Alpair 10.2 in 8 liter sealed - Too good to be true? - Page 5 - diyAudio
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Old 6th October 2012, 12:18 AM   #41
cotdt is offline cotdt  United States
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I put the Alpair 10.2's in 8L sealed enclosures and was surprised by the bass extension for a 5.5".

The frequency response without any crossover components is as flat as I've ever seen for a fullrange, thanks to the built-in BSC. That said, the 8kHz and 10kHz breakup peaks were not seen in the official datasheets, and the Fs is 40Hz (after break-in) and not the advertized 36Hz. Since the other official T-S parameters are off as well, the box calculations still end up the same.

Harmonic distortion I measured to be very low. It sounds good, very good. Upper midrange clarity would be improved if crossed over to a tweeter at 2.2kHz LR2. To me, everything sounds better with a tweeter.

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Old 6th October 2012, 12:58 AM   #42
cotdt is offline cotdt  United States
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I must say that built-in BSC is pure genius. It makes it soooo easy (and cheap) to make a quality speaker. So simple.
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Old 6th October 2012, 01:39 AM   #43
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Quote:
Originally Posted by cotdt View Post
I... and the Fs is 40Hz (after break-in) and not the advertized 36Hz. Since the other official T-S parameters are off as well, the box calculations still end up the same.
Your have to remember that T/S parameters are curves notscalars. Typically us DIYers ar emeasuring in quite a different spot on the curves. That your numbers are soclose to the factory ismore an indication of how horizontal the MA T/S curves are --backed up by other's measures.

dave
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Old 6th October 2012, 03:25 AM   #44
rongon is offline rongon  United States
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Thanks! That is great info. I got some proper sized baffles cut, got a compass to draw the outlines for the circular holes. Now I just need to cut the holes, glue the two layers of the baffle together (to form the rebate for flush mounting the drivers) and glue them to my old B&W boxes. Maybe this weekend I'll do it...

But you've given me more reason to get to it. Thanks again for the data.

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Old 6th October 2012, 10:45 PM   #45
cotdt is offline cotdt  United States
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Quote:
Originally Posted by planet10 View Post
Your have to remember that T/S parameters are curves notscalars. Typically us DIYers ar emeasuring in quite a different spot on the curves. That your numbers are soclose to the factory ismore an indication of how horizontal the MA T/S curves are --backed up by other's measures.

dave
Really? I see. I had always thought that factory specs were computer generated and not measured, due to them always being different from actual measurements.
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Old 6th October 2012, 11:29 PM   #46
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Factory numbers are typically an average from a significant sample (Mark measures something like 8%) using LEAP or LMS. Tight drivers like Mark's will be +/-8-12%, Fostex as high as 18%, less tightly controlled, you take a guess.

More than once i have posted my measures of an FE127 -- far from factory -- and then Mark measured them with factory kit and got numbers essentially the same as factory. Fs of 75 vrs over 90 IIRC.Both sets of measures eqully valid.

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Old 10th October 2012, 02:36 AM   #47
JR_W is offline JR_W  United States
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I have a pair of Alpair 10.2s breaking in, running them hooked up to my chip amp PC amp while sitting in their cardboard boxes.

Sound great, all things considered. One seems to be a little more sensitive than the other, I'll give them a few days of low power jazz to loosen them up.
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Old 11th October 2012, 12:06 AM   #48
JR_W is offline JR_W  United States
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After just 24 hours the difference is pretty stark, they really loosened up a lot in just a day. Not much bass sitting in a cardboard box, but man the detail and imaging is right on up there. And they have evened up, I thought they probably would.

I'll build some of these small boxes to run them and probably do a Pensile or whatever that large TL box is for these over the winter.
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Old 11th October 2012, 12:28 AM   #49
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Hi Guys,

Emil Askov in Europe has sent me details of his home built Alp10 small enclosure project using IKEA bowls (see pics). These bowls appear to be increasingly popular for smaller projects. I've not had any opportunity to listen to spheres, would be interesting to know if any members have any experience with smaller size projects like Emil's.

Cheers
Mark.
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Old 11th October 2012, 01:52 PM   #50
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Looks fantastic this Ikea sphere Is that the big one, the 28cm bowl? In that case the total volume should be about 15L, how is that for a sealed enclosure?
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