Since changing car, ive got a nice pair of polk audio 6.5 inch 2 way door kits and a "250 watt" alpine car amp gathering dust in the attic.
Rather than let the surrounds rot away, i would like to use them for an (ideally) compact portable soundsystem. Add a 12v, 20ah lithium battery, the guts of a car phone charger to keep the source of the music charged.
Ive spoken to the guys at Polk, who after a surprisingly large amount of persuasion, gave me the T/S parameters of the woofers.
Problem is they have a rather high qts of 1.01 and are designed for use without an enclosure. They sounded surprisingly good in a leaky old door panel, but i worry that putting them in boxes of a manageable size (i.e. As small as possible) they will never sound good.
I eas reading about aperiodic enclosures as an option, or even (for use outside) just leaving the enclosure open at the back.
Specs are as follows:
Fs 80.385
Re 2.9345
Res 15.29
Qms 6.324
Qes 1.214
Qts 1.018
L1 0.1895
L2 0.257
R2 2.77
Vas 6.665
Mms 14.13
Cms 277.85
BL 4.1535
LE 0.34
Any tips on what kind of (very small) enclosure might work well with such a driver would be most appreciated.
As mentioned, aperiodic enclosures seem promising, but a) there seems contradictory info available on design, b) no software to hold my hand, and c) the suggestion that they only work when the "vent" exits into a space seperated from the driver front face, which is hardly ideal for a portable, which ideally would sing indoors and outside.
Thanks guys.
Rather than let the surrounds rot away, i would like to use them for an (ideally) compact portable soundsystem. Add a 12v, 20ah lithium battery, the guts of a car phone charger to keep the source of the music charged.
Ive spoken to the guys at Polk, who after a surprisingly large amount of persuasion, gave me the T/S parameters of the woofers.
Problem is they have a rather high qts of 1.01 and are designed for use without an enclosure. They sounded surprisingly good in a leaky old door panel, but i worry that putting them in boxes of a manageable size (i.e. As small as possible) they will never sound good.
I eas reading about aperiodic enclosures as an option, or even (for use outside) just leaving the enclosure open at the back.
Specs are as follows:
Fs 80.385
Re 2.9345
Res 15.29
Qms 6.324
Qes 1.214
Qts 1.018
L1 0.1895
L2 0.257
R2 2.77
Vas 6.665
Mms 14.13
Cms 277.85
BL 4.1535
LE 0.34
Any tips on what kind of (very small) enclosure might work well with such a driver would be most appreciated.
As mentioned, aperiodic enclosures seem promising, but a) there seems contradictory info available on design, b) no software to hold my hand, and c) the suggestion that they only work when the "vent" exits into a space seperated from the driver front face, which is hardly ideal for a portable, which ideally would sing indoors and outside.
Thanks guys.
Car speakers sound awesome in cars primarily because of cabin gain. Cabin gain can easily add 6 dB of boost in the lowest octaves. Even super cheap 6.5" speakers can provide some punch is a smaller car.
Hi Q + high Fs (80 Hz) = tricky to get bass in a reasonable enclosure. I see you already figured that out.
I've seen a few implementations of car speakers as home speakers. One of them sounded OK; it was 6x9 speakers. It sounded OK for the same reason they sound OK in a car: room gain. They were in a smallish room in the basement with highly reflective walls and placed close to the corners. Dude knew enough to put them in large enclosures; he had built towers. It was pretty much a near field application. They played loud and sounded decent.
Hi Q + high Fs (80 Hz) = tricky to get bass in a reasonable enclosure. I see you already figured that out.
I've seen a few implementations of car speakers as home speakers. One of them sounded OK; it was 6x9 speakers. It sounded OK for the same reason they sound OK in a car: room gain. They were in a smallish room in the basement with highly reflective walls and placed close to the corners. Dude knew enough to put them in large enclosures; he had built towers. It was pretty much a near field application. They played loud and sounded decent.
Thanks for the replies. I feared they might be unsuitable for my suggested use.
One clarification, scottjoplin, you suggested a "simple cardioid enclosure"
However im not familiar with the term, and google theows me in the deep end of sub arrays with digital delay to create directional bass. All very interesting, but not exactly simple, and seems specific to subwoofers. Im guessing you were referring to something else..?
One clarification, scottjoplin, you suggested a "simple cardioid enclosure"
However im not familiar with the term, and google theows me in the deep end of sub arrays with digital delay to create directional bass. All very interesting, but not exactly simple, and seems specific to subwoofers. Im guessing you were referring to something else..?
