..., any dock that will extract... ?
Yes.
Yes.
Is iPod Digital Output Possible?
I've been scouring through all the ipod accessories and cannot find what I am looking for. Perhaps it does not exist. I was wondering if there is any cable or dock that will allow me to extract a digital output from my iPod video (or any iPod for that matter)? There's plenty of adapters to pull the analog out, but it seems like you always need a computer interface to get digital output. Why? Is it just a matter of software to sort out the library? More to the point; I want to connect my iPod directly to my DAC or even to my Waveterminal (requires the squareish delivery end of a USB cable) to my DAC...is this possible? Has this been discussed previously? If so, where the heck was I? No, don't answer that last part! The authorities may be listening in! Just tell me how to get a digital stream out of my iPod if it's possible.
Marco
Marco
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03-06-11: Gordguide Man, this thread was resurrected from the dead. I started it back when the task was not possible - As I understood it, that was because of technology or permissions that Apple was not releasing/licensing. That changed with the Wadia 170i I believe around 2007 or so(?). The Wadia unit somehow extracts a digital stream from the iPods connector dock. You can then hook the Wadia's output to a DAC and, Viola - mo betta zeros and ones! Since then, as Larry_S pointed out, others have followed (probably paying the license fee to Apple I'd bet). However the early iPods with FW I still don't believe will work, going back to the earlier point about no digital audio data available in the iPod. Whether USB or FW, the iPod is seen simply as a Hard Drive, not a Digital Audio Stream. I've never seen an iPod with Firewire - just connectors that hook up to the Dock below and yield a USB or FW connection. I don't see your point about the iPod being seen simply as a hard drive - with a digital stream you just need a hard drive with digital audio files on it, and a devise capable of delivering (in this case the Wadia for instance), and translating them (a DAC). What's wrong with being just a hard drive? As I understood it, the only thing keeping anyone from extracting a digital audio stream from any iPod was Apple. |
So what are Wadia, Cambridge Audio and other using when they are (supposedly) sending PCM from the iPod to a DAC? If what you say is correct, then they must be doing A/D. And assuming that is correct, why do they have to get a special license from Apple to do that? (From reading what others have said, Apple has to be involved somehow to get data that bypasses their DAC.) |
There is no digital out available via the iPod's USB (or Firewire) ports on the 30-pin connector. There is an analog out at line level there, and it is much superior to the iPod's built-in headphone amplifier, so that is the output of choice for best sound quality on a bone-stock iPod. However, you can go inside the iPod and take an I2S output from the Woflson DAC chip. This involves very good soldering skills and fine wire. You could then send the I2S out to a DAC's I2S input. Again, this probably would involve soldering skills. There is such a thing as DACs with I2S inputs, but for the most part they only use the I2S internally. Thus the mods. If you understand USB it's fairly obvious why an iPod won't be able to connect to a DAC this way ... USB is a "dumb" interface that requires a controller chip and CPU cycles to manage the connection. The iPod and any DAC are just the "dumb" ports, so there is nothing there to do the controlling. Firewire is somewhat different in that a Firewire controller is "smart" and does not need to be told what to do. Connect any two Firewire devices and they can talk to each other and self-manage the data stream. FW chips actually are mini-computers, with a CPU, memory, and data buses. However the early iPods with FW I still don't believe will work, going back to the earlier point about no digital audio data available in the iPod. Whether USB or FW, the iPod is seen simply as a Hard Drive, not a Digital Audio Stream. |
That is not the unit I mentioned. That is a generation or two old. I went to the Alpine USA site and all I could find there was the same KCA-420i adapter box that I have in my van, which definitely does not extract a digital output from the iPod. Would you provide a link that tells about the newer unit you are referring to? Thanks in advance. Marco |
That is not the unit I mentioned. That is a generation or two old. It is a new product that does not even have a CD player. It specifically states that it uses the Ipod digital outputs. I personally have their best current CD receiver which interfaces with the Ipod through a simple cable, but nowhere does it state that it is doing the digital conversion, so I suspect it does not. If the Wolfson is as good as so many people claim then the mods to the analog section that Red Wine does may achieve the results claimed. But I have not heard it, only read about it. Caveat Emptor. |
