An externally hosted image should be here but it was not working when we last tested it.
2x10" drivers running in isobaric configuration, using MiniDSP for crossovers,
Housed in two attached, sealed 36cm Ikea Blanda bowls. A wooden frame would hold a detached granite slab for the bowls to sit on, spikes in-between the ground/wooden frame & granite/metal bowls.
Thoughts?
The depiction appears to be of the push push variety with the bowls connected at the bottom. Push push being a force cancellation strategy would not require the granite...
Yes they would run push pull. If im right in thinking this allows the cabinet size to be half of the recommended size.
My hi fi racks and orb like speakers all sit on granite (kitchen counter savers sm £4 lrg £9) these help to isolate vibrations and give a sturdy base thats cheaper than the oak, really flat and really stable.
For £20 on metal spun bowls, £9 granite, £4 spikes and £6 oak with a small sheet of mdf, £45 +/- I think I could be a great sounding and looking enclosure.
Looking at the peerless xls 10". Any have any idea how to model this?
My hi fi racks and orb like speakers all sit on granite (kitchen counter savers sm £4 lrg £9) these help to isolate vibrations and give a sturdy base thats cheaper than the oak, really flat and really stable.
For £20 on metal spun bowls, £9 granite, £4 spikes and £6 oak with a small sheet of mdf, £45 +/- I think I could be a great sounding and looking enclosure.
Looking at the peerless xls 10". Any have any idea how to model this?
Ps. This design also only needs two holes cutting in a round piece of mdf. With a good router it could be constructed within a hour or two.
Maybe you could also consider Scan-Speak 26W/4558T00 in addition to Peerless 10" XXLS/835016. The Scan-Speak has a lower free-air resonance frequency and might achieve lower total Q in a similarly sized enclosure.
http://www.scan-speak.dk/datasheet/pdf/26w-4558t00.pdf
"If im right in thinking this allows the cabinet size to be half of the recommended size. "
Sorry, that's not isobaric. The drivers will have to work in whatever size the bowels are. I would run them Push-Pull and use a Linkwitz transform.
Sorry, that's not isobaric. The drivers will have to work in whatever size the bowels are. I would run them Push-Pull and use a Linkwitz transform.
To be isobarik the drivers need to be couple together driving the same volume (with a small coupling cavity between the 2 drivers (ie 2 drivers act as a single compound driver). I can dig out pictures to illustrate if necessary.
I would go push-push over push-pull (cancelling 2nd order without doing anything about 3rd order creates a non-monotonic series of harmonics). Besides, push-pull probably wouldn't fit this configuration of half-spheres.
dave
Ok thanks Dave, let me try and be clear, as my understanding seems to be way off.
My goals were to try and design a sub, using two drivers to cancel/dampen each others forces, making a non-vibrating cabinet (within reason). And I believed that you could use two large drivers running in push-pull our isobaric to allow for a far smaller cabinet than if run normally (or a far bigger driver)
These bowls could be two separate sealed units, however joining them seemed to make more sense, a larger overall volume of air and the rear pressure form each driver canceled or balanced by the opposite movement of the other, as a passive radiator would work.
I saw these on the Voodoo thread, and thought they looked amazing, just didn't want to have to cut the metal, and thought this would lead to a more interesting design.
Am I right in thinking my sub would be omnidirectional? As its not got a baffle but is coming from a small slot.
Does anyone know how to model this?
My goals were to try and design a sub, using two drivers to cancel/dampen each others forces, making a non-vibrating cabinet (within reason). And I believed that you could use two large drivers running in push-pull our isobaric to allow for a far smaller cabinet than if run normally (or a far bigger driver)
These bowls could be two separate sealed units, however joining them seemed to make more sense, a larger overall volume of air and the rear pressure form each driver canceled or balanced by the opposite movement of the other, as a passive radiator would work.
An externally hosted image should be here but it was not working when we last tested it.
I saw these on the Voodoo thread, and thought they looked amazing, just didn't want to have to cut the metal, and thought this would lead to a more interesting design.
Am I right in thinking my sub would be omnidirectional? As its not got a baffle but is coming from a small slot.
Does anyone know how to model this?
All subs are omnidirectional.
Isobarik will halve the volume needed for the same box Q, but one has to account for the overhead of the coupling chamber (or live with a magnet sticking out). A smaller coupling chamber is better.
A single pair of drivers in an isobarik cannot be push-push -- well they can, but the complexity & end volume makes the point moot. To do isobarik and push-push you need 4 drivers (top figure).
dave
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"(cancelling 2nd order without doing anything about 3rd order creates a non-monotonic series of harmonics). "
Then you must not like servo subs either.
I've listened to both, and prefer not to have the 'mud'.
Then you must not like servo subs either.
I've listened to both, and prefer not to have the 'mud'.
