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Topic: EMI/RFI and d/a computer audio? (Read 10406 times) previous topic - next topic
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EMI/RFI and d/a computer audio?

I've got an Asus Essence ST sound card, and i like it a lot. I've got all my CD ripped to my pc and i love the laziness....i mean convenience factor.  I'm using the analog outputs and feeding my amp directly.  However, when i try to explain how awesome it is to be able to cue up 50 tracks and just zone out all day i'm almost always told that it should sound bad due to EMI/RFI inside the computer and that the D/A should *always* be outside of the computer or it will "interfere...muddy...ruin" the sound.  In fact my sound card came with a metal 'shield' that covered the chips.  I'm betting that it did nothing to shield the chips and was mearly a place to put their big logo.

Now, using the analog outputs on a CD player doesn't seem that different a situation. They have a processor and circuit boards in them. What's the difference? Why isn't there a concern about rmi/efi doing bad things inside of a cd player or inside an outboard D/A for that matter?

I have not seen any ABX tests on whether people can hear emi/rfi, nor do i have the equipment to preform one (having no outboard D/A for one).  Is there any truth to the claim that emi/rfi is "bad" for a soundcard and the an outboard D/A is the only way to go?

When i was using on-board audio, i believe (no i have not ABXed it) that putting my ear right up against one of my speaker cones and pushing my CPUs cores hard for varying lengths of time, allowed me to hear the sound of my fans spinning through the speaker.  It sounded like a low motor hum that seemed to rise and fall in pitch with the speed of the fans as my system got hotter and cooler. Thats was a mechanical or ground issue, and not related to an emi/rfi "problem" right?

Anyone care to fill me in?  Is all this EMI/RFI fear just a way to get folks to by an outboard D/A?

Thanks.

edit: typo
Music lover and recovering high end audiophile

EMI/RFI and d/a computer audio?

Reply #1 –
If you can't hear the noise then you can probably stop worrying. I know the Xonar cards in general are very good at this. I have a DX and it's as clean as my HDMI output, regarding to what I can hear myself. The chipset/mobo has to be pretty crappy actually, with modern PCs, for you to actually hear this interference. Sometimes if you're wearing very sensitive headphones you'll probably hear something though.

Also, this noise would show up in RMAA tests, so you can search for these graphics on the net, I'm sure there are plenty for that card. AFAIK they're pretty good.

EMI/RFI and d/a computer audio?

Reply #2 –
The potential problems are very real, but equipment designed to avoid these problems doesn't have to be expensive.

This fact - that you can get something more than good enough for very little money - is an anathema to most audiophiles. It doesn't fit with their mindset. It doesn't induce the placebo based improvements they live for. As for convenience - bah humbug - good audio must be inconvenient!

That's fine. Their loss. Your gain. Enjoy great sound with convenience!

Cheers,
David.

EMI/RFI and d/a computer audio?

Reply #3 –
Quote from: BearcatSandor on
Now, using the analog outputs on a CD player doesn't seem that different a situation. They have a processor and circuit boards in them. What's the difference? Why isn't there a concern about rmi/efi doing bad things inside of a CD player or inside an outboard D/A for that matter?


You've been doing some unusually clear thinking about this issue.

If computers were unmanageably noisy for audio, we'd be in a heck of a fix because just about everything has a computer in it these days. For example, my Sansa Clip is basically a 1-chip computer with an on-chip DAC and headphone amp.

Some people have biases against PCs because they use switch mode power supplies. These days so many things are powered by switch mode power supplies, even audio production gear and high end audio.

You've probably noticed that in the past year or two most of the wall warts that come with new gear got smaller, lighter, and work on just about any line voltage. It is all because they are now switch mode power supplies!

EMI/RFI and d/a computer audio?

Reply #4 –
Right...  You don't have to be a "golden ear audiophile" to hear noise.  And, noise is generally the only thing I worry about because it's just not that hard (or expensive) to get low-distortion and (fairly) flat frequency response.  Electromagnetic noise will not make the sound "muddy".

