A bit more details, shown without front trim and top. The fillets (rounding) in the corners are structural and cubic core, 3D printed and glued in place devices. The right hand side rear cavity is spare volume that can will be used for electronics
Shown with front trim in place. Drivers sit under the trim, only the roll surround and cone/cap will be visible after install. This is the design work on the hopeful 20hz soundbar complete. I am curious about the similar size 23hz tuned bass reflex that looks like a TL. Will draw that up in cad next to test against this TL just for some fun
Back to the 40hz box. Scratch all the above re the soundbar. I'll make an MDF BR box to test at 20hz and that should keep the fun going there. The 40hz box is a challenge too with the long port. I do have some flexibility with box dimensions and looking at using PR devices if I can understand them. Its not affordable to bring in from Parts Express. Is there a way to measure the parameters that Winisd needs, for a PR with unknown specs?
Here is a wobbly one, can a cheap driver be used as a PR?
Here is a wobbly one, can a cheap driver be used as a PR?
Interesting reading . . .
Underseat Subs
I'm a little sceptical of some of the specs, particularly sensitivity.
DEEP：95 dB DYNAMIC：100 dB
DEEP：20~200 Hz DYNAMIC：40~160 Hz
Underseat Subs
I'm a little sceptical of some of the specs, particularly sensitivity.
Sensitivity (1W/1m)
DEEP：95 dB DYNAMIC：100 dB
Frequency Response
DEEP：20~200 Hz DYNAMIC：40~160 Hz
I am wondering what magic? Most seem to claim a 20hz ability
Came across some more drivers that might hit the target of around 4L net volume and flat to 40hz or better. Going to sim some and will get back with the results
Also been trying to understand PR drivers more. Do they need to have the same xmax ability as the active driver is something I am still not sure about
A cheap or burnt voice coil driver be used as a PR.
Removing the magnet makes it easier to add mass for tuning the PR. Some DIY folks have clamped tire balancing weights onto the voice coil, or drilled holes in it and used symmetricly placed nuts, bolts and washers.
As a general rule, the passive radiator(s) should have at least double the displacement of air (Vd) as the active woofer(s) in the system.
Vd= Xmax times Sd (cone area). Passive radiators may also be rated in Xmech or Xlim rather than Xmax, but since they are only limited by their suspension, their Xmax is the same as a loudspeaker’s Xlim, so they will make similar bad noises at Xmax as a loudspeaker at Xlim.
When a passive radiator reaches it's limits, it will usually make some sort of bad, loud noise ("whup, whup") unlike ports, which make less audible "chuffing" wind noise.
The moving weight of passive radiators can be enough to shake a wall or make a lightweight "walk" cabinet "walk" around, using a pair of opposed passive radiators will cancel those vibrations.
Removing the magnet makes it easier to add mass for tuning the PR. Some DIY folks have clamped tire balancing weights onto the voice coil, or drilled holes in it and used symmetricly placed nuts, bolts and washers.
As a general rule, the passive radiator(s) should have at least double the displacement of air (Vd) as the active woofer(s) in the system.
Vd= Xmax times Sd (cone area). Passive radiators may also be rated in Xmech or Xlim rather than Xmax, but since they are only limited by their suspension, their Xmax is the same as a loudspeaker’s Xlim, so they will make similar bad noises at Xmax as a loudspeaker at Xlim.
When a passive radiator reaches it's limits, it will usually make some sort of bad, loud noise ("whup, whup") unlike ports, which make less audible "chuffing" wind noise.
The moving weight of passive radiators can be enough to shake a wall or make a lightweight "walk" cabinet "walk" around, using a pair of opposed passive radiators will cancel those vibrations.
