I want my new sound system to have a fully-integrated iPod solution so I can listen to anything in my music collection while I’m on the road. However, the mere mention of iPod usually results in laughter or a load of rubbish about how iPods are such bad quality that you wouldn’t even consider it if you were serious about your music.
Now this is simply not true!
But somehow the car audio industry has managed to remain a bunch of absolute technological dunces in the face of a new technology which is likely to radically change their industry.
Maybe it’s the fact that many of them are scared of computers and the fact that iPods require some measure of computer savvy to use. Or maybe it’s just sheer lack of knowledge and it’s easier to disguise their ignorance by subscribing to the wive’s tale that iPods have poor music quality than actually doing some research into the real story.
Well for all you people out there that still think there’s no way an iPod can sound good, I’ve gone out there and done the research for you. Please have a read, because I swear I’m going to punch the next person that carries on with this crud. Stop being lazy and learn the facts.
Now I don’t claim to be an expert on the topic, but I’ve been around digital music for long enough to know a little bit more than the average guy on the street. I’ve been a computer programmer for quite some time, and did dabble for a while in digital music and even compiled one of the first comprehensive digital audio format files that was used by programmers around the world.
An ex business-partner of mine was also into audio streaming and even co-wrote some of the Windows Media software while working for Microsoft in Seattle. So I’ve been around a lot of people knowledgeable on the subject.
Now there’s 2 parts to the argument on iPod sound quality: the hardware and the actual music formats. I’ll start with the hardware side…
The Hardware
I can understand why there would be some initial apprehension to the notion that such a small device could put out a decent sound output. Most of the space in the iPod is taken up by the hard-drive, battery and screen. How could there possibly be any room for some decent audio electronics? Especially in the car audio industry, it’s all about big amps with big transformers and big speakers with big magnets that gives us sound quality. How could something so small be even considered quality?
Well that’s the nature of digital electronics.. we’re always making things smaller. Not much has happened in decades in amplifier and speaker technology, and there isn’t really that much incentive to make them too much smaller anyway.
The iPod utilises a Wolfson audio 8731 audio codec chip, made in Scotland, to handle all it’s audio output. It has two audio outputs, one for the headphone jack and a line-level output.
From http://www.rane.com/hilovolt.htm:
QUOTE
“Wolfson Microelectronics Ltd. (Edinburgh, Scotland) offers a family of ICs that add digital audio capabilities to digital camcorders, digital still cameras, DVD players and other Internet appliances, including MP3 players, cell phones with MP3, and PDAs. These chips claim CD-quality audio not previously available in portable appliances. For example the WM8731, a stereo codec (including a mic input with bias voltage) with integrated headphone amplifier, level control and programmable sample rates (8 kHz to 96 kHz), boasts signal-to-noise ratios of 97 dB for it's A/D and 100 dB S/N for its D/A (24-bit multibit delta-sigma) converters, with a final headphone output THD level less than 0.1%, all for less than $5.00 in only 1,000-piece quantities. And it is fully compliant with the Secure Data Management Interface (SDMI).”
Signal to noise on Alpine IVA-D310E is 105. Across Alpine range, source CD S/Ns are 90-115.
iPod is 100!. Ie, better than some Alpine source units.
THD is less that 0.1% on headphone output.. This is high compared to other components, but still negligible and far below anything audible.
And don’t forget that the headphones are coming out of a small amp, which can only add distortion. In an integrated car audio iPod install you’ll be using the line output.
Now the main factor in the sound quality of a digital audio device, including CD players, is the quality of the DAC (digital to analogue converter). The DAC is built into the Wolfson chip. Even I was apprehensive that such a small device could have a decent DAC built into it. There are definitely a whole bunch of digital devices out there with VERY good DACs in them though. There’s stacks of sound-cards that are used in PCs in the music industry and their output is well and truly up to scratch.
I’ve found a few articles around with some analysis of the quality of the iPod audio output. Some of the best cite some very good technical analysis performed by the well-regarded audiophile magazine Stereophile.
An iPod audio analysis, citing the testing by Stereophile magazine, demonstrating:
QUOTE
“These figures show that the static performance of the digital circuitry is quite good (better than many CD players as reported by Stereophile), and the line output is well defined as well.”
And
QUOTE
“These measurements of the iPod, far for complete, at least show that the iPod has a decent ouput signal, free from big artifacts, although the bass response on the headphones outut is flawed.”
