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Total Sound Makeover - Sound Deadening, Speakers, Processor, Amp, and Subwoofer

Discussion in 'Gen 3 Prius Audio and Electronics' started by ultraturtle, Jul 11, 2012.

  1. ultraturtle

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    I confirmed that is how I originally wired it. The amp is powered only when the car is in "Ready" mode.

    I finally got around to installing a 2 farad capacitor next to the amp. I took some measurements to see if it was worth the time, effort, and money. To minimize risk of damage to the DC system, I turned off all other power draws before setting volumes on the head unit, processor and amps to near maximum. Using track 14 of the XLO/Reference Test & Burn In CD (a Big Band tune that blasts a very wide swath of the audio spectrum), I measured peak amperage and maximum voltage drop on the line feeding the amp. Highest amperage reached was an instantaneous 64.0A, with an accompanying max voltage drop of 0.9V (from 14.4 to 13.5). That's a 6.25% drop using a capacitor double the recommended size for a 900W amp (in this case only pumping out about 690W: 13.5V x 64A x 80% efficiency) . So yes, a capacitor is definitely in order for operating a system like this at a near maximum volume level in order to protect the DC supply system.

    Done. I have a PLX Kiwi ODB2 feeding the Torque application on my Android phone. It is unecessary, though. See last part of the reply below.

    My guess is that your reading mostly took place on DIYMA. Every online community has its own unique culture. Priuschat participants seem to value efficiency. DIYMA folks seem to dislike capacitors. Perhaps it is the nature of the vast majority of batteries used to power thier equipment (large, cranking batteries specifically designed to power large amperage draws for short periods), or that many of them like to listen to their systems for extended periods of time with the gasoline engine off, and want the additional listening time. A Plug-In Prius is a different animal. It does not even have a cranking battery, but does have a massive additional battery already that could provide power (in "Ready" mode) much longer than any single additional battery solution they might come up with. If ever there were a car that would benefit from a capacitor, it is the Plug-In Prius.

    All that said, this capacitor experiment was an academic excercise. I never before, nor ever will again play anything in this car at anything close to this sound level. In order to get near the car while it was playing at this level, I wore foam inner-ear plugs, and mickey-mouse earphones over the top of the ears in order to protect my hearing from damage - and it was still very loud. After attenuating the volume to the loudest I would ever consider listening on the JBL processor master volume (-20dB), I added 5dB for a little leeway, and measured the same sample audio again. The result? 6.0A peak and a max voltage drop of 0.05V, less than 0.4%. At this power draw, I probably do not need a capacitor at all.

    Another lesson learned - 6 amps is less than 70 watts total being fed to all of the speakers, including the subwoofer, so it also tells me a lot about how much power I really need. If I had it all to do over again, I would power the 6 speakers directly from the JBL MS-8 speaker outputs (20W ea), and use a single 100W to 300W amp for the sub.
     
  2. joedirte

    joedirte Member

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    Thanks for the update. Of course the caps add something. Depending on the Farad rating and the ESR, there will be a an extra "pool" of current available. Sure the amps have their own decoupling caps, and in a normal battery they can handle more instantaneous amps then you would need. But considering in a Prius with the ~30Ah AGM battery, I can see the voltage drop quite a bit with just turning on the headlights, that battery would not sink any high frequency current demands, so then all the current has to come down resistive wires which also have inductance. And it's not clear that the DC-DC on the inverter is designed for current spikes like that.

    Q=C*V so in this case we have 27 coulombs of charge. Which is 0.05Wh...

    Or over 0.25 second that is 100A (except it isn't because you aren't going from 14V to 0V). But yeah, it isn't much compared to a normal lead acid battery, but because of very low resistance, the caps can respond to higher frequencies (ie. very low resistance) and sudden changes in power.
     
  3. ultraturtle

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    Thanks. Nice to know that the capacitor upgrade is not only useful for daily listening, but should I ever have a need to use blaring audio as a psychological warfare weapon to compel a Central American dictator to surrender, that I have the proper equipment to do so.
     
  4. mid jersey

    mid jersey Junior Member

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    Is the Prius battery ~30Wh or ~30Ah? Big difference between the two. I thought it was around the 30Ah range.
     
  5. ultraturtle

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    I think it is 36 amp-hours, but would need to pull it to check. It is not listed in the specification section of the owner's manual.
     
  6. joedirte

    joedirte Member

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  7. Bmr4life

    Bmr4life Member

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    Wish the pictures in this thread still worked. :(
     
  8. Want A Hybrid

    Want A Hybrid New Member

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    WOW!!! Very nice and very inspiring as I'm going through the same questions. Thanks!
     
  9. WE0H

    WE0H Senior Member

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    The original poster could edit this thread to fix the links to the pictures.

    Mike
     
  10. Want A Hybrid

    Want A Hybrid New Member

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    Hmmm.... all pictures show up ok for me...?
     
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  11. Bmr4life

    Bmr4life Member

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    Ha, tried another browser and they show up. Not sure why I don't see them with Chrome, but thanks for replying.
     
  12. Andrax

    Andrax Junior Member

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    Wow, just saw this. Would love to tackle a sound deadening project, but realistically it would be easier and faster to pay someone to do it as I don't have the time or tools...

    Great work!
     
  13. dan_rc3

    dan_rc3 Junior Member

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    this thread is incredible. Thanks for all the info.
     
  14. SageBrush

    SageBrush Senior Member

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    I'm confused why someone would go through all this trouble to listen to 'CD quality' sound.

    Just kidding! Lovely thread, and kudos to OP.
     
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  15. sarals

    sarals New Member

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    Absolutely stellar work! I'd love to hear that system.
     
  16. janice45

    janice45 Dudley Girl

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    With all this work can I ask how's the bluetooth sound to people now
    I know its not a radio or music question but it somewhat a noise one.
    Thanks
     
  17. ultraturtle

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    I frequently stream lossless AAC from my Android phone via Bluetooth, and the sound is about as good as it gets. My unsophisticated ear cannot tell the difference between it and the same files via USB.
     
  18. Ed Law

    Ed Law New Member

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    Mate, this is seriously the best sound deadening job ever done to a prius.

    Personally, i thought i had done a pretty good job on my doors, but this has inspired me to go even further and at do the boot and then redo the door trims.

    I just wish i could get some sound deadening Mass loaded vinyl here in Adelaide, Australia. So I am stuck with Dynamat and Jaycar Sound deadener.

    Great work mate.

    Ed
     
  19. Ed Law

    Ed Law New Member

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    And also, are you still using the standard head unit?
     
  20. afpri

    afpri Hemi-Hybrid

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    This.... THIS WORK RIGHT HERE. This is Prius porn. very impressive work. You, Sir, are the Chuck Norris of Prius installs.Thank you for a great post.
     
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