Pondering Wi-Fi...
Oct 20, 2009 at 9:39 PM Thread Starter Post #1 of 19

oddity

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"The shortest path between two points is a straight line." has important meaning in an audiophiles world. The shorter distance and fewer components your signal has to travel through, the better.

Without pondering the technical data, it would seem that wi-fi is the perfect way to move a signal, with no wires, connectors, and components to potential distort the signal.

So why aren't we all using Wi-Fi?

I am still very much a novice when it comes to audiophile tech, so can anyone explain why wi-fi isn't all the rage around here?
 
Oct 20, 2009 at 9:56 PM Post #2 of 19

revolink24

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Namely because wireless technologies are prone to several things - most notably, interference, lack of bandwidth (not so much with wifi) and, (debatably) jitter.
 
Oct 20, 2009 at 11:28 PM Post #3 of 19

majid

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Horrendous jitter, for the most part, although this can be remedied by delaying play start and large enough memory buffers. The Squeezebox and Apple Airtunes work just fine with WiFi, although the original Squeezebox's buffer was not large enough to play FLAC content without glitches (this was fixed in the Squeezebox 2).

You need 1.2 Mbps of bandwidth to stream lossless uncompressed Red Book audio. Even 802.11b does better than that (even if the actual throughput is far less than the nominal 11 Mbps). Contention for wireless broadband is another - WiFi does not have the ability to reserve bandwidth for the audio stream, so if someone starts a heavy download while you are playing, you can expect problems.

Finally saturation in the 2.4GHz band is a serious problem. I can see well over 20 access points in my apartment building. 802.11n in the 5.4GHz band is a short-term fix, but interference from nearby base stations cuts into available bandwidth and increases jitter.
 
Oct 21, 2009 at 2:51 AM Post #4 of 19

Uncle Erik

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Radio transmissions are far from perfect. An antenna broadcasts in a variety of directions (some are designed to radiate in specific patterns, but they never radiate 100% in one direction), so you end up with transmissions going all over the room. Lots of materials reflect radio waves, so you get what's called "scatter." That means that the receiver will pick up both the intended signal as well as reflections from around the room. Even with error correction, scatter can be a pain.

Next, you have to deal with radio transmissions from others. The radio spectrum is crowded and band allocations can get contentious. Some bands are shared and some bands are for the use of multiple people at the same time. That can generally work a lot of the time, but you do not want to start picking up others' transmissions by accident. Like scatter, receiving others' broadcasts can be a problem.

Another reason is that you do not necessarily want a huge amount of RF around you. Wi-Fi, and all other radio transmissions involve RF. It can lead to long term problems, so I always try to minimize my RF exposure.

You can also get interference from other things, too. Switching power supplies, fluorescent lights, AC motors, dimmer switches, etc. all can throw off broad spectrum noise that can get in the way.

Adding radio transmitters and receivers to every piece of gear would increase the cos and complexity of items. Because things in a power supply can throw off RFI (diodes, for instance, can be noisy) you'd have to isolate the radio bits from the rest of the device carefully. Install it wrong and it'll pick up noise from within itself.

As for complexity, you'd then have another entire system to troubleahoot and repair if something goes wrong. That would just add to the cost.

So while this could be done, it's impractical for a number of reasons. I would stick with cables just for the simplicity. That's the same reason I run tubes - the circuits are much simpler and I want to keep the amount of components that touch the signal to a bare minimum. Everything the signal passes through changes it, so I want the fewest components.

Finally, the "problems" with cables are grossly overstated. I don't want to launch that debate, but consider that cable differences cannot be measured with standard test equipment. We can all agree on that. Further, no one has ever passed a blind cable test. You can argue test methodology, of course, but the lack of results from standard test equipment strongly indicates that the only difference between cables is a psychological one.
 
Oct 21, 2009 at 3:41 AM Post #5 of 19

Lorentz

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Actually, I use wifi. I have a local home server that has all of my music conviniently stored in flac, which can be accessed from my laptop via wifi.

Now, it really doesn't matter whether I access the server from the laptop, my desktop, or even another computer on the internet, as long as I have sufficient bandwidth to fill my buffer up consistently and not cause stutter.

Back to the wifi: From the laptop, I have a DAC connected to the laptop via USB, which is then amped, and then I have my headphones. For note, wifi has more than enough bandwidth for transporting flac, and probably uncompressed wav too.

Now, think. Where _else_ can you use wifi?

There's really no other way to use wifi other than for transport of files. There's no way to use wifi to amp directly; you need a DAC. And in same reasoning, no way to use wifi to headphone directly; you need a DAC _and_ an amp.

