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S/N ratio Balanced input vs. Unbalanced input

Hi, is it normal that signal to noise (S/N) ratio at rated output of balanced input (XLR) is lesser than unbalanced input (RCA) ?

eg. Accuphase E280 , S/N ratio balanced is 96dB, unbalanced is 107dB.

 

Also E280 , at preamp stage , dB gain : balanced/unbalanced to pre output is 18dB gain, power amp stage dB gain : 28dB, total of 46dB.

What about other integrated amplifiers specs for comparison ? 

S/N ratio (balanced) :

S/N ratio (unbalanced):

Preamp gain :

Poweramp gain: 

 

auronthas
auronthas OP
79 posts
 

No more hiss if DAC is disconnected

kijanki's avatar
kijanki
4,413 posts
 

If hiss comes from the DAC and is independent of the volume pot, then likely DAC is injecting some electrical noise into amplifier.  I wouldn't worry about it, since not too many amps are completely quiet with the ear on the tweeter.

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o_holter
961 posts
 

I wouldn’t worry about it but I would be curious. Even if not so loud, the hiss should not be there. I am allergic to anything that gives more digital glare, and the hiss may be a suspect, even if not much notable by itself when playing music in the listening position. So I would wonder, why does this happen. Does the DAC behave that way with other amps also? Are you sure other sources into the amp don’t give the hiss? You’ve said its the same from xlr and single ended inputs. If you have switchable inputs between sources on your amp - the same across these, also? The fact that the hiss does not vary with the volume level makes me pause. Something wrong in the DAC? Or mismatch, amp / DAC?

I just tested in my secondary system, with a Ming Da integrated amp, with a few small DACs including the Fiio x3 and Huawei p30. Aurum Cantus speakers, with top notch ribbon tweeters well able to tell me what goes on. No hiss, but some hum. Varying with volume. Below the "worry" border, though - only heard clearly at max volume.

westcoastaudiophile
245 posts
 

since hiss is not volume cntrl dependent, you may deal with EMI issue. 

adding "Cable Clamp Clip RFI EMI EMC Noise Filters “ to analog bal/unbal cable, close to the amp inputs,  sometimes helps.

auronthas OP
79 posts
 

Are you sure other sources into the amp don’t give the hiss?

@o_holter Ya, I tried my old Sony CD player which connect to integrated amplifier via RCA, I did not notice any hiss near tweeter.  I will do fast "switching" from balanced input (Ares II DAC) and RCA input (Sony CD player) to test the hiss noise.

adding "Cable Clamp Clip RFI EMI EMC Noise Filters “ 

@westcoastaudiophile my audio equipment are connected to a good power conditioner of Novaris brand.  I would think EMI issue shall not be the case, wouldn't it ?

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