Hi, I'm in the slow process of building a car audio system in my new car. I've already built a diffuser into the headliner (doesn't look all that pretty, but doesn't look horrible). I've got a CSS SDX10 sub that'll go into a sealed (I'm pretty sure) enclosure in the rear, and I've got a pair of Mark Audio Alpair 10.1's that I plan on putting in the corners where the dash meet the windshield. I'll probably be crossing the speakers over around 100Hz so low frequency extension on the Alpairs isn't needed - but if I can get the extension then maybe I won't high-pass the Alpairs.
My question is on the enclosure design for the Alpairs - I have nothing built yet so all is flexible.
My current plan (based on the limited space I have) is to create a fiberglass enclosure for each speaker that runs slightly up the a-pillar (about 12" or so) and also runs along the dash just under the windshield. The dash portion of the enclosure will be about 3" wide by about 1-2" tall. It will have either a crescent moon or an eye cross-sectional shape to it and will be about 23" long. I think the general cross-sectional volume of the a-pillar enclosure portion will be in the same ballpark as the dash portion. Directly behind the speaker itself will have a larger volume as it will be mounted on an angle in the corner.
Should I design this as a sealed enclosure or put open holes at the center of the car where the two boxes meet to turn the enclosure into a TL? If it's a TL, should I direct the ports with an angle toward any given direction? Will a center porting of these enclosures loose stereo imaging? Do I even need an enclosure this large if I'm high-passing the speakers at 100Hz - would just the a-pillar portion of the enclosure suffice?
Any other ideas on my design? Am I setup for failure or success? And yes, I know a car is a poor acoustic environment for audio reproduction, but I'm enjoying this project and the challenges that it includes.
My question is on the enclosure design for the Alpairs - I have nothing built yet so all is flexible.
My current plan (based on the limited space I have) is to create a fiberglass enclosure for each speaker that runs slightly up the a-pillar (about 12" or so) and also runs along the dash just under the windshield. The dash portion of the enclosure will be about 3" wide by about 1-2" tall. It will have either a crescent moon or an eye cross-sectional shape to it and will be about 23" long. I think the general cross-sectional volume of the a-pillar enclosure portion will be in the same ballpark as the dash portion. Directly behind the speaker itself will have a larger volume as it will be mounted on an angle in the corner.
Should I design this as a sealed enclosure or put open holes at the center of the car where the two boxes meet to turn the enclosure into a TL? If it's a TL, should I direct the ports with an angle toward any given direction? Will a center porting of these enclosures loose stereo imaging? Do I even need an enclosure this large if I'm high-passing the speakers at 100Hz - would just the a-pillar portion of the enclosure suffice?
Any other ideas on my design? Am I setup for failure or success? And yes, I know a car is a poor acoustic environment for audio reproduction, but I'm enjoying this project and the challenges that it includes.
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Mark should probably address this, but I'd be really careful ( as in wouldn't even thinking about) running any lightweight metal cone drivers in an auto or boat system. CHP or EL70, or Fostex FFxxxWKs, sure - even then I'd want to XO them above 150-200 HZ and tread carefully with the volume control.
The metal cones are very very thin, so can be easily damaged where a paper or poly cone might shrug off any accidental collisions.
That said, the comments about crossover points say he's on about too much LF energy getting to the drivers. I don't think that'll be a problem, and I'd expect a 100Hz XO (so the subwoofer's position isn't obvious when you hear it) would be fine: the fact that you're wanting to use MA drivers says to me you're looking for more quality of sound than being able to do hair tricks.
Chris
That said, the comments about crossover points say he's on about too much LF energy getting to the drivers. I don't think that'll be a problem, and I'd expect a 100Hz XO (so the subwoofer's position isn't obvious when you hear it) would be fine: the fact that you're wanting to use MA drivers says to me you're looking for more quality of sound than being able to do hair tricks.
Chris
Thanks Dave.
Chris I sort of doubt that I'll have any accidental collisions with them on the dash behind grill covers. Anything is possible I guess, but I got a good enough deal on them from Bob at CSS (his old stock, mismatched colors) that should anything happen I'll not be too heartbroken. Still sad, just not heartbroken.
So is sealed the obvious and simple choice then? No high-pass filter?
Chris I sort of doubt that I'll have any accidental collisions with them on the dash behind grill covers. Anything is possible I guess, but I got a good enough deal on them from Bob at CSS (his old stock, mismatched colors) that should anything happen I'll not be too heartbroken. Still sad, just not heartbroken.
So is sealed the obvious and simple choice then? No high-pass filter?
My amp (Memphis ST1300D) has an optional 18db sloped high-pass on those channels. I'll probably just use that unless there's any reason not to (phase coherence?).
