My throw-together cheap subwoofer

nobody special · 3rd February 2003, 05:50 PM

I decided to build a subwoofer...
I'm using 8 MCM 55-1190 8" drivers in a 12 cuft. sealed enclosure, with a Parts Express 250W sub amp. I plan on using electronic enhancement to extend the low end. This is kind of a throw-together project, but I thought someone might be interested. Let me know, and I'll post some pictures of the cabinet. It looks like a coffin (in size, at least).
It is 72-1/2" tall X 15-1/2" wide X 24" deep! Fun fun fun...

SY · 3rd February 2003, 05:52 PM

Did you do anything special to keep those big panels from vibrating?

Coffins. Love it.

nobody special · 3rd February 2003, 05:57 PM

I've got a couple shelf braces in there, and I plan to throw a few 2"X.75"pieces from panel to panel to try and stiffen things up a little...
I did all the cutting yesterday, and the panels have some bracing screwed / glued in. I plan on assembling the cabinets tonight.
Got any ideas that are cheap and easy? (for bracing, that is).

SY · 3rd February 2003, 06:01 PM

My refrigerator-sized units use 2x4s and carriage bolts. That's pretty cheap and easy.

nobody special · 3rd February 2003, 06:13 PM

Quote:

refrigerator-sized units

Cool... what do you have in them?

I like the 2x4 and carriage bolt idea.

I was thinking of gluing/screwing some .75" x 2" piece on end across the cabinet walls- (think fins). I'm already afraid I won't be able to get them out of the basement!

SY · 3rd February 2003, 06:55 PM

Drivers? They're modified JBL 2245Hs with accelerometer servo driven by a chopped Adcom 555. It's a multiamped setup; the woofers are currently lowpassed at 70Hz, 4th order L-R.

I got a deal on the drivers, which made the whole thing less painful than it might have been otherwise.

BAM · 3rd February 2003, 07:49 PM

Tell us more about your accelerometer setup. There have been many rumblings around here about a DIY motional-feedback setup, and I want to know how you did it.

SY · 3rd February 2003, 08:01 PM

I got some freebies from AD. They're +/-100G full range, mounted on the inside of the voice coil former near where the dust cap attaches. As soon as I figure out the $#@&ing schematic drawing software, I'll put the interface up- it's all opamp-based, fed back to the input of the Adcom. Nothing unusual or exotic, just filtering and phase adjusting.

The resulting woofer system is flat (small signal) to a little below 15 Hz.

I have a better idea on how to do this which could be cheaper, better, and more amenable to the typical DIY (less driver surgery), but I need the assistance of someone who really knows their stuff regarding microcontrollers and other digital stuff. Any potential collaborators, preferably in the Bay Area, please email me.

e96mlo · 3rd February 2003, 09:15 PM

I too am interested in your setup so a schematic would be nice.

Did you follow the appnote on Analog's site?

/Marcus

SY · 3rd February 2003, 09:17 PM

Quote:

Originally posted by e96mlo

Did you follow the appnote on Analog's site?

/Marcus

No, I didn't see the app note. I'll go take a look.

3rd February 2003, 05:50 PM	#1
nobody special diyAudio Member Join Date: Oct 2002 Location: USA	My throw-together cheap subwoofer I decided to build a subwoofer... I'm using 8 MCM 55-1190 8" drivers in a 12 cuft. sealed enclosure, with a Parts Express 250W sub amp. I plan on using electronic enhancement to extend the low end. This is kind of a throw-together project, but I thought someone might be interested. Let me know, and I'll post some pictures of the cabinet. It looks like a coffin (in size, at least). It is 72-1/2" tall X 15-1/2" wide X 24" deep! Fun fun fun...

3rd February 2003, 07:49 PM	#7
BAM diyAudio Member Join Date: Sep 2001 Location: Carmel, IN; West Lafayette, IN	Servo Control Tell us more about your accelerometer setup. There have been many rumblings around here about a DIY motional-feedback setup, and I want to know how you did it.

3rd February 2003, 08:01 PM	#8
SY diyAudio Moderator Join Date: Oct 2002 Location: Chicagoland Blog Entries: 1	accelerometer I got some freebies from AD. They're +/-100G full range, mounted on the inside of the voice coil former near where the dust cap attaches. As soon as I figure out the $#@&ing schematic drawing software, I'll put the interface up- it's all opamp-based, fed back to the input of the Adcom. Nothing unusual or exotic, just filtering and phase adjusting. The resulting woofer system is flat (small signal) to a little below 15 Hz. I have a better idea on how to do this which could be cheaper, better, and more amenable to the typical DIY (less driver surgery), but I need the assistance of someone who really knows their stuff regarding microcontrollers and other digital stuff. Any potential collaborators, preferably in the Bay Area, please email me.

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3rd February 2003, 05:52 PM	#2
SY diyAudio Moderator Join Date: Oct 2002 Location: Chicagoland Blog Entries: 1	Did you do anything special to keep those big panels from vibrating? Coffins. Love it.

3rd February 2003, 05:57 PM	#3
nobody special diyAudio Member Join Date: Oct 2002 Location: USA	I've got a couple shelf braces in there, and I plan to throw a few 2"X.75"pieces from panel to panel to try and stiffen things up a little... I did all the cutting yesterday, and the panels have some bracing screwed / glued in. I plan on assembling the cabinets tonight. Got any ideas that are cheap and easy? (for bracing, that is).

3rd February 2003, 06:01 PM	#4
SY diyAudio Moderator Join Date: Oct 2002 Location: Chicagoland Blog Entries: 1	My refrigerator-sized units use 2x4s and carriage bolts. That's pretty cheap and easy.

3rd February 2003, 06:55 PM	#6
SY diyAudio Moderator Join Date: Oct 2002 Location: Chicagoland Blog Entries: 1	Drivers? They're modified JBL 2245Hs with accelerometer servo driven by a chopped Adcom 555. It's a multiamped setup; the woofers are currently lowpassed at 70Hz, 4th order L-R. I got a deal on the drivers, which made the whole thing less painful than it might have been otherwise.

3rd February 2003, 09:15 PM	#9
e96mlo diyAudio Member Join Date: Apr 2002 Location: Helsingborg, Sweden	I too am interested in your setup so a schematic would be nice. Did you follow the appnote on Analog's site? /Marcus

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