[420tabbycat]

So there’s nothing anywhere resonating that’s big enough to matter?

 

[MercuryFlint]

So there’s nothing anywhere resonating that’s big enough to matter?

I put a 20lb weight on the passenger floorboard, stood on the driver, put it against the transmission tunnel, so far nothing.

 

[MercuryFlint]

Just tried the weight on the dash, rear passenger floorwell, nada.

 

[Holmz]

…

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.

 

[MercuryFlint]

I like the general idea of knees and ears all being colinear, but not so much for listening to music.




POR 15 is good for rust. Black is common but they do other colours too.




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.

Yeah, not the optimum configuration, for sure.

Por 15 is the plan! Black is fine, it'll all be covered by carpet some day 😁 The Deadening group recommended some kind of ceramic spray for on top of the Por 15, which I'm debating.

Okay, here are the graphs for tailgate open, different doors open.

 

[MercuryFlint]

I'm pretty sure my neighbors hate me at the moment 😆

 

[Jheitt142]

Time to add a third midbass

 

[Picassotheimpaler]

So maybe I misses this, but you said moving the sub fixed the issue. And I saw you were going to attempt moving the time alignment to see if it helped. But I never saw the results to the test.
180hz is 6 ft long. That's pretty long but, not really. That means if you moved the sub 3ft closer to you when you moved the box, you effectively made the phase 180°. If we take that to the world of time alignment and delay, that is 2.6 ms to get the same 180° rotation at 180hz. Thats not a ton of movement in delay that would cause a massive null within the crossover. And of course if you are off on time alignment, it is going to show up in the highest frequencies of the sub aka 180hz. But much less so the longer frequencies like 80hz which is over twice as long. Since it is roughly twice as long at 80hz around your crossover region, you could easily get fairly good summation at the crossover point that may only be hypothetically 80° out of phase at the same time that 180hz is 160°.
So I would attempt starting there if you have yet to test it. Cause that's where I would put my money if I was a betting man.

 

[MercuryFlint]

Time to add a third midbass

Leaning that direction, for sure 🤣

Time to add a third midbass

That's where I'm leaning, friend 🤣. Might take my boss' idea and replace the lower third of my door panel with MDF and mount. Probably will create resonance issues, but it's a start.

So maybe I misses this, but you said moving the sub fixed the issue. And I saw you were going to attempt moving the time alignment to see if it helped. But I never saw the results to the test.
180hz is 6 ft long. That's pretty long but, not really. That means if you moved the sub 3ft closer to you when you moved the box, you effectively made the phase 180°. If we take that to the world of time alignment and delay, that is 2.6 ms to get the same 180° rotation at 180hz. Thats not a ton of movement in delay that would cause a massive null within the crossover. And of course if you are off on time alignment, it is going to show up in the highest frequencies of the sub aka 180hz. But much less so the longer frequencies like 80hz which is over twice as long. Since it is roughly twice as long at 80hz around your crossover region, you could easily get fairly good summation at the crossover point that may only be hypothetically 80° out of phase at the same time that 180hz is 160°.
So I would attempt starting there if you have yet to test it. Cause that's where I would put my money if I was a betting man.

So, when I moved the sub to the floorboard passenger side the null stayed. When I put it in the passenger seat facing me it was improved but still present. Passenger seat but firing up was the best of the bunch, but still somewhat present. I now have the sub behind the driver's seat firing forward and the time delay correctly set by measurement.

I can toy with the time delay, certainly. Run some tests and see if anything changes. I played with the polarity of the woofers earlier with sub in its current position and the null only became worse, so 180 isn't the way to go.

So do you think it's time delay or my crossover settings? My crossovers are figures and slopes that I toyed with until the null improved, so it's possible it's tied up in that.

 

[Picassotheimpaler]

Leaning that direction, for sure 🤣


That's where I'm leaning, friend 🤣. Might take my boss' idea and replace the lower third of my door panel with MDF and mount. Probably will create resonance issues, but it's a start.



So, when I moved the sub to the floorboard passenger side the null stayed. When I put it in the passenger seat facing me it was improved but still present. Passenger seat but firing up was the best of the bunch, but still somewhat present. I now have the sub behind the driver's seat firing forward and the time delay correctly set by measurement.

I can toy with the time delay, certainly. Run some tests and see if anything changes. I played with the polarity of the woofers earlier with sub in its current position and the null only became worse, so 180 isn't the way to go.