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Thanks man. The SBA PR drivers are available here but expensive. PE is too much shipping charges. There are some good-looking ones on eBay and Ali but without specs and prolly not have a duty cycle to match with any of these extreme lil subs
But I need to revisit Earthquake first to see where they went with SLAPS
https://www.earthquakesound.com/ind...ome-passives/item/slaps-m10-2?category_id=506
Hoping to be able to do some experiments with this on the back panel behind the driver in a 4L box with the 6.5" sub
Hoping to be able to do some experiments with this on the back panel behind the driver in a 4L box with the 6.5" sub
Just be aware that Earthquake "Xmax" is half the stated amount, their 3.5" Xmax is peak to peak travel, while Xmax is one way. To have 3.5" xmax would require 7" peak to peak.
Other than that, they look like good product, and have been around for a long time.
Other than that, they look like good product, and have been around for a long time.
I had a SLAPS 15 system way back with I think a Magma running off a JLAudio 1000/1. It was great for Reggaeton, but not so defined on dub basslines. It did get stolen
https://ds18.com/cdn/shop/files/SRW...-b32f-8828fb696f4b.pdf?v=14957553418375467902
This is a cheap pancake. Seriously considering getting a couple to try back to back with one active and one passive just to see what happens and to try as a super heavy-duty PR for the 6.5" drivers at 600w
https://ds18.com/cdn/shop/files/SRW...-b32f-8828fb696f4b.pdf?v=14957553418375467902
This is a cheap pancake. Seriously considering getting a couple to try back to back with one active and one passive just to see what happens and to try as a super heavy-duty PR for the 6.5" drivers at 600w
Extrapolating a new 4L line, looks like you would need to add around 225 grams of weight to the Slaps M8, 65 more grams than the pre-installed 160 grams.
That would put the Mms near 300 grams, about 1/3 Kilo flapping at 40Hz.
If the 6.5" sub driver can make it move in that small a box, that's gonna be a "whole lotta shakin' goin on" 😉
Lol the challenge is 40hz flat out of the tiniest ported type system. Looks like the 6.5" might shine at that but the port is huge for a 4L net internal, and gross internal gets over 7L with everything. This might be a good fit for the right PR
Found this discussion on the SLAPS-M8. It seems like one of the better presented and easier to use PR. Any thoughts on using an unconnected driver as a PR?
https://www.diyaudio.com/community/...e-w-passive-radiator-enclosure-design.388933/
https://www.diyaudio.com/community/...e-w-passive-radiator-enclosure-design.388933/
I commented on using an unconnected driver as a PR in post #47.
To expand, the spider and suspension on most drivers progressively get stiffer at excursions past Xmax, so you could expect more PR "compression" at higher volume than a purpose designed PR.
5 string bass low B is 31 Hz. If the tuning (Fb) was above the bass line frequency, you'd get a lot of "flop" from the PR.
Also, to get decent (tight) damping factor at low impedance (2ohms) requires either really thick or really short speaker wire.
That said, a ported or passive radiator is always going to be "slow" or "less defined" compared to sealed.
