Just got the goods for my new setup (mostly)

[StereoInstaller1]

Michael, that spec sheet is mighty suspect, IMO. There is nothing there that leads me to believe that any kind of testing has occured.

Just a bunch of guys plotting curves on a theoretical speaker.

I would not be suprised to find that they are fairly close, but that is based more on what any driver would do in those same environments.

Ported midbass? No way, man. Not in a car! It does work in a larger environment, and I have heard it sound great in a car, but no thanks.

Porting basically works because the port is 180 degrees out of phase with the driver. Your sub would be operating in that range, and with much greater force. Far more air moving around is basically what I am talking about. So you would have the upper end of the bass fighting with the lower end of the midrange, and you would have 4 different phase reversals in the signal below 200Hz.

Too small a space for ported midbass IMHO.

As far as my plans, I am thinking about using these Peerless 8 ohm drivers. The specs plot out nicely IF I can find about .75 cu.ft.

[DrMcDave]

why not make some pods for the door? i've been fighting this stupid midbass issue forever. i think i am going to make some bitchen fiberglass door pods and hope they do the trick, if they don't i'll sell my car ;)

[netcsk]

"3 Frequency response of 50Hz to 5Khz at 120db, less than 15% THD"

Oh come on Luke! ;).
Just kidding. I'll be interested in seeing what you end up with! Let me know if I can help you with anything (i.e. I can get you parts if you know what you want).

[mspiegle]

I don't think they have the exact ones for my particular woofer, but this probably isn't TOO far off: http://cdtaudio.com/pdf/ES-600.pdf

The response from the ported enclosure seems pretty gnarly, but it would have to be twice as big. What's your take on it?

Removal of the ABS brain? whoa....

If you put that driver in .3 cubic foot (about 10 liters) I would not expect anything below 100Hz out of it. Considering the HUGE midbass suckout our cars have (about 18db at 80Hz, IIRC) you would need a fairly high crossover point on the sub.

However, the placement will make for far better midrange clarity, far better staging in general. If you are up to that kind of thing, go for it!

You may want to consider a modified aperiodic enclsure, using about 1.5" of closed cell foam as the back wall. That should lower the Fs of the enclosure to about 70Hz, the Qtc of the driver/enclosure to about 1, or a bit over. That should improve the midbass drastically.

Do you know if CDT will give you Theil/Small parameters for that midrange?

You may also want to try a chunk of 6" PVC tubing with 1.5" of closed cell foam in it just to see how things will sound position-wise.

Oh yeah...my secret midbass cabinets are a secret! On my early body (non-aribag) coupe I had to move my ABS brain (hint hint) to make room for what I want...

Luke

[StereoInstaller1]

If you put that driver in .3 cubic foot (about 10 liters) I would not expect anything below 100Hz out of it. Considering the HUGE midbass suckout our cars have (about 18db at 80Hz, IIRC) you would need a fairly high crossover point on the sub.

However, the placement will make for far better midrange clarity, far better staging in general. If you are up to that kind of thing, go for it!

You may want to consider a modified aperiodic enclsure, using about 1.5" of closed cell foam as the back wall. That should lower the Fs of the enclosure to about 70Hz, the Qtc of the driver/enclosure to about 1, or a bit over. That should improve the midbass drastically.

Do you know if CDT will give you Theil/Small parameters for that midrange?

You may also want to try a chunk of 6" PVC tubing with 1.5" of closed cell foam in it just to see how things will sound position-wise.

Oh yeah...my secret midbass cabinets are a secret! On my early body (non-aribag) coupe I had to move my ABS brain (hint hint) to make room for what I want...

Luke

[mspiegle]

I see what you're saying. That certainly sucks.

You've excited my interests with information about your speaker setup, but you give me nothing to work with :)

For the time being, i'm thinking of fiberglassing small 0.3cu enclosures for the woofers. If I placed them right in the corner of the footwell and pointed them directly at opposite passengers, do you think that might work? Heck, I could even make enough room to mount the tweeter to the same unit to try and minimize any possible PLDs between the tweeter/woofer of the same channel (even tho it probably isn't terribly noticeable).

IMO, a midbass like that is going to be designed from the ground up to be in an "Infinite Baffle" install. Generally, this means no "box" behind it...thus nothing to raise the resonant frequency, or control cone motion.

I can get into numbers and all, explain WHY this does not work, but why waste our time...let me explain the mechanics of why your bitchin' little midranges sound like ass. (it is not the speakers' fault, believe me!)

If you put it in that tiny little area (obviously audio was an afterthought) that is allowed for our front speakers, it is no longer an infinite baffle application, thus the resonant frequency is rasied (likely into the upper 300Hz range, by my guesstimate) and even though it is nowhere near sealed, some kind of cone control will happen (consider the mechanical difference between this application and a normal door panel install) albeit nothing like a true "Accoustic Susupension" (thank you mr Kloss).

