Why does my jeep liberty hit its max spl of 142.7 at 50hz ? Box is tuned to 35 hertz

your vehicle has a resonate peak where it's loudest.

If you want to find that seal off your box and meter it.

your vehicle has a resonate peak where it's loudest.

If you want to find that seal off your box and meter it.

Burp box?

your vehicle has a resonate peak where it's loudest.

If you want to find that seal off your box and meter it.

What's that gonna prove? The box volume ported will be too big for sealed, the alignment would be WAY off. The concept behind using a sealed box to find vehicle resonance works, sorta. You have to have the optimal sealed box volume to give a flat response (in open air anyway), you also have to have the speaker in the same position, firing the same way. Another factor I've found is the louder you get, the more the frequency can change.

For the OP, more than likely the vehicle peak is a very strong 50 hz. I did a single 15 in one tuned to 32 hz and I would agree it seemed loudest around 45-50 hz. Another possibility is you may have mistakenly actually made your tuning higher when you built the box.

I saw a guy with a VW Golf (rabbit) with the same results : box was tuned to 32 Hz(my old one) and the sub was a SSA Icon 15". He has his peak at around 50 Hz too !

All the cars were peaking at the same frequencies (quite) : 40 to 50 Hz.

your vehicle has a resonate peak where it's loudest.

If you want to find that seal off your box and meter it.

What's that gonna prove? The box volume ported will be too big for sealed, the alignment would be WAY off. The concept behind using a sealed box to find vehicle resonance works, sorta. You have to have the optimal sealed box volume to give a flat response (in open air anyway), you also have to have the speaker in the same position, firing the same way. Another factor I've found is the louder you get, the more the frequency can change.

The sealed enclosure wouldn't necessarily need a flat response or be in a certain alignment as long as you had a method by which to reliably measure the enclosure both inside and outside of the vehicle. Doing this you would be looking for relative differences in response rather than absolute values.....the frequency with the greatest variance between interior and "anechoic" (outside using proper measuring techniques) measurements would be the peak frequency. You are probably right that as things become highly pressurized and resonating the frequency will change so it's not perfect, but it might help get someone in the ballpark and a starting point to fine tune from. SPL ain't my game though. And I realize this would be extreme overkill for answering the OP's question.

your vehicle has a resonate peak where it's loudest.

If you want to find that seal off your box and meter it.

What's that gonna prove? The box volume ported will be too big for sealed, the alignment would be WAY off. The concept behind using a sealed box to find vehicle resonance works, sorta. You have to have the optimal sealed box volume to give a flat response (in open air anyway), you also have to have the speaker in the same position, firing the same way. Another factor I've found is the louder you get, the more the frequency can change.

The sealed enclosure wouldn't necessarily need a flat response or be in a certain alignment as long as you had a method by which to reliably measure the enclosure both inside and outside of the vehicle. Doing this you would be looking for relative differences in response rather than absolute values.....the frequency with the greatest variance between interior and "anechoic" (outside using proper measuring techniques) measurements would be the peak frequency. You are probably right that as things become highly pressurized and resonating the frequency will change so it's not perfect, but it might help get someone in the ballpark and a starting point to fine tune from. SPL ain't my game though. And I realize this would be extreme overkill for answering the OP's question.

Yeah, you could take the difference and figure it out, but that's more testing that is really necessary when you could just build the right box to start with. I will be the first to tell ya, low volume (say 130's) when your SPL setup is much higher (say 150's) testing isn't accurate, it could be off by quite a bit. Will it give you a start point? Yeah, sorta, but it sounds like he's already got a starting point based on what he's said.

The sealed enclosure wouldn't necessarily need a flat response or be in a certain alignment as long as you had a method by which to reliably measure the enclosure both inside and outside of the vehicle.

This.

Also, my truck peaks hard in the mid-upper 50's. I've tuned anywhere from 28-52hz and I always seem to peak at 56-57hz.

Also, my truck peaks hard in the mid-upper 50's. I've tuned anywhere from 28-52hz and I always seem to peak at 56-57hz.

The tuning of the box wont determine what your truck with peak at, not at that low of a tuning, will it? I would see if you were tuned above your peak freq (considering you already know that number from previous builds) it would change your peak tone, right?

Why does my jeep liberty hit its max spl of 142.7 at 50hz ? Box is tuned to 35 hertz

because its made by DODGE! but seriously ^^^^^^^^ all that pretty much covered it!

Also, my truck peaks hard in the mid-upper 50's. I've tuned anywhere from 28-52hz and I always seem to peak at 56-57hz.

The tuning of the box wont determine what your truck with peak at, not at that low of a tuning, will it? I would see if you were tuned above your peak freq (considering you already know that number from previous builds) it would change your peak tone, right?

Depending how hard the vehicle itself peaks, the box could change that. If the box peak is stronger than the vehicle peak, the box peak will be louder. Most vehicles don't naturally peak below mid 40's. The only potential exception is if you're box is peaking an octave below vehicle frequency, then you could be using both.