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New SVS Ultra 16"


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#21 Kyle

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Posted 08 October 2016 - 04:26 AM

The ported probably needs more motor because its driving a port. You typically want a lower Q driver in a ported box to keep things flat or tilted downward. What you want to avoid is a high Q hump. Sealed drivers on the other hand can sound thin if the Q is too low and thus would require extra EQ to boost the low end. Having a little less motor force is a natural way to deal with that and keep the response flat. I believe one of these drivers is under hung and the other is overhung. Different variants for different systems.


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#22 shadyJ

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Posted 08 October 2016 - 07:25 AM

The PB16-Ultra is underhung and the SB16 is overhung. I thought that sealed designs have a greater need for motor strength than ported? And also that underhung motors tend to be not quite as powerful as overhung?


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#23 shadyJ

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Posted 08 October 2016 - 07:27 AM

Did you guys notice the PB16U driver has 41mm of Xmax when the SB16U's driver is only 32mm? 

 

Why is the sealed version getting the lower Xmax and lower motor force driver? The ported one should be the one getting the lower excursion driver with the port managing the excursion levels down low. It doesn't need as much motor force either since the enclosure is so much bigger. The sealed version should be getting the ported driver. It needs that extra excursion and motor force in that little sealed enclosure. 

Where did you get those Xmax numbers? I don't see them. All I can find is peak to peak.



#24 lowerFE

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Posted 08 October 2016 - 04:08 PM

Where did you get those Xmax numbers? I don't see them. All I can find is peak to peak.

 

It's in the owner's manual. It says overhung for both. 

 

SB16U: https://system.na1.n...44fe4a&_xt=.pdf

 

PB16U: https://system.na1.n...35feaf&_xt=.pdf



#25 lowerFE

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Posted 08 October 2016 - 04:11 PM

The ported probably needs more motor because its driving a port. You typically want a lower Q driver in a ported box to keep things flat or tilted downward. What you want to avoid is a high Q hump. Sealed drivers on the other hand can sound thin if the Q is too low and thus would require extra EQ to boost the low end. Having a little less motor force is a natural way to deal with that and keep the response flat. I believe one of these drivers is under hung and the other is overhung. Different variants for different systems.

 

I agree with what you say when designing without DSP signal shaping. But what if DSP shaping is used, like in SVS's case? Wouldn't a higher motor force woofer perform better for a sealed enclosure?



#26 Kyle

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Posted 08 October 2016 - 05:55 PM

The PB16-Ultra is underhung and the SB16 is overhung. I thought that sealed designs have a greater need for motor strength than ported? And also that underhung motors tend to be not quite as powerful as overhung?

 

Good questions!

 

Motor power is not really what the right factor it, its a contributor to the Q and its the Q that's what matters for system design. That's a big topic...

 

In general, underhung usually has less motor force, but not always. A lot of things can effect this. Another big topic, but the primary reason underhung cuts BL is because you're reducing the coil across the effective gap so you're leaving B directly uncoupling with wire at all times to create the xmax geometry. It is true as you reduce the size of the coil you reduce the relative Re so you also gain BL^2/Re that way, and you reduce moving mass too (but only a little). Those two things sound like a big gain, but generally not as much as the BL loss you already incurred. This is all of course assuming the same motor for both coils options.


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#27 shadyJ

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Posted 09 October 2016 - 01:01 AM

Good questions!

 

Motor power is not really what the right factor it, its a contributor to the Q and its the Q that's what matters for system design. That's a big topic...

 

In general, underhung usually has less motor force, but not always. A lot of things can effect this. Another big topic, but the primary reason underhung cuts BL is because you're reducing the coil across the effective gap so you're leaving B directly uncoupling with wire at all times to create the xmax geometry. It is true as you reduce the size of the coil you reduce the relative Re so you also gain BL^2/Re that way, and you reduce moving mass too (but only a little). Those two things sound like a big gain, but generally not as much as the BL loss you already incurred. This is all of course assuming the same motor for both coils options.

Interesting stuff, thanks for the explanation, I will have to read up on this. 



#28 shadyJ

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Posted 09 October 2016 - 01:03 AM

It's in the owner's manual. It says overhung for both. 

 

SB16U: https://system.na1.n...44fe4a&_xt=.pdf

 

PB16U: https://system.na1.n...35feaf&_xt=.pdf

Huh, I have it directly from SVS that the PB16-Ultra uses a underhung design and the SB16-Ultra uses a overhung design. Also, that is a monster Xmax. If that is correct, I think the 16-Ultra subs will be a huge jump over the 13-Ultras in performance.



#29 Infrasonic

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Posted 09 October 2016 - 02:31 AM

Good questions!

 

Motor power is not really what the right factor it, its a contributor to the Q and its the Q that's what matters for system design. That's a big topic...