Ok got it
I just got this crazy image of something I am doing in another project. It’s an electronic transmission using two motors connected by wire
I so have to try an experiment. Its just too crazy not to have a go with a mic and measuring software
Two chambers, one with an active driver on the front and unconnected driver as PR on the back
Coil from back pretend PR connected to a second driver on the front face of the second sealed chamber, out of phase
Will this bring port output to the front and in phase (I am looking at BR and PR being same effect)
I just got this crazy image of something I am doing in another project. It’s an electronic transmission using two motors connected by wire
I so have to try an experiment. Its just too crazy not to have a go with a mic and measuring software
Two chambers, one with an active driver on the front and unconnected driver as PR on the back
Coil from back pretend PR connected to a second driver on the front face of the second sealed chamber, out of phase
Will this bring port output to the front and in phase (I am looking at BR and PR being same effect)
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https://www.parts-express.com/Dayto...ore-Neodymium-Woofer-4-Ohm-295-248?quantity=1
New tech…..very promising…..40hz in a small sealed box with boost is possible
New tech…..very promising…..40hz in a small sealed box with boost is possible
How do one know that one is spending too much time CADing! When one clicks on a PE link, tries to grab the item in the pic and rotated it with the mouse 😀
Looked interesting, but sealed? I am not too fond of the sound results with sealed attempts. It just doesn't seem to sing the bass, maybe contribution from the back of the woofer shouldn't be dampened out. Bass guitar lines sound half complete. It doesn't match with string vibration feeding back into my thumb tip. Say I am letting the string sustain over a couple of steps or so, sealed already dampens before I want to mute. But I should qualify that I am using very stiff drivers for bass. The first time I tried a high efficiency driver for bass, it didn't have the control. Trying lots and lots of drivers over 7 or so years, the current smallest box I have come up with is an SBA 7" in a 15L 43hz ported as a minimum with 150wrms and a loudness compensation to define bass notes and separate them from the kick at about 70db home playing with volume about 1/4 and the school hall with volume about halfway
Mystifies me why everyone keeps recommending sealed when It's not very accurate sounding
Looked interesting, but sealed? I am not too fond of the sound results with sealed attempts. It just doesn't seem to sing the bass, maybe contribution from the back of the woofer shouldn't be dampened out. Bass guitar lines sound half complete. It doesn't match with string vibration feeding back into my thumb tip. Say I am letting the string sustain over a couple of steps or so, sealed already dampens before I want to mute. But I should qualify that I am using very stiff drivers for bass. The first time I tried a high efficiency driver for bass, it didn't have the control. Trying lots and lots of drivers over 7 or so years, the current smallest box I have come up with is an SBA 7" in a 15L 43hz ported as a minimum with 150wrms and a loudness compensation to define bass notes and separate them from the kick at about 70db home playing with volume about 1/4 and the school hall with volume about halfway
Mystifies me why everyone keeps recommending sealed when It's not very accurate sounding
Sealed will ALWAYS be more ‘accurate’ all else being equal. Significantly less group delay, a tighter impulse response all from the enclosure air compliance commanding full control of the cone. Where folks go wrong is the wrong enclosure size to optimize Q to match the driver, insufficient amp current to sustain longer notes, or poor enclosure build with air leaks or insufficient bracing allowing enclosure to flex.
Ported systems are RESONANT systems and the added output comes from an enclosure resonance…..this will NEVER HAVE the equivalent accuracy of sealed. I suspect what you ‘prefer’ is simply more output in the lower frequencies. Match the F3 of both alignments and the sealed wins each and every day…….this is why we’re recommending it for you with such small size constraints on your build. The ONLY way to overcome the size issue is high motor strength, long excursion and plenty of amplifier current…….there’s no free lunch here.
Ported systems are RESONANT systems and the added output comes from an enclosure resonance…..this will NEVER HAVE the equivalent accuracy of sealed. I suspect what you ‘prefer’ is simply more output in the lower frequencies. Match the F3 of both alignments and the sealed wins each and every day…….this is why we’re recommending it for you with such small size constraints on your build. The ONLY way to overcome the size issue is high motor strength, long excursion and plenty of amplifier current…….there’s no free lunch here.
Am I mistakenly thinking amp power, motor/suspension and the recorded or live information is mainly responsible for cone control and pneumatic suspension applies not control but a dampening that works well with implulse type stuff like 808 and 90i9 kicks in doof doof and fights or deadens continuous string notes? I have only done sealed as per manual recommendation and
Does the ZR6 not have a motor xmax and thermal on the extreme side of what is normally found on a 6.5"? I fail to see how it has a smaller motor then any of the drivers suggested in this thread so far? I am really confused now as to what has a larger motor in all the drivers brought up so far
Each voice coil can have either 150wrms, 300wrms, or 500wrms from the choice of amps I have on hand to try for this project. I really don't see how that is not enough serving for a tiny 40hz sub
To me a sealed sub feels like a dead instrument, I can't play it