# Sealed mid/bass or not



## TXBoudy (Aug 12, 2018)

So with the exhausted efforts we go through to deaden doors trying to improve mid range performance, I'm wondering how much if anything is to be gained by running them in sealed enclosures as compared to basically converting the door into something rivaling a Yeti cooler.

In my case, I'm working with a set of Hertz MPK 163.3 3-way components which contains a 6.5" and a 3". I plan to run each 6.5" fully active with 75 watts from a 5 channel JL VXi. The 3" and tweeter will be run passive on the Hertz X-over sharing another 75 watts.

So give me all the pros, cons, yays, nays, and what fors.


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## minbari (Mar 3, 2011)

Done it. Didn't really hear any difference. Get a midbass that works in free air and you are golden

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## Onyx1136 (Mar 15, 2009)

Most car audio midrange/midbass drivers are specifically designed to work ”best” in a large, leaky enclosure- basically free air. Putting that type of driver in a small sealed enclosure will only result in less than optimal sound quality. I specifically say small sealed enclosure because, especially in a car door, it can be very difficult to build a large enough sealed enclosure to achieve optimal driver performance. 

Ultimately, it’s all down to the specific driver you’re using and how the engineer designed it. Don’t waste time and energy trying to fit a square peg in a round hole.


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## SPLEclipse (Aug 17, 2012)

Onyx makes good points. In theory using a "real" sealed enclosure should make a big difference, but with most car doors you'd have to make the enclosure too small and this can kill midbass performance. if your speaker has a moderately low qts, low fs, and large vas, it might work well as that would push your resonance into the lower-midbass territory without making it super peaky.


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## TXBoudy (Aug 12, 2018)

The good news is that I'm working with a '72 Chevy truck, it's got tool boxes for doors and I'm building door panels from scratch so finding cubic inches will not be an issue. Except behind the seats but a shallow sub is my friend back there. Here's my specs:


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## SPLEclipse (Aug 17, 2012)

I modeled it. Above ~150hz there will be no difference (which makes sense). Going as small as 4 liters you start to drop off gradually as you get lower in frequency getting down to about -3dB at 70hz vs an infinite baffle setup. Getting that up to about 8 liters changes the difference to around 1.5dB at 70hz. There's no reason to make them larger than about 10 liters as you stop gaining any real difference. Ideal 0.7 q happens at 5 liters, so no worries of a big peak from being in a smaller enclosure.

They will definitely work fine sealed up if you've got room, especially if you've got a really leaky door situation going on and infinite baffle would not be ideal. They will work even better vented if you _really_ need some midbass output.


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## Bayboy (Dec 29, 2010)

SPLEclipse said:


> Onyx makes good points. In theory using a "real" sealed enclosure should make a big difference, but with most car doors you'd have to make the enclosure too small and this can kill midbass performance. if your speaker has a moderately low qts, low fs, and large vas, it might work well as that would push your resonance into the lower-midbass territory without making it super peaky.


Avoiding rattles is the main advantage & objective, but the above is key. As it's been said many times before, treat all of your drivers like subwoofers. IE, give the same attention to box modeling & Q/response targeting so that you'll know which drivers are more suited to the enclosure. Enclosing most car audio mids probably won't lend the results most are looking for. I would think more along the lines of home audio midbass with beefy motor structures (low Q/mid to slightly high EBP) to keep the enclosure size attainable, then hope you can at least achieve an F3hz around 80hz or so for dovetailing with the sub. It's been done before with success but is it worth the work for you is the question.


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## TXBoudy (Aug 12, 2018)

SPLEclipse said:


> They will work even better vented if you _really_ need some midbass output.


Awwwe Snap, I'm a fish on the hook now brother! Considering that one could raise a family of kittens in these doors, 8 to 10 liters or more isn't a problem. I'm building custom door panels already along with bass enclosure, center console, and associated trim panels. Could I impose on you to run and share the numbers for a vented enclosure? Please, please, pretty please.


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## Bayboy (Dec 29, 2010)

TXBoudy said:


> Awwwe Snap, I'm a fish on the hook now brother! Considering that one could raise a family of kittens in these doors, 8 to 10 liters or more isn't a problem. I'm building custom door panels already along with bass enclosure, center console, and associated trim panels. Could I impose on you to run and share the numbers for a vented enclosure? Please, please, pretty please.