 

In general, underhung usually has less motor force, but not always. A lot of things can effect this. Another big topic, but the primary reason underhung cuts BL is because you're reducing the coil across the effective gap so you're leaving B directly uncoupling with wire at all times to create the xmax geometry. It is true as you reduce the size of the coil you reduce the relative Re so you also gain BL^2/Re that way, and you reduce moving mass too (but only a little). Those two things sound like a big gain, but generally not as much as the BL loss you already incurred. This is all of course assuming the same motor for both coils options.

 

Kinda like have a RWD car with 1,000hp and an AWD of the same car also with 1,000hp.

 

One puts a ton of motor in a small amount of space. The other spreads it evenly across all.



#30 Kyle

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Posted 09 October 2016 - 05:00 PM

I agree with what you say when designing without DSP signal shaping. But what if DSP shaping is used, like in SVS's case? Wouldn't a higher motor force woofer perform better for a sealed enclosure?

 

Yes, I believe you should always go for maximum BL no matter what  and use EQ to fix things if you need to.  If you have more motor you reduce the current demand of the amp for the same output and that has huge benefits. Of course BL and xmax counter each other in all practical applications so these are the real trade offs. The highest BL you can get from a motor is even hung , or depending on fringe field distribution, very slightly overhung. This would really reduce linear BL curve and you would have higher distortion at high displacement.



#31 Electrodynamic

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Posted 11 October 2016 - 04:40 AM

Huh, I have it directly from SVS that the PB16-Ultra uses a underhung design and the SB16-Ultra uses a overhung design. Also, that is a monster Xmax. If that is correct, I think the 16-Ultra subs will be a huge jump over the 13-Ultras in performance.

 

If we took a page from SVS's new marketing strategy we could list our HST and HS series drivers at 76 mm Xmax and 130 mm Xmech. I wonder how this forum and other forums would take that adjustment vs. what SVS has done? I could tell you but it would piss people off and start finger pointing towards us and not SVS. 

 

Xmax is, has been, and always will be one-way linear excursion unless stated differently. Even then, stated differently is skating around the true meaning and definition of Xmax wether you adhere to 70% or 82% BL. 



#32 shadyJ

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Posted 11 October 2016 - 05:53 AM

If we took a page from SVS's new marketing strategy we could list our HST and HS series drivers at 76 mm Xmax and 130 mm Xmech. I wonder how this forum and other forums would take that adjustment vs. what SVS has done? I could tell you but it would piss people off and start finger pointing towards us and not SVS. 

 

Xmax is, has been, and always will be one-way linear excursion unless stated differently. Even then, stated differently is skating around the true meaning and definition of Xmax wether you adhere to 70% or 82% BL. 

Agreed, SVS is inflating numbers with marketing gobbledygook. Still, even 41 mm and 32 mm xmax, which is what I take that they are implying, is not bad, but we don't know what they really mean by Xmax. What would be interesting is if someone took the driver out and measured its bare performance without the processing of their amp.



#33 Kyle

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Posted 11 October 2016 - 07:39 AM

Ya, it would be best to know the gap height and coil winding width. That's all we really spec here at data-bass.com anyway.  You can nearly derive everything else form that with reasonable accuracy.



#34 Ricci

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Posted 11 October 2016 - 03:58 PM

I believe they list peak to peak in the literature but yes for people not as informed they will not understand that it should be divided in half for comparison to most xmax specs. Not sure if they actually call it xmax either. Haven't read the owners manuals. The specs on the website appear to be referencing the peak to peak xmech.

 

Also the cutaway pics of the PB16U seem to show a very large spider. Looks like possibly 13" if I had to guess maybe even slightly larger. Could even be a 14".

 

Knowing the gap geometry can give a much clearer idea of what type of useful stroke a driver may have. For example you may have 2 drivers both rated at 20mm xmax. Without knowing the gap geometry and going off of just the spec it might be assumed that both offer similar excursion behavior but that may not be true.

 

Driver 1 could be a 43.5mm coil wind height with a 10mm gap height. 

Driver 2 could be a 65mm coil wind height with a 25mm gap height.

 

Both could claim 20mm xmax quite easily. Driver 1 could use the common mathematical coil overhang + 1/3rd of the gap depth for the rating. 43.5-10= 33.5/2=16.75mm physical coil overhang. 1/3rd of the gap would add an additional 3.33mm resulting in a rounding to 20mm. Driver 2 could just be using the physical coil overhang method, with no adders, of 20mm. If it did add in 1/3rd of the gap it would be closer to 28.3mm. Another consideration is that the shorter magnetic gap in driver #1 will mean that the coil physically leaves the gap at 26.75mm displacement from center. In all likelihood no matter how much power you put into the driver it will not be able to travel further if even that far. Driver 2 has a much larger gap height plus a longer coil. The coil doesn't leave the gap of driver 2 until 45mm from center. Despite having similar basic xmax ratings the 2 drivers differ quite a bit and driver #2 should have much higher effective displacement. This is very simplified and ignores a ton of other factors like fringe field and suspension performance of course.

 

Actual coil and gap specs are much more useful than an xmax figure in many cases.


