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For those of you with external amps - floor noise
#418547 04/12/16 06:02 PM
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spiroh Offline OP
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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

Re: For those of you with external amps - floor noise
spiroh #418548 04/12/16 06:08 PM
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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.


Enjoy the Music. Trust your ears. Laugh at Folks Who Claim to Know it All.
Re: For those of you with external amps - floor noise
spiroh #418549 04/12/16 07:17 PM
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are you using XLR or RCA connections?

Re: For those of you with external amps - floor noise
spiroh #418550 04/12/16 10:56 PM
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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


Alan Lofft,
Axiom Resident Expert (Retired)
Re: For those of you with external amps - floor noise
spiroh #418551 04/13/16 12:21 AM
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Alan, you're a treasure to have on these boards!


::::::: No disrespect to Axiom, but my favorite woofer is my yellow lab :::::::
Re: For those of you with external amps - floor noise
spiroh #418552 04/13/16 12:27 AM
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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.

Re: For those of you with external amps - floor noise
spiroh #418554 04/13/16 12:36 AM
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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?


A-LFR/1000-8 & 2/500v4x2
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Re: For those of you with external amps - floor noise
spiroh #418555 04/13/16 12:37 AM
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At louder volumes the signal to noise ratio improves. Don't worry about it and enjoy the noise...I mean the music smile.


A-LFR/1000-8 & 2/500v4x2
1000-3,1500-3
100,160,QS10x2,800,M5x2,M2/3/50v4
Air Force, Freedom
had v2
Re: For those of you with external amps - floor noise
spiroh #418556 04/13/16 12:43 AM
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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.
Re: For those of you with external amps - floor noise
spiroh #418557 04/13/16 12:58 AM
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A-LFR/1000-8 & 2/500v4x2
1000-3,1500-3
100,160,QS10x2,800,M5x2,M2/3/50v4
Air Force, Freedom
had v2
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