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View Full Version : BASS: Small Enclosure better than Door Sealing & Dampening?



90MaximaSE
11-26-2009, 03:07 PM
To get a good front soundstage, most of us are stuck with putting relatively small 6-1/2" (or smaller) drivers in the front doors. Speakers in Kick Panels just don't cut it in my experience. I'm going for 6.5" Component sets (with crossovers and separate tweeters) for the build I'm working on: My 1990 Nissan Maxima SE.

To get decent Bass out of door speakers, for sure the speaker enclosure MUST be air tight AND well dampened. This is a tough proposition for a car door, and you can spend an TON of effort and $$$ on Dynamat products to do this properly. Just take a good look at the Sticky "Proper Door Sound Deadening and You" if you disagree. Plus, you have to worry the effects of water coming down past your window seals: electrical corrosion of connections and voice coils plus degrading of speaker cones.

Seems to me you can avoid a lot of effort and $$$ by a llittle planning and fabbing a small custom enclosure for the mid-bass driver from MDF, which is pretty easy to work with (fiberglass isn't that bad either). I'll guarantee that the ability of small rigid enclosures to give great bass from small speakers is vastly underestimated by most DIY car audio people. You see this in computer speakers alot.

The biggest example of this is what Bose has been doing with their factory systems for Nissan and GM for decades - and it's been right underneath my nose. After listening to my Bose system (now Kaput) in my Maxima for years , I was flabbergasted when I finally saw what was in the F door pods: a little weiny plain jane 4" paper cone speaker. These produced GREAT Bass. Here's a photo of this F door Nissan-Bose Box:
http://members.cox.net/rhamil54/NissanBosePod.jpg


Currently I'm working on a custom box for the Polk MM6501 series 6.5" driver that will bolt into the same place the Bose enclosure did. The crossovers and tweeters WON'T be inside the doors. I already have 6.5" MDF adapter plates, and may just box those in with more MDF. There's more available space in my doors for added volume, so I've been playing with the WinISD speaker box design program.

Any one else our there tried this approach?
I'd like to know the enclosure volume you used for specific speakers if so.

There's great potential here to save a lot of money and hassle with subwoofers and buku amp power. Unless you're just hell bent on vibrating the teeth out of anyone sitting next to you at a stoplight.:D

JimJ
11-26-2009, 03:18 PM
I'm just curious why kick panels didn't work out for you.


I'll guarantee that the ability of small rigid enclosures to give great bass from small speakers is vastly underestimated by most DIY car audio people. You see this in computer speakers alot.

Most computer speakers have horrific midbass response, consequence of tradeoffs from Hoffman's Iron Law, so I'm not exactly sure where you're going with that :) You can get lots of midbass out of a 4", but it requires a floorstanding MLTL or horn, not something Logitech is likely to offer :D

90MaximaSE
11-26-2009, 05:09 PM
I'm just curious why kick panels didn't work out for you.

Speakers in the Kick Panels are simply too far 'off axis' from your ears, and they are firing right into an acoustically 'dead' divided footwell and directly into your legs & shoes. Too much speaker sound simply gets absorbed, and never reaches your ears. Highs? Forget it with kicks. I've mounted 6" Coax speakers in kicks that were inaudible with ANY other speakers at all in the car playing, even when the others were in the rear deck. A possible exception might be custom kick panel enclosures I've seen that are angled both upwards and towards the driver, but you're still not going to get the sound imaging or fill that door speakers will do.

As for the computer speakers, I was referring to some older models that had larger satellite speakers than are the norm now. The Boston Accoustic MediaTheater speakers I'm using go substantially into the mid-base range when I turn the sub-woofer off entirely. And they are mounted in light plastic cubes.

The really impressive example is the Nissan Bose enclosures above. Maybe you just have to have heard them to believe. They produced very good Bass for Car Audio. They were so good that I'm enthused about what some really good drivers like the Polk MM6501 might sound like in a scaled up enclosure. Those 4" Bose drivers have MAYBE a 2 oz magnet - the Bose enclosure does a magic transformation using an ultra cheapo driver. Unfortunately, all 4 Bose amp boards are shot along with the HU, and are more trouble than they are worth to fix. So am starting over.

Part of this is I've come to detest those massive/expensive subwoofers in the trunk, and want some SQ Bass up front in the Soundstage where I am. Not behind me, and not vibrating the heck out of the dash and body of the car next to you.:verymad: Not to mention attracting the attention of any potential thief within 200 Feet that will do incredibly expensive damage to your car while he's Ripping Out your audio gear.

perfecxionX
11-26-2009, 06:27 PM
I was just about to start a thread asking about this. I've seen a few people mention fiberglassing an enclosure inside the door but Ive never seen or heard it done. I've never wanted to do kickpanels because of how obtrusive they are down where your feet are supposed to be, and i'm tired of spending hundreds on deadening materials and still ending up with lackluster response in the 80-150hz region.