If the goal is just to have portable sound and these drivers are collecting dust then don't worry so much about perfection! Put them in a sealed box as large as you can tolerate, stuff it really well, and see how they sound. There won't be much low end but at least you'll have music you can take with you and the speakers will be put to use. Otherwise you might as well try to sell them.
I'd also just put them in a sealed box as big as you can stand.
When it comes to small outdoor systems, the high Qts isn't necessarily a bad thing - you'll get a rise in the bass response right where it's useful: 100-150Hz. Going for deep bass outdoors is the realm of larger drivers that can move plenty of air, but the rise around 100-150Hz makes it sound like there's plenty of bass, without the drivers having to work too hard.
Chris
When it comes to small outdoor systems, the high Qts isn't necessarily a bad thing - you'll get a rise in the bass response right where it's useful: 100-150Hz. Going for deep bass outdoors is the realm of larger drivers that can move plenty of air, but the rise around 100-150Hz makes it sound like there's plenty of bass, without the drivers having to work too hard.
Chris
Aperiodic can be simulated by adjusting Ql in most software. It will not allow you to usea smaller box than a comparable performance sealed design. It will only reduce the bass output (flatten it) compared to a sealed and will raise your F3 point.
Car speakers are designed for cars, dust, water and high Qts are among the leading constraints when designed. For battery power you need two things - a super efficient amp, class H or D and a speaker with highest possible efficiency, Qts 0.2-0.25 and lowest possible Vas. I`d rather sell these on ebay.co.uk and buy the needed components. Cheap home use woofer will very likely sound better than these. Monacor :: Monacor SP-60/4 PS11.11 these can be used sealed with great results and you can fit 2 or more of them.
Car speakers are designed for cars, dust, water and high Qts are among the leading constraints when designed. For battery power you need two things - a super efficient amp, class H or D and a speaker with highest possible efficiency, Qts 0.2-0.25 and lowest possible Vas. I`d rather sell these on ebay.co.uk and buy the needed components. Cheap home use woofer will very likely sound better than these. Monacor :: Monacor SP-60/4 PS11.11 these can be used sealed with great results and you can fit 2 or more of them.
Thanks for the continued suggestions everyone. Selling them on ebay might be a little problematic, as i had to remove (by force) the tweeter covers, and epoxy them into their previous home, so although they work fine, aesthetically they are damaged goods. Im now deciding between u-frame and sealed (maybe experiment with an aperiodic vent). Nobody has mentioned bass reflex i note. Could explain why this option is not a good one?
Given these options, between sealed or u-frame which would generally require a smaller volume?
Given these options, between sealed or u-frame which would generally require a smaller volume?
Another question: i assume with a u-frame it is necessary to have the rear exit directly behind the driver and parallel to it? To get a more portable form, something folded, or a chamber with the driver and rear exits on the longer sides of the "box" maybe on opposite sides and opposite ends? From what i have understood however, seems it would no longer be a u-frame.
Also worth noting, a portable system with the drivers mounted close to each other, it might not be too painful to forego stereo sound. That would open up possibilities for isobaric arrangement etc. However, again , im not sure of there are any arrangements which are beneficial, output or quality wise, over a simple pair of sealed chambers.
10 litres (or so) sealed box will be just fine, everything other is unnecessary complication. Use glass or mineral wool for stuffing, just protect the driver with one layer of polyester wadding immediately behind the driver.
Bass reflex with a high Qts driver results in a bad one-note sound.
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Ok, i will accept the advice given. Sealed box it is! I might add a minidsp to correct the hell out of it to compensate for some of the design constraints. The speakers seem to be very tough and take a fair amount of power, ive never heard them distort, even at punishing volume, so a bit of heavy eq might be in order.
On a totally unrelated note, are there any "stuffing" or damping options which do not involve filling the cabinet with fluffy stuff? I was daydreaming about a combination speaker/coolbox, with a sturdy construction, and a lid you can clamp down tight. Be easier to justify a larger box to cart round if i coud keep stuff in it during journeys and empty it to play. However your typical acoustic filler kinda messes with this cunning/silly plan.
Well the speakers are marine rated, and the amp etc will be in a seperate compartment. I can cover the terminal block with silicone or something, and paint the inside of the cabinet with waterproof paint. I do think the acoustic fill will end up all squashed.. Are there other methods to provide the same effect in a cabinet as acousic fill? Thick foam on the walls? A cup of sponge around the back of the speaker chassis? I did read that an aperiodic vent has similar effect to stuffing, but every design ive seen uses both a vent and stuffing. Probably im asking the impossible...
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