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O/T new project?


michael hurd

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Been searching for suitable subwoofer drivers lately, but keep coming back to this ( relatively ) inexpensive Infinity 12" subwoofer, designed for car audio. Certainly has potential, it has a much higher BL2/Re than the 10" JBL drivers that I have now, more Sd and also more x-max. Fs is ok at 27.27 hz.

Using unibox and also Win-ISD, I come up with a 4.2 cubic foot box tuned to 22 hz, for one driver. Port 6" x 32". ( Win-ISD is giving a different measurement than unibox ). -3 db at 20 hz ( roughly)

Maximum power handling about 200 watts, coming close to 97% of x-max ( lose 3% in a downfire application ) The best part? $ 225 cdn+ tax a pair, just down the street for a limited time.

INFINITYRef1230wTechSheet.pdf

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At 200 watts, it looks like I will be able to generate 111 db@ 22 hz with one enclosure, if two enclosures, then approximately 117db@ 22hz before room gain.

In Win-ISD there is a section to add in voice coil temperature, it looks like as the voice coil approaches 300F, there would be an increase in output near 40 hz ( + 3db ), with a rise in excursion. Consequently, 120 watts would be about the maximum you could input before running out of x-max. Whoops, forgot about the parametric eq of 2 db boost at 20 hz with a q =2.

Cutting power handling back to 120 watts would net 108 db@ 22hz with one operating and 114 db at 22hz with 2.

Any suggestions?

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On 8/22/2005 2:05:18 PM michael hurd wrote:

Been searching for suitable subwoofer drivers lately, but keep coming back to this ( relatively ) inexpensive Infinity 12" subwoofer, designed for car audio. Certainly has potential, it has a much higher BL2/Re than the 10" JBL drivers that I have now, more Sd and also more x-max. Fs is ok at 27.27 hz..... The best part? $ 225 cdn+ tax a pair, just down the street for a limited time.

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I didn't take the time to model it, but the TS parameters look pretty good... ironically it reminds me of a JBL car driver which required a relatively large enclosure for a car, but performed pretty well in the home (a 12" in the GT series, but I can't remember the model).

You can't get alot in Canada for that price, transport included... so I can see why you keep coming back to it. The T/S parameters are what count, and not it's "car audio" label... so if it models well, go for it.

Obviously more money can buy you more sub... but that becomes a slippery slope...

Rob

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I'm not sure but of late most people are spending soo much more time modeling then actually creating. I know since there are some great modeling programs it is fun to model and dream. But what's the fun in that compared to the real bass. I am just saying if the model looks good and you checked and double checked that the specs are great. Then check your checking account. And if your married check with the wife. I say go for it. Hey remember computer models cannot incorporate real life factors such as room nodes and so forth so build, test, audition, keep if like not if it sounds sub-par. Also do again when new driver comes out and wets you appetite.

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On 8/22/2005 2:05:18 PM michael hurd wrote:

Been searching for suitable subwoofer drivers lately, but keep coming back to this ( relatively ) inexpensive Infinity 12" subwoofer, designed for car audio. Certainly has potential, it has a much higher BL2/Re than the 10" JBL drivers that I have now, more Sd and also more x-max. Fs is ok at 27.27 hz.

Using unibox and also Win-ISD, I come up with a 4.2 cubic foot box tuned to 22 hz, for one driver. Port 6" x 32". ( Win-ISD is giving a different measurement than unibox ). -3 db at 20 hz ( roughly)

Maximum power handling about 200 watts, coming close to 97% of x-max ( lose 3% in a downfire application ) The best part? $ 225 cdn+ tax a pair, just down the street for a limited time.

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How much do you want to spend on a caraudio subwoofer? I know some great brands with lots of watts.

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These drivers are intended for the car audio market, however, they do model quite nice for a home theater application, and such is my intention. Unfortunately, I live in the middle of nowhere, and there is not much I can buy off the shelf here.

I can order out the United States, but I have to : drive to the border to pick the items up, pay the going exchange rate, and what the credit card companies tack on as well. When I bring them across the border, I have to pay a duty on the value of the items. Not to mention the shipping, and my time has got to be worth something as well.

One of the only other vendors that carry products that might be useable is Creative Sound Solutions , in Abbotsford, B.C. They carry Adire products, but again shipping is a killer, not to mention the hassle. I did however buy my 4" flared port kits for my last venture through them, and had to wait because my parcel was lost in the sorting facility.

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Just called Harman Intl, and got through to the Infinity car audio division, and talked to a tech guy about procurement of a Dumax sheet on this driver, he was unsure if they had that, took my name and number, and will get back to me tomorrow about that.

If they already have one available, I don't have to pay for testing, it will give me a more accurate idea on just how linear the motor strength and suspension is, also will give me a Xsus, important to know.

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On 8/23/2005 3:32:47 PM michael hurd wrote:

Anyone have any good ideas on how I can obtain an Xsus measurement? I can envision driving the coil with 9 volts dc one way, and then the other way. This will result in 2.65 amps going through the Vc, certainly not enough to hurt it if it is short duration. Any thoughts?

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Your test may not provide you with either Xmax, Xsus, or Xmag, as it'll depend if 9volts will achieve maximum excursion (I don't think the battery has enough amperage), and on how accurate your can measure it's movement .

I don't have an accurate way of measuring it, but the spec sheet you provided does mention Xmax, which theoretically is the shorter of Xsuspension and Xmagnetic... As far as I know, it is all you need to be able to model (or calculate displacement). 1.gif

Rob

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On 8/22/2005 5:46:59 PM colterphoto1 wrote:

I am a brother, we have the same first name!

You sir, are a steely-eyed missle man!

Michael

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well im too young to be a brother 3.gif but I gotta be something for having the same first name too 2.gif

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