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Never heard a servo sub.
If you use good drivers, push-pull gains you little (ref Llambda Nick), and reduces the effectiveness of force cancelation. So i use good woofers & choose to maximize force cancellation.
The only mud is out in the yard after it rains.
I do have a pair of pushpush-pushpull box in the works, my thinking being that to do push-push without sacrificing force cancellation one needs to use 4 woofers/box.
dave
If you use good drivers, push-pull gains you little (ref Llambda Nick), and reduces the effectiveness of force cancelation. So i use good woofers & choose to maximize force cancellation.
The only mud is out in the yard after it rains.
I do have a pair of pushpush-pushpull box in the works, my thinking being that to do push-push without sacrificing force cancellation one needs to use 4 woofers/box.
dave
Thanks for the images.
So is the consensus push-push will be best?
Have been eying the Peerless XLS10 on ebay £69, half the cost of the Scan-Speak. Will they work, will they be good? Any better recommendations?
Peerless XLS10 Subwoofer P830452 Loudspeaker - Speaker. | eBay
Here are the specs:
Specifications
Nominal Impedance (Ohms)
Zd
4
Min Impedance
Zmin
5.2
DC Resistance (Ohms)
Re
3.6
Voice Coil Inductance (mH)
Le
0.99
Resonant Frequency (Hz)
Fs
22
Mechanical Q Factor
Qms
3.86
Electrical Q Factor
Qes
0.24
Total Q
Qts
0.23
Moving Mass (g)
Mms
136.6
Suspension Compliance (mm/N)
Cms
390um/M
Effective Cone Diameter (cm)
D
21.1
Effective Piston are (cm2)
Sd
349.7
Equivalent Volume (Ltrs)
Vas
66.90
Force Factor
Bl
16.75
Reference Voltage Sensitivity
dB
86.6
Weight of Magnet (kg)
2.42
So is the consensus push-push will be best?
Have been eying the Peerless XLS10 on ebay £69, half the cost of the Scan-Speak. Will they work, will they be good? Any better recommendations?
Peerless XLS10 Subwoofer P830452 Loudspeaker - Speaker. | eBay
Here are the specs:
Specifications
Nominal Impedance (Ohms)
Zd
4
Min Impedance
Zmin
5.2
DC Resistance (Ohms)
Re
3.6
Voice Coil Inductance (mH)
Le
0.99
Resonant Frequency (Hz)
Fs
22
Mechanical Q Factor
Qms
3.86
Electrical Q Factor
Qes
0.24
Total Q
Qts
0.23
Moving Mass (g)
Mms
136.6
Suspension Compliance (mm/N)
Cms
390um/M
Effective Cone Diameter (cm)
D
21.1
Effective Piston are (cm2)
Sd
349.7
Equivalent Volume (Ltrs)
Vas
66.90
Force Factor
Bl
16.75
Reference Voltage Sensitivity
dB
86.6
Weight of Magnet (kg)
2.42
A 36cm Hemisphere is approx 12 Litres.
Insert a 12m baffle with cutout and you down to 11.5 Litres! Subtract the driver volume from that again then calculate the bass response for a sealed cab. Methinks it might roll off quite high for a bass cab.....
Insert a 12m baffle with cutout and you down to 11.5 Litres! Subtract the driver volume from that again then calculate the bass response for a sealed cab. Methinks it might roll off quite high for a bass cab.....
@Xoc1 any way to help this along? The two cabinets will be joined i reckon a total of 19L.
Could run x4 like Planet 10's first picture the gap containing 2 magnets sticking out?
Would always rather have less better quality drivers than more cheap ones.
@djk, any recommendations for a 6-1/2" sub woofer?
I hear lots of people talking about Tang Band, just seem really hard to find in the UK.
Tons of drivers on eBay, hard to filter out the less than ideal stuff.
Could run x4 like Planet 10's first picture the gap containing 2 magnets sticking out?
Would always rather have less better quality drivers than more cheap ones.
@djk, any recommendations for a 6-1/2" sub woofer?
I hear lots of people talking about Tang Band, just seem really hard to find in the UK.
Tons of drivers on eBay, hard to filter out the less than ideal stuff.
These'll do the job.
W6-1139SIF - TB speakers 6 inch paper cone subwoofer - Europe Audio
I use mine (earlier Neodymium version, basically the same) in a 11L ported box each and think they're brilliant.
They'll go lower, louder, in tapped horns, but the THs I used were many times that cabinet volume.
Watching with interest
Chris
W6-1139SIF - TB speakers 6 inch paper cone subwoofer - Europe Audio
I use mine (earlier Neodymium version, basically the same) in a 11L ported box each and think they're brilliant.
They'll go lower, louder, in tapped horns, but the THs I used were many times that cabinet volume.
Watching with interest
Chris
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