I've got a laptop with the analog-out connected to my living room system. 

You can get noise...  Inside a PC is a pretty nasty environment, and there are lots of unknown variables...  The soundcard manufacturer doesn't know how much noise is coming from the motherboard, hard drive, video card, etc.  So, they just have to try and make it as noise-immune as possible and hope for the best.  And, audio quality isn't usually at the top of the PC manufacturer's list of concerns. 

So, it's not entirely illogical to choose an external DAC, or a good USB soundcard, or to run digital-out into a home-theater receiver, etc.





EMI/RFI and d/a computer audio?

Reply #5 –
Quote from: BearcatSandor on
Now, using the analog outputs on a CD player doesn't seem that different a situation. They have a processor and circuit boards in them. What's the difference? Why isn't there a concern about rmi/efi doing bad things inside of a cd player or inside an outboard D/A for that matter?


A CD player has a motor, a linear actuator and a processor
In a PC you have the same but the processor is much more powerful, a couple of motors (HD with a very fast head, fans) and a lot of choppers (clocks) each driving a bus at a certain frequency.
So likely any disturbance, EMI, RFI, ripples in the power supply, etc are much stronger than in a low power device like a CDP.

One of the few measurements I know is a Oppo running and in stopped mode.
This do have a measurable impact on the jitter level of the digital out.
Would be very interesting to see a like wise measurement of a PC.


Well, some do care about the noise of a CDP: http://www.ecdesigns.nl/






TheWellTemperedComputer.com

EMI/RFI and d/a computer audio?

Reply #6 –
Quote from: Roseval on
Quote from: BearcatSandor on
Now, using the analog outputs on a CD player doesn't seem that different a situation. They have a processor and circuit boards in them. What's the difference? Why isn't there a concern about rmi/efi doing bad things inside of a cd player or inside an outboard D/A for that matter?


A CD player has a motor, a linear actuator and a processor


So does a CD-ROM. Many of the optical drive mechanisms in use are the same whether in a dedicated player or a PC.  However, the motor, actuator, etc. of a CD player are constantly operating. In a PC the primary source of audio information is probably a hard drive that is heavily buffered by RAM.  The CD drive might not be running at all.  It's hard to compare the two.  Simplistic comparisons based on speculation should be avoided.

Quote
In a PC you have the same but the processor is much more powerful, a couple of motors (HD with a very fast head, fans) and a lot of choppers (clocks) each driving a bus at a certain frequency.
So likely any disturbance, EMI, RFI, ripples in the power supply, etc are much stronger than in a low power device like a CDP.


Actually, its the voltages of the clocks and power supplies that induce the most noise, and they are generally about the same in dedicated players or PCs.

Quote
One of the few measurements I know is a Oppo running and in stopped mode.
This do have a measurable impact on the jitter level of the digital out.
Would be very interesting to see a like wise measurement of a PC.


With the Oppo, you're stuck with the components that Oppo puts into the box. With a PC, you can swap internal and external audio interfaces at will. The better audio interfaces for the PC have extremely high performance, since they are widely used in audio production. 

If you categorically  don't like what PCs do to sound, then you need to stop buying commercial recordings and listening to media outlets, since computers are so widely used in audio and video production.

Furthermore, I see no  correlation between this randomly-chosen jitter plot and audible sound quality.

Quote
Well, some do care about the noise of a CDP: http://www.ecdesigns.nl/


I see no evidence that this manufacturer is doing anything special about noise. One thing I do see is that he is promoting a media player that is based on flash memory rather than optical discs. Of course for many of us, flash-based digital players are the way we mostly listen to music.  It's about time that audio's high end try to catch up!

As long at there are skilled engineers who work hard to keep performance high regardless of the stumbling blocks, generalizations and speculations like the above are meaningless.

EMI/RFI and d/a computer audio?

Reply #7 –
Quote
Is all this EMI/RFI fear just a way to get folks to by an outboard D/A?


You make a good point as regards the potentially inaudible difference in sound quality between an on board or gamers grade soundcard and a dedicated audio interface.