If you do this please create a thread in the build log section, and add lots of pics.:veryhapp:

Is that a little port on the left of the speaker?

90MaximaSE
11-26-2009, 10:26 PM
Is that a little port on the left of the speaker?

Yes, it is a little Port - a Port Tube, actually . 1-1/4" diameter around 7" long. It has 90 degree elbow just past the inside, so most of the run is parallel (and below) the speaker face inside the enclosure.

Sure, JimJ is right about running up against Hoffman's Iron Law (You can have low end extension, high efficiency, or small enclosure size. Pick two ).

BUT I just keep running into speakers that bend that rule beyond recognition. Bose certainly figured out how with my Maxima enclosure. Lots of Boom Boxes seem to also. So I'm seeking input about other exceptions.

T3mpest
11-27-2009, 04:08 AM
Speakers in the Kick Panels are simply too far 'off axis' from your ears, and they are firing right into an acoustically 'dead' divided footwell and directly into your legs & shoes. Too much speaker sound simply gets absorbed, and never reaches your ears. Highs? Forget it with kicks. I've mounted 6" Coax speakers in kicks that were inaudible with ANY other speakers at all in the car playing, even when the others were in the rear deck. A possible exception might be custom kick panel enclosures I've seen that are angled both upwards and towards the driver, but you're still not going to get the sound imaging or fill that door speakers will do.

As for the computer speakers, I was referring to some older models that had larger satellite speakers than are the norm now. The Boston Accoustic MediaTheater speakers I'm using go substantially into the mid-base range when I turn the sub-woofer off entirely. And they are mounted in light plastic cubes.

The really impressive example is the Nissan Bose enclosures above. Maybe you just have to have heard them to believe. They produced very good Bass for Car Audio. They were so good that I'm enthused about what some really good drivers like the Polk MM6501 might sound like in a scaled up enclosure. Those 4" Bose drivers have MAYBE a 2 oz magnet - the Bose enclosure does a magic transformation using an ultra cheapo driver. Unfortunately, all 4 Bose amp boards are shot along with the HU, and are more trouble than they are worth to fix. So am starting over.

Part of this is I've come to detest those massive/expensive subwoofers in the trunk, and want some SQ Bass up front in the Soundstage where I am. Not behind me, and not vibrating the heck out of the dash and body of the car next to you.:verymad: Not to mention attracting the attention of any potential thief within 200 Feet that will do incredibly expensive damage to your car while he's Ripping Out your audio gear.

Sounds like you've had some very bad installs then. Kicks are a much better spot for speakers than a door. Most importantly, kicks help equalize path lengths which helps imaging by keeping both time and intensity information equal between both speakers. Also the speakers are more on axis which is rarely a bad thing. Lastly I find it alot easier to deaden the hell out of a small area like a kickpanel and fabricate around it than to try to add stuff to a door. Adding things to the door while not getting in the way of the window rolling down can be a trick and no matter how much you add the doors are still never fully sealed off and tend to pick up slight resonances. Kicks you build around nothing essentially which means you dont' have to reinforce something that isn't strucurally sound to begin with.

Anyway my car uses kicks for these reasons and I've never heard anyone tell me my car is quiet. It's good to about 120db's from 100-20,000. It also stages far better than any car I've ever heard with door speakers.. Also just so your aware the enclosures bose used in that case is the same as they were in my caddillac stock. They are "special" despite what you seem to think. See that little hole up top, that's a port! The massive midbass your getting is from having a ported midbass. My xs69's absolutely ****ing crush my little bose speakers in the midbass department. I remember running Dave Matthews Band live recording of say goodbye on my bose speakers and realizing the midbass on the speakers was decent and wondered how my new setup compared. First time I cranked my XS's I ****ed near stopped driving my car when the first drum literally hit me in my chest. It literally sent vibrations through my ****ing seats even when crossed over at 80hz 24/db/octave so it really is midbass, not just the low stuff. Sorry for the long reply this thread is just funny coming from where I came from.

Anyway good luck getting a sealed enclosure into your door and not rattling the door to peices. Getting good midbass is very important in SQ installs and it's been tried, alot and it's not worth it and it's very hard to do. You'll be fighting for airspace most mids, there is a reason bose used a 3incher. Also the small box will shoot your speakers q up very high in most cases which will kill you low end and introduce a peak somewhere in the lower midbass. Vocals also start to sound congested. The bose speakers ported right around where the small enclosure would fall off maximizing output just above that point. Without the port your not going to get that effect, just the drop and a congested sounding peak.