With that 6x9 opening, I'm surprised that you aren't using one. More cone area with the 6x9 car audio type should be plenty even with 75 watts. Just deaden good and cushion the door panel with CCF, but that's probably a bit too late now.


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## SPLEclipse (Aug 17, 2012)

Show in the pic is 10 liters sealed (in red) vs 10 liter vented at 60hz (yellow). You get 3+dB in output through all the usable range, and an f3 of 62hz instead of ~100hz.

In the bottom graph I modeled a 2.5" diameter round port (at 8.3" long) in yellow and a 2" diameter vent (at 5" long) in orange. The larger vent (obviously) keep vent noise under control better, but will sacrifice quite a bit more space. The 2" vent increases velocity but on music will still be fine. One suggestion from someone who exclusively uses vented midbass: don't put the port exit near your legs. It's really annoying and distracting to feel that.

You can go smaller on the enclosure, but the increase in port volume makes it not worth it, and you start to get a larger and larger peak ~100hz as you get smaller with less and less low-end extension. If you go larger you will flatten out the response more, but getting over 10 liters even in a pretty large door can be daunting.


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## TXBoudy (Aug 12, 2018)

Actually that's not my door. I just used it to show its inhabitability by kittens. Mine are already painted on the interior side and jams waiting to be reinstalled. One does have a 6" hole but the other is still virgin. Can't be choosey when finding clean donors for these old beasts. 

Sent from my SAMSUNG-SM-G891A using Tapatalk

Edited to add pictures of actual doors. Vast greenfield real estate.


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## TXBoudy (Aug 12, 2018)

SPLEclipse said:


> Show in the pic is 10 liters sealed (in red) vs 10 liter vented at 60hz (yellow). You get 3+dB in output through all the usable range, and an f3 of 62hz instead of ~100hz.
> 
> In the bottom graph I modeled a 2.5" diameter round port (at 8.3" long) in yellow and a 2" diameter vent (at 5" long) in orange. The larger vent (obviously) keep vent noise under control better, but will sacrifice quite a bit more space. The 2" vent increases velocity but on music will still be fine. One suggestion from someone who exclusively uses vented midbass: don't put the port exit near your legs. It's really annoying and distracting to feel that.
> 
> You can go smaller on the enclosure, but the increase in port volume makes it not worth it, and you start to get a larger and larger peak ~100hz as you get smaller with less and less low-end extension. If you go larger you will flatten out the response more, but getting over 10 liters even in a pretty large door can be daunting.


Sweet! I haven't played with box software in 30 years. Is WinISD a good one to download?


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## minbari (Mar 3, 2011)

TXBoudy said:


> Sweet! I haven't played with box software in 30 years. Is WinISD a good one to download?


I find it to be the easiest to use

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## Grinder (Dec 18, 2016)

TXBoudy said:


> Sweet! I haven't played with box software in 30 years. * Is WinISD a good one to download?*


Yup. WinISD - Linearteam

Here's a very helpful post (#36) from "Frustrated with WinISD - alternatives?" thread: https://www.diymobileaudio.com/foru...on/337098-frustrated-winisd-alternatives.html



Triticum Agricolam said:


> Like others have said, the new 0.7.0.950 version of WinISD is MUCH better IMHO.
> 
> As far as entering in driver specs goes, here is the official "right" way to do it:
> 
> ...


I don't recall where I found this, but I've had good results entering these in the following order: Qes, Qms, Fs, Re, Vas, Xmax, BL


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## TXBoudy (Aug 12, 2018)

Thanks, I downloaded 7 but had scaling problems with my Windows 10 so I'm using Pro 0.50a7 Alpha. But yes, you are certainly correct it only took a matter of minutes to realize the entering Thiele Small Parameters was more a matter of style and etiquette over brute force. At least the program self-checks parameters and won't allow save until you've entered them in proper order allowing the balance to auto-calculate. 

