Either everyone else is discussing what it would take for a large driver to go low and loud ina small box while you are on a tangent discussing an optimum large driver under optimum conditions
Making sense of how what you are so vigorously arguing relates to the small box is difficult
I made it easy.
More motor force means more SPL, more weight on the cone means less SPL. If you see something different, you are observing a phenomena called PARADOX, caused by exception, caused by or combined with lack of understanding. That deserves to be explained. The paradox here hangs about the resonant frequency of the system. The exception is true, it just cannot describe the whole system in its range of use.
It is not my problem that someone doesn't understand that. I do not understand stuff too. You can freely continue to do so. You do you. Well, I will continue to name things for what they are. Disagreeing is not a solution though.
It is a ridiculous stance, to not being able to say what Bl does, how it behaves, proceeding to show it behaves contradictory to physics, then showing it works accordingly to physics when mingled with other phenomena, then saying that opposing side has no idea what it is saying. I am at a loss for words here.
More motor force means more SPL, more weight on the cone means less SPL. If you see something different, you are observing a phenomena called PARADOX, caused by exception, caused by or combined with lack of understanding. That deserves to be explained. The paradox here hangs about the resonant frequency of the system. The exception is true, it just cannot describe the whole system in its range of use.
It is not my problem that someone doesn't understand that. I do not understand stuff too. You can freely continue to do so. You do you. Well, I will continue to name things for what they are. Disagreeing is not a solution though.
It is a ridiculous stance, to not being able to say what Bl does, how it behaves, proceeding to show it behaves contradictory to physics, then showing it works accordingly to physics when mingled with other phenomena, then saying that opposing side has no idea what it is saying. I am at a loss for words here.
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I think it's actually more along the lines of you injecting your out of context opinion into a topic, and then just throwing a hissy by covering your ears and refusing to listen when the relevant context is explained to you.
That's not an opinion. And we are not having much of a technical argument either. Both losing time. I laid out the basic claim on Bl and mass. It is conveniently ignored.
Bl adds potential of more SPL in any case, where the proper signal can be provided to the transducer. I have yet to see an exception ever, although again, resonance frequency is close to it and makes it more difficult.
Mass lowers SPL with exception of resonant frequency and near around, and it is paid dearly by losing SPL in the rest of the range so much so, that not wanting to add mass has good merits and use cases. Having nothing to do with price either (proper amp and DSP are more expensive than weight).
Instead of focusing on the problematics, you pull put authorities, what I am and what I am not, what I am allegedly doing. No, this is not an argument what we are doing here.
Bl adds potential of more SPL in any case, where the proper signal can be provided to the transducer. I have yet to see an exception ever, although again, resonance frequency is close to it and makes it more difficult.
Mass lowers SPL with exception of resonant frequency and near around, and it is paid dearly by losing SPL in the rest of the range so much so, that not wanting to add mass has good merits and use cases. Having nothing to do with price either (proper amp and DSP are more expensive than weight).
Instead of focusing on the problematics, you pull put authorities, what I am and what I am not, what I am allegedly doing. No, this is not an argument what we are doing here.
The only one thing that I can add is that I have on hand the physical examples of the regular with a light composite cone in the double motor version and a quadruple size motor and cone heft one. Both versions of of the regular light cone have very high Fs and need larger boxes then the heavy which can go down to 20Hz in much smaller box then the two more sensitive drivers and louder all the way up the band
Randy, that clearly can happen if you add changes and circumstances to things. Weaker car can deliver goods faster if it has lighter load, or shorter distance, or better tires and breaks, or better fuel, or.... The discussion was about very core of the physics. The realworld situation pushes us to using rather heavier solutions anyways, because weak cone would absolutely buckle under excursions we desire. The longer the cone and coil travel, the more sophisticated or stiffer suspensions we need, as the precision coil stabilisation requires that. To add more force to the coil, it again needs to be heavier. Multiple layers on the coil scale up well, because you are not adding formers to the thickness, and coil turns might fall inbetween each other. So this functional weight addition is net gain. That doesn't disqualify the physics.
Cool, so the heavier cone and motor is necessary to go and loud ina small box as per topic. Well done 👍🏽
Not to a point of adding artificial weight, and it has almost nothing to do with small box. It is necessary for large box too. PA speakers still have fairly lightweight cones.
Yes I am officially living in the lalaland with craycray people.
Instead of acknowledging physics... Anyways.
This is 330g assembly with paper cone designed for some abuse:
Fs 32Hz.
But this goes to the playing chess with pigeons.
Yes I am officially living in the lalaland with craycray people.
Instead of acknowledging physics... Anyways.
This is 330g assembly with paper cone designed for some abuse:
Fs 32Hz.
But this goes to the playing chess with pigeons.
It will be interesting to see what it looks like. My curiosity is getting the better of me, so can we please see a teaser pre-Cedia photo?
The SVS SB-3000 comes to mind. It's "only" a 13-inch driver, and the gross enclosure volume based on external dimensions comes in at a very compact 2.15cuft (61.0 litres), so the net volume is likely to be close to that erstwhile goal of 1.25cuft sealed volume in compactness. The SB-3000 has a nicely extended low-frequency response, being −3dB at about 22Hz. That is a true high-end level of performance concerning that parameter. See the frequency response plot below for confirmation.
