Computer Noise - Affect on Audio Quality

o0OBillO0o: you should visit the Computer Audiophile forums - many expert people there report hearing and measuring major effects due to insufficient electrical insulation. First it got me depressed and I was close to going down the way of changing all my setting & spending lots of $$$, but financial reality brought me back and I did my best with what I have. Surely there is some electrical “noise” but as long as I am not bothered by it I decided to just leave it as is…

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We do have to keep this in context of real world effects though. The difference between a -140dB noise floor and a -132dB noise floor is utterly irrelevant to you, I or anyone else. For example most DACs have a theoretical SNR of around 120dB. Unless you’re worried about hearing air molecules vibrating there is no possible audible effect.
Moving your head from side to side at the listening position would be more significant.


The difference between a -140dB noise floor and a -132dB noise floor is utterly irrelevant to you,




or anyone else


There are many people out there for whom noise at that level might be subjectively relevant, even if the numbers say that it shouldn’t be detectable.

For example, there are seem to be many people who have a “favorite” noise-shaped dither, but use 24bit (or higher) output. This is a difference right in that same ~138-144dB ballpark.

For example most DACs have a theoretical SNR of around 120dB.

I agree that we can’t hear sounds at -132 or -140dBFS (and I think I made that clear in my post).

That said,

Human ears have a theoretical SNR of about 95dB, but by now we’ve figured out that the 96dB dynamic range of Redbook isn’t enough.

We’ve also figured out that while humans can only hear frequencies up to 22kHz, 44.1kHz isn’t enough. Both for direct reasons (psychoacoustic significance of impulse response, binning of ultrasonic content), and for indirect reasons (mastering at 44.1kHz requires steep filters that do damage).

Ladder DACs run into the limits of resistor manufacturering somewhere in the 18-20 bit range, but there are 24-32bit Ladder DACs on the market, and people still buy them and enjoy them more than the one they were using before.

DSP processes are routinely optimized to be much better than they need to be, too. Look at the stop-band attenuation of most low pass filters used for sample rate conversion. It’s usually way better than the science suggests that it needs to be.

Over-engineering is a way of life in this space. If we want to make a product that satisfies the people who are hunting down computer noise as much as the people who are staring deep into the eye of the spectrogram, we have to address many ways of thinking about and experiencing audio.


Nope I have to disagree. It’s a purely numbers game for credulous audiophiles to wring their hands over.

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I share this ^^ viewpoint now, could change though.

I have a Macbook Air and a iMac, both connected to USB DACs, and airplay devices. I believe have no noise from the computer, that I can tell. It could be there? How would I test for noise?

It could be there? How would I test for noise?

Subjectively: ABX test between Computer->DAC and Computer->Network->Bridge->DAC.

Objectively: Plug Computer->DAC and Computer->Network->Bridge->DAC into a scope with plenty of dynamic range, play the usual test signals, and analyze/understand the differences.

The first one tells you if the difference matters to you personally. If you iterate the test over a population, you can determine whether it makes a difference to anyone.

The second one tells you what the differences are, and the nature/degree of differences present. There will always be some if you zoom in far enough. That’s just the nature of analyzing analog systems.

These are not easy/cheap tests to run, so in the real world, audiophiles don’t bother. Responsible HiFi manufacturers routinely do both during product development.

When we first brought our PC-in-a-box Sooloos products to Meridian in 2008, one of the first things they did was to put each product inside a metal room, measure what kind of EM/RF interference it was emitting, and measure how it impacted performance measured in the analog domain–and they found the results pretty amusingly bad compared to their usual standards.

I’m not an EE, but I know when to respect another engineer’s measurements and do my part fixing the problem. The end of that road was marked by the release of lightweight networked endpoints that fully met Meridian’s performance standards.


I use the optical out from the motherboard of my Windows 10 PC to my receiver. Would there be a recommended soundcard that I could purchase that would be better in terms of noise ? Or is the fact that it’s in the PC case itself the issue here ?


Are you actually suffering from noise ? Really ?
And if you’re using an optical connection, you can’t be suffering from EMI anyway, so you should be fine already.

