[420tabbycat]

That null is in almost every test measurement, in an open vehicle. I’m curious about a panel resonating. When I built my IB floor baffle there was a small spot that was resonating creating a null somewhere around 60-80hz. I braced it and it’s cured. I’m taking about a 16” by 6” area in 3/4 mdf screwed to the floor.

I knew I had this marked picture, I may have mentioned this to you weeks ago but it’s a thing.

 

[MercuryFlint]

That null is in almost every test measurement, in an open vehicle. I’m curious about a panel resonating. When I built my IB floor baffle there was a small spot that was resonating creating a null somewhere around 60-80hz. I braced it and it’s cured. I’m taking about a 16” by 6” area in 3/4 mdf screwed to the floor. View attachment 316581
I knew I had this marked picture, I may have mentioned this to you weeks ago but it’s a thing.

It would make sense. If not that I'm all of ideas. You did mention that before, I just hadn't put it together with the null. Probably an oversight on my part.

I'm home, about to walk out and test it after I search out a tutorial.

 

[MercuryFlint]

Okay, at 180 I hear things rattling. Honest to God it sounds like the speakers themselves are trying to rattle out of the pods.

 

[420tabbycat]

Okay, at 180 I hear things rattling. Honest to God it sounds like the speakers themselves are trying to rattle out of the pods.

Feel around and press hard against all surfaces. When I found that spot in my IB baffle I put my emergency jump box thing on top and measured again and it was a lot better.

 

[lithium]

You can do a sweep measurement to see if there is a resonance on the waterfall plot.

 

[420tabbycat]

Even the windshield, don’t those jeeps have a flat windshield?

 

[MercuryFlint]

You can do a sweep measurement to see if there is a resonance on the waterfall plot.

Hmm, not sure how to do that. I've seen the waterfall option on REW but haven't fiddled with it. I'll pull it up and look for the sweep option.

Even the windshield, don’t those jeeps have a flat windshield?

Tried the windshield, the dash, all around the speaker pods and the speaker itself. The only thing that's helped slightly is pressing hard on the metal surround of the speaker, but it was just a slight improvement. I swear it sounds like something's rattling around in the speaker or pod. Would the speaker wire vibrating in the pod be enough to cause a null that severe?

 

[420tabbycat]

Hmm, not sure how to do that. I've seen the waterfall option on REW but haven't fiddled with it. I'll pull it up and look for the sweep option.



Tried the windshield, the dash, all around the speaker pods and the speaker itself. The only thing that's helped slightly is pressing hard on the metal surround of the speaker, but it was just a slight improvement. I swear it sounds like something's rattling around in the speaker or pod. Would the speaker wire vibrating in the pod be enough to cause a null that severe?

Na, it’s a floorboard or footwell or cargo area or door if anything.

 

[420tabbycat]

Aren’t the doors flat?

 

[MercuryFlint]

Aren’t the doors flat?

Very. And completely hollow. I'm trying to figure out how I can make the RTA just run without doing averages so I can see if pushing on anything actually impacts what the microphone is picking up, just not having any luck

 

[MercuryFlint]

Nevermind, figured that out. Testing now

 

[lithium]

Hmm, not sure how to do that. I've seen the waterfall option on REW but haven't fiddled with it. I'll pull it up and look for the sweep option.



Tried the windshield, the dash, all around the speaker pods and the speaker itself. The only thing that's helped slightly is pressing hard on the metal surround of the speaker, but it was just a slight improvement. I swear it sounds like something's rattling around in the speaker or pod. Would the speaker wire vibrating in the pod be enough to cause a null that severe?

this is a room measurement but it should get you started. he also covers some stuff for the waterfall plot. Saves me from typing...

 

[420tabbycat]

I looked at some pictures of jeeps, those doors are suspect as hell

 

[MercuryFlint]

I looked at some pictures of jeeps, those doors are suspect as hell

Oh I'm sure they're trouble. I had a suggestion today to cut off the bottom of the inside panel, trace it out on MDF, and mount a speaker on the door panel that way, but my first thought was "I will have a crap ton of problems with that space." Still tempting.

I just tested with me outside the vehicle pressing on the door and the mic held at where my listening level would be. No change. However, as I lowered the mic towards the seat the null got even worse.

this is a room measurement but it should get you started. he also covers some stuff for the waterfall plot. Saves me from typing...

Hey, I'll take that video and appreciate it. Wouldn't expect you to type out a manual for me, though in many ways you already have 😁

 

[420tabbycat]

Just by chance, have you tried measuring with all doors open? I’d be surprised but maybe it’s a null from the dimensions in between the boundaries. It’s a long shot as there’s the whole top open but give it a shot while you are setup to measure.

 

[MercuryFlint]

 

[MercuryFlint]

Just by chance, have you tried measuring with all doors open? I’d be surprised but maybe it’s a null from the dimensions in between the boundaries. It’s a long shot as there’s the whole top open but give it a shot while you are setup to measure.

Got it! Doors open:

 

[MercuryFlint]

Don't know if it matters, but I tried the mic from the back passenger position and the null is worse.

 

[MercuryFlint]

Just for some additional data:

I normally have the polarity of both woofers reversed. Here are tests with them both normal, left only reversed, right only reversed, both reversed.

 

[MercuryFlint]

The effect on the null are minor, but the best is both reversed.