That's not a definitive reason to avoid an audio interface though. They offer a number of very valuable additional features with great convienience and utility. At first you may not feel you need them all but once you have experienced the advantages you may well find you wonder how you managed without.

An Audio Interface doesn't need to be connected to an already booted up PC to be useful. You can usually control gain and EQ levels, route, mix, add effects etc etc with an interface in stand alone mode. This is particularly useful if you are in the process of replacing amp/speakers with powered monitors as the interface replaces and adds utility to the control pre amp section of your old integrated amp.

An audio Interface is not tied to a single PC or location. Use it with your portable when out and about field recording. Use it to connect your desktop, hi fi and television systems when at home.

Any audio interface above the most basic will offer access to Windows multi channel capabilities. I know a sound card or on board chip will usually allow up to 7.1 Dolby out - but - it's still just a single program. You can buy good interfaces for less than $200 that do 4 channels in and four out. For $400 you can expect up to 8 in and 8 out. This isn't just useful to DJs or music producers wishing to cue or blend incoming tracks. You can be playing high quality audio via your hi fi or television and simultaneously listening to youtube clips, chatting on Skype or playing games with your mates. Alternatively you could be routing different programs to different rooms around the house. Radio 3 in the kitchen, iPlayer in the lounge and Spotify in a bedroom. Record anything from any source at the click of a button.

I'm not shilling for any particular company or product here and I realise not everyone will appreciate the same system but I was surprised and delighted to discover how useful an audio interface proved to be and would like to share it with anyone who might as yet be unaware of the benefits.

EMI/RFI and d/a computer audio?

Reply #8 –
Quote from: RonaldDumsfeld on
Quote
Is all this EMI/RFI fear just a way to get folks to by an outboard D/A?


You make a good point as regards the potentially inaudible difference in sound quality between an on board or gamers grade soundcard and a dedicated audio interface.

That's not a definitive reason to avoid an audio interface though. They offer a number of very valuable additional features with great convienience and utility. At first you may not feel you need them all but once you have experienced the advantages you may well find you wonder how you managed without.

An Audio Interface doesn't need to be connected to an already booted up PC to be useful. You can usually control gain and EQ levels, route, mix, add effects etc etc with an interface in stand alone mode. This is particularly useful if you are in the process of replacing amp/speakers with powered monitors as the interface replaces and adds utility to the control pre amp section of your old integrated amp.

An audio Interface is not tied to a single PC or location. Use it with your portable when out and about field recording. Use it to connect your desktop, hi fi and television systems when at home.

Any audio interface above the most basic will offer access to Windows multi channel capabilities. I know a sound card or on board chip will usually allow up to 7.1 Dolby out - but - it's still just a single program. You can buy good interfaces for less than $200 that do 4 channels in and four out. For $400 you can expect up to 8 in and 8 out. This isn't just useful to DJs or music producers wishing to cue or blend incoming tracks. You can be playing high quality audio via your hi fi or television and simultaneously listening to youtube clips, chatting on Skype or playing games with your mates. Alternatively you could be routing different programs to different rooms around the house. Radio 3 in the kitchen, iPlayer in the lounge and Spotify in a bedroom. Record anything from any source at the click of a button.

I'm not shilling for any particular company or product here and I realise not everyone will appreciate the same system but I was surprised and delighted to discover how useful an audio interface proved to be and would like to share it with anyone who might as yet be unaware of the benefits.


Thanks Ronald (great username btw), i'm looking at the MOTU Traveller today, thanks to your post. Not to buy just yet, but my ears are perked at it and it would handle the 4-channel ambisonics b-format (4 mic inputs anyway) which i'm very interested in.

Well, i'm not going to worry much about computers, jitter and emi/rfi anymore. What i'm hearing you folks say is that based on your experience the contaminates exist but not at a level that is audible.

I am however concerned with PC noise, so i have made an effort to get a dampened cabinet, and quieter fans.  Instead of worrying about RFI/EMI i wish more companies put efforts into things like quieter drives (both hdds and 5" media) and quieter fans and cases.  Building it all myself i was able to get it pretty quiet (if i keep things clean).

