When you hookup to the out via a toslink it sends the pure digital signal to whatever you hook the toslink to, such as a DAC. If you use 1/8" to rca from the same jack the airports internal DAC does the conversion and sends out an analog signal. The airports internal DAC is not that great, a budget DAC will work wonders. Pickup a mini toslink cable from monoprice.com and run it into a DAC or processor with a digital input so that the processor can do the conversion. Search on stereophile.com for their article on using the airport express in a hifi system, very informative. |
Better yet, for much improved sound IME, get an inexpensive jitter device like a Monarchy DIP...run the mini-Toslink into the Monarchy (or other device), then use an alternate connection from the Monarchy to your DAC. If your DAC already has excellent de-jitter capabilities then this route may not be necessary. |
Thanks guys - I was thinking about the MF V-DAC - which I don't think has good jitter reduction. I can always add a re-clocker later...I have a birthday coming up and I want to get into PC audio. DAC would be connected to an ancient Yami receiver, running B&W 685s and a HSU VTF-1 sub (connected via speaker terminals).
BUT I would need a toslink cable with a mini-plug on one end and a full size plug on the other. I found one on monoprice.com, thanks, these look good. Any idea where I can find a high end one? I think I saw "van Den Hul" or some such makes one? |
Realremo - I think that Airport Express receives files in Apple Losless format. Keeping files stored in Apple Losless makes one conversion less. |
the airport express will receive any type of file that you ship it. you can use itunes or airfoil for xm/sirius radio. if you want a better connection, get a glass toslink cable. big difference over a plastic toslink. i go from the airport express or apple tv into a jitter device using glass toslink, then use a coax digital cable into an external dac. |
You can buy a great mini to full toslink cable, all glass fiber, from Van Den Hul- the Optocoupler II. Highly recommended. Or you can buy a convertor (full to mini) that works perfectly well and use that with a standard toslink. I do however recommend glass fiber- the difference is not subtle. |
I believe that Kijanki is saying that airtunes protocol utilizes apple lossless as the file type from the pc to endpoint. So any file sent via airtunes is converted to lossless and then back- aiff, aac, mp3, etc.
That is how I understand it works as well. |
Robr45 - That's what I meant, except I don't thing it goes back to MP3. If you start with MP3, for instance, Apple Lossles Compressor will uncompress it to some temporary format to compress again into APLL and then on receiving end it uncompresses to temporary format again to convert it to s/pdif format that goes out to toslink - no need to invoke MP3 compressor again. I'm not sure if it even needs to uncompress on receiving end - it might have algorithm converting APLL to s/pdif on the fly. |
if something starts as mp3, it will end up as mp3. the codec that the AE uses won't add bits to the file to make it anything else. thats like saying compress a picture of 3Mb over the network, then have the codec on the other end create a 12Mb picture out of it. can't happen. the AE is a fancy modem that uses a codec to transfer data from a source to a destination. |
Rbstehno
If you take Jpeg and convert it to compressed TIFF(G3) and uncompress it later you won't get jpeg anymore but much larger file. That's exactly what is happening with MP3.
In order to be compressed into APLL it has to be decompressed first and MP3 format is lost forever. APPL file size will be larger than original MP3 but smaller than one compressed from original recording since MP3 lost part of the data.
Airport Express have no way of knowing what was original format used to convert to APLL. Everything looks the same and only amount of detail is different.
Perhaps you meant that Airport Express decompressed file has amount of data (quality) equivalent to original MP3. |
you can't add bits of information that wasn't there in the beginning. if you send 8 bits of info to an airport express, even after all of the codec manipulation, you will get 8 bits of useful information after the AE. sure you might get 24 bits after the conversion, but it will still only be 8 useful bits. for example, once you rip a cd to a low quality format, say mp3, it will always be mp3 quality, you have lost all of the info and will not get it back. sure you can convert it to acc/apll/etc..., but it will always sound like mp3, those compressed/dropped out bits are gone forever. |
"but it will always sound like mp3, those compressed/dropped out bits are gone forever." - I agree. |
Percisely- I understood it to take it to unpack the alac on the ae side to digital or analog. The point to all of this seems to be that if you are going to use airtunes, there is no point in using any other losslec codec other than alac. I see many people state that aiff/wav sounds better but I don't see how this could be. |
I see many people state that aiff/wav sounds better but I don't see how this could be. I don't understand it either, but I have most definitely heard some high-rez files sound better than others to the point where I could identify the files blind. One possible factor is that the Apple Lossless codec requires processor power and time, no matter how minute, to uncompress the file on the fly. WAV and AIFF do not require any decompression. WAV is native to PC, while AIFF is native to MAC. I only can speculate as what I know about the inner workings of this stuff could fit inscribed on a pin-head. I also don't know why an interconnect or a power cable might effect the sound of a system, but indeed I've heard them do just that. Come to think of it, there's a whole lot of things in life I cannot explain, or begin to understand. it will always be mp3 quality, you have lost all of the info and will not get it back. sure you can convert it to acc/apll/etc..., but it will always sound like mp3, those compressed/dropped out bits are gone forever. I agree that it will always sound inferior to the full-resolution files. But if you convert an Mp3 to an acc/apll/AIFF or other higher-rez version, it will not necessarily sound just like the original Mp3. It may sound worse. If you up-rez a file, the software you use to do that is having to interpolate what bits go in between and fill out the Mp3's existing zeros and ones to create an AIFF file, for instance (which has many more zeros and ones). Those fictional zeros and one fillers are most certainly bound to have an effect on how the file sounds. Could be worse, could be better, could indeed occur to one as unchanged, but it will definitely not be an identical file to the original. I certainly agree that all of the original information that was lost in the first place by converting it to an mp3 is gone for good, short of re-ripping from the original. Someone correct me here if I'm off base so I can get to work on this pin-head inscription I mentioned earlier. |
Jax2 - Stereophile tested digital output of Airptort Express and compared to original uncompressed file they sent from I tunes and they are bit for bit identical with 255ps of word jitter.
