"Need Major Help On DIY Sub" - Page 2

HO = small/average sized ported box

HF = large sealed box/huge ported box

Also the HO requires quite a bit more power. If you don't mind a huge ported box you can save money on the amp with the HF.

ep4000 for (2) 15" HF's? Yes, that would more than do the trick. I can't remember exactly but I think it puts out around 600 watts per channel at 4 ohms which is actually a little too much, so if you hear distortion don't push it any further. When I had my HF tuned to 18hz with only 300 watts I could push it to distortion, so it isn't very power hungry.

if you have plenty of space for a sub, build an F20 or THT (as mentioned earlier). You will spend less on drivers and have less of a power requirement. Even a decent home stereo receiver or amplifier will give you surprising output, you may already have something like this laying around. YOu will need an eq, but for $50 on ebay you could pick up a Beringer Feedback Destroyer and use as a parametric EQ. OR....get an INUKE 1600DSP or 3000DSP, which will have the eq and limiters built in.

I thought about recommending that but he doesn't want anything huge. If it were me I would sell the svs and build (4) F20's and not have to spend a dime.

Whoops posted the svs response in the wrong thread...

If you do the 27hz box the EP4000 is all you need (30hz HPF). If you go with a 20hz tune you will need a different HPF. With the 27hz box you could actually dump 2000 watts from a single bridged ep4000 into each sub without bottoming it (might melt the driver though). With the 20hz tune a single ep4000 channel at 650 watts is a perfect match.

You can incorporate the 8"s, not sure which model they are? Obviously they wont be able to keep up at full output, but smoothing the response at lower levels is possible.

The ep4k will work but you will need a different high pass filter. The feedback destroyers are used for their parametric EQ abilities and because they work with REW.

A high pass filter will cut off the frequencies below what you set it at. Ported designs need one because the driver will unload once past tuning and damage itself. It's a safety.

I believe the Minidsp allows you to set hpf's. then you could use it for that and a sub EQ. You would want the balanced version with that amp.

The EP4K has either a 30hz or 50hz filter. It's a pro audio amp, there's no need for a 20hz setting.

Well the inuke 3000dsp amp is $293 at amazon right now. It has a 20hz hpf and EQ.

I wonder if anyone has experience with these. Would be a cheap way to still use a ep4k

http://www.parts-express.com/pe/showdetl.cfm?partnumber=266-246

Yes if it works as advertised. I don't see why it wouldn't. I would make a call to Parts Express to verify. Unless someone is familiar with them.

I'm not familiar with them, but have heard bad things. I was going to us them before but was shot down by reputable avs members. I don't remember who and when but you could look through all of my posts if you wanto to find out why.

As stubborn as I am I would still like to know how they work, even though I was told no...

They do work, but not very well. Being passive their high pass frequency is defined by the input impedance of the device being driven. As that's not a standard value for amps the actual high pass frequency could range anywhere from 5 to 50Hz.

That won't work then.

IME all they're good for is blowing drivers. Put the money into a DSP.

I've used the FMODs, they have their place but I don't like the non-adjustability of them. It was great for throwing together a quick system with an extra amp and sub, back before we had the tools like BFD and miniDSP but unless you get lucky and have just the right one, you almost need to try a couple. And it seemed like it dropped the level of the freqs I wanted to pass a bit too but I could be wrong on that part.

That box is about 1 ft3 larger then you were originally discussing. A pair of 3x17 ports will tune you to 18hz, if you cut them down to 13.5" you will have 20hz. You could even do three 3x17 ports (think svs ultra) for a 23hz tune. The pair of 4x17 ports would actually tune you to 24hz now in this larger box. Just make sure you put some kind of a cross brace or two in there.