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Old 12th February 2013, 01:26 AM   #1
JR_W is offline JR_W  United States
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Default Alpair 12.2P Modeling Help

I'm not having any luck entering the driver parameters in my version of WIN ISD, was wondering if somebody could shoot some quick numbers for me.

Alpair 12.2P, Vented Cab, ~15L, single 6 sq in vent 1/2" long. Outside dimensions of the box are 9 1/2" W X 8 1/2" D X 15 3/4" H and 1/2" thick.

I was breaking in a pair of 12.2Ps and decided I'l mount them in a pair of old cabs I had, 2-way bookshelfs. I pulled the tweeter, that's the 6 sq in X 1/2" vent now.

Anyway, the things sound surprisingly awesome. A lot more bass than I would have imagined, and I don't run them very hard, I just want to see what the sim says about this.

Thanks, I'll see if I can get WIN ISD going in the meantime.
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Old 12th February 2013, 01:40 AM   #2
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Looks pretty awful, there's a huge peak centered around 130Hz, and then it heads for the bottom, with F3 around 90 Hz, and F10 around 75Hz. If your vent was 5" long, the FR plot looks much better, with F3 around 66Hz.

jeff
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Old 12th February 2013, 01:47 AM   #3
JR_W is offline JR_W  United States
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Thanks for the reply, I could tell with the RTA that there was a lot going on in the ~125hz area, but I'm not trying to get a lot of bass below 100 or so, anyway.

About how many dB is the 130 peak above the freqs higher than 130?

TIA.
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Old 12th February 2013, 01:48 AM   #4
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The volume will work fine (15.4 litre before bracing and driver).

Vent needs to be longer -- lengthened. Reponse as is is not very good.

dave
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Old 12th February 2013, 01:59 AM   #5
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I suppose that I am going to confuse you more but....

I just got my pair of A12P's yesterday and it may be a while until they are in cabinets , but I did some modeling anyway. 15L is the QB3 answer, but I think that a 20-30L EBS alignment might better utilize the driver's potential. It will get another 10Hz of bass. I am looking at a proper MLTL with an F3 ~ 40Hz.

Bob
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Old 12th February 2013, 02:22 AM   #6
JR_W is offline JR_W  United States
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I'll see if I can whip up some 5" long ports.

This wasn't intended as a permanent solution, I was just surprised that they got going as good as they did.
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Old 12th February 2013, 09:27 AM   #7
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For BR duties I quite like ~16 litres tuned to 50Hz - 55Hz. Works quite nicely with gain from a typical moderate sized British room, or a higher output impedance amp.

Last edited by Scottmoose; 12th February 2013 at 09:30 AM.
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Old 12th February 2013, 03:05 PM   #8
GM is offline GM  United States
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Quote:
Originally Posted by Bob Brines View Post
.......but I think that a 20-30L EBS alignment might better utilize the driver's potential.
Agreed, a ~standard pre-T/S formula design routine from when tuning to Fs was the norm works particularly well overall with low Qts drivers, so 'cheating' with T/S I get 29.86 L/42.14 Hz Fb

GM
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Old 12th February 2013, 09:59 PM   #9
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Oh I like that. With ~4ohm SR mimicking the typical output impedance of many SET amps these days, that's one nicely balanced alignment.
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Old 3rd March 2013, 05:56 AM   #10
zman01 is online now zman01  Bangladesh
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Default Shorter BLH for the A12P?

Recently had a chance to listen to Fostex 206EN drivers in the FE208 Sigma cab - must say I liked the sound. Powered by a 5 wpc tube amp the speakers sounded effortless, with very clear mids and clean bass. Read that Ron Clarke's Dallas is likely to be even better.

Wondering if a similar BLH (single front facing horn mouth) design can work for the A12P. Understand that Scott's Avebury is excellent, but at ~6ft, WAF is a challenge. Also room placement and distance from back wall can be a challenge in medium size rooms?
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