The overall effect of this useless location is that instead of making a nice clean upper bass/midrange "thwap", you get a puny "thwink". Instead of a decent rumble, you get a ripple of rattle.

Why does this issue with midbass make the midrange sound so shitty? Simple. it is called "Intermodulation Distortion" and is basically (in this case) noise caused either by the cone itself, OR by noise caused in the environment behind the cone traveling through the cone and to your ears.

Combine IM with a generally unhappy driver, add a touch of off-axix crap caused by pointing a speaker at your ankles and you get fairly crappy sound out of an otherwise really nice driver.

Bummer, huh? This is WHY I tell people all the time that the stock drivers are absolutely amazing. Power them with 4 seperate channels of power, buy a GOOD electronic crossover and last is the speaker change.

So now that you have spent all of this money, what can you do? Well, first off, work on the panel BEHIND the speaker. If you can find it, there is a product called "Dynasorb" but I am sure there are other names. It is a thick kind of gummy mat that absorbs the backwave. It is roughly hexagonal, has small "waves" cast into its gummy surface, and is typically 3/16" thick.

Install this stuff BEHIND your speaker, then use Dynamat "Extreme" on the metal panel that the speaker is mounted to. This is gonna be about as good as you will get in that shitty stock location.

This is why I am doing something serious about my front speaker install. Once I get it done, I will be posting pics. I have been designing this plan for 3 years in my head, and have made several attempts at getting something together as a test fit. When it is done, it will have several advantages:
1. Less than 20 degrees off axix, from either passenger.
2. Pathlength differential of less that 2 feet for driver/passenger.
3 Frequency response of 50Hz to 5Khz at 120db, less than 15% THD.

The plan I have will require no cutting of the car, either.

GL, HTH.
Luke

[StereoInstaller1]

IMO, a midbass like that is going to be designed from the ground up to be in an "Infinite Baffle" install. Generally, this means no "box" behind it...thus nothing to raise the resonant frequency, or control cone motion.

I can get into numbers and all, explain WHY this does not work, but why waste our time...let me explain the mechanics of why your bitchin' little midranges sound like ass. (it is not the speakers' fault, believe me!)

If you put it in that tiny little area (obviously audio was an afterthought) that is allowed for our front speakers, it is no longer an infinite baffle application, thus the resonant frequency is rasied (likely into the upper 300Hz range, by my guesstimate) and even though it is nowhere near sealed, some kind of cone control will happen (consider the mechanical difference between this application and a normal door panel install) albeit nothing like a true "Accoustic Susupension" (thank you mr Kloss).

The overall effect of this useless location is that instead of making a nice clean upper bass/midrange "thwap", you get a puny "thwink". Instead of a decent rumble, you get a ripple of rattle.

Why does this issue with midbass make the midrange sound so shitty? Simple. it is called "Intermodulation Distortion" and is basically (in this case) noise caused either by the cone itself, OR by noise caused in the environment behind the cone traveling through the cone and to your ears.

Combine IM with a generally unhappy driver, add a touch of off-axix crap caused by pointing a speaker at your ankles and you get fairly crappy sound out of an otherwise really nice driver.

Bummer, huh? This is WHY I tell people all the time that the stock drivers are absolutely amazing. Power them with 4 seperate channels of power, buy a GOOD electronic crossover and last is the speaker change.

So now that you have spent all of this money, what can you do? Well, first off, work on the panel BEHIND the speaker. If you can find it, there is a product called "Dynasorb" but I am sure there are other names. It is a thick kind of gummy mat that absorbs the backwave. It is roughly hexagonal, has small "waves" cast into its gummy surface, and is typically 3/16" thick.

Install this stuff BEHIND your speaker, then use Dynamat "Extreme" on the metal panel that the speaker is mounted to. This is gonna be about as good as you will get in that shitty stock location.

This is why I am doing something serious about my front speaker install. Once I get it done, I will be posting pics. I have been designing this plan for 3 years in my head, and have made several attempts at getting something together as a test fit. When it is done, it will have several advantages:
1. Less than 20 degrees off axix, from either passenger.
2. Pathlength differential of less that 2 feet for driver/passenger.
3 Frequency response of 50Hz to 5Khz at 120db, less than 15% THD.

The plan I have will require no cutting of the car, either.

GL, HTH.
Luke

[mspiegle]

I currently have:

JVC KD-AVX2
CDT Audio ES-620s
Audison 2.150
Image Dynamics IDMAX12
Audison 1.400

To get things rolling, I cut some "custom" kickpanels out of 3/16" wood and mounted everything up. At higher volumes, I seem to be getting some funky cancellation and I can tell the panels aren't sealing very well. I'm looking to get these speakers to fit well, seal perfectly, and NOT modify the sheet metal in any way. Does anyone have pictures of their mounting rings and opinions on the best way to go about this?