Interestingly, the SB-3000's measured response in the 40Hz to 150Hz region is also very flat, which helps to simplify the user's job of setting the low-pass/high-pass filtering on the system where it is being used. It is not an easy task for a subwoofer to exceed the capabilities and usability of the SB-3000. I guess that's where the SVS SB-16 Ultra might come to the fore.
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The SB3000 has roughly 1.6cf of internal airspace, it is close but not as compact. It is a very close contender, though.. they nailed it. The external dimensions of mine work out to roughly 1.85cf. Also keep in mind that the simulated response of mine based off just the Fb and Qtc alone isn't a representative of its measured low end response, especially in different sized rooms. We have measured -3db @ 17hz with an 80hz L/R4 in nearfield during testing on an earlier revision.
I would love to leak some pics and more info, but it's ultimately not in my best interest since I only designed and built the raw driver itself while the enclosure and the rest of the system is proprietary to the company who contracted the product. Hope you can understand. But Cedia is just a couple weeks away so I will be able to share more of it after its display there.
I would love to leak some pics and more info, but it's ultimately not in my best interest since I only designed and built the raw driver itself while the enclosure and the rest of the system is proprietary to the company who contracted the product. Hope you can understand. But Cedia is just a couple weeks away so I will be able to share more of it after its display there.
The information that has been presented, consisting of Fb = 39Hz and Qtc = 0.62, fixes the response shape of the woofer in whatever size sealed enclosure it might have been placed. How a natural frequency response that is −3dB at about 45.6Hz is converted to a response that is −3dB at about 17Hz is not immediately clear. To achieve that with a low-pass LR4 filter would require a low-pass cutoff frequency of 28.8Hz. The simulation shown below gives the before and after frequency response functions.
It seems apparent that the action of the LR4 filter is noticeably affecting the response below 20Hz, and over 12dB of attenuation has been introduced. It seems quite clear that a choice of Fb = 39Hz comes with significant acoustic penalties.
It seems apparent that the action of the LR4 filter is noticeably affecting the response below 20Hz, and over 12dB of attenuation has been introduced. It seems quite clear that a choice of Fb = 39Hz comes with significant acoustic penalties.
This is somewhat confusing. Potentially it seems to point to the provided Fb and Qtc values being somehow in error; or the system being measured is greatly nonlinear in its dynamic behaviour (undesirable). Those two parameters, correctly determined, are sufficient to define the low-frequency response of a sealed enclosure. Can it be assumed that Fb was determined from the measured peak in the impedance curve? And how was the value of Qtc estimated?
The measurements that were provided appear to have a very well-defined 24dB/octave roll-off at low frequencies. That's double what a sealed enclosure typically produces. This result just adds to my confusion.
A VituixCAD model can be created to represent the system response. It is shown below.
This simple model produces a quite close approximation to the measured results that were provided, corresponding to the curve with the higher output. The simulated frequency response function is shown below. The driver sensitivity was set to 119.5dB for this example.
The measurements that were provided appear to have a very well-defined 24dB/octave roll-off at low frequencies. That's double what a sealed enclosure typically produces. This result just adds to my confusion.
A VituixCAD model can be created to represent the system response. It is shown below.
This simple model produces a quite close approximation to the measured results that were provided, corresponding to the curve with the higher output. The simulated frequency response function is shown below. The driver sensitivity was set to 119.5dB for this example.
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What BL product do you achieve with these magnets and a reasonably long voicecoil? This of course is a bit of a generic question, but we do not know any details about your motor dimensions, other than the magnets you mention. Care to reveal some dimensions and basic data your motor dimensions and data?
Ofc is it also dependent on cms but if nothing else changes, Vas and Sd are directly linked. And your second sentence explains perfectly why they aren't used for home HiFi. And it also confirms (well, at least indirectly) the lack of resolution and fine dynamics.
No! High losses create distortion! Measure such mud pumps at a few mW and you'll be surprised to realize some easily break 10% THD there or even much more! You exclude the losses from your reality, that doesn't work that way. Bernd Timmermanns explains that in every issue of 'Hobby Hifi' if there are drivers on the test bench if you want to read anything about it.
Aside from that, especially very small sealed enclosures kick your Kms out of the water because with high excursion the enclosure air pressure goes up when the cone goes in and the added pressure makes the Kms(x) unlinear, going opposite (softer) on the cone going out. So you can completely forget about any linearity of the excursion parameters measured in infinite baffle. Ignoring the facts doesn't makes them go away.
So, since you have posted the results of the SVS SB3000 response earlier, I am curious if you know its Fb and qtc?
Guys, I don't know enough about these things, so can only ask when something remarkable catches the eye. Don't take it as arguing anything. You guys seem to be talking about a big sub ina small box going low and loud, and many are calling it a mud pump. I just want to be clear that I am not wasting my time. My interest is in learning about what makes the linked item tick
https://stereo-magazine.com/review/jl-audio-gotham-v2-review
Seems like the type of driver and box in discussion, is this what many of you see as a mud pump? This writer, Tom Frantzen, doesn't mention any of the bad things you folks are talking about
https://stereo-magazine.com/review/jl-audio-gotham-v2-review
Seems like the type of driver and box in discussion, is this what many of you see as a mud pump? This writer, Tom Frantzen, doesn't mention any of the bad things you folks are talking about
