Hello,
I have a problem: my floor and walls easily catch vibrations from a box and transmit them to the room upstairs, creating noise. This peaks at 50 Hz for the floor, slightly higher freq and much less intensity for walls.
I have a Pioneer SX-315 AVR, satellites and a sub. That sub, apart from having rather poor sound (I think), also excites the floor or walls easily. But there is not much noise transmission if I hold it on outstretched arms.
So I need a box to play me some bass (the sub range for the SX-315 is 45-200 Hz, so really a "midsubwoofer") without shaking at all, at all, so it can't excite the house. I was looking at an open-baffle two-speaker design named Visaton Petit Orgue PETIT ORGUE | Visaton and I saw user reports that it does not shake at all; it is quiet and that is fine, but also I can't place a dipole speaker properly in my room.
I suspect that the Petit Orgue doesn't shake because it has two drivers in counter-phase, so their mechanical vibrations cancel each other in the box. I was thinking of whether a similar design, with two speakers in counter-phase and close to each other, existed without being a dipole. I was told the word "PPSL" and after some searching found the image I wanted here: https://www.diyaudio.com/forums/subwoofers/245114-finally-finished-dual-18-ppsl.html (though I'd want 6.5 to 10 inch, not 18)
The thread mentions that it is a bigger version of DJK's design. Further googles for DJK PPSL yielded a few photos of similar boxes and a mention of DJK RIP 🙁
So I have questions:
- Do DJK or similar PPSL subwoofers have significantly less box vibration than others? Pure theory would say so, but what about practice?
- Where can I find the blueprints/explanation for the DJK design? The thread seems to explain that the two (sealed?) chambers are somehow joined, but I's like to understand the details, and also how one calculates the size/volume of all the parts.
Thanks!
I have a problem: my floor and walls easily catch vibrations from a box and transmit them to the room upstairs, creating noise. This peaks at 50 Hz for the floor, slightly higher freq and much less intensity for walls.
I have a Pioneer SX-315 AVR, satellites and a sub. That sub, apart from having rather poor sound (I think), also excites the floor or walls easily. But there is not much noise transmission if I hold it on outstretched arms.
So I need a box to play me some bass (the sub range for the SX-315 is 45-200 Hz, so really a "midsubwoofer") without shaking at all, at all, so it can't excite the house. I was looking at an open-baffle two-speaker design named Visaton Petit Orgue PETIT ORGUE | Visaton and I saw user reports that it does not shake at all; it is quiet and that is fine, but also I can't place a dipole speaker properly in my room.
I suspect that the Petit Orgue doesn't shake because it has two drivers in counter-phase, so their mechanical vibrations cancel each other in the box. I was thinking of whether a similar design, with two speakers in counter-phase and close to each other, existed without being a dipole. I was told the word "PPSL" and after some searching found the image I wanted here: https://www.diyaudio.com/forums/subwoofers/245114-finally-finished-dual-18-ppsl.html (though I'd want 6.5 to 10 inch, not 18)
The thread mentions that it is a bigger version of DJK's design. Further googles for DJK PPSL yielded a few photos of similar boxes and a mention of DJK RIP 🙁
So I have questions:
- Do DJK or similar PPSL subwoofers have significantly less box vibration than others? Pure theory would say so, but what about practice?
- Where can I find the blueprints/explanation for the DJK design? The thread seems to explain that the two (sealed?) chambers are somehow joined, but I's like to understand the details, and also how one calculates the size/volume of all the parts.
Thanks!
This thread has a lot of discussion on PPSL enclosures.
Over the years Planet10 has posted a lot of good info on push push loading without a slot chamber, with some good diagrams on bracing the 2 opposing drivers together.
Over the years Planet10 has posted a lot of good info on push push loading without a slot chamber, with some good diagrams on bracing the 2 opposing drivers together.
The push pull doesn't vibrate, I've made 3 of them (2x12", 2 boxes of 2x18", and a 4x12").