I ran a few tests and tried to duplicate the graphs posted by SPLEclipse to learn my way around the package and see if I was doing it correctly. Still not sure if I am but I'll play more tomorrow and post questions for sure.


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## garysummers (Oct 25, 2010)

https://www.diymobileaudio.com/foru...llery/139236-mercedes-midbass-enclosures.html

Not to step on others opinions, but this was one of the most significant sonic upgrades to the car in the 6 years I have been building it. I spent years deadening with all kinds of products from clay to lead. As others have said the volume of airspace must be adequate for the driver.
Tight, controlled, rattle free mid bass. The door is silent!


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## Focused4door (Aug 15, 2015)

Entering driver parameters I use the steps found here:
Red Spade Audio: WinISD - entering new driver data


I like kick panels better than in the doors, not always possible due to box size needed or footwell room though.


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## Grinder (Dec 18, 2016)

TXBoudy said:


> Thanks,* I downloaded 7 but had scaling problems with my Windows 10 so I'm using Pro 0.50a7 Alpha.* But yes, you are certainly correct it only took a matter of minutes to realize the entering Thiele Small Parameters was more a matter of style and etiquette over brute force. At least the program self-checks parameters and won't allow save until you've entered them in proper order allowing the balance to auto-calculate.
> 
> I ran a few tests and tried to duplicate the graphs posted by SPLEclipse to learn my way around the package and see if I was doing it correctly. Still not sure if I am but I'll play more tomorrow and post questions for sure.


Hmmmm... no scaling issues with 7 on either of my Windows 10 machines.


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## TXBoudy (Aug 12, 2018)

Grinder said:


> Hmmmm... no scaling issues with 7 on either of my Windows 10 machines.


The window was oversized but the fonts were so small I couldn't read them. Tried some manual scale adjustment but other things were getting adjusted as well so I quit while I was ahead. I'll try again tomorrow. 

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## TXBoudy (Aug 12, 2018)

Sorry for the delay but it's been a busy week so thank you for the comments, advice, and patience. I designed my door panels and determined that I can give the 6.5" driver up to 13.34 L minus the port and maybe 5% for fiberglass thickness while keeping the panel completely outside the door. (on the surface, much easier to build for me without intruding into the inner door)

In fact, if push comes to shove I could even provide about 1.5 L to seal off the 3". My own tinkering in WinISD showed that 12L would be great but I'm still grasping the program's crossover setups and haven't even played with plotting the 3".


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## gijoe (Mar 25, 2008)

If you're going through all that trouble to fabricate door panels and enclosures for the midbass, I highly recommend that you relocate the midrange and tweets. If you put them higher up, and further away you can improve your staging significantly.


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## JH1973 (Apr 21, 2017)

Sealing doors is VERY over rated.I've done it on 2 builds now and I can say with no hesitation that strengthening the sheet metal on both the outer and inner skin with a descent CLD is all that is needed to get your driver(s) playing optimally.I tested before and after,while one side was deadened and 1 side stock,1 side deadened and sealed and other side only deadened.The biggest Sonic improvement has consistently been by simply adding mass to as much sheet metal as you can so that both the inner and outer skins on the door are rattle free.


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## TXBoudy (Aug 12, 2018)

I'm thinking that there's 2 options to get the mid/tw higher. Calculations show that I can fit the mid near the top of the door panel. My panel depth is shallow but I can extrude the driver by 1/2" and get it to work. Then I can locate the tweeter in a pod at the corner where the vent window was thus lifting both drivers by approximately 5".

Or... I could reacquaint myself with the idea of building front A-pillar pods gaining another 5" or so. But actually NOPE, building A-pillar pods isn't an option. I've talked myself out of it for a number of practical reasons and I need to stick to that.

Anyways, I'd like to hear more about the staging. The JL VXi amp I'm going with has built in DSP with timing delays. I can't claim to totally understand staging today, years ago we used center channel speakers so I'm eager to learn. Is the 5" I can elevate them to the top of the door panel going to make an appreciable difference or is it not enough to accomplish desired results? 

Oh, I'm pretty sure I can get the tweeter on axis and the mid maybe 1/2 way there without it simply looking stupidly hanging sideways off the door. Does that contribute to the staging?


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