Sony CDX-MP40 Car CD / MP3 Player

The best way to really write about anything is typically to tell people what you are going to tell them, then tell them, and lastly follow up by telling them what you've just told them. I'll try and stick to this train of thought.

First, I will explain a little about my background and my reasons for purchasing this product. Secondly, I will give details about the Sony CDX-MP40 unit, and then I will explain my experience in installing this unit on my automobile as well as some comments which are only personal opinions not based on hard facts or specs.

To begin, I am an electrical engineer by training, and I suppose that you could say that I am very handy and good at putting things together (although I usually prefer the fun involved in taking them apart without worrying about putting things back the way they were - I probably would have made a wonderful coroner or forensic pathologist). I have extensive, expert knowledge in electronics, wiring, signal processing, power electronics, audio, and for the most part know my car inside out, backwards and forwards. This is a nice skill set to have if you are a DIY (Do-It-Yourself) type of person, but somewhat pointless if you prefer to just cough up the cash and avoid the headaches of performing installations on your own. Lastly, I should mention that I have been following MP3 audio from essentially its infancy, have long-term, hands-on experience with MP3 coding/decoding from a personal point of view and lastly have studied the theory and concepts associated with audio signal processing and perceptual audio coding (What can I say? - I'm in university and I have time on my hands).

Anyhow, my situation for installing a new stereo deck in my car only happened because I was looking into purchasing a CD changer. My car was previously fitted with a Sony XR-U550 tape deck which has a CD control via Sony's UNILINK. I was using my RioVolt 250 portable CD/MP3 player with a tape adaptor in my car, and the whole process of accessing the unit from under the seat and switching CDs was starting to get very tiring. Thus, the changer I was looking to purchase was actually an MP3 changer (Sony CDX-757MX 10 Disc MP3/CD changer), but I was really not 100% certain if the 757-U550 changer-deck combo would work properly (i.e. display song names, etc). In order to minimize my work time in case of poor performance (I don't like having to pull out decks, and do car audio wiring over and over again), I bit the bullet and purchased a CDX-MP40 deck in case I was to be dissatisfied with the 757-U500 combo's performance (i.e. replace my new deck with the mp3 capable mp40, and return the changer *OR* return the mp40 and keep the changer if my tape deck worked just fine with it). I won't leave you hanging. I kept both of them.

The CDX-MP40 is a very no-nonsense product when compared to both Sony's current line of MP3-capable CD decks, and MP3 enabled CD decks available from other manufacturers. By no-nonsense, I mean that there are not too many flashy and/or useless things which you will not really use/appreciate unless you are extremely bent on showing off (i.e. extreme car audio enthusiasts), and no motorized faceplates to increase the price, complexity and probability of failure. With this said, however, the MP40 is actually highly functional with MANY features for future application (e.g. XM satellite radio enabled, MP3 ID3 tag reading, remote control, etc.)

Some of the specs from Crutchfield's page (associated with Sony for Sony Xplod items).

* Detachable, Fold-down faceplate (non mechanized)
* CD, MP3, CD-RW capable
* MP3 text/ID3 tag reading
* 23.2 Watts(RMS)/channel (4 Channels)
* Peak output 52W
* SSIR-EX tuner (Sony's proprietary tuner technology for high-sensitivity digital radio tuning)
* FM Sensitivity 9dBf (usable)
* FM Selectivity 75dB @ 400Hz
* FM Signal-to-Noise Ratio 67db (Stereo), (69dB mono)
* AM Sensitivity 30uV
* N. American tuning frequencies only(odd decimal digits only - i.e. 92.1, 100.3, etc)
* CD Signal-to-Noise Ratio 90dB (this is about typical for almost ALL CD players nowadays)
* 18 FM presets, 12 AM presets
* Dynamic Soundstage Organizer (audio processing for adjusting sound localization - i.e. soundstage height)
* XM Satellite Radio controls (requires an XM satellite radio tuner unit for hundreds of digital audio feeds - monthly subscription fee)
* Compact Disc/Mini Disc changer controls
* Front & rear pre-amp outputs
* Wireless remote control (includes battery)
* White on Blue display (backlit), Red key/trim lights.
* NO SUBWOOFER PREAMP OUTPUT
* NO ANTI-SHOCK MEMORY
* NO DVD PLAYBACK
* NO VIDEO CONTROL

