Maybe, we'll never know unless it's actually built. I am not volunteering, there is enough stuff here as is.
Actually we do know. Look at the graphs in post 32 and browse around data-bass.com for awhile to see more measurements of similar drivers. All the high excursion drivers have a droopy top end that is not accurately reflected in simulations.
Your sim is only 3 db down at 13 hz. Add a droopy top end (not reflected in your simulation) and some room gain and you've got a sub that's WAY too strong at low frequencies. So you can eq it flat or you can use a very low crossover point but it certainly won't measure the way your simulation predicts.
If you want less xmax and more sensitivity, don't expect to see it from Stereo Integrity, it's not what they do. You want a pro driver. The b&c 18tbw100 has been receiving a lot of good press and rave reviews lately, including but not limited to this forum. The Klippel data is beyond reproach and it's got huge power handling, a large diameter voice coil and a very strong cone. It definitely won't have a droopy top end. But it's going to run out of xmax very quickly if you try to do a 13 hz tuning.
There's also the 21SW152 if you want something larger and a bit more fancy (neo) for about the same price as the SI 24.
B&C 21SW152-4 21" Neodymium Subwoofer 4 Ohm 294-689
Data-Bass
Your sim is only 3 db down at 13 hz. Add a droopy top end (not reflected in your simulation) and some room gain and you've got a sub that's WAY too strong at low frequencies. So you can eq it flat or you can use a very low crossover point but it certainly won't measure the way your simulation predicts.
If you want less xmax and more sensitivity, don't expect to see it from Stereo Integrity, it's not what they do. You want a pro driver. The b&c 18tbw100 has been receiving a lot of good press and rave reviews lately, including but not limited to this forum. The Klippel data is beyond reproach and it's got huge power handling, a large diameter voice coil and a very strong cone. It definitely won't have a droopy top end. But it's going to run out of xmax very quickly if you try to do a 13 hz tuning.
There's also the 21SW152 if you want something larger and a bit more fancy (neo) for about the same price as the SI 24.
B&C 21SW152-4 21" Neodymium Subwoofer 4 Ohm 294-689
Data-Bass
I think you do mean mm ... like 3mm and 4mm (instead of 0.3mm and 0.4mm)
but does not matter much
point is clear enough ... that 6 foot woofer is barely moving in any case
question is, how much of that big cone is actually following the voice coil
Wow, I can't believe I missed this part. Maybe I was just skimming, maybe I need to buy some spectacles for my eyeballs or maybe I should quit drinking or something but this is important.
To paraphrase, you couldn't find anyone willing to test a 24 inch driver so you bolted your pre prototype motor onto a 15 inch frame (which obviously will use all different soft parts than a 24 inch frame), and then you measured only Bl (which probably isn't correct anyway since I'm assuming the soft parts have an effect on the Bl curve) and used this single graph of a pre prototype motor (that doesn't show anywhere near your claimed xmax, btw) on a completely different driver as a basis to claim you have the highest displacement driver on the planet.
Feel free to correct any incorrect details in that summary.
Now I'll be the first to admit that I'm not intimately familiar with the Klippel testing process, but don't you just have to mount the driver onto a rigid baffle and let the machine run it's tests? Why can't you find someone that will do that? And are you sure soft parts don't affect the Bl curve? Since you only showed the Bl, I assume you KNOW this will affect all the other Klippel graphs.
To be honest, I'm starting to question the xmax specs on all your drivers now. The level of scientific rigor here seems to be insanely low.
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Just in case anyone doesn't know how to read a Bl graph, here's a quick explanation. (Some manufacturer's I've encountered don't even know how and present wildly incorrect info.)
The horizontal legend is driver excursion in mm.
The vertical legend is Bl.
82 percent Bl is the standard for 10 percent distortion, 71 percent is the standard for 20 percent distortion.
So determine Bl at rest position (0 mm) and take 82 (or 71) percent of that figure.
Then look to see where the Bl curve drops to that level (it's usually not perfectly symmetrical so it could be inward or outward excursion that first reaches the limit), and read how many mm of excursion the driver has at that point.
On the attached pic we can see that Bl at rest is about 27.
82 percent of 27 is 22.14, represented by the green line in the graph below.
71 percent of 27 is 19.17, represented by the blue line.
So we can see that at 10 percent distortion Bl is limited to about 24 mm and at 20 percent distortion it's limited to about 30 mm.
This is nowhere near the published xmax for this driver. (Not to mention this isn't even the production driver, it's a pre prototype motor on a 15 inch frame with all different soft parts.)