In my experience lowering the noise in my room has made a difference in my overall appreciation of music and lowered my stress levels a bit. That's better than most 'audiophile' upgrades i can think of.

Thanks all.
Music lover and recovering high end audiophile

EMI/RFI and d/a computer audio?

Reply #9 –
Getting a really quiet PC is quite an art. BTW, there is some BS in the PC fan "community", believe it or not. Rule of thumb, bigger and lower RPM is always better, and the bigger the case usually the quieter. Antec sells cases with a 200mm fan. I have the mini P180 and have taken out the 12 cm rear fan and covered the hole so air is forced from the lower part, where I put a fanless PSU. I also took out the fan grill cause it doesn't do anything but block air... the fan won't cut anyone's fingers considering which way it's rotating. In can keep running it in the lowest setting which according to specs on the net seems to be about 400-500 RPM. The only other fan running is a 90mm CPU fan at about 900-1000 RPM with a relatively big Thermaltake cooler.

It's a Core 2 Quad Q9450 BTW, stock 2.4 GHz but I have overclocked it before to 3.2 without problem with the same fan RPMs. I have an ATI 5770 whose cooler I swapped for a fanless Arctic Cooling Accelero S1. All this requires a big case. This case though is micro ATX, but it's big and heavy anyway, it has thick panels too to damp noise.

In my experience, modern HDDs are very quiet. The most noise is usually made by the video card. My PC is running 2 5400 RPM laptop HDDs, 2 Western Digital Black (I think) 640 GB HDDs, one WD Green Power 1.5 TB, and for the OS and programs, one SSD (noiseless and super fast). When I tested the ATI 5770 with its original fan or the Nvidia GTX460, they were still by far the most noisy component. I can't hear any of the HDDs even with only the 200mm and the 90mm fan running at ridiculously low RPMs.

EMI/RFI and d/a computer audio?

Reply #10 –
Quote
Getting a really quiet PC is quite an art.


Ain't that the truth. I think it's really amusing how so many of the studio/producer type guys agonise  over 0.001% harmonic distortion in an amp while they have an monster i7 blast  furnace roaring away only feet awau from their ears.

I tried with an Antec special quiet, rack mount case, a small i3 processor, passive CPU and graphic card coolers and Antec fans which claim to be silent but aren't. I was hoping I could underclock it and do without case fans unless i turned the on manually. Didn't really work. I still leave the fans on low. It's quiet but not silent and considering the time and money that went into it it could have been more successful.

I think the way forward now is to use one of those new Intel Atom N330 chips on an mini ITX Ion board. Small, ultra low power, built in Nvidia graphics, no CPU, GPU or case fans required. Even the power comes from a wall wart. What does piss me off is the thought of giving Microsoft the full whack for a copy of windows. Adds over 25% to the total cost. Bah.

EMI/RFI and d/a computer audio?

Reply #11 –
Ronald your mini-itx comment reminds me of related issue to emi/rfi. It might be the same issue. I donno.
As far as EMI/RMi goes i've seen a lot of talk about power conditioners for audio and multi-hundred (sometimes thousand) dollar power cables for audio components.  I keep hearing things like

"Have you ever noticed that your audio sounds better at night? That's because all that electrical noise is getting into you amplifier and coming through your speakers! Even your neighbors TV will interfere with your listening enjoyment! Buy our silver power python!" 

I keep thinking..."No, at night lots of things are turned off so the noise floor in the room is lower. Also, i'm more relaxed and i'd bet tension levels effect our enjoyment of music."  However, my computer, lights and fridge are still on.

So i was thinking of making sure that my amps (class t) , mini-pc and D/A (say like a MOTU Traveller) could all run on battery power to de-couple it from the power grid.

Has anyone ever done any testing on that? I looked but i can't find a thing. Would running off of batteries make an audible difference (aside from when the mains power goes out of course).  My research promises "deeper blacks", "wider sound stages"  and "more lushness" whatever the heck that is. Sounds messy.
Music lover and recovering high end audiophile

EMI/RFI and d/a computer audio?