So do you think it's time delay or my crossover settings? My crossovers are figures and slopes that I toyed with until the null improved, so it's possible it's tied up in that.

View attachment 316609

I would start by flipping the phase of the subwoofer and playing a test tone at 180hz or some bandwidth limited pink noise centered there. Then play with the time alignment of the sub until you hear that 180hz note basically disappear because of cancelation. Then switch the polarity of the sub back to normal and see what the measurement looks like.
Another idea would be to verify polarity of the speakers. If the sub is reversed polarity, the tape measure dealy is going to make you have a null

 

[Holmz]

I like the general idea of knees and ears all being colinear, but not so much for listening to music.
….

Yeah, not the optimum configuration, for sure.
…

It is optimum for something

(You just need to visualise what I am saying. )

 

[dumdum]

It’s very likely it’s a room mode down to the length of the car, move the sub to the back seat and see if the nu

I would start by flipping the phase of the subwoofer and playing a test tone at 180hz or some bandwidth limited pink noise centered there. Then play with the time alignment of the sub until you hear that 180hz note basically disappear because of cancelation. Then switch the polarity of the sub back to normal and see what the measurement looks like.
Another idea would be to verify polarity of the speakers. If the sub is reversed polarity, the tape measure dealy is going to make you have a null

the null is present in the midbass with each driver playing solo’d, so the sub position may reinforce the 180hz dip and fill it somewhat, but that doesn’t solve the issue of the null itself

in one post I read the enclosures buzz and resonate at 180hz, this will give enough out of phase output to effect the response

enclosures should be solid and a nearfield measurement may be close enough to miss the effects of the resonance cancelling stuff out

does the null appear as you move the mic away from the driver in its enclosure

put bluntly of the enclosure isn’t sealed do that, that alone could be the root cause of your dip (use butyl from deadener with the foil removed. It’s perfect for this job and also for using like blue tack for mounting tweeters) and also you need to make sure the enclosure is deader than a dead thing, on a dead day, coming first in a being dead competition!

 

[MercuryFlint]

It is optimum for something

(You just need to visualise what I am saying. )

🤣🤣🤣

Clear as glass, now 😆

I would start by flipping the phase of the subwoofer and playing a test tone at 180hz or some bandwidth limited pink noise centered there. Then play with the time alignment of the sub until you hear that 180hz note basically disappear because of cancelation. Then switch the polarity of the sub back to normal and see what the measurement looks like.
Another idea would be to verify polarity of the speakers. If the sub is reversed polarity, the tape measure dealy is going to make you have a null

Am I leaving the LPF above 180 on the sub or keeping it at the 120 I have now? Heck, I can do both. I'll test this in a few hours.

It’s very likely it’s a room mode down to the length of the car, move the sub to the back seat and see if the nu

the null is present in the midbass with each driver playing solo’d, so the sub position may reinforce the 180hz dip and fill it somewhat, but that doesn’t solve the issue of the null itself

in one post I read the enclosures buzz and resonate at 180hz, this will give enough out of phase output to effect the response

enclosures should be solid and a nearfield measurement may be close enough to miss the effects of the resonance cancelling stuff out

does the null appear as you move the mic away from the driver in its enclosure

put bluntly of the enclosure isn’t sealed do that, that alone could be the root cause of your dip (use butyl from deadener with the foil removed. It’s perfect for this job and also for using like blue tack for mounting tweeters) and also you need to make sure the enclosure is deader than a dead thing, on a dead day, coming first in a being dead competition!

The sub is between the back seat and front seat now, I'll move it directly on the back seat and test.

Okay, I was wondering if that pod rattling could be something. Pushing on it doesn't seem to improve anything, but I guess if it's the whole darn pod it might not make a difference.

The enclosures are strange. The portion where the screws mount feels a little hollow, because when I tightened them to the dash the material collapsed where the screws bolt down. It's solidly held, but I thought that was odd. The pods themselves feel solid. The null appears as the mic moves away, but I've only tested moving it towards the listening position, not moving it towards other positions.

As for using the butyl (I have some spare deadener since I never fully started my deadening project) am I putting that on the inside of the pods or the outside? Do I peel the foil off first and then lay the rubber, or lay it with the foil and remove the foil afterwards? I haven't played much with it, but I might have time to do it on my lunch break. I'll make sure to knife it until the bleeding stops 😁.

