Please look over my subwoofer design

[50 watt head]

I have one of these (door prize):

http://www.madisoundspeakerstore.com...d22rn4x-h1192/

and I'm finally getting around to designing a subwoofer. This will be for 2.1 music and movies in our small (14' x 14') living room.

Lou has kindly donated a matching Seas H9946 10" passive radiator to my cause (thanks Lou! ). I plan to use the 240W Dayton plate amp, and my receiver to high pass my mains @80Hz.

I'm attaching screenshots of what I've got so far; please let me know if you see any problems or concerns. Thanks!

[johnnyrichards]

The Seas is actually a 7mm Xmax driver, the spec sheet calls it 14mm P-P. It may be capable of mechanical excursion greater than the 7mm, though.

I think if you pay close attention to the volume knob, it would sound fine but it will easily get ugly on you with the limited excursion

[50 watt head]

The Seas is actually a 7mm Xmax driver, the spec sheet calls it 14mm P-P

Oh, now that *is* a bummer! Back to the drawing board

[daryl]

Oh, now that *is* a bummer! Back to the drawing board

The design is very nice but 50 watts will be all it needs.

I don't know if 100db halfspace will be enough for you.

[contoursvt]

I wouldnt give up on it. It will likely turn out to be a very nice sounding sub.

[50 watt head]

I wouldnt give up on it. It will likely turn out to be a very nice sounding sub.

Agreed, I think the Seas driver will make a nice sub. All the same, though, I think I will put it back in the closet, and save it for a project more suited to its strengths (probably pair it with the Dayton 70w amp) and gift it to someone.

[50 watt head]

Alright ... changed gears completely. Super simple!

This:

http://www.parts-express.com/pe/show...number=295-442

models very nicely in 30 liters sealed, without exceeding Xmax:

104dB @ 200w
F3 - 32 Hz
F6 - 27 Hz
F10 - 22 Hz

[fastbike1]

This driver models great in that alignment. However, there are persistent claims that it will "oil can" in a sealed box of ~ 1 ft3.

It's a diifficult choice because there are passionate claims on both sides. That is, experienced people have claimed to personally witness oil canning, while other experienced people have stated trouble free operation in similar boxes.

Good luck.

I can confirm your sim since I have similar results in 29 liters. It also looks good in 37 and 45 liter vented. I haven't modeled a PR version but expect it would mirror the vented results.

[50 watt head]

This driver models great in that alignment. However, there are persistent claims that it will "oil can" in a sealed box of ~ 1 ft3.

Ahh, yes ... I knew it was too good to be true

But, seriously, thanks for the heads-up. I'll take another look at the HO-versions. Too bad, since I liked the idea of an 8-ohm driver.

[50 watt head]

Well, no worries, I just modeled the RSS265HO-4, and it does as well in 30 liters sealed. Even at full 240W, I'm still coming in under Xmax.

F3/F6/F10 = 32/26/20 Hz @ 102 dB

[Chris Roemer]

Well, no worries, I just modeled the RSS265HO-4, and it does as well in 30 liters sealed. Even at full 240W, I'm still coming in under Xmax.

F3/F6/F10 = 32/26/20 Hz @ 102 dB

Maybe you're looking at a different RSS265HO-4 than I am, but I see more like 60Hz F3 in 30L Cb. It DOES look great though in 30L tuned to 22 Hz.

Chris

[50 watt head]

Maybe you're looking at a different RSS265HO-4 than I am, but I see more like 60Hz F3 in 30L Cb. It DOES look great though in 30L tuned to 22 Hz.

Chris, that's weird ...

I'm using Bagby's Woofer Box Designer, and working from the specs on the datasheet from PE.

I'll run the model again, and post some screenshots.

[Chris Roemer]

Chris, that's weird ...

I'm using Bagby's Woofer Box Designer, and working from the specs on the datasheet from PE.

I'll run the model again, and post some screenshots.

I guess +6dB @ 20Hz could do it.

[lunchmoney]

This driver models great in that alignment. However, there are persistent claims that it will "oil can" in a sealed box of ~ 1 ft3.

This statement requires its own discussion. Go here:

http://techtalk.parts-express.com/sh...d.php?t=228610

[edgecreek]

Can someone please tell me what is meant by "oil canning"?

[Chris Roemer]

Can someone please tell me what is meant by "oil canning"?

Just like when you push in on the Tin Man's chest hard enough to make it pop, with the "bawung" sound.

Like the little "cricket" clickers we had when we were kids. Like when you squeeze the sides of an old (metal) Energine bottle, or a "3-in-1" oil "can", back before they went plastic.

When some of the (thinner cones than the HO series) HF cones get highly pressurized - as in a small closed box, they can "oilcan". I've never heard one, but I can imagine exactly what it sounds like.

chris

[rpb]

Chris, that's weird ...

I'm using Bagby's Woofer Box Designer, and working from the specs on the datasheet from PE.

I'll run the model again, and post some screenshots.

The lowpass filter is altering the relative SPL. The potential problem is that the x-over -6 dB point is now about 150 hz. For a sub, that might not matter at all.

Do you need the 18 hz highpass filter? Many amps naturally roll off on the low end.

[fastbike1]

That model doesn't have boost. The screenshot shows that stage:OFF

I get similar, although my overall box size is smaller, it's still 29Liters net. I get F3/F10 33/20

rpb: The 18Hz hipass is what is built into the amp. I'm not seeing the 150Hz. The -6db at the high end is about 100 Hz given the 80Hz hipass settings

I guess +6dB @ 20Hz could do it.

[rpb]

That model doesn't have boost. The screenshot shows that stage:OFF

I get similar, although my overall box size is smaller, it's still 29Liters net. I get F3/F10 33/20

rpb: The 18Hz hipass is what is built into the amp. I'm not seeing the 150Hz. The -6db at the high end is about 100 Hz given the 80Hz hipass settings

Where's my glasses? The 10 dB scale fooled me. I'm so used to looking at 5 dB scales, I didn't notice.

[50 watt head]

Where's my glasses?