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#418547 - 04/12/16 02:02 PM For those of you with external amps - floor noise
spiroh Offline
veteran

Registered: 01/06/05
Posts: 125
Loc: Chicago, IL
I recently went with an external amp to test out the differences between receiver power compared to external. So far my findings have been extremely positive but since I am fairly new to this I was curious what is acceptable floor noise when using external amps. If I have the volume half way up and mute the sound I can hear hiss about a foot away between my speaker and ear. What are you seeing with your external amps? I just don't know what is the acceptable standard when it comes to floor noise. I'm using RCA connections from a Marantz SR7010. Thanks

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#418548 - 04/12/16 02:08 PM Re: For those of you with external amps - floor noise [Re: spiroh]
2x6spds Offline
connoisseur

Registered: 03/16/02
Posts: 3121
Loc: CA, USA
Make sure the volume of your television is zero.

I use an Integra M504 external amp with a 9.2 AVR for front L/R. No hiss.
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Enjoy the Music. Trust your ears. Laugh at Folks Who Claim to Know it All.

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#418549 - 04/12/16 03:17 PM Re: For those of you with external amps - floor noise [Re: spiroh]
spiroh Offline
veteran

Registered: 01/06/05
Posts: 125
Loc: Chicago, IL
are you using XLR or RCA connections?

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#418550 - 04/12/16 06:56 PM Re: For those of you with external amps - floor noise [Re: spiroh]
alan Offline

connoisseur

Registered: 01/29/02
Posts: 3262
Loc: Toronto/New York/parry Sound
Spiroh, what you are hearing is more correctly called "thermal noise", the residual random noise generated by active electronic circuitry. Assuming you don't have ground loop hum or buzz, the "hiss" from well-designed power amps or the power amp section of a receiver shouldn't be audible more than a foot from the speaker and you certainly wouldn't hear it from a normal listening distance.
Some receivers will generate more thermal noise than a separate power amplifier because of the more densely packed circuitry.

Typically, separate preamps are quieter than the preamp sections of a receiver, especially those with phono inputs, moving magnet or moving coil.

Regards,
Alan
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Alan Lofft,
Axiom Resident Expert (Retired)

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#418551 - 04/12/16 08:21 PM Re: For those of you with external amps - floor noise [Re: spiroh]
MarkSJohnson Offline
shareholder in the making

Registered: 09/27/04
Posts: 11437
Loc: Central NH
Alan, you're a treasure to have on these boards!
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::::::: No disrespect to Axiom, but my favorite woofer is my yellow lab :::::::

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#418552 - 04/12/16 08:27 PM Re: For those of you with external amps - floor noise [Re: spiroh]
spiroh Offline
veteran

Registered: 01/06/05
Posts: 125
Loc: Chicago, IL
I would say I cannot hear the thermal noise more than a foot away. Does this thermal noise affect sound quality at louder volumes? I guess my debate is do I sell the SR7010 to go to the AV7702mkii to be able to go from receiver with builtin amp and only rca output to a pre-amp with XLR outputs.

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#418554 - 04/12/16 08:36 PM Re: For those of you with external amps - floor noise [Re: spiroh]
Mojo Offline
connoisseur

Registered: 01/21/07
Posts: 4700
What Alan said. You can put a resistor on your kitchen table and measure the voltage across it as a result of intrinsic and extrinsic noise. Intrinsic from thermal fluctuations and extrinsic from stray fields.

To answer your question, a signal to noise ratio of over 85dB referenced to a 1 Watt output into the rated load with the inputs shorted and measured over a band from 20Hz to 20Khz at maximum gain is a figure your ears won't object to.

If you are really concerned about the noise, drown your amp in liquid nitrogen.

Does that help smile?

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#418555 - 04/12/16 08:37 PM Re: For those of you with external amps - floor noise [Re: spiroh]
Mojo Offline
connoisseur

Registered: 01/21/07
Posts: 4700
At louder volumes the signal to noise ratio improves. Don't worry about it and enjoy the noise...I mean the music smile.

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#418556 - 04/12/16 08:43 PM Re: For those of you with external amps - floor noise [Re: spiroh]
2x6spds Offline
connoisseur

Registered: 03/16/02
Posts: 3121
Loc: CA, USA
No thermal noise from my 25+ year old Integra M504, or Yamaha M80s. My newer anthem 5 channel amp ... no noise. Oh, my 5 wpc distortion generator (thanks Alan you treasure you) no hum, no thermal noise.

Good luck with your amp.
_________________________
Enjoy the Music. Trust your ears. Laugh at Folks Who Claim to Know it All.

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#418557 - 04/12/16 08:58 PM Re: For those of you with external amps - floor noise [Re: spiroh]
Mojo Offline
connoisseur

Registered: 01/21/07
Posts: 4700

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