Alpine makes a head unit for cars that does not have a CD player. It claims to take the digital output from an Ipod. So it must be possible. I have the Alpine iPod interface in my van. I'm not certain it is the one you are referring to but it was the only one they offered when I purchased it - basically a separate black-box interface that connects to the dock of the ipod and feeds the signal to the head unit. It works great (very convenient and sounds OK as far as car stereo goes, but is easily bested by a CD in the same head unit). It does not claim to take digital out from the iPod. It is a $150 accessory (when I purchased it) and I assume it is just taking the line output like all the other inexpensive docking devices for iPod and amplifying the line signal. I am quite sure that the Alpine head unit that I use does not have an internal DAC, nor is the black-box interface contain a DAC itself according to the manual. That Alpine iPod interface has been around for a couple of years now if it is the same one I have. With all due respect to Vinnie and Red Wine, my experience with the Wolfsan DAC in my iPod simply judging from the line output and decent interconnects would certainly not suggest it is a top notch DAC. I have no doubt Vinnie can improve the line-output signal, but that would not improve upon the DACs abilities which are critical in what you hear at the other end. I found the iPod line output to sound 2-dimensional and lacking in dynamics in the systems I've listened to it...fine for casual listening, but sure wouldn't want to sit in front of it for long. I've read some positive words for Vinnie's iMod, but can't recall any giving it the specific praise you mention as "reference quality" digital front end. Is there a new review out recently or any changes to the iMod? Marco |
Alpine makes a head unit for cars that does not have a CD player. It claims to take the digital output from an Ipod. So it must be possible. Also, check out Red Wine Audio. They do upgrades on Ipods though not the latest ones. They upgrade the analog section because they claim the DAC is top notch already. One review I read said that the upgraded unit is pretty much reference quality. |
Johnmhuntbch - I took an iPod Video apart and mapped-out the signals. The problem in this particular unit is that the signals necessary for I2S are not present. The D/A chip is run from a 12MHz clock. It is a proprietary chip from Wolfsen, cannot find a datasheet. It also uses a half-speed bit-clock. With some effort and logic, I could generate S/PDIF from this externally, but it would be jittery. The whole point of this was to get a low-jitter I2S out of the thing. Looks like maybe a different iPod is needed. The new ones evidently use the WM8741. This I have the data sheet for. This probably has I2S going in. Not sure which iPod to buy though. This is getting expensive. I managed to put the video iPod back together and I'm giving it to my wife for use when walking the dog... Higher priority is getting my new Formula One DAC to market right now. Steve N. Empirical Audio |
Bwhite - The digital iPod docking station is called the iRod, for Hot-rodded iPod. It will essentially replace all of the analog circuits in the iPod with external circuits of my own design. I will bring-out the I2S interface on the docking connector. The connector will dock with my own portable box, which will have rechargable batteries, D/A, headphone amp and analog volume control (Alps). It will use the AD1853 D/A converter and be non-upsampling. I may also try to drive a low-jitter master clock back up to the iPod, locating it at the D/A chip. I am considering putting line-outs on it as well, but it may not have the space. Steve N. Empirical Audio |
I just stumbled upon what appears to be a (lower priced) iPod dock solution that has a Toslink digital audio output - Escient FP-1. Here are photos of the FP-1 Does anyone know anything about this solution for potentially interfacing an iPod to a DAC? |
Wow. The MSBTech devise is exactly what I have been waiting for... until I saw the price. No doubt a similar product will be around soon for much less. You might as well buy a spare laptop, with all its advantages. In the mean time I am using my ipod in a docking station that is connected to my pre-amp through a modified Musical Fidelity X-10D tube buffer. Surprisingly good. |
"I imagine once Apple begins releasing products with that protocol they would be very popular among audiophiles." Marco- I'm afraid their marketing plans will be ruled by the MP3 world and the new iPhone. PS- I agree the MSBTech devise is way over priced, but I'm sure some iPod groupies will still buy it. PPS- I'd love to hear that MSB Power DAC. |
