Could that be due to, so called, cabinet ballooning? If so, would a small vent be useful to relieve the pressure?
As you talk about satellite we can deduct xover in the 60 to 100hz frq for xover. Let's say 80hz.
From my experience with recent 'metamaterial' like sorbothane it could work to decouple the sat. You may need to put some weight on them and pad under the sub box too.
If you really want to decouple the sat hang ropes from ceiling and fix them throug them. There is even some ceilling attaching method which could help decouple even more. But it's not practical for every place or every people. And you better be sure the location choosen is the (good) one.
From my experience with recent 'metamaterial' like sorbothane it could work to decouple the sat. You may need to put some weight on them and pad under the sub box too.
If you really want to decouple the sat hang ropes from ceiling and fix them throug them. There is even some ceilling attaching method which could help decouple even more. But it's not practical for every place or every people. And you better be sure the location choosen is the (good) one.
Internal pressure, modes and panel resonances are not particularly affected by this woofer arrangement. A small vent will not have a significant effect and a regular one will of course increase pressure.
reaction-forced cancelling
Even with a direct-coupled dual opposed woofer system, 100% vibration cancellation is not possible. It is, however, quite effective and vibration control percentage is waaaaaaay yonder higher than with a conventional front-mount.
I have built these devices and ran my hands all over the enclosure while loud music, with bass heavy content, is playing. Zero vibration exists for a major portion of the cabinet, but you can still feel "vibration" is some places along the side panels. WE must conclude this is a result of the air pressure forces created. The stiffer the enclosure walls, the less likely of ballooning.
Now, we ask, how much of this can be transferred to the enclosure above this, if that is the arrangement required? The short answer is, not much.
The ideal arrangement would be that of using "outboard subs". This is also known as a 4 piece system. Keep the distance between the main arrays, and the sub, to within 1/4 wavelength. If we use 80Hz as an example:
1130/80= 14.125 ----- 14.125/4= 3.53125 feet
If domestic protocols forbid a 4-pc system, then a decoupling attempt can me made. I have seen videos of those springy feet devices, sort of like shock absorbers, that are quite effective. Sorry, but the brand name escapes me at the moment. Some sort of iso-puck (?)
ISO-PUCK Series | IsoAcoustics
Even with a direct-coupled dual opposed woofer system, 100% vibration cancellation is not possible. It is, however, quite effective and vibration control percentage is waaaaaaay yonder higher than with a conventional front-mount.
I have built these devices and ran my hands all over the enclosure while loud music, with bass heavy content, is playing. Zero vibration exists for a major portion of the cabinet, but you can still feel "vibration" is some places along the side panels. WE must conclude this is a result of the air pressure forces created. The stiffer the enclosure walls, the less likely of ballooning.
Now, we ask, how much of this can be transferred to the enclosure above this, if that is the arrangement required? The short answer is, not much.
The ideal arrangement would be that of using "outboard subs". This is also known as a 4 piece system. Keep the distance between the main arrays, and the sub, to within 1/4 wavelength. If we use 80Hz as an example:
1130/80= 14.125 ----- 14.125/4= 3.53125 feet
If domestic protocols forbid a 4-pc system, then a decoupling attempt can me made. I have seen videos of those springy feet devices, sort of like shock absorbers, that are quite effective. Sorry, but the brand name escapes me at the moment. Some sort of iso-puck (?)
ISO-PUCK Series | IsoAcoustics
I built manifold loaded infinite baffle subs and the "hit" against the room is negligible where a plain wall mounted woofer shakes the whole room and is unusable. The high frequency cutoff has to be below the 1/4 wavelength on the manifolds longest dimension. With 15" woofers that's about 100hz.
The manifold gives us the ability to add compression to the party, increasing air velocity while adding mass to the cones. Depending on the woofer this can be good or bad.
The manifolds sit on the floor and opens into the room. This view is from the rear and should be rotated 90 degrees.
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Gotcha, thanks. Sorry, I meant when you said, "where a plain wall mounted woofer shakes the whole room and is unusable." That could be sat on the floor too, isolated if need be, and then that wouldn't shake the room either?
I think so, the baffle would have to overlap the wall but not touch it. There may be some leakage between front and rear. Some one would have to give it a try and see.
If you need the cone area, that takes it a step further. But spreading things out, so you have more woofers is better than concentrating the woofers in one place.
dave
dave
I agree, less vibrations of the cabinet with push-push. But, I think there is another advantage : the position of the sound emitting source is more stable, less affected by the action-reaction of the movement than with a single driver.
invertered push-push
For the infinite baffle bass section that I built, the area behind the device is a closet, which is not heated, nor cooled. It does maintain some of the ambient temperature of the house, but I wanted the magnet assemblies occupying the space shared with the listening room. Thus, I am listening to the backs on the cones. This also allowed me to direct-couple the magnets, for true 100% force-cancelling. The closet space is just shy of 500 cubic feet. The I.B. was built into a jutted out corner. The Fc/Fs of the system is 17Hz.
There is a horizontal brace between each of the 4 banks of woofers. I had a listener visit me and walk over and grab the brace. He proclaimed with the most confounded expression on his face,
"I don't feel any vibration ??"