Note that in most reports, including this one, they state that the sound quality is top notch out of the line out (which is what we will all use when integrating iPods into our cars). It is the headphones that cause the most controversy and has possibly also spawned many of the iPod quality rumours.
http://members.chello.nl/~m.heijligers/ipo...asurements.html
Another article in Stereophile, where they discuss a tube-amplifier created for the iPod.
QUOTE
“Conley explains: "My first impression of the iPod and MP3-type music in general was a negative one. I was not fond of the idea of data compression that would sacrifice audio quality for the sake of download convenience. By chance, I read a review of the iPod in Stereophile that was forwarded to me by my father quite some time back and discovered that the iPod had a pretty good DAC and Apple actually had a lossless format as well.”
http://www.stereophile.com/news/032805itube/
Here’s the actual original article from Stereophile, where it is concluded:
QUOTE
“The iPod's measured behavior is better than many CD players—ironic, considering that most of the time it will be used to play MP3 and AAC files, which will not immediately benefit from such good performance. But if you're willing to trade off maximum playing time against the ability to play uncompressed AIFF or WAV files, the iPod will do an excellent job of decoding them. Excellent, cost-effective audio engineering from an unexpected source.—John Atkinson”
http://www.stereophile.com/digitalsourcere...934/index5.html
THD
From FHRX:
QUOTE
“Total harmonic distortion
THD is the measurement of the how much the amplifier can distort the sound signal through the introduction of added harmonics or overtones. THD figures are usually given as percentages and a THD figure below 1% are generally inaudible to most people. However, distortion is a cumulative phenomenon so if your head unit, eq, crossover and amplifier are all rated at less than 1%THD each, together they could produce 5%THD which may well be noticeable to most of you.”
THD is the measurement of the how much the amplifier can distort the sound signal through the introduction of added harmonics or overtones. THD figures are usually given as percentages and a THD figure below 1% are generally inaudible to most people. However, distortion is a cumulative phenomenon so if your head unit, eq, crossover and amplifier are all rated at less than 1%THD each, together they could produce 5%THD which may well be noticeable to most of you.”
iPod audio analysis, using headphone out, showing 0.003% THD:
http://www.audiosense.org/results/portable/iPod.htm
PCmag.com review:
http://www.pcmag.com/article2/0,1895,1634140,00.asp
QUOTE
“With Apple Lossless compression, the iPod is just as capable as your CD player is of driving a high-end audio system”
QUOTE
“we've tweaked our audio performance evaluation measures. As a result, we've identified some minor audio issues with the iPod's equalizer (EQ) presets.”
QUOTE
“Harmonic distortion is minimal with no EQ, but at higher volume levels most of the EQ settings showed audible distortion.”
So, iPod similar to CD player quality, provided EQ settings are not used. Most audiphiles will tell you not to use EQ settings anyway, especially from the source. If you need to use EQ, then your source isn’t that great to start with.
So as you can see from the articles above, there is no question that the sound quality, at least from the line output of the iPod, is top notch and is on par with most CD players. Of course, it has nothing on the audiophile-quality CD players out there.. there are some extremely expensive ones out there with separate CD transports and DACs with awesome output. I think we can safely say though that the iPod sound quality would be as good, if not better, than the average CD player found in most head units on the market.
Now if only iPods put out a digital signal… there’d be no debate at all. Lossless + digital output would mean the same DAC in the head unit would be used as for the CD player.. or better still for the audiophiles, an external high-quality DAC.
It is not entirely unlikely that Apple will include a digital out into a future version of the iPod, especially with all the unfounded rumours around about the bad quality of the sound.
Digital Audio Formats
The second part of the argument relates to the actual audio files themselves, and I think this is the primary reason for all the misinformation about iPods. Without knowing it, I think the naysayers are generally referring to the poor quality of low bitrate mp3s and nth generation mp3s that you can download illegally from the net.
There’s a tonne of digital music formats out there, but I’ll focus on the ones playable on the iPod, and in particular the most popular format, MP3.
Most of the rumours of quality issues stem from the nature of the MP3 format. Like jpeg images, it is a lossy format, using a bunch of complicated algorithms to emulate the original input sound while keeping the resulting file quite small. The original audio source will more often than not be the standard PCM audio on a CD, which is a raw stereo, 16-bit , 44.1khz sound sample, no compression, just the raw data. 5 minutes of this audio will take up about 50meg of space. A standard CD can hold 74 minutes of audio or around 650 megabytes of data.
