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Old 12th October 2008, 01:05 PM   #1
Luke352 is offline Luke352  Australia
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Default Need a little enclosure help!

So I'm currently building some Zaph Mini Monitors and will eventually build something bigger and better, but for now they'll do and in search of a little low end I've grabbed an old car audio sub I had lying around and proceded to plug the figures into WINISD and quickly relised I have no idea how to design an ideal enclosure for in house, designing an enclosure for in car use I can do but in house I'm clueless as to what I'm looking for and what sort of room gain to expect.

So I was hopeing for a little guidance and help in coming up with an appropriate size and type of enclosure.

The room is 4.5m x 3.7m with 2.4m ceilings and has a large opening into the kitchen and also has a hallway coming off it.

The sub is an Orion XTR series II 10" dual 4 ohm VC's, the specs are as follows


Parrallel and Series
Nominal Impedance 2 ohm 8 ohm
Re 2.2 ohm 8.2 ohm
Levc (mH) 0.71 2.79
Sensitivity 95db 89db
Fs 33hz 33hz
Qms 8.20 8.20
Qes 0.37 0.37
Qts 0.36 0.36
BL (TM) 8.2 17.3
Sd (sq.In) 50 50
Vas (cu ft) 2.23 2.23
Xmax 7.48mm 7.48mm
Pmax (watts) 500 500

I'll be running it in series but figured I'd list both sets of specs.


Winisd suggests about 1.5cuft tuned to 37hz, but I think I'd prefer a bit lower extension but I really don't know how much room gain to expect and if the gain will be low enough so as to not require lower tuning.

Playing with the figures I didn' mind the look of 2cu ft tuned to 33hz, but I'm no pro so thats why I'm here!

Any help you guys can give me would be great thanks!!!

Luke
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Old 12th October 2008, 01:20 PM   #2
AndrewT is offline AndrewT  Scotland
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Qts of 0.36 will suit sealed or vented cabinets.
try looking at the various shapes of response that WINisd pro shows.
Then look at maximum SPL.
Does Xmax limit too early. Many vented alignments use up your Xmax at quite low SPL levels when trying to use low frequencies.
Try looking at the response @ 20Hz. How far is it down compared to the midrange?
Now look at the max SPL @ 20Hz, now how far is it below the midrange. What power will overstroke the Xmax. I'll guarantee you won't find any vented alignment that will allow 500W @ 20Hz. Some might exceed Xmax at just 10W.
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Old 13th October 2008, 12:44 AM   #3
Luke352 is offline Luke352  Australia
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Ok,

Well I've been looking at all the areas you have suggested, although I'm mainly looking at 30 hz rather then 20hz because this sub tends to roll off just before 30hz and therefore doesn't produce any real output under about 25hz, with the 2cu ft enclosure tuned to 33hz I have a f3 of 30hz essentially. My cone excursion peaks at under 1mm in the useable freq range, though with what amount of power is that? I'm assuming these graphs are with 1 watt how do I see them with more power to get an idea of more real word application, or is there a calculation I can use to determine my cone excursion with more power?

Thanks

Luke

p.s. I just found the signal power input box in Winisd.
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Old 13th October 2008, 03:00 AM   #4
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I take it you're using Win isd beta. If you use the Win isd Pro Alpha you can change power input to see cone excursion. It has a few more useful graphs too.

Don't uninstall your beta version though. I can't get alpha to give vent machs. I do basic modelling in Pro Alpha then input detail into Beta to check vents.

Get Pro Alpha here
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Old 13th October 2008, 08:56 AM   #5
AndrewT is offline AndrewT  Scotland
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WINisd allows one to alter the voltage of the standard test signal. It's usually 2.83Vac, being the equivalent to 1W into 8r0, but can be made to any level.

However, Pro also has a graph of max SPL, that takes account of input power AND Xmax and plots that.
It shows very easily the Xmax limitation at low frequencies.
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Old 13th October 2008, 12:01 PM   #6
Luke352 is offline Luke352  Australia
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Yeah I've been playing with the signal strength vs cone excursion today, which is a part of WinISD Pro i've never played with before since I'm generally a sealed enclosure person for my in car subs and exceeding xmax has never been a huge concern for me in the sealed setups. Well since this is only going to be powered off a small home receiver type amp which is only making about 20-30rms, and it won't exceed xmax under 20hz till it goes over 20watts, although obviously the more power it gets the higher up i exceeds xmax.

So I think I'll go with about 2cu ft tuned to 34hz but I'm in the search for some kind of subsonic filter now, I've seen those ones that are like a RCA adaptor plug and they come in 20hz and 30hz though ideally I'd like about 25hz, is there anything you guys could suggest, or anywhere you can direct me to a guide on construction of low level signal (RCA) subsonic filter I can make.
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Old 13th October 2008, 11:00 PM   #7
GM is offline GM  United States
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Quote:
Originally posted by starburst

I can't get alpha to give vent machs.
Works for me.

Are you looking at the front or rear vent plots? The rear ones are for vented (BR) alignments. Note too that some of the plot limits aren't suitable for some drivers/alignments, but you can change them by right clicking on the plot to open the 'options' menu. Also, highlighting an entry field such as box volume can be scrolled using the up/down keyboard arrows.

There's probably some other 'good to know' type user info I missed in the few minutes I played with it, so don't be afraid to experiment and tailor it to suit your needs as required. I mean the first thing I did was change the colors of some of the plot lines since between my fading monitor and eyes I couldn't see some of them.

GM
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