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Discussion Starter #1
Hi all,

First post here and looking for advice from the experts. I'm in the proces of building my dedicated HT. Size is 4.2m wide 6.3m long and 3m ceiling. I have prepared a sand stage where the speakers will stand but I also have two 40*40 cm holes down to my crawlspace. So I'm investigating the IB option.

I have found a subwoofer that I kind of like. It is the hifonics ATX 15". It has a Xmax of 35mm. I calculated that 4 will give me 23L of displacement. I have modeled them in bassbox but I really have no idea if I'm doing it right so would appreciate some feedback.

Model ASX 15

D in mm 387
Xmax mm 70 (two way travel)
SD qcm 804
Mms g 223
Re Ohm 4
Fs (Hz) 27
Qms 4,5
Qes 0,42
Qts 0,39
VAS (L) 139
SPL (dB) 90
Le mH 1,5
VC mm 76
RMS (W) 850
Depth (mm) 189
Opening(mm) 352

I'm looking to use 4 of these in two line arrays or manifolds.

Following graphs are for 4 of the Hifonics ASX 15" subwoofers in an IB (20m3 box). First scenario is with 1200W power (one amp board of 300W for each woofer) and second one with 3400W power.

First scenario give me 116db at 20hz and 108db at 10hz with a cone excursion of 20mm at 10hz. Second scenario give me 120db at 20hz and 112db at 10hz with a cone excursion of 33.6mm at 10hz.

Does this look good? What does these figures really mean though. To little, enough, or to much? The extra amp power will cost a bit so is the difference of 4db going to be noticeable?
 

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I can't find much information on the ASX 15 but strongly suspect the 35m Xmax is really Xmech, the mechanical limits of the driver, but I could be wrong. 2000 watts into 4 drivers would be 22mm Xmax at 20 hz, a safe assumption for the drivers. With an output of 118 db at 20 hz plus room gain, it would be excellent performance.
 

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Mike,

I looked for this last night too and the only xmax figure I could find was 20mm. I will see if I can find it again.

Alot of the websites I can across were in Europe and not in English.

cheers

Graham
 

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Discussion Starter #9
official site says 70mm xmax which is probably two way travel so that corresponds to your 35mm I hope. Otherwise they won't be the best bang for the buck...
 

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I am not getting anywhere near your figures. I have put them in winisd and I am getting 107db at 10hz with 4000 watts input power for 4 drivers in a 15 cu ft box.

I am also only showing 26mm off excursion with that input power.

Perhaps Mike would cast his eye on it. I didn't get any errors in the winisd file so all seems fine.

cheers

Graham
 

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Discussion Starter #13
Well I'm using bassbox pro but I'm not sure if that will give me different results. Attached are the input data I used.

More importantly though is this a good driver for IB use? The figures seem to show that its powerful enough and at a total of 22L of displacement I assume it should be plenty for my room? How do they model with 300w per driver for you?

Somebody told me that it may not be usable since this driver likes a smaller box and that a qtc of over 0.5 might overdamp the cones. Thats my biggest concern now and its holding me back from ordering them.

Advice?
 

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Discussion Starter #15
How big is the back area the drivers "see"?
you mean the crawlspace that the woofers will shot into? the immediate area under the ht is about 40m3 but its also open to another area of an extra 60m3. the two holes that the IB will shot down into the crawlspace are 40cm by 40 cm each.
 

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Discussion Starter #17
WinISD is getting the same results as you for 4 drivers with 1200 watts.
great thanks for checking. So then its good enough right? Whats your take on the following comment.


Somebody told me that it may not be usable since this driver likes a smaller box and that a qtc of over 0.5 might overdamp the cones. Thats my biggest concern now and its holding me back from ordering them.

Thanks
 
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