help me reverse engineer this sub

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all right, for my party sub you guys convinced me to go with an 18" Peavey to hit some crazy SPL levels on the power that I already have. I will be underpowering it a little bit, but it leaves room for expansion and it shouldn't be so bad that I get clipping all over the place.
http://www.partsexpress.com/pe/showdetl.cfm?&DID=7&Partnumber=294-301

In looking around for what would be the most suitable box design, I discovered that Peavey sells an already boxed version of the same subwoofer:
http://www.peavey.com/products/brow...mber/00571290/cat/256/QW%AE+118+Subwoofer.cfm

That's basically the sub that I want. I'm not too concerned about the size of the box I guess (though they've managed to keep it very small), but what do you guys think is going on in there as far as venting and construction is concerned?
 
it shouldn't be so bad that I get clipping all over the place.
What makes you think that?

Clipping is strongly advised against, if you're going that way you will soon find out why. An undersized clipping amp can easily destroy the VC. A more powerful amp will just speed things up a bit.

You will also find out that your warranty is useless when clipping is determined as the cause of failure.

As far as bracing concerned I don't think there is much more going on in there than some pieces of ply (3/4" x 4/6") on their sides, dividing the panels in halves or perhaps even thirds.
The vent is a typical one with such one bracing in the middle.

With kind regards Johan
 
I don't think I'll get clipping because I'm not underpowering it by that much. If it's noticeable I can always turn it down until I can put more power into it, but I really don't think it'll be a problem.

For construction - the box is trapezoidal and I'll want to maintain that. I'll use 3/4" Ply or MDF for construction. The vent is split in two by a brace, but I'm not sure how deep the vent goes. This one isn't exactly adjustable so is there anyone who could shine some light on that? (one of the modeling programs maybe?) The specs on the page say the vent has a long path length, but that could mean 8" or some complicated horn apparatus in there.

I'll probably do a rib brace in the main compartment, combined with the vent shelf and the brace that splits it I think that should be plenty sturdy..
 
Rademakers said:
What makes you think that?

Clipping is strongly advised against, if you're going that way you will soon find out why. An undersized clipping amp can easily destroy the VC. A more powerful amp will just speed things up a bit.

You will also find out that your warranty is useless when clipping is determined as the cause of failure.

As far as bracing concerned I don't think there is much more going on in there than some pieces of ply (3/4" x 4/6") on their sides, dividing the panels in halves or perhaps even thirds.
The vent is a typical one with such one bracing in the middle.

With kind regards Johan


I think there's a miscommunication here: He means "It's not so badly underpowered that the amp will clip much or often", not "I'll get clipping all the time, but that's not a big deal."
 
Hey i just bought 2 of the same exact subs. I'm planning on a 250 liter enclousre tuned to 25Hz. I'll probably build it out of birch ply and double the front and rear of the box. Let me know if you have any other plans.

I'm also planning on 2 of the EP2500's each running in bridged mono mode, it seems like the best bang for the buck.
 
Actually I lied, I meant a 450 liter enclosure, about 16 cubic feet, each tuned to 25 Hz. I'm also still contemplating a sonosub, but I'm not sure how well defined the bass is when you use them. I think it becomes more of a muffled bass response better suited for home theaters because its firing into the ground as opposed to at you. But I could be wrong, actually I do hope I am because it would be a lot cheaper to build it with sonotube. I just wish someone would tell me the difference, if there is any at all.
 
No problem there, its just that the EP2500 will output 1500 wrms, almost twice the rating of the lowrider. So the urge to turn it up will have to be quelled in order to keep the subs alive. If the EP2500 were to input its 1500 wrms, the sub would melt. In fact, I doubt the peavy could take its full rms rating if given it.

I do not have experience with Peavy, but several subs I have owned previously (none worth mentioning as I learned) cooked when they recieved their true rms rating.

Basically, just wanted to offer up the advice to watch how high you turn the dial, since the EP2500 (if rated correctly) could cook those subs in that configuration.
 
CARTRulz said:
The low rider takes 800 watts rms, 1600 watts program, and 3200 watts max. Well thats according to its user manual.


Whatever you say, chief.

If you or anyone is planning to pound the crap out of this woofer with more than the 800W rating (the others are just marketing numbers), you better put it in the small vented box and heed the warning about the low cut below 30Hz.

Linear mechanical sims show this woofer will be at its limits with just 100W at 20Hz. The spider in actuality will probably allow maybe twice this power before mechanical damage sets in at low frequencies. Note that the 800W rating is from 50-500Hz.

There is a reason thay use huge arrays of woofers at rock concerts....
 
Do you have a better sub in mind for my application? I'm using it mainly for music and cant afford to spend more than 1000-1200 total with drivers, box, and amp. I've got 4 floorstanding speakers with 15 inch woofers, and the main reason I chose 2 of the Peaveys is becasue of its 97db sensitivity rating. If you do please let me know, Id still be willing to eat the shipping costs to send em back.
 
CARTRulz said:
Hey i just bought 2 of the same exact subs. I'm planning on a 250 liter enclousre tuned to 25Hz. I'll probably build it out of birch ply and double the front and rear of the box. Let me know if you have any other plans.

I'm also planning on 2 of the EP2500's each running in bridged mono mode, it seems like the best bang for the buck.

I calculate:

Vb=190 L
Fb=34.5 Hz

Dont go with too big box, and low Fb. Enormius group delay, too long excursions. You will got much distorsion at low freq.
 
Some PA amplifiers have high pass filters Incorporated, most active crossovers and of course processors do.

will a single EP2500 clip when driving 2 of them, just one per channel?
Depends on you doesn't it?

As to down firing and muddy sound: My 18" TL's become more muddy when down firing, my 18" reflex (sonotube alike) become less muddy when downfiring.

I don't think I'll get clipping because I'm not underpowering it by that much. If it's noticeable I can always turn it down until I can put more power into it, but I really don't think it'll be a problem.
Ok, I misunderstood..

I don't know your requirements nor the rest of your system but for parties a good rule of thumb is: Estimate what you need, then double that.

Material: If you're going to move the cabinet (a lot) use ply (birch, the high price pays back). Vent: Nothing complicated in there just a vent. Trapezoidal: It looks better, it doesn't have much meaning other than that in that frequency range. It makes construction a bit more complicated too.

With kind regards Johan
 
500W RMS

Doesn't the trapezoidal box help a lot with standing waves? Is this one of those things that becomes less important with subwoofers because of the different wavelengths?

If it's not worth it to make the box trapezoidal I definitely don't want to worry about that construction headache.
 
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