Building a cheap high powered sub.

pikipupiba

Member
2010-11-03 7:09 pm
I am building a high powered subwoofer from the ground up and trying to do it as cheaply as possible. I intend to use this sub for DJ and all around party purposes, so it needs to be loud, compact, and still sound good.

I am using a PYLE PLCHW15 driver and 3/4 inch MDF.

The Loudspeaker Design Cookbook is my main source so far.

Using the book, I have decided the size of the box should be 4.57 cubic feet, but seeing as a lot of it is still over my head, thats all i really have. Any suggestions on shape, driver placement, etc.?

From the book I see one of the relevant parameters is something called the Qtc, is it something you 'pick' instead of measure?

Driver: http://www.amazon.com/PYLE-PLCHW15-...LH78/ref=sr_1_1?ie=UTF8&qid=1288812649&sr=8-1

Amp I am using: Amazon.com: PYLE PWMA3003T 3000 Watts Hybrid PreAmplifier with AMFM Tuner/USB/Dual Wireless Mic: Electronics
 
If this is for real DJ purposes what you should be looking to build is a high power bass bin not a sub. That chest thumping that you hear and feel at clubs is mostly around 60 to 80Hz and most clubs roll off anything below 40Hz because it just muddies up things.

You should also look into Pro drivers such as the Eminence Kappa Pro, not cheap but they will stand up to constant high power use such as DJ / club work.

btw - that Pyle driver is meant for in vehicle use and uses the closed "cabin gain" of the vehicle for most of it's punch - a very bad choice for what you are trying to build......
 
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pikipupiba

Member
2010-11-03 7:09 pm
Well crap haha. I would say the most important thing is cheap. It's not that I don't want to spend the money, I just don't physically have the money, so cheap is the front and foremost concern. I already have this driver, so any suggestions that don't involve spending more money?
 
Since Pyle doesn't publish any specs let alone the t/s parameters for that driver there is not much I can do to help. Put it in a car and it will probably sound OK, but try to design an enclosure for your use without the t/s parameters for that driver is just a crap shoot, sorry....

You could just try it in a 2 cu ft sealed box with medium amount of stuffing, won't be ideal but should be reasonable.
 
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tb46

Member
2006-01-09 7:04 pm
Texas
Hi pikipupiba,

If you already have the speaker on hand, you could measure the T/S parameters, and at least you would have a starting point. If you don't know how to do this try the google. If you haven't bought it yet, I'm with djk, and the salt mine.

Regards,
 

nac134

Member
2008-09-04 1:47 pm
Qtc is something you pick. 0.7 is usually what you are aiming for. You dont need to understand why, as long as you can figure out how to achieve it.
What will you be using to drive these subs? Are you using a mixer or a crossover? Yes you can get some slam out of those woofers. You also mught want to consider a sealed box - it will be much easier to build, and will give you more reliability out of those low priced woofers.
 
Thanks! Is there a reason I want to aim for 0.7? I know that 0.5 is 'transient perfect', but what does that mean? When I plug 0.7 in to my equations I get a negative number for my box volume. A Qtc of 0.75 (equal to Qts) would give me a box volume of 0, so it would need to be higher than that, right? Or am I using the wrong equations?

Here are the equations:

alpha= (Qtc / Qts)^2 - 1
Vb = Vas / alpha

The amps I am using are in my initial post. I am just running the sub signal out of one amp into the input of another. They are both the amp in my initial post.
 
I am using a PYLE PLCHW15 driver and 3/4 inch MDF..The Loudspeaker Design Cookbook is my main source so far..Using the book, I have decided the size of the box should be 4.57 cubic feet..

Hi, A wild guesswork:

b:)
 

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Here are the equations:

alpha= (Qtc / Qts)^2 - 1
Vb = Vas / alpha
That looks right, Here's how it works:

The driver starts with it's own resonant frequency (Fs) and Q (Qts). When you stick it in a sealed box, the resonant frequency and Q both go up.

The smaller the box, the greater the increase. That's why Dave says "large box" - because you don't want to push Q up too high.

Note you can't get Q lower than what you started with, hence the silly "negative box size" answers from the calculator when you try.

Apparently the relevant TS specs for your drivers are: Fs:21.2 Hz, Qts:0.75, Vas 5.204 Cu ft, so you can forget about getting a system Q of 0.5 or 0.7.

However you can get BASS and you can get LOUD. For one driver, a box of about 5 cu ft should give you a resonance frequency of about 30 Hz and a Q of about 1.1. Sounds good to me.

For max SPL, you'd need something more complicated like a reflex box or horn, but that would require fiddling around with modeling software to sort out the design.

Cheers - Godfrey

edit: I see Bjorno's done some homework for you:)
 
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Don't be discouraged by what some people say about your choice
of woofer.
When I was 18 I was doing house and dub parties with my trusty
Realistic MPA 100 amp and two radio shack 15" ers in 7 cu.ft
boxes and it worked.
Now I have a much bigger rig for MUCH bigger gigs and by chance
I had to replace two 21"s with two 18" Pyramid OUSX woofers into
existing boxes for a party of 70 in a 60'x60' hall. I drove them
with a Crest 5500 and they took it like champs.
Even with all those dancing waterbags my eyeballs were still
bouncing around.... So yes you can make anything work, as long
as its set up properly:)
 
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