Skipping and Mounting Concerns

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POLL: Skipping Survey

In a poll taken by rexkerr between the dates of 5/11/2005 - 5/14/2005 members were asked to participate in answering the following questions:

  1. Does your DMP1 skip?

    2. __ Never, I'm lucky!
    __ Frequenly on all road surfaces
    __ Only on bumpy roads
    __ Only at freeway speeds
    __ Only at excessive freeway speeds (80+)

  2. Vehicle Type:

    3. __ Subcompact (Echo, Accent, Metro, etc)
    __ Compact (Corolla, Elantra, Cavalier, etc)
    __ Mid-Sized (Camry, Sonata, Malibu, etc)
    __ Large Car (Town Car, Caprice, etc)
    __ Luxury Car (charactarized by especially soft ride)
    __ Small SUV (CR-V, Rav4, Escape, Santa Fe, etc)
    __ Large SUV (Expedition, Suburban, etc)
    __ Small pickup
    __ Full sized pickup
    __ Bicycle
    __ Motorcycle
    __ RV/Boat/Other

  3. Orientation

    4. __ Vertical
    __ Horizontal
    __ Oblique

  4. Mounting Surface

    5. __ Rigid mount to rigid surface
    __ Mounted to soft surface (eg, carpet)
    __ Gravity, Friction & Intertia Mount
    __ Levitation (if you give this answer, you'd better include a good explanation!)

  5. General Location in vehicle

    6. __ Passenger area, under seat
    __ Passenger area, other
    __ Cargo area, rear -- far from wheel well
    __ Cargo area, rear -- close to wheel well
    __ In-Dash

  6. If known, approximate bitrate of most files (esp of songs that skip)

    7. __ < 128
    __ 128
    __ 256
    __ 320
    __ VBR

  7. Anything else that I missed that might be pertienent?

Responses & Conclusions

Around 22 respondents participated from which rexkerr made the following analysis: 

OK, I've ammended you to a new category that I created for somebody else
called "Semi_Rigid"... that said, I'm up to 22 responses and I see
something interesting:


Skips, of the 8 that skip 8 are at freeway speed, all are small vehicles
which tend to have bumpier suspension (that, and a boat). Only ONE of
the 15 no skips report having a compact car, all others report midsize
or larger (mostly larger). As for mounting location, it looks like
horizontal wins for best orientation, but that's still mostly a wash...
right now we have more skips in vertical than horizontal, and more
no-skips in horizontal than vertical. As for mounting, no skips BY FAR
are unmounted or on carpet, and skips are 6 rigid, 1 unmounted, and 1
that I listed as semi-rigid. Most of the skippers are in the cargo
area, and most of the non skippers are in the passenger area. Data rate
doesn't seem to be a factor. Anyhow, i'll post the actual data once the
submission rate slows down (it's already slow!) and you can draw your
own conclusions, but I'm DEFINITELY thinking of reconsidering my
mounting based on the data received so far!!!

-Rex

Based on these findings, a DMP1 placed HORIZONTALLY on the floor without any mounting hardware seems to have the best results. This is contrary to what the DMP1 installation manual suggests.

As a corollary, smaller cars that tend to have stiffer suspensions experience more skipping, and rigid mounting also aggravates that skipping.

Other Reasons For Skipping

Oddly, there seems to be other types of causes for skipping. Several forum members have reported that their DMP1 skips alot when they listen to music very loudly. The music typically contain a lot of heavy bass sequences.

The prevailing theories for this phenomenon are broken up into two:

  1. The Head Unit / Amplifier is causing a power drain thus dropping the line voltage below some threshold where the DMP1 temporarily ceases to function properly and halts for an instance - thus resulting in a skip;
  2. The loud, low repetion-rate of the thumping music causes the DMP1 HDD head to jar / bounce at some resonant frequency and the Mp3 player software starves for new data while the head settles down and the HD Controller attempts to retry the disc read.

The first phenomenon would be addressed by placing large capacitors in parallel with the power source to augment the power delivery to the amplifier unit.

The second issue can easily be remedied by either

  • moving the DMP1 to a location that is isolated from the speaker vibrations (especially away from the subwoofer)
  • not playing the music with the bass turned up so high (doh)

Stock Hard Drives Skip

The stock HD doesn't have enough shock protection. It is five year old technology and the shock absorption of 2.5" drives has improved immensely.

Replace them with newer hard drives. I have replaced them with Seagate Momentus 5400 drives and the skipping is gone. Other people have used other drives have realized this as well. Check out DMP1 the Compatible Replacement Hard Disks list here: http://finance.groups.yahoo.com/group/omnifi/database?method=reportRows&tbl=5

Related Links


External Links


--Lumkichi 20:22, 3 Nov 2005 (CST)

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