 

[Picassotheimpaler]

🤣🤣🤣

Clear as glass, now 😆



Am I leaving the LPF above 180 on the sub or keeping it at the 120 I have now? Heck, I can do both. I'll test this in a few hours.



The sub is between the back seat and front seat now, I'll move it directly on the back seat and test.

Okay, I was wondering if that pod rattling could be something. Pushing on it doesn't seem to improve anything, but I guess if it's the whole darn pod it might not make a difference.

The enclosures are strange. The portion where the screws mount feels a little hollow, because when I tightened them to the dash the material collapsed where the screws bolt down. It's solidly held, but I thought that was odd. The pods themselves feel solid. The null appears as the mic moves away, but I've only tested moving it towards the listening position, not moving it towards other positions.

As for using the butyl (I have some spare deadener since I never fully started my deadening project) am I putting that on the inside of the pods or the outside? Do I peel the foil off first and then lay the rubber, or lay it with the foil and remove the foil afterwards? I haven't played much with it, but I might have time to do it on my lunch break. I'll make sure to knife it until the bleeding stops 😁.

I would keep all settings the same for the moment. Your doing an audible test of phase alignment by trying this out.
I did also just do a quick skim of the rest of the thread and didn't see that you already have a null at 180 with only the midbass playing that dumdum was speaking of. If that's the case you will probably need an allpass to help remedy the problem. But I would try the thing I mentioned first to see what happens

 

[dumdum]

I would keep all settings the same for the moment. Your doing an audible test of phase alignment by trying this out.
I did also just do a quick skim of the rest of the thread and didn't see that you already have a null at 180 with only the midbass playing that dumdum was speaking of. If that's the case you will probably need an allpass to help remedy the problem. But I would try the thing I mentioned first to see what happens

in the first post he states it’s in both midwoofer playing separately

If this is the case an all pass won’t help at all as it’s present when solo’d, an all pass will only help when it’s between two drivers, it’s also unusual to get a modal dip at the same freq in both drivers in two locations

this is why I’m coming to the conclusion that maybe him saying he can hear resonance at the exact freq in the pods, and also what’s common to both drivers… the pod 👍🏼 That’s where I’d start

 

[dumdum]

🤣🤣🤣

Clear as glass, now 😆



Am I leaving the LPF above 180 on the sub or keeping it at the 120 I have now? Heck, I can do both. I'll test this in a few hours.



The sub is between the back seat and front seat now, I'll move it directly on the back seat and test.

Okay, I was wondering if that pod rattling could be something. Pushing on it doesn't seem to improve anything, but I guess if it's the whole darn pod it might not make a difference.

The enclosures are strange. The portion where the screws mount feels a little hollow, because when I tightened them to the dash the material collapsed where the screws bolt down. It's solidly held, but I thought that was odd. The pods themselves feel solid. The null appears as the mic moves away, but I've only tested moving it towards the listening position, not moving it towards other positions.

As for using the butyl (I have some spare deadener since I never fully started my deadening project) am I putting that on the inside of the pods or the outside? Do I peel the foil off first and then lay the rubber, or lay it with the foil and remove the foil afterwards? I haven't played much with it, but I might have time to do it on my lunch break. I'll make sure to knife it until the bleeding stops 😁.

If deadening the enclosures I leave the silver foil on, do the inside as you don’t see that…

if it’s for sealing the holes or anything for that matter remove the foil and make it into a malleable butyl sealer that is self adhesive and will seal it up a treat 👍🏼

 

[MercuryFlint]

So just line the whole inside of these with deadener

Just clarifying before I start.

 

[lithium]

Ya but you don't have to get too crazy with it. If these are out of site and you have enough clearance the outside could be done instead. Make sure its sealed up as well. The trick mentioned above is great for sealing the wire.

 

[MercuryFlint]

Ya but you don't have to get too crazy with it. If these are out of site and you have enough clearance the outside could be done instead. Make sure its sealed up as well. The trick mentioned above is great for sealing the wire.

I was wondering if I could do the outside. It's not a huge deal, but the volume in these is so small I hate to lose any space, even if minimal. Size constraints in the dash are silly.

Oooo, I'll try that for the wires.

 

[MercuryFlint]

Question: this wouldn't have any sort of negative effect, correct? I'm not sure how well I could scrape this stuff out if there was a problem.