You can try to fiberglass an enclosure into your door but its going to be an uphill battle for sure and for a location that is less than optimal.

jake21
11-27-2009, 05:50 AM
have you tried these?
http://akamaipix.crutchfield.com/products/2002/237/h237xt55p.jpg
they actually work quite well in my experience

90MaximaSE
11-27-2009, 02:18 PM
Sounds like you've had some very bad installs then. Kicks are a much better spot for speakers than a door.

T3mpest, I'd be very interested to know what your vehicle is where you've had good luck with speakers in the Kicks.

All the cars I've worked with have been either sports cars, or med to small sized sport sedans. All have had low slung driver positions, and narrow deep footwells divided by the transmission 'hump' and the console.

This puts the kick panel speaker at the bottom side of a long deep sound absorbent (carpeted and padded) tunnel with the driver firing across the 'bottom' of the tunnel towards padded carpet. Then insert 2 human legs right on the speaker axis taking up a large fraction of the 'tunnel' volume. I just don't see how speaker sound can get out of these two isolated absorbent wells that don't join until well past the front of the dash. And in trials, it has not. Not with mine, and not any others I've seen in this vehicle type.

I can see it might work with larger vehicles that have a higher and much more erect driver position.

perfecxionX
11-27-2009, 05:39 PM
found this:
http://www.rockfordfosgate.com/forum/topic.asp?ARCHIVE=true&TOPIC_ID=26709



http://i111.photobucket.com/albums/n158/wachuku/front%20door%20midbass/PartialIn-DoorAssemblypassenger.jpg
http://i111.photobucket.com/albums/n158/wachuku/front%20door%20midbass/InnerSideDESealpassenger.jpg
http://i111.photobucket.com/albums/n158/wachuku/front%20door%20midbass/Soundlocpassenger.jpg

WrenchGuy
11-27-2009, 05:57 PM
I'm glad I have a deep door panel. I got close to a cube sealed to work with for a Peerless SLS 10" mid. I even get to throw an Elevation Audio LC8 in there too!

I think door modding is fun tho.

90MaximaSE
11-27-2009, 07:58 PM
Great Find, PerfecxionX !
I'll be studying wachuku's post on that Fosgate forum in great detail. Just the sort of info I've been fishing for. Thanks! You Too, WrenchGuy! Care to share some more details on your build? I'd love it!

I've no plan to go to these extremes; I've got bigger fish to fry as I'm restoring my 19 yr old Maxima (Mechanicals are almost complete, but Body and Interior are next). I'm still determined to avoid the Dynamat Dance.

Here's a shot of some 6.5" speaker adapters (MDF) I got from a fellow Maxima.Org member before I'd thought thru the door mounting issues. Won't be using them as-is, but they were worth it just as templates and location tools to build a MDF box that mounts where the OEM Bose pod did.
http://members.cox.net/rhamil54/6.5in Door Mounts-comb.jpg


>>Anyway good luck getting a sealed enclosure into your door and not rattling the door to peices
Not gonna happen. I'm fortunate to have those 4 rigid mounting points on the door structural bracing (not thin sheet metal). If necessary, I can mount the new box with rubber washers to cut transmitted vibration. Those Bose pods were filled with glass cloth, which I will duplicate, and will help with vibration issues.
Here's a shot of those adapters in use.
http://members.cox.net/rhamil54/Maxima F Lower Door.jpg

Gives you a feel for my door depth (Thanks, Nissan!) , and how large the factory door panel grille is. No Window interference problems - the Bose pod location is below the travel of the windows. There is at least 3" in front of those speaker adapter plates, and more than 4" behind. There's also additional area past the adapter plate on sides and above/below. I just might come up with a substantial enclosure volume.

What's Next
I'll be pulling my door trim (Again!) to take exact measurements, and will cut some foam sheets for shape reference. I'm out of those plastic trim clips, and need to round up some more first so I can put the trim back on.

Meanwhile, I waiting to see if Polk Audio respondes on my request for driver T/S paramers to input into WinISD.

I said in my first post that building the speaker box was worth it just to avoid the Dynamat Dance alone - both cheaper and easier. If I don't get any more base than what the Bose put out, then I'll think of adding a small subwoofer somewhere as makeup. Under the seats is very tight. Amp will barely go. Whether a low profile sub will fit will come down to how thick the floor carpet and padding are. It's that close.