Therefore, the real answer to why we don't use wifi for interconnects in audio is that it's un-needed and really, can't even be used except for the source stage. You'll be duplicating dac, then adc, then dac, then adc, over and over again uselessly.

That said, nothing's stopping you from having a PDA with wifi and a USB port, a USB DAC/amp combo, and then powering your headphones with that. In fact, it'd probably sound better than any wireless headphone offerings around. Or at least much more customisable.
 
Oct 21, 2009 at 7:18 AM Post #6 of 19

oddity

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Damn, ask and you shall receive!

Thanks for all the info
biggrin.gif
 
Oct 21, 2009 at 1:46 PM Post #7 of 19

m1abrams

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Ok stuttering and jitter are NOT the same thing please do not confuse the 2. Wifi will NOT introduce any jitter to the system, just like sending the data over ethernet will not introduce jitter. What wifi can cause is stuttering if the data can not keep up with the playback.
 
Oct 21, 2009 at 4:12 PM Post #8 of 19

krmathis

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Speed limitations maybe?WLAN is currently afaik limited to 54MBit/s, while for LAN 1GBit/s is common.
Then there are of course safety issue (never stronger than the WLAN password), interference from other devices, and more.

That said, I have been a sole WLAN user at home the last 6-7 years and am pleased with it.
smile.gif
 
Oct 22, 2009 at 1:29 AM Post #9 of 19

somestranger26

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Quote:

Originally Posted by krmathis /img/forum/go_quote.gif
Speed limitations maybe?WLAN is currently afaik limited to 54MBit/s, while for LAN 1GBit/s is common.
Then there are of course safety issue (never stronger than the WLAN password), interference from other devices, and more.

That said, I have been a sole WLAN user at home the last 6-7 years and am pleased with it.
smile.gif



802.11n is 108-300Mbps depending on how it's configured.
 
Oct 22, 2009 at 7:33 AM Post #10 of 19

majid

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Quote:

Originally Posted by Lorentz /img/forum/go_quote.gif
That said, nothing's stopping you from having a PDA with wifi and a USB port, a USB DAC/amp combo, and then powering your headphones with that. In fact, it'd probably sound better than any wireless headphone offerings around. Or at least much more customisable.


Bluetooth A2DP makes more sense for that application. You can stream music from an iPhone or iPod Touch over A2DP to something like a Chordette Gem Bluetooth/USB DAC.
 
Oct 22, 2009 at 7:47 AM Post #11 of 19

Lorentz

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Quote:

Originally Posted by majid /img/forum/go_quote.gif
Bluetooth A2DP makes more sense for that application. You can stream music from an iPhone or iPod Touch over A2DP to something like a Chordette Gem Bluetooth/USB DAC.


AFAIK using a2dp will force re-encoding your music to another codec, most likely something inferior, which is then yet again decoded. Transcoding is bad. Maybe avoided by using mp3 or aac, but I'm not really sure if that'll just pass through. I know the default is SBC, which isn't very good.

But anyway, I really think it's better to sit down and enjoy music. If you're enjoying it while walking around, a nice DAP with an IEM of your choice should be more than enough.
 
Oct 22, 2009 at 8:05 AM Post #12 of 19

pcf

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I have two squeeze box duet receivers in two different systems and never had any streaming problems. I can choose any tracks or albums from my ripped music collection, plus internet radio including international stations like BBC. It is great and let me concentrate on listening to music and not worry about equipments. If there is a compromise in sound quality, so be it. I run the Squeeze box's digital out to a DAC and am totally happy with the sound anyway.
 
Oct 22, 2009 at 8:13 AM Post #13 of 19

krmathis

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WLAN probably wont be able to handle bandwidth like this.
wink.gif

Sitting on 1GBit/s LAN at the office, with my X200 laptop.

 
Oct 22, 2009 at 4:40 PM Post #14 of 19

Omega17TheTrue

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Quote:

Originally Posted by oddity /img/forum/go_quote.gif
So why aren't we all using Wi-Fi?


Personally i don't use it because its bad for the health, despite all the waves around, less is always better. And high sensible component like high-end audio can be affected too.
 
Oct 23, 2009 at 5:31 PM Post #15 of 19

majid

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Quote:

Originally Posted by krmathis /img/forum/go_quote.gif
WLAN probably wont be able to handle bandwidth like this.
wink.gif

Sitting on 1GBit/s LAN at the office, with my X200 laptop.




I once benchmarked my Airport Extreme (802.11 pre-n in the 5GHz band) at 200Mbps real-world throughput using ttcp on my old MacBook Pro 3G. Many people report getting closer to 300. Actual throughput depends heavily on the 802.11 chipset you have (my current MacBook Air does not get any better than 160Mbps).
 

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