I have 8 KEF B139s and plan on using 4 per cabinet to
make a stereo pair of subs. I heard they work great in
TL, but for 4 units per cab, I think it would be too large
to build suitable enclosure for ordinary size living room.
Any other ideas on sealed box or passive radiator based
design?
They are SP1044 by the way.
Anybody else ever use multiple SP1044s in any type
enclosure?
make a stereo pair of subs. I heard they work great in
TL, but for 4 units per cab, I think it would be too large
to build suitable enclosure for ordinary size living room.
Any other ideas on sealed box or passive radiator based
design?
They are SP1044 by the way.
Anybody else ever use multiple SP1044s in any type
enclosure?
I once found a web site describing two B139s in an OB H frame Sub. It looked interesting and was quite a small enclosure, (if you can call it that). Four of them should be pretty cheap to make and might give you some good results. Unfortunately the link was on my Mac, which is currently dead, but google should help.
well you could...
build them into four "W frame" dipole cabinets that would be very compact and go as low as you will ever get them to go. Would make for excellent loading of the room with four cabinets distributed. There is a link in the Ripole thread somewhere if you are interested. Just found the link here...http://www.tech-diy.com/Dipol-Subwoofer.pdf Regards Moray James.
build them into four "W frame" dipole cabinets that would be very compact and go as low as you will ever get them to go. Would make for excellent loading of the room with four cabinets distributed. There is a link in the Ripole thread somewhere if you are interested. Just found the link here...http://www.tech-diy.com/Dipol-Subwoofer.pdf Regards Moray James.
You can use them in Isobaric configuration to reduce box size.
Isobarik: Also known as compound loading. By using two low frequency drivers (generally mounted face-to-face and wired electrically out-of-phase or mounted front-to-back in a shallow tube and wired electrically in phase) you can halve the volume of the cabinet without reducing the low frequency extension of the subwoofer.
http://www.audiogearreviews.com/tech/theory/enclosure_design/isobaric.asp
The Bricks (aka Linn Isobarik DMS) used two B139 (isobaric). Maybe not the best speaker but the bass is very good (and it makes me happy: ).
😀
Isobarik: Also known as compound loading. By using two low frequency drivers (generally mounted face-to-face and wired electrically out-of-phase or mounted front-to-back in a shallow tube and wired electrically in phase) you can halve the volume of the cabinet without reducing the low frequency extension of the subwoofer.
http://www.audiogearreviews.com/tech/theory/enclosure_design/isobaric.asp
The Bricks (aka Linn Isobarik DMS) used two B139 (isobaric). Maybe not the best speaker but the bass is very good (and it makes me happy: ).
😀
Have a look at what Linkwitz did way back with his breakthrough satellite & subwoofer system. Speaker Builder 1980 I think, it's on his website.
Dag....
Quote "You can use them in Isobaric configuration to reduce box size."
With "W Frame Dipole (Ripole)" there is almost no box at all and the design will reduce the driver Fs by about 7-10 Hz. Add to this the fact that you will also have directivity control (cardioid pattern) what more could you ask for? If you only want two cabinets then double up the 139's so they provide an almost square composite driver which should actually work better than running just two per cabinet as the height and depth ratio will be closer to being equal. Regards Moray James.
Quote "You can use them in Isobaric configuration to reduce box size."
With "W Frame Dipole (Ripole)" there is almost no box at all and the design will reduce the driver Fs by about 7-10 Hz. Add to this the fact that you will also have directivity control (cardioid pattern) what more could you ask for? If you only want two cabinets then double up the 139's so they provide an almost square composite driver which should actually work better than running just two per cabinet as the height and depth ratio will be closer to being equal. Regards Moray James.
moray james and everyone else:
You are right, no box is the smallest box! I do like the "W Frame Dipole"! It is a very clever design (I want to try one under my bed!!!)
But I have not heard one (yet!) so I do not know how they sound. I have heard the isobarics and I liked the sound. But I can't tell which one I like more. Has anyone tried both????
One advantage of a closed box (or isobaric) could be that the air in the box is linearizing the excursion of the woofer!? (Air pressure vs. volume is very linear) I think I red that somewhere.... But if you have 8!!! B139 that might not be an issue. 🙂
D
Hey, you Colorado and Calgary guys make me wanna go skiing......but the globalwarming is making Europe green : (
..and you UK guys make me want to drink beeeer : ) Thank G.. it's friday!!!!
You are right, no box is the smallest box! I do like the "W Frame Dipole"! It is a very clever design (I want to try one under my bed!!!)
But I have not heard one (yet!) so I do not know how they sound. I have heard the isobarics and I liked the sound. But I can't tell which one I like more. Has anyone tried both????
One advantage of a closed box (or isobaric) could be that the air in the box is linearizing the excursion of the woofer!? (Air pressure vs. volume is very linear) I think I red that somewhere.... But if you have 8!!! B139 that might not be an issue. 🙂
D
Hey, you Colorado and Calgary guys make me wanna go skiing......but the globalwarming is making Europe green : (
..and you UK guys make me want to drink beeeer : ) Thank G.. it's friday!!!!
Here's another idea. Use the four per side but use them in isobaric as well as opposed excursion. This will reduce the 2nd order distortion due to opposing cancellation effects. This will probably benefit the B139 greatly as the drivers from that era did not have the newer distortion reduction technologies that better drivers of today have.
Mikett said:
Push-push push-pull
This is the most effective way to do it from a distortion & reaction cancellation... not so high cosmetically. Front woofer removed in the sketch.
Make the box as big as you need -- in this configuration a box modeled for a single driver supports all 4.
For instance a 96in line, 6:1 taper ratio. So=2.25Sd, Sl=0.375Sd. Zdriver at 32.25in. Stuff 0.5lbs ft from the top of the line 80in along.
Sd = 55in^2
(2.25+0.375) x 55 = 145 in^2 (total cross-section area for a folded once box excluding partions. -- that is a box ~ 14" x 14" x ~50" tall (those exact wxd would need juggling to fit the drivers.
dave
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Thanks guys,
I know about adding slight mass to the cones to help
stagger resonance and I think that may be something I
incorparate into the design as well. Not sure how that
will work in P-P system if I use a slightly different res. freq.
for each driver. Will I get same distortion cancellation?
I'm pretty sure it wold work if I use to un-moded drivers
in opposition and two modified the same, but will four
different freqs work?
I would probably either drive all four in parallel (<2 ohms?)
or series/parallel combo with maybe an extra 16 ohm power resistor in each leg to lower and even out the impedance peaks.
I know about adding slight mass to the cones to help
stagger resonance and I think that may be something I
incorparate into the design as well. Not sure how that
will work in P-P system if I use a slightly different res. freq.
for each driver. Will I get same distortion cancellation?
I'm pretty sure it wold work if I use to un-moded drivers
in opposition and two modified the same, but will four
different freqs work?
I would probably either drive all four in parallel (<2 ohms?)
or series/parallel combo with maybe an extra 16 ohm power resistor in each leg to lower and even out the impedance peaks.
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