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I drive a 99 Jeep Wrangler TJ. I have 5.25s mounted in speaker pods in the dash. They're about seat level and face straight into my leg…
I like the general idea of knees and ears all being colinear, but not so much for listening to music.


… I'm about to start a deadening project, but I have to rust treat and rust proof the interior first, so it's been delayed a bit.
POR 15 is good for rust. Black is common but they do other colours too.



I didn't notice any resonances, but I'll play with sine sweeps in the morning. If you don't mind me asking, is there a way to test resonances with measurement gear?
For modes… maybe get the graph going, and then open side doors one by one, and the rear door.

For resonances… maybe get the graphs going, and then do the “laying on the hands” (onto panels) to feel for vibrations and look for the plots changing.
 

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Would there be any benefit to deadening the outside of these as well? I have CLD I can spare.
Maybe

There's still some resonance, I think. Still buzzes a bit on some notes.
However if the resonance is somewhere else, then apply it there.

But how to find it usually the crux of the problem.
 

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Now that I know what a resonance sounds like I'm noticing it a lot in the midbass region in different parts of the dash. Shy of taking my dash apart I'm not sure how to address them…
You have trying tones right?
 

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I presume he means use a tone generator off your phone to play sweeps on individual drivers, it’s a great way to find those annoying resonances or driver issues 👍🏼
Yeah…what ^he^ said.
(My dumdum doppelgänger.)
 
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Is it possible that it could be something else shaking away?
 
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So, since I'll be using a splitter which will decrease the input voltage, is compensating for that as simple as increasing the gain?
  • How will it decrease the voltage?
  • And by how much?
(The output impedance of the sources is ~100 higher than the input impedance of the amplifier.)
 
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From reading it looks like it's reduced, but not more than -3 dB at most, so possibly not noticeable.
It would be 3dB if you had say a 600 ohm output impedance driving into two 600 ohm input impedances.
You would have something like 600 ohms driving 2x 10k to 100k input impedances.

it would bepossibel to measure thevoltage drop., but I doubt you (or I) could do it with any precision… and you would not be able to hear it as quieter.

I would still suggest you work through the math of it.
 

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I'll take a look at the math later...
Vout = Vin * R(In) / (R(In) + R(Out) )
  • You multiply R(in) by 2 when using a splitter.
  • You get the input and pout impedances from the specifications.
 
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