Open baffle With cheap, large, low Fs car drivers - diyAudio
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Old 27th May 2006, 05:14 PM   #1
bigwill is offline bigwill  United Kingdom
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Default Open baffle With cheap, large, low Fs car drivers

I've had my eye on these woofers:

http://www.monacor.de/int/en/produkt...yp=full&spr=EN
Click the image to open in full size.

They seem to be quite suitable for open baffle operation, and you can get them for 35 each from CPC. They have a large surface area, low Fs and high-ish Qts. I'm a bit dubious about their x-max though, but they're not exactly PA drivers so they be alright. I'm thinking about buying four of them (two per side) and wiring them in SERIES to make a more benign 8 ohm load. Hopefully, this will raise their Qts value to something a bit more usable in an open baffle. Any reason why this wouldn't work?
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Old 28th May 2006, 01:31 PM   #2
bigwill is offline bigwill  United Kingdom
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Anyone?
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Old 28th May 2006, 02:10 PM   #3
Volenti is offline Volenti  Australia
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Going by the published specs they look allright, Le is nice and low, x-max probably isn't going to be all that much (as hinted at by the specs) but they seem to be efficient so you won't need much power.

I'd say their worth a shot.
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Old 28th May 2006, 03:48 PM   #4
bigwill is offline bigwill  United Kingdom
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Hmm, if I bought just one as a test, would I be able to determine how suitable it was? I could buy a powerful resistor to raise the Qts to around the 0.7-1.1 range and put it on a baffle (I have quite a big peice of MDF I could use)

Could be fun
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Old 28th May 2006, 04:21 PM   #5
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putting them in series won't raise Qts
it'll still be the same
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Old 28th May 2006, 04:28 PM   #6
bigwill is offline bigwill  United Kingdom
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Quote:
Originally posted by hitsware
putting them in series won't raise Qts
it'll still be the same
Are you sure? How can the driver have the same electrical damping with another driver in series?
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Old 28th May 2006, 10:00 PM   #7
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Re doubles, but so does Zmax so the result is the same as a single driver. Inverse is true when you parallel drivers.
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Old 28th May 2006, 10:37 PM   #8
bigwill is offline bigwill  United Kingdom
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Hmm, I see. I wonder what size resistor I would need in series with one of them to raise the Qts to 0.71, hopefully nothing too big.
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Old 28th May 2006, 10:45 PM   #9
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i actually have a couple of those EXACT drivers! they came in my first ever speakers i bought, they are in 3 way speakers with a 6" mid and a 4"tweeter but none of the drivers are original, someone just put them in the goodmans boxes..lol.. they actually sound pretty good, its the midrange and tweeters that let those speakers i have down not the subs, mabey if i wasnt moveing away over summer i would have been persuaded to rip the subs out and try them open baffle for you and let you know how i get on but at the moment it isnt going to happen, i have had them out and had them in ported boxes and they sounded pretty good in the ported boxes.. also had them in sealed boxes and they sounded pretty good but i have never tried open baffle before with any driers so i cant really comment on how they would respond.. they do seem to be quite cheaply made BUT they also seem to be very robust and have stood up to many a thrashing at parties at my place so they pass all my tests as far as good value.. hope this helps some..
Owen
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Old 28th May 2006, 11:03 PM   #10
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Monacor have obviously fairly recently changed the design of that driver. Me and Nuuk were looking at getting them about a year or so ago, back then Qts was about 1.2 IIRC. So it would be worth checking that CPC stock the more recent version.

As for how to calculate the new Qts when inserting series resistance, here is a formula that should be what you want:

R = [(Qts_required / Qts) * Re] - Re
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