But drivers on opposite sides of a box will cancel vibration also.
Djk was a fan of 6th order.
There are papers by keele and jbl.
Basically, you made a sub out of a driver that normally doesnt go low due to a low qts (say .3).
6th order gives you a high spl 1w/1m in a smaller box, but you need a high pass filter that basically boosts +6db at tuning frequency (usually at fs = -9db).
It sound like a lean quick sealed without the booster box.
Curiously, the sub goes much louder when relieved of output below 27hz.
When i tried my 18's without the booster box, 60hz was strong then quieter and quieter down to below 20hz.
With the booster box in, 60hz down to 30hz was basically the same volume (wow, 126db for 100 (400 at tuning) watts into each box, 2x94db 8ohm drivers wired in parallel for 100db at 4ohm per box), but 20hz was gone.
Djk was thinking 6th order for tapped horns for boost (low qts drivers) and subsonic protection.
Then you can mount your drivers push pull for harmonic distortion reduction.
Get the slot as narrow as you can.
You can get away without a slot, m&k subwoofers did this.
Push pull can be sealed, transmission line, or whatever.
I've been on the fence to make a 2x15" sealed with f3 near 30hz.
But drivers on opposite sides of a box will cancel vibration also.
Djk was a fan of 6th order.
There are papers by keele and jbl.
Basically, you made a sub out of a driver that normally doesnt go low due to a low qts (say .3).
6th order gives you a high spl 1w/1m in a smaller box, but you need a high pass filter that basically boosts +6db at tuning frequency (usually at fs = -9db).
It sound like a lean quick sealed without the booster box.
Curiously, the sub goes much louder when relieved of output below 27hz.
When i tried my 18's without the booster box, 60hz was strong then quieter and quieter down to below 20hz.
With the booster box in, 60hz down to 30hz was basically the same volume (wow, 126db for 100 (400 at tuning) watts into each box, 2x94db 8ohm drivers wired in parallel for 100db at 4ohm per box), but 20hz was gone.
Djk was thinking 6th order for tapped horns for boost (low qts drivers) and subsonic protection.
Then you can mount your drivers push pull for harmonic distortion reduction.
Get the slot as narrow as you can.
You can get away without a slot, m&k subwoofers did this.
Push pull can be sealed, transmission line, or whatever.
I've been on the fence to make a 2x15" sealed with f3 near 30hz.
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Thanks a lot!
I am currently looking at avoiding the slot trouble and just putting two Dayton Audio DA175-8 drivers at two sides of a 38 l box. This gives me both a decent sealed option and a great vented option according to the modeling I could run online so far. I need to double-check with better software, but my hope would be to build a box which I could use both sealed and vented, therefore working out which I like more.
Question: if the sides that bear speakers are circa 30 cm apart on different sides of a narrow-ish box, would it still make sense to reverse one of the speakers and reverse its polarity, thus creating a push-pull configuration? Would it still help with distortion, or would it just be a useless exercise at this distance?
I am currently looking at avoiding the slot trouble and just putting two Dayton Audio DA175-8 drivers at two sides of a 38 l box. This gives me both a decent sealed option and a great vented option according to the modeling I could run online so far. I need to double-check with better software, but my hope would be to build a box which I could use both sealed and vented, therefore working out which I like more.
Question: if the sides that bear speakers are circa 30 cm apart on different sides of a narrow-ish box, would it still make sense to reverse one of the speakers and reverse its polarity, thus creating a push-pull configuration? Would it still help with distortion, or would it just be a useless exercise at this distance?
Well, lets see.
His rule of thumb was you want to be 1/4 octave apart for an octave above how high you want to run the sub. Othewise it doesn't reduce distortion much.
So, if you want to run the sub up to 100hz, you need to be 1/4 wavelength of 200hz, or (1129 / 200) / 4.
Or 1.4 feet.