The size of an MP3 is largely determined by the bitrate of the encoding. The bitrate will vary depending on where you get your music or how your rip it, but it will generally be around 128kbps. This results in a file about 5meg for 5 minutes, or roughly 10% of the size of the original audio.
128kbps mp3s are not exactly high-quality audio, but they are not all that bad either. Compared to your average car stereo system you will barely know the difference.
People who love their music though will encode their music in at least 192kbps or 256kbps. This does result in larger files, but it is much better sound quality. It is still lossy, but even to a well trained ear, the differences are minimal.
The problem with the rumours about sound quality stem from the average users who aren’t that big on sound quality and see the options in their ripping software that allow them to store much more music by decreasing the bitrate. I know a guy who ripped all his CDs with media player and stored them in 48kbs WMA files!! However, he just played them through his laptop into his mediocre mini-system at house parties and nobody cared. If someone who liked their music was to play one of these files through their hifi system, they’d quickly turn it off.
Now the whole argument about bitrates and encoding algorithms is totally baseless when you consider the new wave of audio formats. Apple themselves have recently released their Apple Lossless Format, which roughly halves the size of the original music file, but as the name suggests, it is a LOSSLESS format. Ie the bitstream of an Apple Lossless format file is the EXACT same bitstream that you’ll get out of your CD.
Now I was just down at a certain car audio joint in Castle Hill and the guy there was giving me the same line of rubbish that everyone else preaches. I told him about the Apple Lossless format, and this was the first he’d heard of it (come on guys! Do your homework!), but in full defensive mode his response was, “but you can’t store as much music can you?”.
Umm… exactly how much music do you want to store? All these iPod detractors have only one other solution for the person who wants to play more music in their car – the CD stacker. This can hold up to 12 CDs.. So what’s the argument?
iPods currently come in up to 60gig variations. That’s over 900 CDs in 128kbps mp3!!!!
How much more do you want?
If you go the whole hog and want the ultimate perfect sound reporoduction and use the Lossless format, you can still store about 190 full CDs in there.
iPod Hardware + Audio File Formats
So in summary of the 2 sections above, you have a hardware device which produces an audio output on par with most CD players, and audio file formats which produce EXACTLY the same bitstream of music that your CD player produces. All in a portable device that can store up to 190 CDs of perfect CD reproductions. So why wouldn’t you install one of these in your car??
Why are all these car audio installers carrying on about bad sound quality of iPods?
There’s only one answer – sheer lack of knowledge. They haven’t done their research and are just subscribing to the popular line of thought out of sheer laziness.
Why audio installers should know more about iPods
According to stats quoted in an SMH article in March 2005 (http://www.smh.com.au/articles/2005/03/26/1111692675758.html ) 4.4 million iPods were sold in Australia last year. Now if there’s 20 million people in Australia, then last year alone 22% of Australians bought an iPod.
Now if you consider that many couples may have 1 car between them and may only buy 1 iPod between them, then it would be more like 30-40% of car owners in Australia have an iPod that they would like to use in their car.
Add to this the fact that iPod owners are generally of a higher socio-economic group than the average Australian, and thus have a much larger disposable income, you have a prime market to sell value-added car audio installs to allow these people to listen to their music collections in their car.
The way we buy music is also changing and more and more over the coming years people will be buying their music online rather than going to a music store. It’s cheaper and it means they don’t have to “rip” their music to their iPod… It just goes straight on there. Of course they can still burn their music to CDs, but this will just be an extra hassle that the average Joe won’t want to do.
As an audio installer, you would have to be insane to not be well versed on the options available to allow people to use their iPods in their cars. For most people, the only solution they know of is to use the FM transmitters which are widely available. It would be very easy to up-sell these people to much more powerful and better quality integrated install options.
Now guys, I’ve done your homework for you! Please let this be the end of all the misguided rumours going around about the iPod’s sound quality. iPods are becoming ubiquitous, so save yourselves some face and know the facts when somebody comes in for advice.
Most of the guys who have been carrying on about iPod sound quality claim to be "Audiophiles".. hmm.. how could you be so ignorant to the new wave of music if you were that into music? Most musician's freely admit that they illegally download music because they are just so into music and couldn't possibly buy all that music. They just buy the stuff they like. So if you are really into your music, you should KNOW about these things.
And really, audiophiles? Can you please tell me the THD of your tyres, your engine and the wind resistance on the car..
This post has gone far longer than I had intended, and it’s definitely not the last word on this subject, but lets hope it at least raises awareness of this gaping deficiency in the industry and sparks some discussion on the topic.