Reply #12 –
It is quite possible to hear a background hiss with internal sound cards, under the right conditions.  Mainly with the analog inputs and when everything around my listening area is quite silent.

One of the PCs I have is an older model I put together myself about 10 years ago.  It is running Windows XP and has a Creative SB Live! PCI internal sound card as it's main sound card.

I have headphones attached to the card's output.  Just regular "cheapo" $30 headphones:  Sennheiser HD202.

I've noticed that if I enable the Line-In and/or CD Audio (analog) in the big "Play Control" application (the one where you also set the WAV, MIDI, Telephony, etc.) , with the slider levels set to max, I can hear a really faint background hiss.  It is more pronounced if both Line-In and CD Audio (analog) are enabled as it appears both inputs cause an additive background hiss.

However, if I mute both of those, then the background hiss goes away completely.

Furthermore, when regular audio, or music, is playing, that extremely faint background hiss is masked by the volume of the audio.

All in all, it really doesn't bother me, since I know that in regular listening conditions, it's unnoticeable.


Note that when I'm talking about CD audio (analog) on the sound card, I mean the CD Audio input  connector on the sound card, which uses that small red/white twisted cable to connect to the analog audio out on an internal CD/DVD drive.

I can mute that CD audio (analog) and still use CD Digital, which just reads the audio bitstream as data using the IDE cable.  In fact, that's the preferred method, since it bypasses the CD/DVD's DAC.

EMI/RFI and d/a computer audio?

Reply #13 –
Quote from: BearcatSandor on
So i was thinking of making sure that my amps (class t) , mini-pc and D/A (say like a MOTU Traveller) could all run on battery power to de-couple it from the power grid.

Has anyone ever done any testing on that? I looked but i can't find a thing. Would running off of batteries make an audible difference (aside from when the mains power goes out of course).  My research promises "deeper blacks", "wider sound stages"  and "more lushness" whatever the heck that is. Sounds messy.

I did exactly that several years ago with a couple car audio amplifiers in my apartment (in Bothell, WA, kinda-sorta a distant suburb of Seattle).

I had a regulated 13.8V DC benchtop power supply (so basically a version of what you would find inside any decent home audio amplifier), and a good-sized lead acid 12V battery (something like 100 Ah).

The amps were olde-skool Soundstream and a/d/s amps, so solidly engineered and built.

The speakers at the time were the "mighty" NHT SuperZero's, so not exactly full-range, but nice sounding little speakers, nonetheless.

There wasn't really a way to do a true ABX with that setup, but I did the switches between power sources as fast as I could...and despite straining to hear a difference (like you, I had heard all manner of promises of "deeper blacks" yadayadayada...), I never heard anything remotely resembling a repeatable difference.

So, just like with my LAME ABX results, I embraced my new freedom and never looked back.
"Not sure what the question is, but the answer is probably no."

EMI/RFI and d/a computer audio?

Reply #14 –
Quote from: BearcatSandor on
I am however concerned with PC noise, so i have made an effort to get a dampened cabinet, and quieter fans.  Instead of worrying about RFI/EMI i wish more companies put efforts into things like quieter drives (both hdds and 5" media) and quieter fans and cases.  Building it all myself i was able to get it pretty quiet (if i keep things clean).


If you're really serious about having a quiet room and using a PC, you put long cords on the keyboard, mouse, display, and audio ports and then put the PC itself in some other room.  Been there, done that.

A similar approach is a machine that is very low-powered and acoustically quiet with you, and ten use remote control software to operate the heavy hardware that is again, someplace else.

EMI/RFI and d/a computer audio?

Reply #15 –
Quote from: mixminus1 on
I had a regulated 13.8V DC benchtop power supply (so basically a version of what you would find inside any decent home audio amplifier), and a good-sized lead acid 12V battery (something like 100 Ah).

The amps were olde-skool Soundstream and a/d/s amps, so solidly engineered and built.

