Car simple USB/MP3 player - > weight VS performance - diyAudio
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Old 11th August 2007, 10:00 PM   #1
JinMTVT is offline JinMTVT  Canada
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Default Car simple USB/MP3 player - > weight VS performance

Hi all !

i have a car where weight savings are an utmost priority,
but this car will be used on street for a few years before going to war on come racetracks ...

so i'd like to be able to design a simple stereo sytem that could make me save some weight VS regular stereo and be of a different control ...

what i would like to be able to do,
is to accept only USD cards with music on em,
and play those in MP3 format
then send this to a small class D amplifier
and find some suitable in door lightweight drivers

I know that some regular car players now accept USB and play MP3 songs on them ..

is there any good quality DIY stuff available for playing MP3 direct from USB wich some basic controls?
i need it to be as small and lighweight as possible

what i'd like to do is only have an USB hole somewhere in the middle console, so it is hidden
and use the already on the dash audio controls from my car ( car is a honda S2000 wich on dash radio contro ...need to see if the volume and other buttons can be reused to control something other than the OEM radio)

Then are class D amplifiers good to use on 12-14V directly? i wouldn't need much power, only a few good watts could make the cut, i'll be putting an HARD top on this car, and the "living space" is going to be pretty small so probably easy to energize ..

thanks all for your help
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Old 11th August 2007, 10:03 PM   #2
JinMTVT is offline JinMTVT  Canada
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smething like this perhaps ??
http://www.teuthis.com/html/mmc_mp3.html


thing is that i would like to use a very good quality DAC if possible as this results in less required power to be able to get clear soun in a car i believe ..
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Old 18th August 2007, 02:45 AM   #3
dangus is offline dangus  Canada
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About the lightest possible source would be a little flash memory MP3 player. Get a 1/8 to phono cable, and plug it directly into a modest 2 channel power amp, and feed a couple of 6.5" speakers. If you get a player that has an SD card slot, you can leave a few essential tunes on the internal memory, and load other stuff off an SD card.

The old RCA Lyra players aren't at all bad, like the RD1022, RD1028, RD1072. Internal memory isn't much by current standards, but they accept SD cards up to 2 gigs, which makes them well worth considering. There's only 8 buttons for volume up/down, play/stop, fwd/rev, tone and play mode, so it can be easily operated by feel. I'm tempted to modify one for dash mounting, by adding external switches, and maybe backlighting the display if possible.
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Old 18th August 2007, 02:56 AM   #4
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Do you seriously think the negligible weight of an MP3 player will effect the performance of your car?

That's like saying "I think I'll wait to eat lunch until AFTER the race because I don't want that cheeseburger to slow me down".
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Old 18th August 2007, 04:19 AM   #5
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Quote:
Originally posted by theAnonymous1
Do you seriously think the negligible weight of an MP3 player will effect the performance of your car?

That's like saying "I think I'll wait to eat lunch until AFTER the race because I don't want that cheeseburger to slow me down".

Well it IS a Honda....
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Old 18th August 2007, 04:23 AM   #6
dangus is offline dangus  Canada
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(more stuff I was going to add, but it timed out, so anyway, if anyone is into hacking solid state MP3 players, read on...)

The old RCA Lyra players aren't at all bad, like the RD1022, RD1028, RD1072. Internal memory isn't much by current standards, but they accept SD cards up to 2 gigs, which makes them well worth considering. There's only 8 buttons for volume up/down, play/stop, fwd/rev, tone and play mode, so it can be easily operated by feel. I'm tempted to modify one for dash mounting, by adding external switches, and maybe backlighting the display if possible.

You can find the RCA players used very cheap on eBay, or locally. I just bought one for $25. Of course there are many other flash MP3 players on the market well under $100, but not many of them have both the SD card slots and simple push-button operation of the RCAs.

I just took a look inside the RD1028: there's only two chips (that I can see). One flash RAM hynix HY27UF081G2M, and one SIGMATEL STMP3505. There's an unused memory chip location.

An overview of the STMP family:
http://www.eetchina.com/ARTICLES/200...URCES=DOWNLOAD
Datasheet: http://www.datasheets.org.uk/datashe...rticle=3160355

Specs on the headphone output:
<0.05% THD headphone driver, including anti-pop and short-circuit protection
 High performance 18-bit ΣΔ technology Line in to Line-out SNR >94 dB typical
There's a rumour that the Sigmatel SDK can be found on some file-sharing networks, and I found a program that claims to extract the firmware (Sigmatel Firmware Extractor). I dunno if this means this family of players can be readily hacked or not. My one real wish for the Lyra would be a resume function that remembers the track position, and/or to eliminate the helpful automatic power down when on pause.
FWIW the Ipod Shuffle uses a similar Sigmatel chip.

If you're willing to spend more money, and want a player where you can customize the firmware to your particular needs, there's the the open-source Rockbox firmware.
http://www.rockbox.org/
Supported players:
"# Archos: Jukebox 5000, 6000, Studio, Recorder, FM Recorder, Recorder V2 and Ondio
# iriver: H100, H300 and H10 series
# Apple: iPod 3rd gen, 4th gen (grayscale and color), 5th/5.5th gen video, 1st gen Nano and Mini 1st/2nd gen (Nano 2nd gen is not supported)
# Cowon: iAudio X5 (including X5V and X5L), M5 (including M5L)
# Toshiba: Gigabeat X and F series (the S model is not supported)
# SanDisk: Sansa E200 series (the R models are not supported)"

There's also the S1MP3 project, which has firmware for a family of related inexpensive players. All firmware supports WAV (PCM), WMA, and MP3; some supports OGG.
http://wiki.s1mp3.org/index.php/Main_Page


Yes, it's slightly possible that I've gone off on a tangent, but you have to admit there's something cool about a complete music player that is smaller than a gear shift knob and holds more music than a CD changer on a card you can fit in a nostril.
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Old 19th August 2007, 05:56 PM   #7
JinMTVT is offline JinMTVT  Canada
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theAnonymous1 : what i meant is not a concern about a small portable mp3 player's weight,
but rather the complete car audio system's weight.
This car will be my "Street toy" and occasional amateur racing for a few years to come, before going to a full race car when our other cars will be done ..
so i am very serious as to not add some unnecessary weight to it like regular sound systems and cd players..

The usualy in dash cd player weights between 3-7lbs,
then the supposedly good quality door drivers ,
and if required an amplifier ...and so on

i don't even need it, so what i want to do is get good quality pro drivers that are usually quite a bit lighter in design, and use a diy kit amplifier...probably a smlal class-d + a very good quality source to get decent sound with minimum weight for the few years it'll be used on street !


DigitalJunkie: what kind of car do YOU drive?
i challenge you to design a more efficient engine than the S2000's F20C 2.0lp ... then we'll talk more


dangus: thanks for giving me more options!
i hadn't really think about using a complete MP3 player
( commercial portable ) and sending its sound to an external amplifier ..

what i though was more like getting a DIY mp3 reader then sending it to a very good quality DAC
probabbly something using 1794
then sending this out to a class D amplifier

do you believe that the Lyra Mp3 players will have sufficient sound quality???
i have been listening to a RAKK DAC+ passive output
for a few years now at home, not sure that i am ready to listen to very sub-performance if it is possible to get near to it ..

i own a sony 2g MP3 player, the smallest one with the OLED screens that my GF bought to me for b-day
it plays fairly well for its size, and is 2gig
but a stupid SONY software is required for transferring music as it doesn't allow mp3 format to be transfered directly ... i do not have info about the ouput electronics and its dac, but i assume they are of very good quality for the size, because the sound is great with the fontopia 17 earbuds

you think i could use this player and mount it in dash directly ...the controls are all at the end of it, and it it would be in the dash with its controls sticking out, i guess it would be pretty easy to control,
and that would be very lightweight total system

http://audiovisual.kelkoo.co.uk/ps_15333831/122701.html

sony nw-a608


so back to electronics,
what kind of class D amplifier could run pretty good directly on the 12.6-14.5VDC car power ?
and would be quite small ??
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Old 19th August 2007, 06:42 PM   #8
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I made my comments because it sounded like you were worried about the weight of a standard mp3 player vs. some barebones type board. I can understand the weight of the whole stereo system adding up; mostly the subs and their enclosures.

For speakers you would obviously want to go with drivers that have neodymium magnets because of their relatively low weight compared to ceramic magnets. You can even find woofers with neodymium magnets......

http://www.partsexpress.com/pe/pshow...number=264-862

For an mp3 player my choice would be the discontinued iRiver H100 series. The H140 is a 40gb player that you can connect to an external remote and has optical in AND out. The optical out is a very rare feature for an MP3 player and I can't think of any current models on the market that have one.

For a small class-d amp that can run directly from the cars voltage; you can't beat the AMP32 from 41hz.com. This amp will give you 2 channels of output about the same as a standard head unit. There are some other kits from there as well that could be used for your subs.
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Old 19th August 2007, 08:28 PM   #9
JinMTVT is offline JinMTVT  Canada
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happy i explained it correctly this time

i will not use any subs or enclosures..so driver will have to fit to the door enclosure volume and will be of single location ( no place to put tweeters at )

( this car will not have a trunk, as this space willbe used primairly for the mounting of the rear spoiler and under diffuser ... )
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Old 19th August 2007, 09:39 PM   #10
JinMTVT is offline JinMTVT  Canada
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also will look into the iRiver H100 series
as you pointed out ...thanks
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