound a little.

I must admit the more I listen the M80's the more i'm enjoying the sound.

Thanks for the advice.

Troy
_________________________
M80 VP150 4-QS8 EP600 Monitor Audio S8 NAD T 773 Anthem MCA3 II Hitachi 57" projection

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#94683 - 05/19/05 01:59 PM Re: Hum &/or hiss from speaker
michael_d Offline
connoisseur

Registered: 07/23/04
Posts: 3915
Loc: Up yonder
In theory, if a source is not sending a signal to the amps for amplification of that signal, then there should be no electrons traveling through the speaker wires to the speakers. But I did notice that with my HK 7200, I would hear a very slight hiss/hum under these conditions, and the 7200 was HK’s flag ship AVR a year ago. With the Rotels, I hear nothing. This lends itself to a thought that possibly, the amps in a receiver are still sending a ‘stray’ signal to the speakers, while separates do not. I’m still in the learning stages of how all these critters actually work, so I’m just speculating here. Maybe others with knowledge of the intimate workings of audio electronics can provide insight.

Or, you could be picking up stray noise from other AC wiring in close proximity of your speaker cables. Again, just guessing.

I too enjoy the M80’s more every time I listen to them. I’m in love with them now. They were great before with the HK, but they’re fantastic now with the Rotels.

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#94684 - 05/19/05 04:09 PM Re: Hum &/or hiss from speaker
BrenR Offline
connoisseur

Registered: 12/10/03
Posts: 3602
Loc: Winnipeg MB Canada
In reply to:

In theory, if a source is not sending a signal to the amps for amplification of that signal, then there should be no electrons traveling through the speaker wires to the speakers.


There's an inherent DC voltage in pretty much anything in the real world. (ever made a potato battery? - yes I realize that's an electrolytic reaction...) that along with a little wee bit bouncing around in the amp are what gives you the hum.

Speaking of hum... does anyone watch American Idol? I've started watching it with the S/O the last season or two and I'm surprised how much hum the "pin 1 problem" in FOX's crowd mics exhibit!

Bren R.

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#94685 - 05/19/05 04:13 PM Re: Hum &/or hiss from speaker
michael_d Offline
connoisseur

Registered: 07/23/04
Posts: 3915
Loc: Up yonder
Any thoughts in why it would be more pronounced in some gear and / or situations vrs others?
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#94686 - 05/19/05 04:23 PM Re: Hum &/or hiss from speaker
BrenR Offline
connoisseur

Registered: 12/10/03
Posts: 3602
Loc: Winnipeg MB Canada
Depending what the source of it is - I'd venture shielding and isolation. Also, some amps may have a gate circuit that clamps anything below a certain signal to 0.

Bren R.

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#94687 - 05/19/05 04:29 PM Re: Hum &/or hiss from speaker
michael_d Offline
connoisseur

Registered: 07/23/04
Posts: 3915
Loc: Up yonder
Interesting....what would a person look for on a spec sheet indicating this?
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#94688 - 05/19/05 04:40 PM Re: Hum &/or hiss from speaker
bigjohn Offline
connoisseur

Registered: 01/21/04
Posts: 3016
Loc: San Angelo, TX
In reply to:

does anyone watch American Idol



NO, i am too busy watching good reality shows like the Gotti Boys and Show Dog Mom's and Dad's..

bigjohn
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EXCUSE ME, ARE YOU THE SINGING BUSH??

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#94689 - 05/19/05 05:10 PM Re: Hum &/or hiss from speaker
Craig_P Offline
veteran

Registered: 12/06/02
Posts: 158
Loc: Ottawa, Ontario
From what I've been reading in other forums, the "hiss" sound is coming from the pre-amp section of your NAD T 773 receiver. Apparently the NAD contains no muting circuitry (a kind of pure sound philosophical standpoint), and because of this there is always a hiss present. Check out this thread at Home Theater Forum for more info.

