just my very humble intepretation of the datasheet: the cone starts severely breaking up below 500 Hz, also visible in impedance plot. that seems too close to your proposed crossover frequency.
Not at all……only random musings presented so far…..I’m waiting for rational and evidence based responses as to pros or cons.
So, you don't know what does and doesn't represent a meaningful problem. A 4 dB "Blip" is an artifact driven by some issue in the driver, right in the midrange. You don't understand how this works, that much is obvious, but you're arguing with the answers that don't' validate your premise. "What do you mean about the surround?" "What's so different about those other drivers?" "What is Le(x) distortion?" would all be good questions if you were seeking knowledge, but instead you're arguing with the feedback you're getting, and you don't seem to have a good grasp of the basic TSP derived behaviours, much less how they interact in a practical sense.
Yes that's the start of much more severe breakup, just as I wrote. I remember the recommendation to stay at least one octave away from any breakup.
I don’t think your debating your points based on some woofer structure
here’s a $300 Scanspeak highly regarded midwoofer with a 3/4db resonance blip SMACK at 1khz…..FAR more audible an egregious that would be down 24db from the fundamental at 400hz ( remember a 2nd order LP filter was mentioned)
there’s an accompanying resonance in the impedance plot.….but i suspect some of this is simple diffraction from the edge surround……and I suspect the UM15 is the same
400hz fundamental tone is what it is…nothing special here…..there’s not a lot of information other than the tone…it’s the harmonics that give the information…..,the harmonics will be handled by a different drive unit.
Yep bought some 12s when they came out absolutely junk subs they refused to take them back
What exactly is the point you're trying to make about resonances? Your resonances aren't going to be 24dB down they're right next to the gd XO. It's more likely to be spider resonances, IMO, but it doesn't really matter because you can't really do much to fix either apart from trial and error modding.
If the harmonics from the midtweeters are everything why even bother with woofers? Stop trying to be "right" and start trying to hear what more experienced people are saying. Those who have used them in this thread hated them. Those who have made a kajillion speakers think the resonances are an issue. Like I said, you came for validation not information. You thought you found some outlier that would overperform in an application it's not well suited for. Never mind the AE speakers as vastly better options, made for the application....
No, this is:
https://www.oneaudiousa.com/product-page/ib3
The 18" version, specifically. 36mm Xmax. I'm hoping to pick up a pair soon. I have a pair of the v2 version I bought in 2019 IIRC and they are not bad.
https://www.oneaudiousa.com/product-page/ib3
The 18" version, specifically. 36mm Xmax. I'm hoping to pick up a pair soon. I have a pair of the v2 version I bought in 2019 IIRC and they are not bad.
@CharlieLaub Whoah those are pretty beastly, though I'm not sure I'd be okay with that low a baseline efficiency. With all those shorting paths it should handle some pretty ridiculous power as described
And how do you reckon they are going to make a high efficiency driver with low Fs and 36mm Xmax? Magnetic materials only have so much flux and physics can not be violated. Anyway, the 18" version has a sensitivity of 88.1dB/W. I would NOT call that low for a subwoofer like this.
Also, you should consider the overall efficiency, that is how much power is required to achieve a given SPL, including ALL losses (like the dipole losses). When you do that, a high Qts driver like this as a subwoofer makes a lot of sense compared to your usual Qts=0.4 or less driver for home audio, or even less for a pro audio driver. You can only make up for losses with as much power as the driver can take, and at some point if the losses at LF are too high it doesnt' work. So those who say Qts doesn't matter tend to overlook the reality of the situation for OB and dipole bass.
Also, you should consider the overall efficiency, that is how much power is required to achieve a given SPL, including ALL losses (like the dipole losses). When you do that, a high Qts driver like this as a subwoofer makes a lot of sense compared to your usual Qts=0.4 or less driver for home audio, or even less for a pro audio driver. You can only make up for losses with as much power as the driver can take, and at some point if the losses at LF are too high it doesnt' work. So those who say Qts doesn't matter tend to overlook the reality of the situation for OB and dipole bass.
@CharlieLaub I didn't say high efficiency (Call it mid 90s) was the target, but you can indeed make a high Xmax with higher efficiency, it just takes a ridiculous amount of magnet to saturate an extremely thick top plate. Obviously this has limits of both practicality and scaling, and 88 is much more in-bounds vs. 82 regardless.