APLC does not reduce quality of MP3. There is no missing bits in MP3 (nothing to interpolate) - it has 16 bit resolution. Bits are not lost - the musical information is (simplified). In order to play MP3 it has to be uncompressed first. APLC is decompressing MP3 and then compressing it to APLC format to decompress it to uncompressed MP3 ready to send to s/pdif out. No missing bits.
I have no idea why APLC sounds different to some people. Time to process data has nothing to do with it since it goes thru output buffer. It is possible that people compare sound from different devices like CDP versus computer while not every device is "bit transparent". Some CDPs have digital volume control or some form of DSP processing. In addition Itunes might have volume control enabled as well as equalizer. Finally it might be placebo effect. |
Thanks for explaining that, Kijanki! I always thought of it as akin to uprezzing a graphics file, but as you are explaining it, it is not like that(?). I don't know how much stake I'd put in Stereophile's tests personally. I fI were to rely on their numbers and graphs I might never listen to tubes. I choose to rely my own ears. The file's that struck me as sounding distinctively different from each other were files ripped in EAC and converted to Apple Lossless, and to WAV and played in iTunes...vs. the same files ripped directly to those formats in iTunes. The EAC rips sounded better every time. This is with a previous version of iTunes and a very revealing system. I have not tried the same with the current version of iTunes, but will eventually try it with the MAX ripping software. |
Jax2 - Itunes is not the best choice for ripping, I agree. I also agree that numbers published by Stereophile or other magazines are meaningless. I would even say that best tested devices have often the worst sound (there are reasons for that).
Stereophile reviews are pretty good but they tend to review only companies that advertise with them. |
going to mp3, the bits are lost. compare file sizes. there is a reason why people use mp3 on ipod's because of the storage savings. also, it really doesn't matter what the AE uses to compress or manipulate the data from itunes, when it comes out of the AE, it will be the same as what it is feed.
an AE device is no different than the modems 30 years ago. the transmitting modem would send the data in a certain compressed mode (itunes on a mac) possibly with security built in, then the receiving modem (AE) would unbundle the data, strip the security bits,uncompress the data, and the remote data is byte for byte the same as the source.
this might be the only time i would agree with stereophile.
also, try xld if you are using a mac.
if you get a chance, listen to the amarra software for the itunes/mac combination. it sounded pretty good at ces. |
Now, can someone tell me why, when running my airport express to a CA 840c using optical, that I periodically have an awful, glassy, fingernail-on-chalkboard sound?
Files are either alac or mp3 and with or without error correction when put on the confuser.
It doesn't happen at the same spot each time, but seemingly randomly.
Any suggestions? |
Rbstehno - I rip files into ALAC not only to save space but also to avoid additional operation (ALAC compression) that computer has to do in real time to send data to AE (it is not a dedicated server). |
the computer can do this and much more if you have a decent machine. when you stream your music, how much cpu are you using? are you telling me that you are maxing out your cpu? the computer has to do quite a bit of work to get data off the disk, into it's memory buffers, and then package it up to send it over the network. all of this messaging of data happens in memory, after it is read from disk. if you system is using less than 80% of your cpu, it is not a big deal. now if you are saturating the cpu, now you need to offload some processing. |
the computer can do this and much more if you have a decent machine. when you stream your music, how much cpu are you using? are you telling me that you are maxing out your cpu? the computer has to do quite a bit of work to get data off the disk, into it's memory buffers, and then package it up to send it over the network. all of this messaging of data happens in memory, after it is read from disk. if you system is using less than 80% of your cpu, it is not a big deal. now if you are saturating the cpu, now you need to offload some processing. I don't believe streaming music, either from the native hard drive, nor from an optical drive, is very CPU nor memory intensive. My tower is a dual 2.7ghz processor. I can monitor CPU usage in real time on the Activity Monitor utility. Streaming files from itunes runs average around 4-6% capacity of the CPU with a few spikes now and then to 13% which are very brief. It take 87mb of real memory and around 1gb of virtual memory to stream music as well. Not even close to the machines capacities on any of those demands. I have three Squeezebox devices around the house and can stream music to all three, different tunes to each one, without a hiccup and still check email and surf the Internet. This is on a Mac. The Squeezebox interface does use the iTunes library, but NOT iTunes. It uses a web browser and indicates even less usage of the computers resources than iTunes demands. It is not a demanding task for a computer as far as I can tell. I'm comparing it to something like Photoshop, video or gaming software that is very graphics intensive. Someone correct me if I'm wrong. |
jax2 - you are correct. that was point in my thread above. unless your computer is saturating the cpu, then it will have the capability to do a few more instructions to stream audio. i have 3 separate zones off my mac and it is barely doing any cpu or IO. what you will see normally is higher IO and not CPU. but again, nothing that a newer computer can't handle. |
Just supporting/echoing your post, Rbsthno...sorry I didn't make that clear. |
Realremo: Lifatec offers Toslink cables with the mini on one end and the full size on the other. I have used one from a Mac to the main system with good results (via iTunes). You can also get an adapter for almost pennies to go over the full size end and thus conform to your needs on the computer end. |
Thanks Puerto, I have seen a link to their site in another thread, they are the ones who convinced me that maybe a plastic Toslink cable is OK. I am really interested in a mini/full toslink cable, just more of a pure thing than using the adapter, and will definitely check them out when I invest in PC audio. |