Furthermore, Bl is not the only thing that can limit xmax. IM distortion, compliance variation, inductance variation etc, can limit xmax to values lower than the Bl curve alone would indicate.
Sources of info on how to read a klippel graph - What to look for in a Klippel measurement - Car Audio | DiyMobileAudio.com | Car Stereo Forum
CSS VWR126X Klippel Testing - Page 3
http://medleysmusings.com/category/speaker-driver-tests/understanding-the-data/
The horizontal legend is driver excursion in mm.
The vertical legend is Bl.
82 percent Bl is the standard for 10 percent distortion, 71 percent is the standard for 20 percent distortion.
So determine Bl at rest position (0 mm) and take 82 (or 71) percent of that figure.
Then look to see where the Bl curve drops to that level (it's usually not perfectly symmetrical so it could be inward or outward excursion that first reaches the limit), and read how many mm of excursion the driver has at that point.
On the attached pic we can see that Bl at rest is about 27.
82 percent of 27 is 22.14, represented by the green line in the graph below.
71 percent of 27 is 19.17, represented by the blue line.
So we can see that at 10 percent distortion Bl is limited to about 24 mm and at 20 percent distortion it's limited to about 30 mm.
This is nowhere near the published xmax for this driver. (Not to mention this isn't even the production driver, it's a pre prototype motor on a 15 inch frame with all different soft parts.)
Furthermore, Bl is not the only thing that can limit xmax. IM distortion, compliance variation, inductance variation etc, can limit xmax to values lower than the Bl curve alone would indicate.
Sources of info on how to read a klippel graph - What to look for in a Klippel measurement - Car Audio | DiyMobileAudio.com | Car Stereo Forum
CSS VWR126X Klippel Testing - Page 3
http://medleysmusings.com/category/speaker-driver-tests/understanding-the-data/
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It was an assumption that I now realize is probably incorrect.
Bl - The product of magnet field strength in the voice coil gap and the length of wire in the magnetic field, in tesla-metres (T·m).
I probably should have known this and don't mind admitting when I'm wrong. Thanks for pointing this out and correcting me.
Regardless, it's still absurd to bolt a pre prototype motor to a completely different driver and present a single Bl curve showing 24 mm xmax as proof that the production model will produce 36 mm xmax, especially if IM distortion, inductance variation, and compliance variation can't even be tested.
Bl - The product of magnet field strength in the voice coil gap and the length of wire in the magnetic field, in tesla-metres (T·m).
I probably should have known this and don't mind admitting when I'm wrong. Thanks for pointing this out and correcting me.
Regardless, it's still absurd to bolt a pre prototype motor to a completely different driver and present a single Bl curve showing 24 mm xmax as proof that the production model will produce 36 mm xmax, especially if IM distortion, inductance variation, and compliance variation can't even be tested.
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May I suggest to hold the flaming until the driver is ready as it's intended and has been retested again?
Any which way we look at it now is pointless and only comes out negative.
That would be perfectly logical... if the driver wasn't already listed for sale on the website with a full set of parameters and billed as the highest displacement driver on the planet with no proof of that claim.
Electrodynamic joined this forum specifically to refute my comments on this driver, which has only led to more and more points to discuss.
I think SI jumped the gun here a bit with this driver and their website description, and made some indefensible claims. I think this is VERY worth talking about. How are we supposed to trust the specs on any of their products? Do you see any evidence that this driver can do 36 mm xmax? If not, why is that number on the website? In post 21 he asked for proof of MTX's claims but can't provide proof of his own.
Though I agree with most of what you say, competition is usually good, and SI have obviously received a bit of feedback on a not yet released driver in this thread. Why not give them some slack and a few days to clarify/rectify claims and specs.
just a guy,
It's clear that some statements were still (and perhaps still are) incorrect with regards to the advertising of the driver. What is also clear is that you have a serious bone to pick with them. We are all now in this forum aware of what you have been posting. Further rhetoric upon the same substance serves no purpose but to make you look like you have a personal vendetta against them.
My 2 cents.
It's clear that some statements were still (and perhaps still are) incorrect with regards to the advertising of the driver. What is also clear is that you have a serious bone to pick with them. We are all now in this forum aware of what you have been posting. Further rhetoric upon the same substance serves no purpose but to make you look like you have a personal vendetta against them.
My 2 cents.
Ok guys, let me clarify my position. I'm a regular guy, a consumer that doesn't have a lot of money. Since I can't buy every driver I see I spend a lot of time educating myself and making what I hope are smart choices. So how do I pick a driver to purchase? Most of the time all consumers have to go on are published specs.
