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How good is the ipod's DAC?

post #1 of 187
Thread Starter 
At what point does the ipod's DAC become the weakest link in the audio chain?

Meaning, I won't give up the convenience of the ipod. So knowing that, can you give specific examples of an amp/receiver that would be appropriate (one whose quality does not signficantly exceed or limit the ipod's DAC quality.)
post #2 of 187
as good as any other DAC.
post #3 of 187
Thread Starter 
so $1000 DAC's are a waste of money?
post #4 of 187
The DAC in the iPod is produced by Wolfson and is pretty respectable. When using the digital dock connector and Apple Lossless files you can get very respectable sound from the iPod.

However any well made CD player from NAD, Cambridge, Rotel or Arcam will sound more refined all the way around.

But overall considering what someone pays for the iPod and what its capable of doing is pretty impressive in my book.
post #5 of 187
You can't get a digital out from your iPod, which makes $1000 DACs a bit ineffective with the device.
post #6 of 187
If you're playing mp3's, then really, you needn't look anywhere else to find your weakest link. That said, as with any modern DAC today, the limitations of that hardware far exceed the perception abilities of your (I presume) human form.
post #7 of 187
surprisingly decent, even better with something like the Red Wine Audio iMod. you won't find much better from other portable sources. however it definitely doesn't compete with most external DACs. stuff like the Zhaolu, Stello DA100, PreSonus Central Station and especially the stuff approaching $1000 like the Benchmark DAC1 and Lavry DA10 outclass it in every sense of the word. probably not night-and-day with the Zhaolu and PreSonus, but it is when you get to the $600+ range. the DA100 is a real giant killer and would beat the iPod to a bloody pulp. still, it's perfectly fine for portable listening, and an iMod would probably suffice as a source for a budget bookshelf speakers + sub + integrated amp setup. some people think that the iPod is truly worthless and i disagree. if it only had digital outputs...

as i listen to my iPod nano right now, i find its main offense to be lack of tightness in bass.
post #8 of 187
I'll be another to say that the DAC in the iPod is quite good for a portable device. Sounds terrific using Apple Lossless (the only compression I use) and outputting to my Grado RS2's with a Musical Fidelty X-Can v2 tube headphone amp.

From time to time, I also throw my iPod on the dock cable interface feeding my Alpine head unit. That goes through JL Audio amps and a Dynaudio speaker system. Not quite the refinement of a CD, but hey, it's convenient...
post #9 of 187
Quote:
Originally Posted by pufftissue View Post

so $1000 DAC's are a waste of money?

I have a 1,000 DAC & it isn't a waste of money to me..
post #10 of 187
Measurements of the various iPods out there were performed using the Rightmark Audio Analyzer (RMAA) and can be seen here (http://www.daefeatures.co.uk/rmaa.php) and elsewhere. I would think the primary limitation would be the headphones you use and how you've got your music stored.
post #11 of 187
If you're interested, here's some more charts and graphs from an iPod bench test.

http://www.hometheaterhifi.com/volum...07-part-1.html


Scott
post #12 of 187
The limitations of the Ipod is in it's analog stages after the conversion. The only reason you would get better sound by passing the DACs, because you also bypass the analog stage.
post #13 of 187
Quote:
Originally Posted by Chu Gai View Post

Measurements of the various iPods out there were performed using the Rightmark Audio Analyzer (RMAA) and can be seen here (http://www.daefeatures.co.uk/rmaa.php) and elsewhere. I would think the primary limitation would be the headphones you use and how you've got your music stored.

I'm getting much better RMAA measurements from my iPod than any of those guys. I used an E-mu 0404 USB for these measurements. (I get even better distortion figures than these with an 1820m.) At maximum volume full-scale sine waves produce a little over 1V. It has good measurements--it outperforms a Toshiba SD4960 (same as a Samsung HD841), which isn't saying much. It also measures better across the board than my iPod dock. If you guys want, I can upload those comparisons too.

Naturally these numbers will get worse when driving a lower-impedance load like a pair of headphones. But if you're hooking it up straight to your stereo, it's surprisingly clean. I included the original 16-bit RMAA test file in the comparison. It represents a "perfect" score and shows the limits of the 16-bit RMAA test.

I suspect that the guys on that site weren't as careful with their measurements. It might lead you to think that the iPod measures horribly.

Edit: Removed attached files, added link to test results page.
post #14 of 187
The 5G and newer iPods, when directly connected to a good integrated stereo amplifier, is damn close if not the equal of a good DAC or CDP. iPods tend to lose performance when connected to low impedance earphones, especially in the bass.