Not that I am aware of but now i’m worried !! :scream:

Only kidding, but I am curious if a dedicated soundcard could improve my system ? I’m guessing not…

Slightly tongue in cheek @Jaap74, but I suspect that removing the soundcard (that’s the humorous part) and sending audio by RAAT over Ethernet to a network renderer and then to your receiver by Optical or USB (as you prefer) would give better results than the most expensive soundcard/SPDIF solution that money can buy. You can buy an expensive network renderer (Aries) or an inexpensive one (SonicOrbiter SE), and will soon (after Roon 1.2) be able to DIY, as you prefer.

Edit: Of course, if your receiver (brand not stated) becomes RoonReady, then it will be it’s own network endpoint and you won’t need a renderer.

@Jaap74 A dedicated sound card can definitely be better than the internal audio chip set, especially if you use it as a DAC and send analogue out. To that end, I can recommend the Asus Xonar Essence STX, because I’ve used it to great success. It has EMI shielding, Burr Brown DAC and ASIO drivers.

@Jaap74: you might have jitter on the optical output, but if your DAC reclocks the audio on input you won’t have an issue.

great post!!!

Beyond ABX, the personally “method”, the resources, time&/money, have to be proportional to the desire to know the truth. …and then in the results, the truth could be not a desireble outcome!

I suggest all be selfish in this quest, but please share your results.

Absolutely agree @brian.

The noise level mentioned are indeed extremely low. However, whether or one can hear it is an opinion ultimately. Whether or not it truly exists as a problem is very personal.

I remember in the 70’s chasing down those numbers in THD, channel separation, etc. I bought equipment that chased numbers and I bought so I tended toward solid state. Friends of mine thought I was a shallow audiophile and rolled their tubes. They didn’t worry, and still didn’t worry a whole lot about noise (of course they do to some degree, but I’m make a point). They wanted what sound good to them.

There is nothing wrong with pushing the limits. For some it’s well worth it, for some a fools errand. The more the envelope is pushed the better the state of the art and for some of us, our audiophile pleasure.

Science changes, and so does art.

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No, it really isn’t. You do not have the physiological tools to hear that far down into the mix. Otherwise you’d be listening to the vibrations of air molecules.

It’s important to note that in a house the baseline noise level can be in the 50-60dB range so perceiving noise at -120dB when playing music at a reasonably loud volume (90dB) will be extremely challenging.

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That’s understatement, right there :slight_smile:

@pwright92 Noted- but when you listen to music on, say, a set of Shure SE846 In Ear Monitors, which isolate the listener from environmental noise, you can hear everything.

50-60dB is remarkable for a baseline noise level. I whipped out my Radio Shack SPL meter and my JL Audio iOS app and got a ~35dB ambient noise level- and that’s with a open concept living room. (I can hear the fridge humming along too.)

Further, with FLAC/CD’s 96dB of signal to noise, I am already swimming in 35dB ambient, thus I would have have to crank it up to like 131dB (!) to even hear the noise floor on a CD/ 16bit FLAC file.

You make an excellent point with your suggestion of 90dB program volume and 60dB ambient volume, you’d be just fine with anything from 1955 LPs all the way to today’s downloadable lossless files. Cars? PPFFF!

@anon55914447, Mark, you are unclear, to me, here. “physiological tools??”

I have a background in analysis, math, and tools. More often then not, I use the numbers to justify a reason/hypothesis/viewpoint, eyes glaze over; even the smartest of the smart wander off to toon town. Big decisions are made in this world through intuition, instinct, and intangibles… …and if we had it all figured out we wouldn’t have to discuss it.

Yes just to add my 2 pennies worth here. I have a raspberry Pi with a switch mode PSU, I have a Devialet 400 (soon to be 800) which has a switch mode PSU and Magico S5 speakers. If I turn the volume up to +30 on the Devialet with nothing playing and put my ear against any of the drivers there is utter silence. Considering that I run an IT business from home with servers, router (with SM PSU’s) NAS PC’s with noisy internals all running on the same mains network I begin to doubt the noisy PSU assertion.

If I actually played music at that level in my room I would literally be pinned to the wall with the sheer volume of sound, even at 0 on the volume my wife comes in, gives me one of those looks and shuts both the doors!!!

The background noise level is about -36 dB according to my Netatmo.