To which I replied, "That's the whole point"
For the infinite baffle bass section that I built, the area behind the device is a closet, which is not heated, nor cooled. It does maintain some of the ambient temperature of the house, but I wanted the magnet assemblies occupying the space shared with the listening room. Thus, I am listening to the backs on the cones. This also allowed me to direct-couple the magnets, for true 100% force-cancelling. The closet space is just shy of 500 cubic feet. The I.B. was built into a jutted out corner. The Fc/Fs of the system is 17Hz.
There is a horizontal brace between each of the 4 banks of woofers. I had a listener visit me and walk over and grab the brace. He proclaimed with the most confounded expression on his face,
"I don't feel any vibration ??"
To which I replied, "That's the whole point"
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Scott,
Very nice!
The area between the magnets which appears to have the horizontal brace you mentioned, is that a PVC pipe with a hole drilled in it? Is there a rod coupling the magnets internally?
Thanks,
Anand.
Very nice!
The area between the magnets which appears to have the horizontal brace you mentioned, is that a PVC pipe with a hole drilled in it? Is there a rod coupling the magnets internally?
Thanks,
Anand.
It should be noted that the small, braced, top panel (on my 2x10” push-push woofers) was the only thing i could get to move. A slab of marble or granite (or solid surface material) sitting on something squishy should squash that. if you just want to isolate the sats, this is where spikes or springs can work. Or half teenis or squash balls)
dave
Hey there Anand,
Good to hear from you, ole buddy. You've got a good eye for detail. Here's what I did for the mounting configuration:
Considering each driver has 8 mounting holes, I devoted 4 of them to threaded rods connected between/and/to the opposing driver, and 4 to mount them to the baffle boards. As I created the tension fit, I slipped in a fabricated for size, PVC pipe, such that the magnets would also be coupled. In this manner, both the driver frames and the magnets are coupled; hence 100%. Considering that the drivers have vented pole pieces, I calculation the cross section area and [yes] drilled holes in the pvc pipe, to avoid air constriction. For the most part though, the cones barely move. For average playback levels, we are talking about maybe 1mm~~probably less.
Eight 15's have a total cone area of 1064 square inches. It's a very high efficiency system. Most times the amps loaf along at less than 1 watt.
Take care, and we'll chat atcha later.
When creating a push-push enclosure like this, is it alright to design the box with a single compartment? Is that a factor at all, is it a requirement, or completely irrelevant?
Also, slightly off topic, but if one was using this as the bottom of a 2.5 way is there still value in push push? I'd imagine there are still cancellation benefits among the shared frequencies, but I'd prefer not to assume anything.
Also, slightly off topic, but if one was using this as the bottom of a 2.5 way is there still value in push push? I'd imagine there are still cancellation benefits among the shared frequencies, but I'd prefer not to assume anything.
As long as the bass drivers are equaly loaded it can be 1 enclosure (all the ones i have built (or drawn), Monitor Audio has an example where the push-push drivers load into a central slot and there are 2 enclosures. In the latter case it could be more difficualt to get good coupling between the drivers.
dave
The Monitor Audio is interesting. But a lot of effort to try to do the sam ething as a KEF blade, but inside out and a “virtual” coax.
The woofers are push-push pairs inm a single unit… tricky to install looks like.
And the virtual coax fits tightly around it.
dave
The woofers are push-push pairs inm a single unit… tricky to install looks like.
And the virtual coax fits tightly around it.
dave
The slot loaded open baffle (SLOB) woofer (inspired by Nelson Pass) that I developed does not have a reflex chamber like the Monitor Audio, but I can attest to the wonderful bass that this type of slot loading push push design makes. I am also using a similar AMT tweeter, and a pro-audio 5in midrange for a 3 way but not in a coax. This is one of the best sounding speakers I have heard.
Here is how the slot loaded push push chambers work:
Although it’s a dipole, the slots give some directionality to the bass and enhance the efficiency by about 2-3dB. The slot chamber also acoustically modifies the upper bandwidth to give it a natural falloff (based on depth), so that I can get a really steep 4th order filter at 470Hz using only a second order electrical filter.
The dual driver design with one woofer flipped helps to cancel suspension induced distortion and the bass is very low distortion - even at high SPLs.
I normally don’t listen to music this loud, but this speaker has the ability to play loudly and very clean. Organ pipes in Bach’s Fugue in D minor at 98dB at listening position sounds glorious:
More info in thread.
A recent and very nicely done build of this speaker by member @wirewiggler:
Here is how the slot loaded push push chambers work:
Although it’s a dipole, the slots give some directionality to the bass and enhance the efficiency by about 2-3dB. The slot chamber also acoustically modifies the upper bandwidth to give it a natural falloff (based on depth), so that I can get a really steep 4th order filter at 470Hz using only a second order electrical filter.
The dual driver design with one woofer flipped helps to cancel suspension induced distortion and the bass is very low distortion - even at high SPLs.
I normally don’t listen to music this loud, but this speaker has the ability to play loudly and very clean. Organ pipes in Bach’s Fugue in D minor at 98dB at listening position sounds glorious:
More info in thread.
A recent and very nicely done build of this speaker by member @wirewiggler: