"Invisible" audio for the Porsche 914 |
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"Invisible" audio for the Porsche 914 |
horizontally-opposed |
Dec 20 2020, 12:43 AM
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#1
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Advanced Member Group: Members Posts: 3,430 Joined: 12-May 04 From: San Francisco Member No.: 2,058 Region Association: None |
Plans to go for a drive in my 914 this weekend were dashed by yesterday's stay-at-home alert, so I finally dug into a minor project I've been putting off: Rebuilding the car's 28-year-old audio system. While it performed well for 15-20 years, a mixture of age, heat, moisture, etc eventually caught up to it.
System goals: 1) Install a system powerful enough to be enjoyed with the top on or off; 2) maintain/improve "period correct" appearance with no head unit and, if possible, no visible speakers; 3) minimize weight; 4) avoid or minimize additional holes/etc. I'm going into this with the understanding that it's entirely possible the exercise will be futile with a 2.2-liter flat six, but I have been collecting the parts over time and figure it's worth a shot. Some of this stuff has been sitting for years and thus may not be available anymore—but plenty of alternatives are. Old system components: Pyle graphic EQ turned on/off by factory rear defrost switch Pioneer fan-cooled amplifier (~1991) Boston Acoustics four-speaker set in doors (~1991) Pioneer ducted bass wedge in passenger footwell New system components: Smartphone with a proper mount > EQ Blaupunkt five-channel parametric EQ JL five-channel amplifier JL six-speaker set for factory speaker enclosures and door ?? subwoofer in passenger footwell (prepare for now, add later) Fair warning: This thread may proceed at a glacial pace, as midlife plus a small business means my days in the garage are fairly rare in this chapter. I'm also figuring this out as I go, and will use this thread as a journal and a place to share ideas. |
Chris914n6 |
Jan 13 2021, 02:08 PM
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#2
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Jackstands are my life. Group: Members Posts: 3,301 Joined: 14-March 03 From: Las Vegas, NV Member No.: 431 Region Association: Southwest Region |
I had to flip your end result and mount the tweeter low.
You will want to surround the speakers with closed cell foam or equivalent. The single plane baffle won't stop sound wave canceling so you won't be getting 100%. Cover the sheetmetal behind the boxes with vinyl and stuff it with polyfill. Should make the mid range cleaner. When your done run a tone generator/sine sweep to find vibrations. |
horizontally-opposed |
Jan 14 2021, 09:36 AM
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#3
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Advanced Member Group: Members Posts: 3,430 Joined: 12-May 04 From: San Francisco Member No.: 2,058 Region Association: None |
I had to flip your end result and mount the tweeter low. You will want to surround the speakers with closed cell foam or equivalent. The single plane baffle won't stop sound wave canceling so you won't be getting 100%. Cover the sheetmetal behind the boxes with vinyl and stuff it with polyfill. Should make the mid range cleaner. When your done run a tone generator/sine sweep to find vibrations. More good input. Have always noticed the hard metal with the dimple die hole; didn't think about ideas on how to improve sound back there. That little tweak to the great template PDF from @johannes, which crops off the opposite corner so that two corners are cropped off, allows each board to be used on either side of the car—so experimenting with the tweeters low or high will be a snap. The JL tweeter mounts are also pretty neat, allowing you to "aim" the tweeters (a bit, anyway…but it might be enough). Funny you mention a tone generator/sine sweep to find vibrations. My car used to be tight, but two paint jobs later has an annoying buzz I've been trying to trace. Thought it was in/around the seatbelt, but nope. Thought it was in the door, but nope. Thought it was in the dash, but… Will look into this, as it would sure beat having someone else drive over a road that triggers it while I try to isolate it (my next plan). |
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