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#35 Electrodynamic

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Posted 12 October 2016 - 03:12 AM

Ya, it would be best to know the gap height and coil winding width. That's all we really spec here at data-bass.com anyway.  You can nearly derive everything else form that with reasonable accuracy.

 

Unless you have a FEM or FEMM modeling program sheer gap height and coil winding width are not accurate if either (or both) measurements are large. Back in the day of smaller drivers with simple overhung drivers with 10 mm of overhang with a 5 mm thick top plate, sure. But today with 30 to 50 mm top plate thickness and 75 mm long coils the simple overhang model falls short of actual 70% or 82% BL. ...basically what Ricci said in his post above. 

 

But on a realistic note: No one is going to purchase SVS's 16" woofer system, pluck the driver, and send it into Ricci to be tested. People may say they are going to but no one will. 

 

And is no one going to chime in on their verbage for their notes on the response plot [red/orange arrows]? I had a lot respect for SVS until I saw their web page for this subwoofer system and the verbage and specifics (technicalities) they used for this subwoofer system. Or am I just "that guy" that is saying what everyone else is thinking but no one is willing to say it? 



#36 Kyle

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Posted 12 October 2016 - 06:23 PM

^ Sure, I understand. Normally I do the 25% gap rule. Its pretty close to 70% BL in most cases I have seen. For example, the Pro 5100 is 25% out of the gap at 28mm. It's true FEA'ed 70% orignal BL value comes in at 31mm -- pretty darn close. But like I said, as long as you have WW and gap size, you can pretty much get a good ball park of the motor stroke. What SVS has done is thrown out p2p values with no coil WW or gap height. I understand that the underhung 16" Ultra has more p2p throw than it's overhung sibling but is that a function of motor clearance or real xmax? We don't know :\



#37 Kyle

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Posted 12 October 2016 - 06:34 PM

I posted this on the AVS forum, but I'll re-say it here. I think the 8" coil is a move to retain a high B ceramic motor but avoid going with the super wide-style magnets like the LMS Ultra or others like it or change to an even more costly  neodymium motor. An 8" ceramic t-yoke magnet would generate a lot of B but still end up being a smaller motor than something like the LMS Ultra.
 
At the retail $2500 price point, a high power neo motor is probably out of the question. This is a bold and cleaver way to side step that issue but still have a very powerful and not-too-heavy motor. I think the power handling, coil centering and structural advantages of an 8" coil are secondary despite SVS's nomenclature and also not without opposing considerations -- added weight & potential spider throw limitations. 


#38 Ricci

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Posted 12 October 2016 - 08:24 PM

Agreed.

 

The driver is "only" 64lbs which is kinda surprising to me. I'd have guessed more. I find the driver to be the most interesting part of the new SVS's and it seems like so does everyone else, but they are just one part of a finished turn key system and not sold separately. The whole sum of the parts is what matters and how they will be reviewed by a dozen or so publications I'm sure.

 

Not sure what other claims or marketing blurbs there are to take issue with other than listing peak to peak xmax? Sure there's a lot of rather splashy buzz words and marketing hype going on there but that's par for the course. It's maybe a little thick but pretty similar to that seen a lot of other places IMO.



#39 Electrodynamic

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Posted 13 October 2016 - 04:00 AM

 

I posted this on the AVS forum, but I'll re-say it here. I think the 8" coil is a move to retain a high B ceramic motor but avoid going with the super wide-style magnets like the LMS Ultra or others like it or change to an even more costly  neodymium motor. An 8" ceramic t-yoke magnet would generate a lot of B but still end up being a smaller motor than something like the LMS Ultra.
 
At the retail $2500 price point, a high power neo motor is probably out of the question. This is a bold and cleaver way to side step that issue but still have a very powerful and not-too-heavy motor. I think the power handling, coil centering and structural advantages of an 8" coil are secondary despite SVS's nomenclature and also not without opposing considerations -- added weight & potential spider throw limitations. 

 

 

The 8" coil is for power handling.* Edgewound is a nice touch but 8" diameter does not always indicate higher motor strength. I quickly modeled a 4 layer [similar motor strength to a two-layer edgewound] round wire 3.7 Ohm by 25 mm WW 8" ID former cup motor (what the SVS is) using Y35 magnets 50 mm thick with a 40 mm top plate and came up with a BL of 18. Kudos for the edgewound coil but that 8" coil can handle four or five of the amplifiers they are pairing a single unit with. :D

 

I'm not sure what their play is other than buzz words now that SVS is handled through Best Buy [Magnolia]. Neat driver design though.

 

*If you look at our BHS vs our HS mkII you'll see that the BL^2/Re of the HS mkII motor is actually a little higher than the BHS motor. The HS mkII motor uses a 3" coil where the BHS motor uses a 4" coil. But the power handling of the BHS motor is double that of the HS mkII.



#40 Kyle

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Posted 13 October 2016 - 04:18 AM

Kudos for the edgewound coil but that 8" coil can handle four or five of the amplifiers they are pairing a single unit with. :D

 

That's why I came up with my alternate theory :)

 

Its a plot against neodymium! :P






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