Thanks Kana813! That appears to be the real deal. From another thread, compliments of Peter_S and Monitor Audio: The digital/ audio over USB protocol has only just been released to us by Apple in September, which will mean that products in the future may use the digital data stream with local D/A conversion. I imagine once Apple begins releasing products with that protocol they would be very popular among audiophiles. As for the MSBtech device; for $2K you can buy a Mac laptop, an 500gig external drive and have money left over for lots of music. Marco |
Ooops, I guess I prematurely jumped into a thread that's a bit out of my league late at night or something. But now that I've actually read most of it, I'm curious about this quest for the ultimate iPod sound if it's for on-the-go listening in the car or out in the world, where a previous Audiogoner already pointed out, there's unavoidable ambient noise issues. In most cars and noisey environments, dynamic compression is a good thing. I don't know if it's possible to compress the dynamic range to spare storage space, but that would make sense in portable music player. I've enjoyed this thread and learned a few things, and I hope I didn't kill it with my previous off track response. But it will be innovative companies like Psiberaudio that will offer solutions. |
When John Atkinson of Stereophile tested the iPod's DAC he found it tested quite well. Psiberaudio offers passive/active preamp docking stations that raises the iPod signal output to a standard 2V. Psiberaudio's website may give you some ideas and useful information on getting the most out of your iPod. Their site is http://www.psiberaudio.com/iPod_2.htm. |
edsherlingmd@yahoo.com writes: The iPod uses a cruddy, standard Wolffson Microelectronics low-power DAC;The iPod has always used a Wolfson Microelectronics DAC. The first and second generation iPods - WM8721; third generation - WM8731L. Fourth generation - WM8975 CODEC; fifth generation - WM8758 Audio codec. Some think the WM8975 is the best sounding of these. As some know, Arcam changed from the dCS "Ring" DAC to a Wolfson DAC. Obviously there were many business reasons involved in this, but Arcam are a savvy company with a good reputation for sound quality, and Arcam chose to use chips from this Scottish DAC manufacturere. For example, the Arcam CD33 uses the WM8740 DACs, and it's a good sounding player (though I prefer the earlier "Ring" DAC). I'm not saying the WM8975 is a great DAC. I just don't think it's "cruddy". headphone amplification is handled by the same chip. It is built into the ipod, rather than the dock, unfortunately.No. The headphone amplifier is handled by an opamp output stage following the Wolfson DAC. This can be bypassed as Red Wine Audio do with their iMod. We take the analog output (line out) off of the dac chip and send it directly to the internal 1/8" headphone jack (converting it into a dedicated line-out jack) via high-end Black Gate Non-Polarized NX-Hi-Q coupling capacitorsThe pin outs have been published. See http://pinouts.ru/Devices/ipod_pinout.shtml. There is digital data coming out of the iPod on both the Firewire and USB outputs. But it's not in SPDIF and you can't feed it to an external DAC. The MSB modification extracts the digital data higher up in the chain and run it through custom circuitry, as shown on their web site. This is a $2000 "mod" as you cannot get the $200 iPod mod without buying the system. Regards, |
The iPod uses a cruddy, standard Wolffson Microelectronics low-power DAC; headphone amplification is handled by the same chip. It is built into the ipod, rather than the dock, unfortunately. You might as well use your computer or one of the newer digital media servers as a lossless source, and then rout this into a good upsampling DAC. Some of the newer upsampling CD players (eg. Cambridge Audio, Quad) will allow for digital inputs, as well. |
I haven't read this whole thread, but I found this thing Nope, that's just a line output. The digital output would have to be in the form of a single S/PDIF (RCA type connection), or a Toslink connection. Anything that goes directly into an amplification source is using the Ipod as a DAC. With a digital output you would need to go firt to an external DAC. Thanks for posting, regardless. Marco |
I suppose it is possible that the i-deck reads data directly off the ipod disk as data files, treating it as just a USB hard disk, and uses it's own software to play and decode the files. The only strange thing about that is that you can control whats being played with the interface on the ipod... I haven't seen any definitive explanation yet. |