Edit: I'm also going to be running a Rockford Fosgate 3sixty.2 digital signal processor that will digitally EQ everything, so maybe I've already waved goodbye to phase coherence?? Like I said, I'm slightly new to the DIY scene - loving it though.
Edit: I'm also going to be running a Rockford Fosgate 3sixty.2 digital signal processor that will digitally EQ everything, so maybe I've already waved goodbye to phase coherence?? Like I said, I'm slightly new to the DIY scene - loving it though.
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if for no other reason than the very high ambient noise floor, car audio speakers tend to get abused far more than we think, and as wonderful as they might be, the Alpairs are quite simply not designed for the task
proceed at your peril- and that's all I'll say on the subject
Hey, that's not your final statement here I hope. I like your line of reasoning acoustically. Regular car noise floor is ~83db or so? How high does the rms need to climb before I'll be happily listening to music and not noise? The clarity advantage aside, they will obviously get stressed more than I would prefer Alpair drivers to get stressed, but what will the failure decline be? I only plan on owning the car for so long. Will they degrade slowly in clarity or just finally kick into distortion on frequency x?
If I seriously increase the STL of the car with mass loaded vinyl and some UV tint on the windows, would that help for these drivers? The roof is done now with a significantly higher STL. Just brainstorming.
had to tease another response eh?
I have no doubt that the Jordans, or any of the Alpairs would be substantial sonic improvements over most stock auto drivers, but even with careful XO to reduce low frequency duty cycle and appropriate enclosure volume/installation location (e.g. not door mounted ) , my concern would be the long term durability of the lightweight metal cones.
Perhaps I'm just being paranoid - like I said earlier, it would be most interesting for the manufacturer of the drivers to comment on the advisability of the project, as well as the warranty implications.
I have no doubt that the Jordans, or any of the Alpairs would be substantial sonic improvements over most stock auto drivers, but even with careful XO to reduce low frequency duty cycle and appropriate enclosure volume/installation location (e.g. not door mounted ) , my concern would be the long term durability of the lightweight metal cones.
Perhaps I'm just being paranoid - like I said earlier, it would be most interesting for the manufacturer of the drivers to comment on the advisability of the project, as well as the warranty implications.
Visibility is going to be very minimally compromised. Only the corners of the front view will be obscured (i.e. if I want to see directly toward my front tires I may see slightly less and I may see less of my wiper blades at rest, but daily driving will be unimpeded). I'm more worried about the events of a collision and how I plan to secure the enclosures in place.
As far as the durability of the metal cones, the aluminum that they're spun from would probably have a better time with humidity and temperature fluctuations than a basic paper cone. I do understand that excessive xmax stress will crinkle the cone slightly, but how much sonic implications will this type of abuse incur on the driver?
I'm not worried about warranty for the Alpairs due to the great deal on Bob's old stock that I got - I don't think I have any warranty from that transaction (maybe I do, but I don't care).
Oh, and chrisb, spoken like a true worried Canadian eh?
Visibility is going to be very minimally compromised. Only the corners of the front view will be obscured (i.e. if I want to see directly toward my front tires I may see slightly less and I may see less of my wiper blades at rest, but daily driving will be unimpeded). I'm more worried about the events of a collision and how I plan to secure the enclosures in place.
As far as the durability of the metal cones, the aluminum that they're spun from would probably have a better time with humidity and temperature fluctuations than a basic paper cone. I do understand that excessive xmax stress will crinkle the cone slightly, but how much sonic implications will this type of abuse incur on the driver?
I'm not worried about warranty for the Alpairs due to the great deal on Bob's old stock that I got - I don't think I have any warranty from that transaction (maybe I do, but I don't care).
Oh, and chrisb, spoken like a true worried Canadian eh?
if you've got a sub in your car, then cross the MA's over well above the point where the cone is actually going to be moving. outside of that you'll deafen yourself before you max the driver out. i've ony got a single car sub dealing with 20-100hz, the MA's have a high pass on to protect them from ever getting enough excursion to hurt them. the boxes they were in were originally made to go in the house, i've just screwed them onto the back shelf.
although i don't go to SPL meets or similar stuff like that. i run them at moderate listening volumes.
Never had an issue with the Jordans. The cones are quite thin but also quite strong and can't be easily damaged by over-driving. Also they are much more resilient to aging than paper. The Ford speakers I replaced were warped, faded and degraded. The Jordans have held up with no damage, even under high volumes. It's not an issue. I don't know about the Mark Audio drivers, I haven't tried them long term. They are quite different to the Jordans as the metal cone is alot thinner. I would imagine they give better off-axis HF response though.
The multiform cones are thin. The 1st gen like the A10 in question here are closer to the Jordan than they are to the multi-form cones.
dave
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