I have a serious bone to pick with anyone that publishes incorrect specs and/or claims.
I like diversity in the marketplace and I like small companies but only if they are honest. This is not the first time I've questioned questionable specs. For example (the worst example I know of), independent 3rd party Klippel testing showed that the a popular mid driver is Bl limited to 2.4 mm xmax but yet the spec sheet still claims 5.9 mm xmax and it specifically says it was measured on a Klippel. That is a MASSIVE discrepancy. This makes me question every product this company produces.
In all fairness, that driver is by all accounts a world class driver of extreme quality and the Bl was limited due to an intentional offset to provide advantages in other areas. But the fact remains that their xmax spec is completely wrong by almost 250 percent.
Things like that worry me a lot. Companies like Stereo Integrity get a lot of publicity by maintaining a public presence in forums (especially avsforum). Having to answer questions about incorrect specs is the flip side of that coin.
Other companies like B&C (since I've already mentioned them in this discussion) choose to present accurate specs. Below is a 3rd party Klippel of the 18TBW100 Bl graph (Bl was the limiting factor). They advertise 12 mm xmax and the Klippel clearly shows about 12 mm xmax at 82 percent Bl variance. They could have chosen to use 70 percent variance to show even more xmax but they chose the industry standard tightest definition of xmax as measured by Klippel.
Honesty is everything here. Xmax is measured in several ways by different companies so you have to know which company measures by Klippel (and what level of variance they use as a guideline, and whether they've actually tested a production driver at all) or by gap height (which is basically a completely useless spec) or by other means. There's already enough to worry about without having to try to sort through outright incorrect specs. This is a disservice to the entire market because EVERYONE wants to claim relatively high xmax and it leads to more and more cheating.
We should all be pushing hard for accurate specs, it's literally the only reference we have unless we can afford the time and money to just buy and test everything.
In other words, I have no specific grudge against SI (other than what's been discussed here), if I did I would have conducted this discussion at avsforum where SI is wildly popular. Originally all I wanted to do here was question the "largest displacement driver on the planet" claim and that's as far as it would have gone if Electrodynamic didn't join the forum to engage me.
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Have you had this sort of discourse on AVS Forum, then?
What about this shitty Seas Excel driver? Go ahead and start a thread in Multi-Way if you feel so strongly about drivers not meeting paper spec (and in this case, by a factor of 57%).
Car Audio | DiyMobileAudio.com | Car Stereo Forum
E0042-08S W18NX001
What is "absurd" is to question a piece of data that you clearly cannot read. The Klippel BL curve that I posted clearly indicates/shows a little over 31mm Xmax, not 24mm. Again, that was our prototype motor with a much smaller pole extension (larger pole extensions extend the coils immersion in the BL field which increases Xmax) along with a shorter coil than what we are using on the IB woofer (longer coils yield higher Xmax values). Combine the two pieces of information and you get higher Xmax. We have calculated the Xmax based on the results of fifty previous iterations of topologies that have all worked out to within a single mm or two of projected...which are backed up by Finite Element Analysis modelings.
It is people like you that keep companies from posting any data. Specs like Le are taken out of context when one is shown lower than another when the differences are attributed to temperature, latitude, and most notably frequency at which Le is measured. Le measured at 10k Hz is going to be lower than is measured at 1k Hz. But these specifics are never asked about but rather bickered about and thrown around like you are doing on here.
Other people on this forum seem to be willing to hear what we have to say and want to hear/see it. However, you are working very hard to have us not post any further data/information about our development of this woofer.
I can read the graph just fine. As I showed earlier it has 24 mm xmax with 82 percent variance or 30 mm with 71 percent variance. So you are not incorrect here but you did use the most lax standard definition of xmax by Klippel standards.
What is not correct is to assume your production driver is going to perform the way you expect it to without measuring it and posting that info on your website. Bl is NOT the only thing that can limit xmax but you are not testing anything other than Bl with a motor strapped to a completely different frame with different soft parts. And at this point you are not even testing the production motor.
People like me that want accurate data?
I'm clearly not the only one. You stopped posting at avs a couple of days ago when other people (not me) started to call you out on posting incorrect data.
Feel free to post anything you want. If it's accurate you won't see any complaints at all from me. Like I said earlier, I was a huge supporter of your SI HT 18 driver when it was selling at presale prices. The proof is right here in this forum in my previous posts. Make a good product and advertise it honestly and I'll be the first and loudest one to back it.
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