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#94690 - 05/19/05 05:38 PM Re: Hum &/or hiss from speaker
BrenR Offline
connoisseur

Registered: 12/10/03
Posts: 3602
Loc: Winnipeg MB Canada
In reply to:

Interesting....what would a person look for on a spec sheet indicating this?


Shielding and isolation are built into the build quality of the amp. There's really no technical spec for either... but they will show up good or bad in the THN+d graph of course.

As for whether or not there's gate circuitry - that would be kind of a "cheat" to make an amp sound cleaner - you'd have to look through the schematic for that.

Maybe I should talk a bit about C/L/E/G - compressor/limiter/expander/gate. I bring these up a lot, not sure if everyone "gets" them.

Limiter - we keep talking about amps going into "clipping" where the waveform peaks are cut off. A limiter works by sensing when a signal will enter clipping and adjusts the gain (volume) to prevent this. It's like having Superman ride your levels for you - when he senses the amp will go into clipping, he turns it down to, say 99% of full range, just below clipping levels.

More technically, it works by reducing levels above it's threshold by a certain ratio "crushing down" the highest levels.

Of course, this changes the divisions of output (which is a distortion of the sound). Say if program audio that's 80% as loud as the loudest sample in the program plays out at 95% of the range of the amplifier before clipping, the top end will be compressed (that top 20% of program loudness has to be made to fit into the remaining 5% of available amp headroom) hope that makes sense.

Gate - the opposite end of the spectrum. Think of a gate as, well... a gate... audio waiting on one side to get out into the speakers, but the gate doesn't open until it's triggered by a signal at least as loud as whatever it's threshold is. A hard gate cuts in and out immediately at that threshold, a soft gate fades into and out of the program material to make a smoother transistion. These are especially useful for analog sources, where tape hiss and groove swish can be nullified to pure silence in "silent" parts.

Compressor/Expander/Compander - A compressor reduces dynamic range of program audio above it's threshold. Again, using our percentages of total program loudness (I'll coin an abbreviation here for my theorical scale - TPL), say the sound of a flutes keys being worked is at 5% of TPL with the trill between a D and D-sharp note the flotist is playing is at 90% of TPL. Say the compressor is set to be 5:1 with a threshold of 50% of TPL. The sound of the keys is untouched, but the note being played is reduced to 58% of TPL (40% over threshold of 50, compressed 5:1) meaning the master gain can be cranked up to make up that 32% quieter that the note is back at 90% of TPL, but that will also bring the sound of the keys up by a relative amount. Voila - the wall of sound. Sick, isn't it?

An expander works just in reverse - expanding the dynamic range of program audio.

A compander does both in the same circuitry - for instance, most CB Radio mics are companding mics - which trade off dynamic range for high RMS (root mean square) signal strength, which gives you a more powerful signal to send out over antenna.

Bren R.

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#94691 - 05/19/05 08:57 PM Re: Hum &/or hiss from speaker
michael_d Offline
connoisseur

Registered: 07/23/04
Posts: 3915
Loc: Up yonder
No time to digest all that right now, but thank you. It's printed for further study. Now what data can I dump to make room for this......hmmmmm I din't like her much anyway...
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#94692 - 05/20/05 12:26 AM Re: Hum &/or hiss from speaker
BrenR Offline
connoisseur

Registered: 12/10/03
Posts: 3602
Loc: Winnipeg MB Canada
I find the more I type the more confusing I make the issue. I wobble between trying to be as accurate as possible and keeping from being technical to the point where most people's ears will smoke... and I think I walk the line badly.

Sit down over a beer with a napkin and a pen and I make a lot more sense.

Bren R.

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#94693 - 05/20/05 01:44 AM Re: Hum &/or hiss from speaker
pmbuko Offline
shareholder in the making

Registered: 04/02/03
Posts: 16289
Loc: Leesburg, Virginia
I put a glass of beer with a napkin and a pen in it under my chair about an hour ago. When are you supposed to start making sense?
_________________________
"I wish I had documented more…" said nobody on their death bed, ever.

