# Simple XTC Foam Baffle Test with REW



## rob feature (Nov 15, 2015)

Howdy folks,

I've read dozens of anecdotes supporting or dispelling the idea that XTC foam speaker baffles in untreated doors make a difference. The claims are all over the map. Some claim they're suitable for rain-guards only, some say they change the character of the sound dramatically and some claim no difference at all. 

That said, I've decided to see for myself. I have a set of NVX VSP 525 components in my doors which leave a bit to be desired - at least in the midbass and lower midrange. I plan to install the baffles without any cuts or holes if possible. Changes may be made later, but I want to start like this. 

I've decided to analyze the truck before and after to see if any quantifiable difference is present in this application. But before I get started, I wanted to post up & solicit any advice and offer a qualifier. The main issue with this idea is that I don't have a calibrated mic. I only have the mic which came with my Sony home tuner & it has no calibration file. 










However since this is a single-parameter comparison, I assume that relative differences will be sufficient. In any event, it's all I have, so it's all I'll be using. 

I guess any advice going forward would be appreciated...as in if there's any way I can make this test more accurate or useful for the likes of you all, I'd love to hear about it. Otherwise I'll be measuring a baseline soon. With any luck I'll be able to get all this done by this evening. Wish me luck 

......


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## hot9dog (Mar 23, 2013)

I would like to see what happens with this.....


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## seafish (Aug 1, 2012)

Great idea...in for results.


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## rob feature (Nov 15, 2015)

Still waiting for the UPS man, but I went ahead & measured the cabin like it sits - before baffles. This is an average of 4 sine sweeps, 2 each side @ 20Hz - 20kHz. I've applied 1/12 smoothing to the average. I'll do the exact same once the baffles are in & overlay them on top of one another. 

Here's my starting point. Could use a bit of help, huh? Or maybe the mic's just really off. I'm gonna go with that 










Gonna go pull the door panels now. Maybe UPS will show up soon.


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## bradknob (Oct 26, 2009)

I'm interested in this..... I recently did something similar with some homemade F.A.S.T rings.

Where was the mic located when you took the measurements? May be a good idea to do a few by the head and another right in front of the speaker, to try and get the response before the car environment does its thang to it.


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## seafish (Aug 1, 2012)

bradknob said:


> I'm interested in this..... I recently did something similar with some homemade F.A.S.T rings.
> 
> Where was the mic located when you took the measurements? May be a good idea to do a few by the head and another right in front of the speaker, to try and get the response before the car environment does its thang to it.


GOOD points…also a good idea to mark or exactly jig the EXACT position for mic placement in order to get comparable results every time.


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## seafish (Aug 1, 2012)

If you had $200 to spend, you coul'd aslo buy this mic below for better and more accurate results. Maybe he would even discount it more since you are benfitting the forum…Hell. I'll chip in $20 myself if that helps...LOL

http://www.diymobileaudio.com/forum/car-audio-classifieds/262674-dayton-omni-mic-v2.html


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## strohw (Jan 27, 2016)

I tested a set on some 2118h a month or two ago. Pretty much no change for those particular drivers. I only bought them to protect the cone from moisture though. Wasn't able to fit them though in the end as the basket on the driver is quite wide.


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## rob feature (Nov 15, 2015)

Thanks for the suggestions folks, but I got to them a bit late. But first a word on placement since that's on your minds. It's on mine too. I'm doing this in the most practical way I know how...try to put my head and mic in the same spot each time. I realize that just a bit here and there can make a difference, but I don't have a dummy beyond myself. Now that I think of it, I could have set up a tripod or boom, but the deed is done. It also seems to me that I want to measure the truck the way it sounds when I'm in it. If I use a tripod I take myself out of the picture and I know that will have some effect. But, none of that matters for this go 'cause I'm not gonna go pull 'em back out & do it again 

But thank you all for the suggestions and I'll keep them in mind for next time. If it makes you feel any better, I've done this dozens of times recently and my results have been pretty consistent. But enough talking for now. Let's look at the graphs!

Here's the final result. The blue line represents the base measurement *without* baffles. The red line represents the test line *with* baffles.










Here I've zoomed in on the frequencies most likely affected. 










Qualitatively I hear a difference. The mids seem louder and clearer. I fed them more volume knob than normal on a short shakedown drive and they did it very well - not a hint of distortion. Keep in mind that I have these crossed pretty high. My sub is taking up the slack, which I don't like, but somebody's gotta do it. And sometimes it does add a bit of depth...probably not what most of you are looking for but sometimes we must compromise. I need to listen to it more, but initial response is positive.

These are sealed pretty well. If I move the foam, the cone moves in lockstep. This makes me think this application would be bad for midbass, but these don't like to make midbass anyway. There's a bit of airspace left in there - maybe an inch behind the woofer and whatever's filling the voids. 

So there it is. Maybe you geniuses can read something from that graph that I'm not, but at least in my case it appears to have filled much of the gap between 650 and 850 while smoothing things out a bit to ~3k. The only potential downside I see is between 500 & 600.

Thoughts?


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## rob feature (Nov 15, 2015)

seafish said:


> If you had $200 to spend, you coul'd aslo buy this mic below for better and more accurate results. Maybe he would even discount it more since you are benfitting the forum…Hell. I'll chip in $20 myself if that helps...LOL
> 
> http://www.diymobileaudio.com/forum/car-audio-classifieds/262674-dayton-omni-mic-v2.html


That's a really awesome offer, but my next $200 is already spent on sound deadening & a new pair of Silver Flute W17s for the doors. These NVX drivers sound nicer with the baffles, but I wanna lower my sub's crossover frequency & these won't let me do it.


