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DIY crossover for subwoofer (1 Viewer)

Dave_Gib

Stunt Coordinator
Joined
Oct 1, 2002
Messages
81
I still haven't found a grill to cover the hole, I need to look harder

I did get the amp, I hooked it up to a coulpe of high excursion car audio subwoofers in a 3 cu.ft. ported box tuned to ~30 Hz

I have watched some movies, played some video games, and listened to music, I see now why you guys tune your subwoofer enclosures down in the low 20's - mid teens

the output out the back of my reciever sounds like it's a LPF 80Hz with not too steep a roll off, it's not good for the subs at all, and very directional, kinda annoying

I helped it out with my twin 30 band EQ, but it's not a permanet solution, I went and got a wall wort at PE, I found one that said 120 AC to 12V 4.5 amps, and thought it would be perfect to power my little car audio xover, then I got home and looked at it, it's 12v AC 4.5 amps, didn't say that on the outside of the box, that's what I get for assuming

I guess what I will be looking for eventually is some type of EQ that has crossovers in it

I'm taking my time getting into this HT stuff, but I can see myself turning into a junkie, don't know if that's good or bad
 

Arthur_King

Stunt Coordinator
Joined
Jun 14, 2002
Messages
62
I dont know what the problem is with your 80hz rolloff, but a LF crossover is probably one of the easier things to build. Any x-over design software can get you there.

I would highly recommend not trying to "put the square peg into the round hole" by trying to power your Car crossover in the home. You're better off either buying a real BFD, or build a simple filter to roll your freqs off steeper. You do realize that with your tune at ~30hz you have a lot of sub 25hz (hell even sub 15hz in some movies) content that's getting to your subs and thats rough when its below tuning...

Daffy Arthur King
with the brain of a duck
 

Dave_Gib

Stunt Coordinator
Joined
Oct 1, 2002
Messages
81


yeah, I did bottom them out playing video games, but I wont watch movies loud enough to do any damage, I'm not worried about them too much, they've seen much worse abuse

I got to do something for now, I can't see any problems from using a car crossover in the house, what could go wrong?

Anybody know of any EQ's that have crossovers in them, for less than $500?

is there any good, free x-over design software out there?

ever used an FMOD? http://www.hlabs.com/colors/
 

ThomasW

Senior HTF Member
Joined
Nov 6, 1999
Messages
2,282
F-Mods are fine for car audio, and or bass shakers where the roll-off slope isn't critical. They don't work very well with home subs.

There's only one EQ to get for a home sub, and that's to use a Behringer DSP-1124P aka the feedback destroyer.

You already have a fairly good XO in your receiver.

Unless a sub is in-line with and centered between the mains, a good pair of ears can ALWAYS locate a sub as a pressure source.

The fact that you have the sub basically sitting beside you in going to be a problem. There's no piece of gear that can fool the ear into thinking the sub is elsewhere.

I see your multiple statements about duplicating the effects of your truck sub in your HT. Note that a room is a MUCH different acoustic environment from that of a car/truck.

This is fundamentally impossible in a room unless you want to spend several thousand dolars. The amount of lift from cabin gain is much more than room gain from your house.

So you have a few of options. Change your expectations, put a TV on the hood of the truck, or get ready to spend A LOT more money!
 

Dave_Gib

Stunt Coordinator
Joined
Oct 1, 2002
Messages
81


I read that on these forums in one of my searches, when I brought it up at parts express the guy looked at me like I was crazy, oh well, silly salesman.

Parts express has Behringer products now, they had another Behringer product there that was just a crossover, for $90, I thought about it but spent $20 on the wrong adaptor anyway.

When I said I wanted my living room to sound like my truck I wasn't talking about being that loud, that's a little crazy, I want the subs to sound as good, and get as deep, sound as crisp, basically to sound natural

and of course that didn't happen overnight

when I build ported boxes for a vehicle, I use a 10" test sub in a sealed box, I put it inside the vehicle where I plan on putting the box, run single freqs from 20Hz up to about 70, measure the results, compare it against what the sub does without reinforcement, and build from there

what should I do to get ready for an IB?
 

ThomasW

Senior HTF Member
Joined
Nov 6, 1999
Messages
2,282
This thread is going in circles.

Where are you going to put the IB? Is there a crawlspace or basement below the sofa?

Or are you talking about a movable sealed box?
 

ThomasW

Senior HTF Member
Joined
Nov 6, 1999
Messages
2,282
Just make a box with the largest opening possible into the listening room.

For the best performance from a single manifold containing 4-15" drivers, the opening should be no smaller than 15" square.

If you plan on using fairly small cold air return grates as covers then there's no reason to use 4 drivers, unless you're going to have two manifolds and two openings. Using too small an opening basically creates a bandpass sub. Overly small openings will work but don't provide optimal performance.

I recommend making the manifold from 1.5" thick material. A good way is to laminate a layer of MDF, on the outside with an inner lining of OSB. The OSB provides both strength and a surface where you can mount T-nuts to hold the drivers.
 

JeremiahW

Auditioning
Joined
Mar 17, 2005
Messages
1
I plan on getting a BFD myself, but I do not believe it has a LPF built into it. I DO NOT have a suboutput from a receiver. I simply have a full range preamp to send to an amplifier and I need a low pass filter! Can someone please suggest a solution for low passing at ~35-40Hz?
 

Mattak

Stunt Coordinator
Joined
Dec 15, 2003
Messages
247
I'd also be interested in a solution to the original poster's question. Mainly a DIY active low pass filter.
 

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