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#94694 - 05/20/05 02:31 AM Re: Hum &/or hiss from speaker
BrenR Offline
connoisseur

Registered: 12/10/03
Posts: 3602
Loc: Winnipeg MB Canada
Someday Alice... er... Peter... bang-zoom, right to the moon!

Bren R.

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#94695 - 05/20/05 07:52 AM Re: Hum &/or hiss from speaker
Merkaba Offline
old hand

Registered: 08/20/04
Posts: 83
Loc: NL, Canada
I have a NAD C320BEE integrated and I get a faint hiss from my M60 tweeters as well. Even when CD/DVD player are not on and volume is zero. It gets a little louder (very little) when the volume is maxed. I basically have to put my ear right next to the tweeter to hear it, so I'm not too worried about it.
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Axiom M60ti Hsu VTF-2 Mk2 NAD C320BEE NAD C542 Systemdek IIX Cables by Unity Audio

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#94696 - 05/20/05 11:15 PM Re: Hum &/or hiss from speaker
winterpeg Offline
old hand

Registered: 03/17/05
Posts: 88
Loc: Manitoba, Canada
I have an Anthem amp that powers the M80's and use the NADT773 as a preamp. When everything else is completely disconnected including power cords and surge bar, there is a small amount of hiss just from the Anthem. When I power up the NAD the hiss becomes louder. It disappears as you move back and around 6 feet becomes pretty well unnoticable. Even the surround speakers have a slight hum to them. However slight, there is some.

From all other manufacturers, are we saying they have no sound at all when left without a source playing, even when listening up close.

From reading the other posted site discussion, this appears to be with only some of the products and not with each one.
Another variable is my main circuit breaker box is within 3 feet of the speaker and within 5 feet of the amp and receiver. Could this, being one item I couldn't shut down or unplug, cause this disturbance?

Troy
_________________________
M80 VP150 4-QS8 EP600 Monitor Audio S8 NAD T 773 Anthem MCA3 II Hitachi 57" projection

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#94697 - 05/20/05 11:30 PM Re: Hum &/or hiss from speaker
michael_d Offline
connoisseur

Registered: 07/23/04
Posts: 3915
Loc: Up yonder
I just tried it again. Same results, nothing. notta, zip...quiet as death.
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#94698 - 05/21/05 12:55 PM Re: Hum &/or hiss from speaker
winterpeg Offline
old hand

Registered: 03/17/05
Posts: 88
Loc: Manitoba, Canada
I am not sure if I mentioned the fact that I did try different speakers other then my M80's. I tried the Monitor Audio towers with the exact same hum issue.

The system sounds real nice. The preamp portion of the receiver is really great to work with and it's easy to operate and control. It seems to me any of the hum I am getting through when all components are powered, but not in use, is from the amp section, as with the anthem as well.

I am still able to return it, but I wonder if it is really enough to worry about.

I think the only thing that stopped me from purchasing the Rotel was their price. With the system I have right now, I am powering up to 9 channels (with one spare channel in the receiver not being used).

Something else I read on another site;

"The 773 uses the CS493263 DSP the same as the hgier end Onkyo, the 9XXX Marantz, the Rotel receivers and the Rotel 1066.
A lot of the higher end receivers such as the Arcam and others have had reports of hiss. I must reiterate that 3 engineers responsible for the topology of the 773 and 763 have told me no hiss at 00 and no increase in the level fro -74 to about +3 is how it is designed to act. That is it is not a malfunction. They could have made it totally silent but all 3 independently told me the sonic tradeoffs were too great. Engineers are not in marketing and as a matter of fact usually could care a less about marketing so they have no interest in lying. We were talking as engineer to engineer rather than customer to engineer.
If folks can't live with it then they're better off with a lesser but possibly quieter receiver. The choice is easy for me as SQ is all that counts."


Troy


Edited by winterpeg (05/21/05 01:21 PM)
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M80 VP150 4-QS8 EP600 Monitor Audio S8 NAD T 773 Anthem MCA3 II Hitachi 57" projection

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