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Discussion Starter #1
Hi

I have been thinking about building a sub for some time now and Im basically doing this as a warm-up project for the bigger one that Ive got planned for a few weeks.

Anyway, Ive managed to get a hold of a Targa Autosound x-150-i, 15 inch 500w (250wrms) 4 ohm sub. The only details i can get for the thing are:
Size 15"
Power 250Wrms
500Wmax
Imp. 3.9 Ohm
Res. 29.5Hz
Sens. 87dB
Mag. 156x20mm (49oz.)
Qms 4.33
Qes 1.16
Qts 0.92
Vas 159L
Box 1.4f³ min.

Also got this from another thread -
X-150
Z=3R9
Fs=29.5Hz
SPL=87dB
Qms=4.33
Qes=1.16
Qts=0.92
Vas=159 litres

I beleive those T/S figures are for the non 'i' model, which as far as a know (which isnt very far at all) looks different but apart from the looks i dont know. It does recomend a 1.4cf sealed box, but Im looking for some subsonics even if its not the worlds greatest sound quality.

Anyway, I need a bit of help designing a box for this driver. I will be extracting a 220w rms plate amp off of a Dream HiFi sub that i got off ebay to use with the Targa. Trying for a ported box with a tuning of around 20hz. Will be used mainly for gaming and HT use with a bit of music every now and then. I would like to keep the box size to a minimum.

I did not pay much for this sub so Im basically just seeing how they hold up when given the proper treatment.

There was NO included paperwork with the driver (it really was just a box with a sub in it!), and the specs that written on the box I have supplied.

Any suggestions or ideas will be greatly appreciated.
 
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Yeah thats what I thought too - I got the same kind of measurements and I thought it was my inexperience with box-plotting software that was causing it.

It may be that this is just a really bad driver - would not surprise me. They retail pretty cheap around here.
 
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The bigger project is going to be a Mach5 IXL 18.2.2 hopefully with an eDesigns 550w plate amp, tuned to <20hz. Going for an upstanding front firing monster. I want this thing to intimidate people before they hear it. Overkill for the room its for, but I have moved around a bit and I just want something that will do me no matter what the situation.

Going for the eDesigns plate cause its prolly the best bang for buck amp I can get (Australia). it goes subsonic, seems to have good output and compared to the other amps on offer around here it runs at less than a $1 a watt after shipping is included. The other option (local jaycar amp) bottoms out at 30hz so is unsuitable for my needs.

Anyway, (original project) since this is an experimental sub that I plan on either selling or putting in my bedroom if its any good, I am just after some rough estimates for a semi-decent box. I know its hard with those kinds of measurements but what would you reccomend as a starting point?
 

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8 cu.ft. tuned to 20 hz with two 4 inch ports 18 inches long. You can always equalize the hump at 45 hz down.

On your Mach5 IXL 18.2.2 project, you will need to get a subsonic filter as the eDesigns plate amps do not have one. Not sure what shipping to Australia is but the O-Audio Bash 500 plate amp is much better. It has an adjustable subsonic filter you can taylor to your needs.
 

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8 cu.ft. tuned to 20 hz with two 4 inch ports 18 inches long. You can always equalize the hump at 45 hz down.

On your Mach5 IXL 18.2.2 project, you will need to get a subsonic filter as the eDesigns plate amps do not have one. Not sure what shipping to Australia is but the O-Audio Bash 500 plate amp is much better. It has an adjustable subsonic filter you can taylor to your needs.
Hi Mike,

I think it's difficult to harm a sub tuned below 20 Hz. I wouldn't care about a subsonic filter.... Well, a subsonic filter wouldn't do any harm either :)
 
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Discussion Starter #9
I have taken your advice and threw together a quick design for a approx 8cf box, only I would prefer to go with a slot port as its easier to just build it in I find.



Does that look ok? Obviously I will have to put some bracing in and I might have to increase the height a little, and I was thinking if having it turned sideways so I can put a heavy chest of drawers ontop. Save some room space :)
 
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Yeah im fully aware - Im not expecting much from it, but worst case scenario is that I sell it for a little more than i built it for. The box in the pic is using a 4 inch port which winisd said need 45cm of length. Should i redeign for a 2 inch hole?
 
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Thanks for that Mike P

Was wondering how long the port would need to be for a 2 inch x 14.5 inch opening - Trying to make the woodwork part as easy as possible.
 

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Put a 2x2 in the middle of the port lengthways. This will give you a brace in the port, and also give you another surface to glue/screw to. I was trying to find a picture of a sub I know I've seen around here that had 2 braces like this, but I don't seem to be able to find it. Think something like this. Instead of using dowels, just run a 2x2 lengthwise down the middle of the port. That will take up your 2 inches to get you 12.5 instead of 14.5.
 
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So essentially, just use a strip of 2x2 to divide the original 14.5 inch port into a 2 smaller ports whos openings total 12.5 inch? Or should I run it down the side and not worry about dividing the ports?
Sorry about the stupid questions
 

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I think either way would be fine, 12.5 inches is not a big enough span to have a lot of problems with flexing, so I don't think it would matter. MikeP or someone else can give you a more definitive answer, as I don't really know, just book learnin' no actual experience with sub building.
 

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So essentially, just use a strip of 2x2 to divide the original 14.5 inch port into a 2 smaller ports whos openings total 12.5 inch? Or should I run it down the side and not worry about dividing the ports?
Sorry about the stupid questions
One big port would be better then 2 smaller ports. Run it down the side or one strip down each side to keep the port centered in the box, it's up to you. As long as the final port area is 25 square inches. And there is nothing wrong with your questions. Read my signature at the bottom of this post. :T
 
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