I believe it needs to be closer to catch the higher stuff, helping the subwoofer disappear better.
His rule of thumb was you want to be 1/4 octave apart for an octave above how high you want to run the sub. Othewise it doesn't reduce distortion much.
So, if you want to run the sub up to 100hz, you need to be 1/4 wavelength of 200hz, or (1129 / 200) / 4.
Or 1.4 feet.
I believe it needs to be closer to catch the higher stuff, helping the subwoofer disappear better.
I found tuning below 30hz is quick.
The 80-100hz crossover adds far more delay.
Quickness is integration with mids and highs.
I'd reverse a driver.
Any subwoofers i build will be push pull.
The 80-100hz crossover adds far more delay.
Quickness is integration with mids and highs.
I'd reverse a driver.
Any subwoofers i build will be push pull.
My crossover is unfortunately fixed at 200 Hz.
if I need to think an octave over 200 Hz, that is 400 Hz. The wavelength is 86 cm, a quarter is 21 cm. Unfortunately I don't think I can make a 38 l box that narrow. Of course the real distance can be somewhat lower as one of the speakers backs inside; with the distance between walls inside at about 30 cm we're really looking at something like 25 cm. Which is quarter of 1 m, which is the wavelength for ~340 Hz.
With this distance does it make sense to reverse a driver? I don't really see how I can make them closer.
As for tuning I might be looking at 20 or 25 Hz but need to work out which port, and how, I can make without a danger of noise.
if I need to think an octave over 200 Hz, that is 400 Hz. The wavelength is 86 cm, a quarter is 21 cm. Unfortunately I don't think I can make a 38 l box that narrow. Of course the real distance can be somewhat lower as one of the speakers backs inside; with the distance between walls inside at about 30 cm we're really looking at something like 25 cm. Which is quarter of 1 m, which is the wavelength for ~340 Hz.
With this distance does it make sense to reverse a driver? I don't really see how I can make them closer.
As for tuning I might be looking at 20 or 25 Hz but need to work out which port, and how, I can make without a danger of noise.
Hard to say.
Close as you can ?
Even if further, it will help at say 100hz and below.
Ported boxes are bigger, and hard to tune low in small boxes.
Close as you can ?
Even if further, it will help at say 100hz and below.
Ported boxes are bigger, and hard to tune low in small boxes.
I would prefer a sealed box, but with every driver I can find, a 2-speaker sealed box with an F3 not much over 50 Hz works out at circa 40 l or more. The ported box with the Dayton Audio DC160-4 works out at 20 l, tuned to 30 Hz, F3=51.1Hz, at 45 Hz I get -4.4 dB, group delay is not over 8ms anywhere over 40 Hz. (I have a high pass at 40-45 Hz).
Tang Band W6-1139SIF gives an even smaller ported box, but is too intolerant of box volume error for a first build, also kinda too expensive. But I have not found anything to get a small sealed box, which would be my preference.
If a push-pull sealed box of 30 l or less with an F3 not much higher 50Hz can be built, please do tell me which driver can support this. With a smaller box volume it is easier to bring the two walls closer, making push-pull an option. And of course it is easier not to have to calculate and implement a port.
EDIT: upon a google I do now realize that I can do a 30 l push-pull box with two HiVi M8N drivers, at a bit of a stretch. But other driver suggestions would be very much appreciated.
Tang Band W6-1139SIF gives an even smaller ported box, but is too intolerant of box volume error for a first build, also kinda too expensive. But I have not found anything to get a small sealed box, which would be my preference.
If a push-pull sealed box of 30 l or less with an F3 not much higher 50Hz can be built, please do tell me which driver can support this. With a smaller box volume it is easier to bring the two walls closer, making push-pull an option. And of course it is easier not to have to calculate and implement a port.
EDIT: upon a google I do now realize that I can do a 30 l push-pull box with two HiVi M8N drivers, at a bit of a stretch. But other driver suggestions would be very much appreciated.
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