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A few months ago I bought some new speakers and an amp for my Jeep. I made a little face plate with an ALPS potentiometer to control the volume and it has an iPod dock (no head unit, just the pot).

A couple days ago I finally was able to order a Raspberry Pi, and I want to make my own head unit for my car that supports 192/24 for my vinyl rips (iPod only outputs 48/16).

Can I use a HDD to store my music on? I know that the gyro effect on the HDD spinning can cause some serious problems if the drive is twisted around a different axis than the platters (because the head of the HDD can scratch the disk).

If I securely mount a HDD in my jeep will it break? When I go off road the jeep probably does up to ±4g of acceleration for short times in random directions. Can a spinning HDD tolerate that?

I will use a SSD if I have to, but even a small and (relatively) slow SSD for my 100GB of music will cost A LOT of money where as a 256GB HDD cost about $10 on eBay.

A more complicated option would be to cache my current playlist to the SD card on the RPi and install an accelerometer. I could monitor the accelerometer and make it stop reading from the disk when the acceleration goes more that 1.2g or so.

m.Alin
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Sponge Bob
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  • Also, for all the people who are going to tell me that RPi doesn't support 192/24: I am making my own USB DAC that does... – Sponge Bob Jul 04 '12 at 19:19
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    I know of several people who wrecked their netbook's HDDs by using them in cars. Maybe it could work if you got one of those HDDs which has integrated accelerometer and will safely park the heads in case of vibration, but I can't say for sure. – AndrejaKo Jul 04 '12 at 19:34
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    Can you really hear the difference in sound quality over the engine, road, and wind noise? – Matt B. Jul 05 '12 at 19:36
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    iPod with hard drive reads out maybe an album worth of data to RAM and spins down the drive. If you have a long playlist rather than skipping tracks all the time, the drive may be spun up less than 1% of the time. – Matt B. Jul 05 '12 at 19:41
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    I have taken my iPod classic off road before and it still works fine. That thing is indestructible. And all of my music is FLAC (well, I convert it to ALAC for my iPod) so it probably can't store more than 10 or 15 songs in memory at one time (at 25MB/song). – Sponge Bob Jul 05 '12 at 19:50
  • What does the data sheet for the hard drive say? – Brian Carlton Jul 05 '12 at 20:07
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    @BrianCarlton Somehow I doubt he has a proper data sheet for a hard drive he might possibly buy on eBay in the near future. But consider this: The read head of the hard drive is skirting along on a cushion of air that's only a handful of micrometers (microns? it's been a while) thick over your data, which is spinning at 7200 RPM. An iPod is designed to be abused in a moving environment. A desktop hard drive is not. – Joe Baker Jul 06 '12 at 09:11

6 Answers6

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192/24 for my vinyl rips (iPod only outputs 48/16).

The audio quality of vinyl discs is way below 48kHz 16 Bit due to the analogue and mechanic process - the "scratching" of the needle generates a relative high background noise level.

I strongly recommend using flash memory technology in a car instead of magnetic platters. While 2.5" notebook HDDs can take a bit more abuse, they are still senstive - shock can damage them quickly.

But audio needs low bandwidth so you can try to use cheap memory like USB sticks or SDHC/SDXC cards. No need to use expensive SSD.

Turbo J
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  • Thanks. And I'm really doing this just for fun. I know the samplerate doesn't really matter once you get above 44.1KHz, but I still record my Vinyl 192/24, it does sound better than CD, but not because of the samplerate. – Sponge Bob Jul 05 '12 at 05:52
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A spinning HDD most likely breaks with \$\pm 4g\$. If you really need to, go for a SSD. On the other hand: Is the audio (and the environment) in the car that great, that you really need 192/24? Wouldn't a lower quality also work (thus reducing the memory requirements)?

suha
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Seagate used to make HDDs specifically for automotive use, with much higher shock, vibration, and temperature tolerance: http://www.seagate.com/docs/pdf/datasheet/disc/ds_ee25_2.pdf

They discontinued them in 2010 as SSD prices began to approach a similar $/GB of the automotive drives. So, you definitely want to use some sort of flash, as it has replaced these ruggedized HDDs, but as TurboJ noted you don't need an SSD for this application. I have all my music in my car on a 32GB USB stick and it works fine. 32GB/64GB USB will run $0.45-$0.50/GB; if you want to go bigger than that you're probably going to be better off with an SSD which are approaching $0.50-$0.55/GB in some capacities.

Toneloc427
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Go for SSD and if it's expensive for You, go for CF card. Keep static files in CF and dynamic in RAM.

Tomas D.
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  • This does not seem different from @turboJ's answer except that it is much shorter. – Kortuk Jul 05 '12 at 20:49
  • Well, CF cards are easily interfaced to IDE buses :) That's the idea of an additional post. – Tomas D. Jul 30 '12 at 13:00
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    @Socrates - there's no IDE bus in the system - only USB, SD, Ethernet (and if you want to make things hard UART, GPIOs, and related options - probably some SPI, I2C, etc). – Chris Stratton Aug 03 '12 at 14:35
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For a Raspberry Pi, I highly recommend using a really big SD card and just storing your music on that.

Alex Chamberlain
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My answer would be dummy, but I suggest you to use a damp cage.

That will smoother and protect the hard disk from the high accelerations. I have disassemble my old Thoshiba dynabook and I could see that there's damped rubber cage around it.

For extreme case you could use a mechanism such like that used in train bogies. It's up to you to design that damped cage.

BTW , Unfortunately while you writing ML code simulation for your new damped cage, you may found there are already designed damping cages for your requirement: http://www.acousticpc.com/gup_japan_smart_damper_hard_disk_drive_antvibartion_mount.html[ Please note that I'm not working for acousticpc.com :P ] Even there are good dampers that could hold accelerations in fighter jets.

SSD or SD are good alternatives too, But it don't address your question.

Standard Sandun
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