Initial Impressions: Alpair 12 full-range driver by Mark Fenlon - Page 4 - diyAudio
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Old 25th November 2009, 08:58 AM   #31
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Not exactly, it's just that the A10 plot has more smoothing. If you applied the same to the A12 plot, it would look very similar, albeit with higher sensitivity; the latest drivers all have published plots closer to the raw data.

Fs on the A10 is indeed slightly lower; it's an earlier design & looses out elsewhere (though it remains an excellent driver). The A12 doesn't chase the lowest possible resonant frequency, but concentrates on greater clarity / refinement. Generally speaking, a few Hz here or there on the bottom end doesn't make a whole lot of difference anyway; in the right box both will be good to the mid 30Hz regions or lower & the A12 has more headroom too, so it's more useable.
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Old 25th November 2009, 09:52 AM   #32
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Hi Guys,
Just in case any contributors to this thread haven't seen the Pensil 12 Damped Air Coupler build thread - take a look at:

Alpair 12 - Damped Air Coupler box design

May be interesting as both the Air Coupler and the 19 Litre BR cabs have just been finished.

Thanks
Mark
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Old 26th November 2009, 04:22 AM   #33
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Hi Scott/Mark:
I like much this Scott/Pensil Air Damped box, better than a bassreflex in my personal taste, in the paper.
Do you think I could move the botton SLOT OPEN to the lateral side of the box for a better ambience and soudstage between the Stereo speakers??
If this is a stupid idea fell free to speak.
Gustavo
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Old 26th November 2009, 08:41 AM   #34
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Well, it'd be different in ambience, although I'm not sure if 'better' is the right word. Anyway, yes, providing the dimensions of the vent are not changed.
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Old 26th November 2009, 08:40 PM   #35
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Quote:
Originally Posted by Scottmoose View Post
Well, it'd be different in ambience, although I'm not sure if 'better' is the right word. Anyway, yes, providing the dimensions of the vent are not changed.
Thanks Scott for your advice.
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Old 27th November 2009, 02:00 AM   #36
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Hi Scott,
Perphaps better show you my project so you will get a complete vision. As the ALPAIR 12 is the finest 8 inches fullrange I have see and I do not like point source and less yet monopole speakers, I think a mini Line Array with four Alpair12 drivers could made me happy, If the lateral wall of the speakers could fire some bass to the middle of the Stereo speakers.
So, the inside box sizes for four Alpair12 drivers are these: Wide 31cm Depth 50cm High 131cm. In inches are W 12,25 D 19,70 H 50,5 I can increase the high of the box for more internal volume if need.

I do not know calc the lateral slot/port, If you can inform me the port size I thank you hugely (or better yet, If you can say me how this calc is made?). Regards, Gustavo
P.S.: A vertical Slot Open could be fine.
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Old 27th November 2009, 08:40 AM   #37
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I'm thinking 4 per channel will most certainly not make you happy unless you can put up with the consequences of the inevitable massive lobing (the HF will vanish, severe midband irregularities, and apalling off-axis response). It's too big. You can get away with arrays of very small FR units, but not big 8in drivers (well, the A12 is a 6 1/2in driver in an 8in frame, but you get the idea).
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Old 27th November 2009, 08:56 PM   #38
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Thanks Scott for clear. Looks this effect exist with any size of drivers. Perphas for this reasons I never see various fullranges in a line array, unless the IDS25 by Roger Russel, but this have a blackbox device, maybe for corrections.
http://www.ids25.com/]
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Old 29th November 2009, 02:46 AM   #39
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Just found this thread. I have been running the 12's OB on top of an Alpha 15a H-frame adapted from Martin King's design. Completely impressed by the speaker. A richness and creaminess that surpasses the Griffin Jordan/AC Mini-monitor that had been up there.

My only dilemma? I also have a pair of Alpair 7's OB to also run on top of the Alphas. The Alphas have electrical 125 hz which goes to about 200 Hz if I follow Martin's work. Both Alpair sets have 2nd order LW at 200 hz, also nice during break in. Initial impression is that the 7's have a bit more detail and stage than the 12's, but not the same creamy texture, especially on female vocals. Still not sure which ones I prefer and need to let them both break-in a bit more. Either way, they are both very impressive speakers.
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Old 29th November 2009, 01:47 PM   #40
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Quote:
Originally Posted by FullRangeMan View Post
Thanks Scott for clear. Looks this effect exist with any size of drivers. Perphas for this reasons I never see various fullranges in a line array, unless the IDS25 by Roger Russel, but this have a blackbox device, maybe for corrections.
http://www.ids25.com/]
Yes, output lobing exists with drivers of any size if run wideband; can't circumvent the laws of physics. The larger you go (greater the centre-to-centre distance) the lower in frequency it will start to occur.

Having said that, providing you choose / design the drivers carefully, an FR based line array can actually work well,, but they (the drivers) need to be small for best results, as seen in the IDS 25 etc. The IDS 25 black box is its active Eq, lifts the bottom end up (it's a sealed box) for output ~flat to 30Hz IIRC, and probably applies a small boost at the top end too. Without something like 1/2 octave smoothing, I suspect they still won't look stellar on a basic FR graph, but fortunately, our brains are not microphones or other forms of test gear and they will in fact sound much better / smoother -Haas effect kicking in to a large extent, as Roger describes elsewhere on his site. I used to be determinedly anti FR driver arrays, however, after having a brief chat about them with Roger, and now working a little bit with Mark, I'm much more convinced. In fact, I've got one for the CHR70 in the works, although I'm not sure whether this particular box will see the light of day. More a stepping stone.
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