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Subwoofer: Buy or build?
- Thread starter Brett a
- Start date
If you are going to go stereo there is nothing wrong with the 4 ohm impedance of the Ultimax drivers.
And in the event of a fan being too noisy it is very simple item to replace it with a quieter model. Tons of em out there that can be a drop in for stock fan.
I would also have suggested this as a high value option but usually get alot of negative response with Behringer for some reason. Fine bass amps.
Brett a
~◦●○o0o○●◦~
I'd like to avoid a fan if at all possible. My listening room can get down to 26 dbs. I know you can get sub-25db fans, but for now, I'll look elsewhere.
I have a Rolls PA amp in the barn, which I thought was low-power. Turns out it's 200w bridged into 8 ohms which isn't totally out of the question.
I've also got a pile of other PA gear FWIW; a paramatric EQ, a mic mixer, gain manager and feedback killer.
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It probably won't like running two subs bridged so I suppose 100W/sub might be a little wimpy, but you could try it, especially if the drivers you choose aren't too low sensitivity. I was just going to say (as ray already kinda suggested) that you could buy a stand-alone DSP crossover to use with an amp you already have as yet another option similar to the pro amps with built-in DSP suggested above.
Brett a
~◦●○o0o○●◦~
Ok.....
Here's where I am in my planning now.
Two usedLambda SB12 raw drivers for which I will build two separate boxes 16"x16"x20 each = 2.25 cubic feet.
This is how they graph. Pretty good, eyh? You can see they chart identically to the woven glass 2 ohm DVC Daytons I was looking at earlier. But the Lambda's are 8 ohm.
I'm thinking I could drive them both with a 500 watt (into 4 ohms) Yung SD500 500W Class D Subwoofer Amp
http://www.parts-express.com/pe/showdetl.cfm?partnumber=301-512
B/C if I run the two subs in parallel, the amp would be seeing a 4ohm load, yes? Would 500 watts into 4 ohms driving two subs work ok for the type of listening I do? (I'm just trying to learn this stuff as I go)
Here's where I am in my planning now.
Two usedLambda SB12 raw drivers for which I will build two separate boxes 16"x16"x20 each = 2.25 cubic feet.
This is how they graph. Pretty good, eyh? You can see they chart identically to the woven glass 2 ohm DVC Daytons I was looking at earlier. But the Lambda's are 8 ohm.
I'm thinking I could drive them both with a 500 watt (into 4 ohms) Yung SD500 500W Class D Subwoofer Amp
http://www.parts-express.com/pe/showdetl.cfm?partnumber=301-512
B/C if I run the two subs in parallel, the amp would be seeing a 4ohm load, yes? Would 500 watts into 4 ohms driving two subs work ok for the type of listening I do? (I'm just trying to learn this stuff as I go)
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JimPA
Distinguished Member
Eminence has a nice page about understanding loudspeaker data.
http://www.eminence.com/support/understanding-loudspeaker-data/
http://www.eminence.com/support/understanding-loudspeaker-data/
Brett a
~◦●○o0o○●◦~
The red line is there...sort of.
If I adjust the box volume just a little so that the Lambda's curve changes slightly, I see that the red line is actually tucked behind the green line; they plot exactly the same!
So I have a pair of these on the way:
They are Lambda LE-SBP12-8 They were hand built in Florida by Nick McKinney back around 2000-01 or so. They do require a rather large box, even sealed. But I'm going for it!
Now, can someone tell me if I can drive them with one plate amp that's rated for 500 watts down to 4 ohms? Like the Yung SD500 500W Class D Subwoofer Amp at PE?
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donprice
Wound up workin' at a gas station....
Just in case you didn't find this already...
http://web.archive.org/web/20021124082847/www.stryke.com/SAL-SB12.htm
http://web.archive.org/web/20021124082847/www.stryke.com/SAL-SB12.htm
Brett a
~◦●○o0o○●◦~
That's probably enough to get you to xmax. Boxes seem a little small even for heavily stuffed... what is your software giving you for Qtc?
Brett a
~◦●○o0o○●◦~
WinISD came up with this:
9.5 cubic feet
0.71 Qtc
When I changed the box volume to 2.5 cubic feet, to gives me 1.01 Qtc
Is that bump going to cause me problems? (you can probably tell, I'm kinda' treading water here; close to going in over my head)
Here's how it graphs in WinISD in a 2.5 cubic foot sealed box:
.
9.5 cubic feet
0.71 Qtc
When I changed the box volume to 2.5 cubic feet, to gives me 1.01 Qtc
Is that bump going to cause me problems? (you can probably tell, I'm kinda' treading water here; close to going in over my head)
Here's how it graphs in WinISD in a 2.5 cubic foot sealed box:
.
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1 dB hump is nothing to worry about, but a heavily stuffed box will drop the Q a bit and that will go away anyway. In WinISD (pro), you can click "advanced" under the "box" tab and change Qa to 5 - that'll be closer to what you'll get. I think your other software was already doing that for you. The optimal box is probably more like 4 ft³, and maybe really not significantly different in practice. I'm not gonna pretend like I know. The ~2dB at 30Hz difference would probably be more noticeable than any of the more murky theoretical differences. I would definitely not go any smaller than what you've got there, though, so at least bump it up to subtract the volume of the driver and any bracing, etc.