Apple improved the audio performance of the iPod with the 5G and newer models.
post #15 of 187
For some reason whenever I hook up an Ipod to my Onkyo receiver through a headphone jack to stereo rca converter, the sound quality is always pretty poor. It sounds noticeably worse than hooking up my laptop computer to the receiver in the same manner. Both methods sound a lot worse to me than a standard cd player. Maybe the SQ would be better with some sort of dedicated ipod dock.
post #16 of 187
Something could be set up wrong, or something is malfunctioning. Which model do you have? When I connect my 5th gen iPod's headphone output to my stereo, it doesn't sound worse than its dock. Also it doesn't sound worse than some DVD players that I've compared it with. It might even be better. I always keep Sound Check and EQ off. For the 5G iPods, I found that a good level is just a touch under maximum volume. I used to have a 1st gen iPod Mini and it too did a good job with the headphone output going to line in.
post #17 of 187
I use the dock port on my iPod to connect to my integrated amp. I have a hybrid cable with twin RCA jacks to an Apple Dock port type connector. This gives the best results I think.
post #18 of 187
I'll have to try that adapter. What kind did you get? I found that the Apple Universal Dock's line out does not perform better than the 5G iPod headphone output when set just under maximum volume. Moreover, it makes the headphone output perform worse. The universal dock has a poorer frequency response, 3dB more noise, and ten times the distortion than the undocked iPod: iPod vs. iPod dock RMAA results.. I'm not the only one with these results: Dock vs Headphone out for 1G iPod mini and 5G iPod at HifiiPod.co.uk.

The iPod headphone out does have a weakness that RMAA doesn't expose with its default test settings. Fortunately it can be remedied easily. Here's the output of a full-scale 1 kHz tone at maximum volume:



I forgot to calibrate Spectralab: 100% = 2V. RMAA tests THD with a 1 kHz tone at 3 dB below full scale. The test can be configured with a 0 dB tone. Reduce the volume level on the iPod just a bit (95% max) and the clipping is gone:



RMAA still has good numbers at this level. My music doesn't spend a lot of time near 0 dB so I don't hear much of a difference. Keep in mind that distortion that lasts only a few milliseconds is usually inaudible. But the measurement bothers me, so I keep it at just under maximum whenever I connect it to line in.
post #19 of 187
I'm embarassed to say that the cable I use was bought off ebay. It's a generic brand but seems to works great. It would be interesting to see a test done with a 5.5G iPod using a similar cable.
post #20 of 187
Hey, I'm a big fan of cheap cable, as long as it does its job properly. The Radio Shack Gold Series cable that I use is reasonably transparent. It doesn't do too much harm to the signal.

The dock's performance got a bit better when I disconnected it from the computer. The headphone out also improved: docked and undocked performance is now the same with the dock unplugged. The dock's line out works without getting power from the computer, so I didn't think that a dock to RCA cable would do better. I thought that the universal dock could be such an adapter itself.

The dock cable that I want has the video connector. I haven't found a cheap one in stores so I borrowed a dock-to-RCA cable that has just audio. It's a cheapie Nyko Stereo Link. The manufacturer claims that it's a distortion free alternative to the headphone jack. Its distortion level wasn't bad to begin with. Naturally, I wanted to verify their claim, especially with the new version of RMAA that was released just two days ago.

This time I set the volume level for the headphone out to two notches below maximum, so that 0 dBFS doesn't clip, even if the test doesn't at max volume. The volume control on the iPod doesn't change the signal level on the dock-to-RCA cable. So it already behaves differently from the universal dock, where the volume control does affect line out. A full-scale tone produces about 0.9 Vrms output, so it's not as hot as the headphone jack at maximum volume. It does not clip a full-scale signal. Here are the results:

iPod headphone output vs. Dock to RCA adapter

Overall, it's pretty good. It does have lower THD than the headphone out, but not by much. But look at the stereo crosstalk! It's still not shabby. The conductors on the iPod dock connector are very closely spaced. Even though we're not dealing with untwisting in CAT5 cable, or the high frequencies where near-end crosstalk would be more of a problem, maybe the cable can still make stereo crosstalk worse and a better cable could help. Or maybe the problem is the iPod itself. Either way, I doubt that you could tell them apart when listening to music normally. I didn't hear any big differences.
post #21 of 187
yuriv, THANK YOU so much for your fine work!!!!! The comparison was very interesting and surprising to me. I expected the dock to RCA connection to be slightly better in all categories. The cross-talk surprised the hell out of me! Since reading your report, I've now ordered a 3.5mm mini-jack to RCA cable..! ;-)...THANKS!!!!!!!!!!!!!!!!!!!!
post #22 of 187
One more question for yuriv. Why do you measure frequency response from 40-15 instead of 20-20? Thanks!
post #23 of 187
The measurement isn't limited to 40 Hz - 15 kHz. Look at the graph again; it goes all the way to 22.05 kHz, which is half the sampling frequency. The HTML report goes down to 20 Hz but RMAA will let you scroll to the left, all the way down to 4 Hz. The 40 - 15k range is the default range for reporting the deviation in the summary table only. Most music has little energy below 40 Hz, and most adults can't hear above 15 kHz anyway. You can reconfigure RMAA to report the response for 20-20k, but I kept it at the default setting so you can more easily make a comparison with measurements made by others. Here's one such test:

Slim Devices Squeezebox v3 vs. Roku Soundbridge (unspecified model)

Unfortunately this report doesn't say much about the testing conditions. Which recorder was used and what were its settings? What are the levels on the tested devices? (Maximum I hope.) But it's still helpfulI could disconnect my Squeezebox and test it, but it sounds just fine. Because their report stuck with the default settings, it's easier to make a comparison with my iPod results.

BTW, if you google ipod dock connector pinout you'll see that they used pins 3 and 4 for the left and right channel outputs. But I'm not convinced that the dock connector itself has more stereo crosstalk. It's possible that the Nyko cable I tested is an inept design. I'll run the test again when I get another cable. Either way, -70 dB crosstalk is good! There's no reason to switch to the headphone jack if it sounds fine now.
post #24 of 187
Where can I buy good quality iPod cables? I need a high quality ipod dock connector pin-out to RCA jack hybrid cable.
post #25 of 187
Here's an interesting divice used to connect your iPod to your stereo!

http://www.xitel.com/USA/prod_hflipod.htm

Xitel hifi-link
post #26 of 187
How do you know that your present cable is bad? You might be getting close to the best performance from the dock port with what you have now. I'm a bit skeptical about that Xitel. Why should it be any better than Apple's Universal dock? I see a control knob on the back, which means that the signal goes through another stage of amplification or buffering. And then it adds SRS Trubass processing, which (I hope) can be bypassed. Granted, it's not too hard to beat the performance of the Apple dock, but I bet that it's even less transparent than the headphone output, let alone your current dock cable.

My reports weren't meant to make people become unhappy with what they have. The iPod wasn't designed to be a precision instrument, and no magic cable will turn it into one. It's just a welcome bonus that it happens to be a reasonably good at playing back music. It beats many CD and DVD players.

I might be able to borrow another dock/RCA cable from someone who works at Geek Squad. It's an overpriced Monster iTV Link cable, which is more expensive than the Apple Universal dock. But it also has S-video and you can charge the iPod via mini USB cable (naturally, not included). I'll let you know if it also has the stereo crosstalk problem.
post #27 of 187
To be honest I am quite happy with the performance of my 5.5G 80GB iPod. I absolutely love it but you know how audiophiles are. Nothing is ever good enough! When we get something in our heads it's hard to think objectively.

Having said that, I will be making a DIY iPod dock-to-RCA cable just for grins. ;-)
post #28 of 187
I just tested the Monster iTV Link cable. With it, stereo crosstalk is significantly lower:

Headphone output vs Dock/RCA cables

Now we know that the iPod dock port does a fine job, and that the problem is the Nyko cable. Did I test a bad cable or was it a flawed design? I really don't care, but I think it's the latter case. But a cable shouldn't have to cost $50 to get the job done right. If you're constructing your own dock adapter, you could copy their dual balanced design, maybe with CAT5 cable.
post #29 of 187
while we are on the subject of ipod cables, i advise you to stay away from alo audio. sky high prices, going to guess the materials required for a $100 cable from them is about $10... or their $400 multi array docks, which use $2/foot auric hookup wire. quite hyped. i have owned a cryo cable from them, it wasn't any better than a turbodock. i don't believe cables make a (big) difference so take this with a grain of salt...
post #30 of 187
>>i advise you to stay away from alo audio<<

I agree alo audio prices are outrageous. They get hyped a lot in Audio Asylum by the die-hard "oxygen free" woven cable crowd. I also agree cables don't make THAT much difference provided they are designed and constructed properly with good (not exotic) materials. I will make my own.

I found a supplier of the iPod dock connectors (link below).

http://www.sparkfun.com/commerce/pro...roducts_id=633
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