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## hot9dog (Mar 23, 2013)

Very interesting, that you for taking the time to do this!


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## stills (Apr 13, 2008)

hot9dog said:


> Very interesting, that you for taking the time to do this!


^ this


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## Weigel21 (Sep 8, 2014)

Definitely in for results, as I tried some 6x9 baffles and swear that it killed the lower end, not to mention causes an odd noise from the speakers. I could clearly see the foam baffle being sucked in and pushed out while playing music at my typical listening levels and up. I've been against them ever since for their intended purpose.

Edit.

I see you actually tested with and without before I posted, I figured that it would be a day or more before you got to test with them installed. 

What you measured sure doesn't seem like the poor performance/sound I got when using them in my car years ago with Alpine SPS-69C2's getting around 50RMS.


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## rob feature (Nov 15, 2015)

Weigel21 said:


> What you measured sure doesn't seem like the poor performance/sound I got when using them in my car years ago with Alpine SPS-69C2's getting around 50RMS.


I've been thinking about that. Err not your example, but why it's working in this application and not others. These went in untreated doors. Totally untreated doors. I cut the baffles for these out of an old clipboard & mounted 'em right to the factory hole. Maybe this decouples the speaker from all that business and the plastic in the door enough to make a difference. And now that the energy going into the door is greatly attenuated, the door isn't responding so much? So I'm not hearing the door - I'm hearing the driver. 

To illustrate. Here's how it started

Untreated door with a plastic baffle on top of another plastic baffle thingie










The victim



















Foam baffle stuffed inside ABS baffle 










All in










I might expect to be disappointed if I tried this in treated doors - especially with drivers willing to play low stuff. But in this particular situation it's proving reasonably dramatic.


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## Weigel21 (Sep 8, 2014)

My installation was on 6x9's in the rear deck. I was going to put them on 4x6's in the kick panels as well, but immediately had second thoughts when I heard them fitted behind the 6x9's.


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## SkizeR (Apr 19, 2011)

you guys using those do know you should be cutting out an opening in the back of them, right..


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## Weigel21 (Sep 8, 2014)

That's what I ended up doing (it was easier than removing the speakers to remove them), but if that's what is supposed to be done, I've never seen any indication anywhere.


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## 1fishman (Dec 22, 2012)

I was always curious about them, Interesting results. I know most people recommend cutting a opening in the back, but I never seen it tested.


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## nineball76 (Mar 13, 2010)

Could the results be due to being better sealed at the plastic to plastic baffle?


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## rob feature (Nov 15, 2015)

After a few days of listening, I'd say it's due to a few things if you wanna start naming names. The improvement is undeniable though. The difference between using and not using these is like changing drivers. In this case it worked out to be like changing to a better driver. The driver stayed the same of course but the environment went from an open chaotic hall of metal, glass and plastic to something much more controlled. And smaller. Things changed behind the door.

Oh, and I almost forgot - these let me turn my crossover point down a bit, but they're less tolerant of lower frequencies than they were before. 

A pair of Silver Flute W14s will be here tomorrow. SDS stuff showed up today. MLV shows up early next week. If the W14s will fit in the baffles, I'll maybe try this again before I set them free :balloon:


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## T3mpest (Dec 25, 2005)

I feel like the best way to use these would be to cut a hole in them and then stuff them with melamine foam. You'd be able to get quite a bit of it back there and since all the sound is forced through, it quite a bit of backwave attentuation before it ever gets into the door.


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## Majik (Jun 22, 2009)

Nice little experiment. Thanks for the effort!



bradknob said:


> I recently did something similar with some homemade F.A.S.T rings.


What were your results?


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## stills (Apr 13, 2008)

Weigel21 said:


> My installation was on 6x9's in the rear deck. I was going to put them on 4x6's in the kick panels as well, but immediately had second thoughts when I heard them fitted behind the 6x9's.




They may work with the smaller 4x6s.


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## bradknob (Oct 26, 2009)

Majik said:


> Nice little experiment. Thanks for the effort!
> 
> 
> 
> What were your results?




Check out post #341...

http://www.diymobileaudio.com/forum...knobs-14-grand-cherokee-limited-build-14.html


Basically, there was a measurable difference before and after.


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## rob feature (Nov 15, 2015)

stills said:


> They may work with the smaller 4x6s.


I'm still thinking the best application for these would be behind factory speakers driven by head unit power...something that isn't moving a cone very far. The NVX woofer only has like 1.5mm xmax & I think that's why it was so effective. I don't think this crowd will get too much use out of it, but I'd drop 'em in behind a stock install without hesitation if it felt like it needed a little help.



Majik said:


> Nice little experiment. Thanks for the effort!
> 
> ...............
> 
> What were your results?


Glad you got a little something out of it. And I'm an idiot, but I totally forgot this discussion on rings was happening here as well. I managed to get the rings off my factory drivers an onto the new baffles, but neglected to measure before & after. I'm playing my usual weather card . So much has changed in the cabin over the last few weeks, but I think I can hear a difference with these on. 

It was a total ***** getting these off, but they were re-usable and you can't beat the fit.


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