Hissing sound from speakers, with/without input signal

[GeekySimar]

Hi,
I just picked Sony STR-DA1000ES from Goodwill to use it for my desktop setup.

Everything is good, it sounds awesome, the only problem I am facing with the amplifier is hissing noise.

Hissing noise come when I turn the volume to -30db and up. Otherwise I am not able to hear hissing sound from listening distance. It is there even I don’t connect anything to the input signal, just the speakers.

Its profound at 0db. When I switch to digital input, hissing goes away. Though I haven’t listen any music through digital input, just switched to check if hissing is there.

How can I fix this problem?

Thanks,
Simar

 

[wiseoldtech]

Hi,
I just picked Sony STR-DA1000ES from Goodwill to use it for my desktop setup.

Everything is good, it sounds awesome, the only problem I am facing with the amplifier is hissing noise.

Hissing noise come when I turn the volume to -30db and up. Otherwise I am not able to hear hissing sound from listening distance. It is there even I don’t connect anything to the input signal, just the speakers.

Its profound at 0db. When I switch to digital input, hissing goes away. Though I haven’t listen any music through digital input, just switched to check if hissing is there.

How can I fix this problem?

Thanks,
Simar

Solid state "noise" or "hiss" is a normal thing, particularly with "wide open" or "unloaded" inputs.
It is not a "problem".
If you short the selected input to ground, the hiss will reduce or completely stop - again a normal thing.
And as you mentioned, at "normal" listening distance, hiss is not a problem, and if not hearable with music playing - it's not a problem.
Enjoy the music, and stop worrying.

 

[GeekySimar]

Thanks for you comment. But the hiss is there even when I connect the input. It is there both ways opened/unopened.

I am able to hear the hiss from listening distance when master volume is -30db and above. Below that it is fine from listening distance.

Is this normal? If not, grounding is possible solution?

How to do that, can you explain a bit? Sorry I am new here, don’t have much knowledge.

Thanks,
Simar

 

[Osvaldo de Banfield]

If the hiss is very notorious and the amp has a decade or more of old, possibly it will need a recap of the unit, because it may be oscillating at ultrasound frequencies.

 

[sgrossklass]

It's got audible hiss above -30 dB? Then feed the amplifier with enough input level that volume setting for normal output level is below -30 dB. Problem solved.
(As the old joke goes: Doctor, it hurts when I move my arm like this. - Then don't move your arm like this.)

Assuming the volume control maxes out at 0 dB, normal volume should be around the -40 to -46 dB mark... that's roughly 1 W output for 2 Vrms input terrain.

This unit has an ANALOG DIRECT function. Enable this for stereo operation to bypass all the A/D, signal processing and D/A stages, which may well reduce the noise further.

If all you can muster is onboard audio, make sure that it can reproduce a 0 dBFS sine undistorted with the volume all the way up. (Sometimes they don't when the board manufacturer was skimpy.) Otherwise note maximum permissible volume setting. When using an Asus card with combined line/headphone output, make sure it's not set to one of the lower-impedance headphone settings, which engage either 6 or 12 dB of digital attenuation.

 

[GeekySimar]

It's got audible hiss above -30 dB? Then feed the amplifier with enough input level that volume setting for normal output level is below -30 dB. Problem solved.
(As the old joke goes: Doctor, it hurts when I move my arm like this. - Then don't move your arm like this.)

Assuming the volume control maxes out at 0 dB, normal volume should be around the -40 to -46 dB mark... that's roughly 1 W output for 2 Vrms input terrain.

This unit has an ANALOG DIRECT function. Enable this for stereo operation to bypass all the A/D, signal processing and D/A stages, which may well reduce the noise further.

If all you can muster is onboard audio, make sure that it can reproduce a 0 dBFS sine undistorted with the volume all the way up. (Sometimes they don't when the board manufacturer was skimpy.) Otherwise note maximum permissible volume setting. When using an Asus card with combined line/headphone output, make sure it's not set to one of the lower-impedance headphone settings, which engage either 6 or 12 dB of digital attenuation.

That quote was hilarious. Lol

Analog direct did help a lot, but then I am not able to use the equalizer. So to conclude, this is normal. And signal processing is amplifying that hiss noise.

What about shorting the input with ground as mentioned above? Will it help? As such it does not bothers me so much, just for knowledge.

I am feeding the amp with Allo Boss DAC, which has good output and it keeps my amp below -50db for normal listening. Thinking of buying dedicated sound card for Desktop though.

Thanks for the suggestions.

Simar

 

[sgrossklass]

Analog direct did help a lot, but then I am not able to use the equalizer. So to conclude, this is normal. And signal processing is amplifying that hiss noise.

Be glad if it's only the DSP section that has a somewhat limited dynamic range. The Kenwood KRF-V8090D that my parents bought in '05 was hissy all the time. Forget about using headphones. The gain staging / PGA design in that one was not good. Classic surround receivers could be really annoying in that regard. H/K carried on this "tradition" for a surprisingly long time.

The converters in this one are heavy on Burr-Brown. ADC PCM1800, DAC PCM1604. I'll have to look those up.

PCM1800: SNR/DR - 95 dB(A) (typical), up to 48 kHz
PCM1604 (EOL): SNR 104 dB(A), DR 105 dB(A) (typical), up to 200 kHz

Assuming unity gain, the ADC would be your bottleneck no doubt. With a 33k/33k voltage divider in front, a 30k input impedance and 2.828 Vpp in max, it would handle approx. 3.1 Vrms in. That leaves a grand total of 91 dB(A) ref. 2 Vrms, correspondingly less for quieter sources.

Which, mind you, still is generally adequate except for those dead-set on testing the dynamic range of their input section.

What about shorting the input with ground as mentioned above? Will it help? As such it does not bothers me so much, just for knowledge.

That's a troubleshooting / measurement technique used to avoid input hum or noise, but at a much lower level than what your DSP section contributes. Not very relevant here.

I am feeding the amp with Allo Boss DAC, which has good output and it keeps my amp below -50db for normal listening. Thinking of buying dedicated sound card for Desktop though.

That should be a multichannel card then, as for stereo you might just as well use an S/P-DIF connection with the receiver's built-in DAC to (probably) good results. You have the advantage of a 5.1 analog input. Doing A/V receiver things on a PC can be a complete nightmare though, so do your research diligently. (I wouldn't recommend my SB Audigy FX, for example, as the channel volumes have a habit of running out of sync when headphone use is involved at times. Really stupid software bug.) Most people these days prefer doing their room correction and other fun stuff on a separate DSP box, though you could certainly give the likes of Dirac a shot.