It’s you who make the assumption that somehow I’m less experienced……..bad call.
So acoustic rolloff from 100hz is roughly 3db/Oct…..considering a desired xo point of 400hz or so, we’d need to start an 2nd order electric at or near 100hz give or take. By 400hz we’ll be down 24db or so in the summed response……that 4db blip is now ‘maybe 2db’ with a passband of a quarter an octave….if that’s a deal breaker for experienced speaker designers, who’s kidding who here?
Maybe it was all just a typo?
Not sure about 400 Hz crossover and being 24 dB down at the same time
If it's now a 100hz down thing, we're in a completely different conversation. That wasn't at all what was under discussion.
While it IS possible to make a high Xmax (e.g. 20mm) high efficiency large driver, it will typically have a higher Fs (e.g. 40 instead of 20) or low Qts (e.g. 0.2-0.3 instead of 0.7 or more).
Example: Faital Pro 18XL1800 sort of gets there (I own one).
Sensitivity 95dB
Fs 29Hz
Xmax 21mm
Qts 0.4
I would love to see an example of:
high sensitivity (e.g. the "mid 90s" you mention)
high Xmax
Low Fs (below 30 Hz, closer to 20 Hz preferred)
high Qts
In a driver that is not more than 18" in nominal diameter. I know there are drivers like the Stereo Integrity IB-24 around, but that is going off into some very different territory. That driver can definitely NOT be operated above 100Hz or so! AT least an 18 can go up to about 200Hz...
Not saying it's practical, just possible with a thick enough plate, long enough coil, and big enough magnet. Added mass of course is an option to trade efficiency for Fs. You can also widen the gap to trade Q for efficiency. Nobody does this, why would they? Power handling is best served by keeping as much coil near as much pole/plate as possible. Look at the failure modes of the JBL SFG motors like the 2226 and 2206; the coils got hottest in the drillthroughs. They moved more air around the coil but created hotspots. In the case of insanely long coils, the top and bottom will be only air cooled and will likely be the first points of thermal failure, while the rest of the coil has convenient heatsinking as close to it as possible. It sounds like there's a lot of shorting in that motor, both through and above/below the gap, so this should be mitigated quite a bit so long as it's pushing some xmax for that power (so the coil is next to the gap). If you fed it 500WRMS for 5 min at 5kHz you'd certainly burn up the top and bottom.
Anyway, all academic, but the issues raised for this woofer, in the originally described configuration (12dBHP @ 400hz), remain
Anyway, all academic, but the issues raised for this woofer, in the originally described configuration (12dBHP @ 400hz), remain
https://www.lencoheaven.net/forum/index.php?topic=31371.0
Somewhere along the line the OP turns to the Ultimax 18 in his baffleless clamshell setup and swears by them
Don’t know if he took measurements and posted them in that thread…to lazy to log in and search
Similar topic came up on here with measurements
https://www.diyaudio.com/community/...m-open-baffleless-full-range-speakers.374043/
I tried this with 4 AE Dipole 18 a while back…still felt I wanted my sub for the bottom end
Somewhere along the line the OP turns to the Ultimax 18 in his baffleless clamshell setup and swears by them
Don’t know if he took measurements and posted them in that thread…to lazy to log in and search
Similar topic came up on here with measurements
https://www.diyaudio.com/community/...m-open-baffleless-full-range-speakers.374043/
I tried this with 4 AE Dipole 18 a while back…still felt I wanted my sub for the bottom end
Here’s the thing……..and u can take this with a grain on salt as I expect your experiences are different than mine…but I’ve had what I like to call the ‘luxury’ of living and working through a period of voicing and listening through to sight supported listening and working……and back again.………and sight assisted working is the greatest red herring fishing expedition ever undertaken. What matters most is will the listener ’hear’ and find objectionable the 4db narrow passband wobble at 3m off axis is the context of complex fundamentals and harmonics at 450hz?…….400hz was presented as a passband range of operation so to my workflow, that expectation would be by the time we’re at 450hz, we’re already down at least 3-db from the fundamental……combine off axis listening and summing distance……..now COMPLETELY untreated with even a high Q notch, that 4db wiggle is 2db at best over a 1/8 octave passband…….it just doesn’t matter when you factor in the goal. Of course everything is a compromise………a $250 15” high Q driver with excellent build quality and suitable efficiency in a world where watts are cheap for OB use isn’t a compromise of significance and worth considering. YMMV.