If you're interested, Stay Tuned and I'll post back after I've advanced further. Hopefully, I get some more great replies with more info to consider. Thanks, All!

PS: lots of cars have door speaker pods, so what I'm doing applies to lots of cars with deep doors designed for OEM pods - the mounting points make things a LOT easier. My buddy's 2006 Suburu Outback (base audio option) has them too.

WrenchGuy
11-27-2009, 08:12 PM
Yeah I got a build log soon to come. I'm either starting at the wall or at the doors again. Prolly doors since everything is around just gotta get my drivers.

raverx3m
11-29-2009, 02:06 AM
http://www.intellexual.net/bose.html
http://www.hometheaterblog.com/hometheater/2006/03/what-about-bose-part-2/
if you want to read about bose.


from what i red online when i was researching about bose
they rely heavily on the processor in order to produce the "appearance of great sound" while using cheaper parts...
they also rely heavily on advertizing and spend massive amounts of money to keep the general public "pumped up" on bose great quality.


so from readin the above articles you can safley assume that you will be getting same deal for car audio

raverx3m
11-29-2009, 02:11 AM
oh and also about the sound

did you notice how bose speakers sound so great on the display?
but they have a preloaded set of songs on an sd card behind pannels
i borrowed that sd card and listened to in on few other speakers and lemme tell you they sounded amazing
because all those songs were edited by bose and we ran thru the eq in order to boost certain frequencies so the system sounds "sweet" in the showroom

FoxPro5
11-29-2009, 02:07 PM
To get appropriate midbass response out of a woofer....
- you need to maximize the ideal Vb of the enclosure
- build a suitable baffle

A baffle, by definition, must do at least two principal things -
1) delay or block the front wave from combining with the rear wave. -12 dB should be sufficient for blocking...which is about what you'd get out of 1' MDF.

2) not resonate within the passband of the speaker. If the driver plays 63 to 1khz, the baffle must be sufficiently braced to make its RF above 1k or damped well enough to make it's RF below 63hz. Those are only estimates; how you tune the driver (ie filtering and EQing) is the final determinant.

Model your drivers using driver modeling software to get an idea of it's ideal performing environment. Avoid making broad generalizations like you did as you'll only limit your potential in the hobby.

There are all kinds of ways and materials to use for in-door midbass's, but you have to satisfy the above if you want the best response. Your speaker rings you posted are only a start.

perfecxionX
11-30-2009, 07:46 PM
- you need to maximize the ideal Vb of the enclosure


what does this mean?

modskwod
11-30-2009, 07:55 PM
Ideal box volume. This is assuming Vb=Volume of box.

90MaximaSE
12-01-2009, 01:28 PM
what does this mean?

To expand on modskwod's answer, and also give you a better insight into FoxPro5's post:

They are referring to designing a speaker enclosure using one of the popular speaker box design programs. WinISD Pro is a free one that lots of people using; mostly for Subwoofer box design. These programs show you sound frequency curves (Bass response) for the speaker and enclosure used.

This is were I'm headed with my work and is my next intermediate stage in the Build design for my Maxima. First step, what I'm doing now, is "Maximizing Vb" ==> figuring out what practical enclosure volume I can fit into my car door based on a 6.5" mid-bass driver. Then I'll run WinISD Pro and see what the Bass response looks like for that preliminary enclosure.

Here's a link to 'WinISD Pro Tutorial and Download':
http://www.hometheatershack.com/forums/diy-subwoofers/6330-winisd-pro-tutorial-download-detailed-guide-how-use-winisd-pro.html

Another useful link - Thiele-Small Parameters glossary. Usually referred to as 'T/S parameters', they describe the characteristics of a particular speaker, and you have to have them to input those into WinISD Pro for box design.
http://www.the12volt.com/caraudio/thiele.asp

The problem I'm running into is obtaining the T/S parameters for the mid-base driver (speaker) used in the component sets I'm looking at - like Polk's MM6501 and Pioneer's TS-C720PRS. Kenwood gives them in the manual that you can download from their site. Pioneer, Polk, and Boston Acoustics don't publish these parameters.

However, T/S parameters are given for individual speakers (drivers) of other brands on sites like Parts-Express.com and Madisound.com. Using these individual speakers seems to indicate, at this point, coming up with our own crossovers, going bi-amp to drive the tweeter and mid-bass separately, or both.

I've e-mailed Polk Audio for T/S info on their MM6501 6.5" driver- no response yet. I'll probably wind up calling Polk Audio, Pioneer, and Boston Acoustics to see if I have better luck that way.