Nnyc - This has me baffled...how the heck is Monitor Audio able get a bitstream from the docking port of an iPod. I thought there was no S/PDIF output within the iPod. This seems so blatantly obvious and marketable, why hasn't anyone else bothered to do this?!?! I wrote to Vinnie over at Red Wine Audio, and he pointed out that it was interesting that Monitor Audio does not list this as a feature of this unit on their own website. They do mention that it can be used with a computer via a USB connection, and I wonder if that is where the interface is coming into play. Using my computer I can pull the content from my iPod via USB or Firewire through iTunes, have the computer spit out a signal to my converter (a Waveterminal U24) and feed the digital stream from the Waveterminal to an external DAC via S/PDIF or Toslink. I wonder if AudioAdvisor and the reviewer are muddying up the description by leaving out the need for a computer in between in order to feed that digital stream to the DAC? If not, how are they getting an S/PDIF feed from an iPod? Vinnie went on to speculate that they may be using the USB port and a custom converter board (like my external Waveterminal, or an internal sound card for a computer), but added that some software would be necessary to govern that interface. Anyone have any idea how Monitor Audio is doing this? Marco |
The Monitor Audio iPod dock, the i-deck, claims to bypass the DAC inside the ipod and take a digital bistream directly from the ipod to it's own internal dac, which sounds much better than the internal dac. I'm not sure exactly how this is implemented, it apparently gets an audio bitstream out of the dock connector because that's all it needs to have connected, but it certainly sounds better than any other ipod dock I've heard. http://www.hometheatermag.com/ipodaccessories/106monitor/ |
As an addendum to my ramblings here, I discovered that the problem I was having was with the $99 device that was providing the line output on my iPod. Can't recall the manufacturer, but I believe they were the only ones offering a dock with dual RCA line-outputs. Whatever circuitry they put between the dock and those RCA's was wreaking havoc with my output signal and the music sounded awful. I exchanged it for the much cheaper iDock and went with a $69 Signal Cable silver iPod interconnect and have been happy as a clam since. I recently noticed this mini-system by Monitor Audio claiming to be getting a digital output signal from the iPod lower connection, which it runs to its own DAC and bypassing the DAC in the iPod. If this is so, apparently it is possible...why isn't anyone making a simple cable or converter to do this? |
The only rumor I've heard that indicates any advantage was in the HeadFi forum where someone opined that the op-amp (line-out) in the more recent (video) iPods was slightly improved from the previous versions with a bit more robust output. I don't know if this is true or not. I find the output on my line out to be just barely adequate for listening on the edge of loud. If others were worse than this then I'd say definitely go for a more current version of the video ipod. Other than that, I just went for the most storage capacity, which happens to be a video iPod (60gb). I don't know if any of the current large-capacity offerings from apple are anything but "video" ipods. The only other type of ipods being offered are the smaller units with much less capacity. Unless you are using mp3's, you will be severely limiting yourself in terms of how much music will fit on one. And if you're using mp3s you may as well just glue some nails to the ends of the earbuds and call it a day. Of course if you have to have some pop star's autograph emblazened across the back of your iPod to go with your celebrity sports-star approved basketball shoes, well, then again you are limiting your selection. Marco |
As a subset of this discussion, can anyone please suggest which of the new iPods might be most suitable to audiophile applications? Would you just get the biggest, most expensive, video iPod? Or as audiophiles, does it make more sense to skip the video, perhaps gaining longer battery life or something? Is the possibility for digital output the same for all models? |
Hector - I have an Alpine head unit in the same series, and the same KCA-4201 iPod interface. That was the unit that made me curious if what I'm asking is possible. Alpine makes a nice head unit, but I find the iPod interface to be a bit tedious...don't you? It's still great to have access to such a great variety of music in the car, especially when driving long distance. Marco |
Joeylawn36111, This is my third hard drive. I keep running out of space, I do burn the entire disks. Of course I always hear the same songs over and over, about 30% of the library. But disk space is getting cheaper and it's easier for me to burn the whole than to manually select the songs I like. Jax2, I just bought an Alpine CDA-9855 and KCA-420I (I-Pod interface) for my Ruf. The I-Pod can be controled from the head unit, even the information can be seen on the dash. Not sure if the unit(KCA-420I) does the D/A conversion or just allow the head unit to control the I-Pod and read its display info. You may want to try to find out more on www.ipodlounge.com. Hector |
Wavelength Audio has USB DAC's Yes, I know about their DACs. There are several companies with USB DAC's but they require a USB input (female). The only dongles cables available from the iPod Dock are USB male. I don't think you can reverse that or use an adapter - someone correct me if I'm wrong. Marco |