The speakers at the time were the "mighty" NHT SuperZero's, so not exactly full-range, but nice sounding little speakers, nonetheless.


An amp running off 12 volts isn't going to have much power unless it  has a voltage up converter, in which case I really doubt it would make a difference if you ran it off battery or a 12V supply wrt power supply noise.

Many car speaker systems are << 8 ohms to allow more power with the voltage available.

EMI/RFI and d/a computer audio?

Reply #16 –
Quote from: DonP on
An amp running off 12 volts isn't going to have much power unless it  has a voltage up converter, in which case I really doubt it would make a difference if you ran it off battery or a 12V supply wrt power supply noise.

Precisely - I just wanted to prove to myself that the whole battery power thing was audiophile BS...and it was.

Quote
Many car speaker systems are << 8 ohms to allow more power with the voltage available.

Yes, most head units can only put out ~10W/ch RMS, and that's into 4 ohms.

Standalone amps with DC-DC converters can put out much, much more, of course, but 4 ohms is still the standard...at least for coaxial and component systems.  Once you start talking about subs...all bets are off.
"Not sure what the question is, but the answer is probably no."

EMI/RFI and d/a computer audio?

Reply #17 –
I didn't read all the other replies but i can address a couple your main concerns: The shield acts as a Faraday cage and blocks out any electromagnetic field --It doesn't take a sophisticated approach like you might think, basically all you need is a metal box. Also, your Asus sound card has a dedicated Molex connector that draws power directly from the power supply, instead of relying on your mobo and its PCI connection.

This is probably one of the best budget solutions to computer audio. Later, if you want, you can upgrade to an external DAC and use your card's S/PDIF connection for a reliable digital output. Plus, the new drivers support ASIO for bit-perfect playback.

EMI/RFI and d/a computer audio?

Reply #18 –
Quote from: mixminus1 on
Precisely - I just wanted to prove to myself that the whole battery power thing was audiophile BS...and it was.

What makes it BS?  Other items in your house can't interfere with your current into your equipment? Steady DC power doesn't make a difference vs AC? You don't loose anything converting from AC to DC?

Is it a case of "yes, it makes a difference at the measuring instruments, but it's not audible?" I would bet that most audiophile claims are true instrument wise, but not ear wise. (If that makes any sense. Not making that distinction is how they get away with a lot of deception?

I'm not arguing as though i know, i'm asking as some of those things make sense to me based on my 'audiophile' assumptions.

I would bet that most audiophile claims are true instrument wise, but not ear wise. (If that makes any sense. Not making that distinction is how they get away with a lot of deception?

Still deprogramming....


Bearcat

Music lover and recovering high end audiophile

EMI/RFI and d/a computer audio?

Reply #19 –
Sure, certain other electrical devices can create enough noise and distortion on the AC lines to actually be audible - mixers/blenders are perhaps the most classic, and extreme, example - but most of the "crud" is effectively filtered out by the amplifier/receiver/whatever's power supply.

I put battery power under the same category as jitter:  the theoretical ideal of zero jitter in a digital audio system can never be realized, but well-engineered equipment can keep/reduce it to levels that are of no audible consequence most of the time.
"Not sure what the question is, but the answer is probably no."

EMI/RFI and d/a computer audio?

Reply #20 –
Quote from: BearcatSandor on
Quote from: mixminus1 on
Precisely - I just wanted to prove to myself that the whole battery power thing was audiophile BS...and it was.

What makes it BS?  Other items in your house can't interfere with your current into your equipment? Steady DC power doesn't make a difference vs AC? You don't loose anything converting from AC to DC?

Is it a case of "yes, it makes a difference at the measuring instruments, but it's not audible?" I would bet that most audiophile claims are true instrument wise, but not ear wise. (If that makes any sense. Not making that distinction is how they get away with a lot of deception?


I'd be a little surprised if you can even measure it on a switched power supply to be honest, at least assuming your idea of noise isn't something like "disconnecting power" or "blowing out the regulator".