The box was packed quite typically, and very securely (i.e. little movement of the components). Included were the following:

* CDX-MP40 unit (wrapped in foam-fabric, case unattached, included a preinstalled, conventional, easy-to-access 10A car fuse on the back of the unit for extra protection)
* Installation manual (One large, single page foldout)
* User's manual (~30 pages)
* Xplod Wiring harness (different from older-style Sony harnesses)
* Mounting chassis
* Removable front faceplate w/ case
* Mounting chassis trim
* Remote control unit (battery included and isolated to prevent leakage)
* Assorted screws.


My experience with installation was quite straightforward. As I had already organized my car's wiring, the only difficult part was actually pushing the unit all the way into the deck slot to clip to the chassis. Everything else was a breeze. All connections are quite easy to make and they are clearly labelled. Since I have an amplifier in my car which I have connected with RCA cables, I did not use the color coded speaker wires on the harness, but simply plugged in the Front/Rear and Left/Right channels as required. The Unilink cable from the changer in the trunk (like I said, I kept the CDX-757MX changer) provides power from the deck, and the RCA plugs from the changer just went into their appropriate slots beside the speaker plugs. Overall, a very smooth setup, and on the first connection (i.e. while the unit was sitting on one of the seats), it worked flawlessly. All my CDs and CDRWs which I had handy worked just fine without errors. I had to adjust the gain on my amp a little bit as the power output on the MP40 is somewhat higher than that of my older tape deck. As always, a heat shrink gun and bullet connectors are useful when doing any kind of car audio installation, and the wiring looked very nice and neat when I was done.

My overall impressions of the unit are extremely good. Sound quality is very high and if you have a semi-decent set up in your car, you will be able to hear the difference between MP3 and conventional CD audio, assuming you know what to look for (it's called perceptual audio coding for a *reason* - i.e. the sounds and data that are missing are very imperceptible). In my opinion, people who make outrageous claims about MP3 audio quality being lossy and full of noise are not very practical, as the auditory noise which is generated by almost every driving environment (i.e. engine noises, wheels, wind, etc.) greatly overpower any noise or parasitic effects which are the result of MP3 encoding. MP3 is a brilliant audio technology and the general population deserves to embrace it, especially in a mobile/portable environment where you want as much music as possible with you at all times.
On another note, I personally prefer the removable faceplate idea as in my experience it does a good job of deterring possible theives. The color combination for the lights is quite nice, and best of all there are no silly equalizers in odd shapes and/or with ridiculous colors running all over the display to distract you or otherwise disgust you (I don't mean visualizations, I simply mean ugly/poorly designed spectrum analyzers/equalizer displays and interfaces). The display is simple and to the point, with the track number, name, etc. scrolling along the bottom, a volume indicator which spans the length of the display when the volume control is pressed and simple, clearly labelled buttons for whatever is required. The remote is also useful if like me, you find that the stereo is too close to the stick shift, and a little difficult to access without having the driver mashing your hand during a shift, or contoring your wrist to fit in the small area. Still, the remote is a little short on sensitivity and only good for line-of sight (just fine for the front passengers - rear passengers might have a little difficulty, but they don't really count anyways...otherwise they'd be in the front! :P ).


To summarize, this unit was purchased to replace a older Sony deck which I was using to play MP3s using a cassette adaptor and a portable MP3 player. The installation was extremely easy, the deck has many useful features with few extraneous/useless capabilites while maintaining a high sound quality and a simple, no-nonsense look. The overall value for the money is exceptional. I would highly recommend this unit to anyone interested in buying an MP3 CD deck for their automobile. There is one caveat however. If you are not electrically or mechanically inclined, pay someone else to do it and spend your afternoon drinking a nice cold one.


UPDATE: I should menion that the mp3 playback on this unit is NOT continuous (i.e. no lookahead buffering for gapless playback). This means that if you take one of your CDs that is say a live, continuous concert/mix, the unit will introduce a gap between songs. For most MP3 CDs where you simply throw together a whole slew of tracks, this is not an issue.