New SVS Ultra 16"

[Kyle]

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.

[shadyJ]

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. 

[shadyJ]

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

 

SB16U: https://system.na1.netsuite.com/core/media/media.nl?id=129769&c=3634088&h=883c60d7de9cf244fe4a&_xt=.pdf

 

PB16U: https://system.na1.netsuite.com/core/media/media.nl?id=130247&c=3634088&h=b3bcb98d34afec35feaf&_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.

[Infrasonic]

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.

[Kyle]

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.

[Electrodynamic]

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. 

[shadyJ]

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.

[Kyle]

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.

[Ricci]

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.

[Electrodynamic]

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? 

[Kyle]

^ 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 :\

[Kyle]

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. 

[Ricci]

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.

[Electrodynamic]

 

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.

 

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.

[Kyle]

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

 

That's why I came up with my alternate theory

 

Its a plot against neodymium!

[Ricci]

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

 

 

Maybe not. The SB16U probably since it is an overhung design and a claimed 32mm xmax so that's probably a lot of coil there. The PB16 is an underhung though so it may not actually have that much wire mass. Doesn't look like it in the exploded view. Should be plenty for what they've paired it with though.

 

I was wondering what the frame diameter is on that driver. Could be actually 16" or could be 17". I read some people discussing the 16" size choice like it didn't make sense to them cause it wasn't "standard". There have been oversized and odd size drivers on the market for years. Orion HCCA 15's are really 16's, RE XXX's are oversized, JL drivers have been odd sizes for years, square subs, pentagons, 11's, 13's, 22's, etc...SVS doesn't sell these except as part of a finished powered system anyway.

[Infrasonic]

People fear that which they do not understand.

[lowerFE]

Maybe not. The SB16U probably since it is an overhung design and a claimed 32mm xmax so that's probably a lot of coil there. The PB16 is an underhung though so it may not actually have that much wire mass. Doesn't look like it in the exploded view. Should be plenty for what they've paired it with though.

 

I was wondering what the frame diameter is on that driver. Could be actually 16" or could be 17". I read some people discussing the 16" size choice like it didn't make sense to them cause it wasn't "standard". There have been oversized and odd size drivers on the market for years. Orion HCCA 15's are really 16's, RE XXX's are oversized, JL drivers have been odd sizes for years, square subs, pentagons, 11's, 13's, 22's, etc...SVS doesn't sell these except as part of a finished powered system anyway.

 

 

Where do you see the PB16U driver is an underhung design? The manual says overhung.

[Ricci]

Where do you see the PB16U driver is an underhung design? The manual says overhung.

 

Regardless of that. It's underhung. The SB16 is overhung.

[Kyle]

Similar OEM counter part. Tymphany makes the SVS drivers so this is probably more similar than not to the ultra driver. 

 

 

 

 

STW-350F188PR01-04.pdf

[radulescu_paul_mircea]

So Audiholics measured and reviewed the sub already

http://www.audioholics.com/subwoofer-reviews/svs-pb16-ultra-subwoofer/measurements

I thought Ricci did the measurements for their subs

[lukeamdman]

Eh.   You'd get more SPL and better response with two PB-13 Ultras.  

[Ricci]

So Audiholics measured and reviewed the sub already

http://www.audioholics.com/subwoofer-reviews/svs-pb16-ultra-subwoofer/measurements

I thought Ricci did the measurements for their subs

They know how to contact me. They probably figured it would be better to go with AH cause they are a vendor sponsor there and it's probably going to get more views from an advertising perspective. I bowed out from reviewing for AH mostly due to lack of time and will to do it among other things. Member ShadyJ is doing their reviews now.

[radulescu_paul_mircea]

Eh. You'd get more SPL and better response with two PB-13 Ultras.

Of course you would. But it would be more expensive.

[Jeff Permanian]

So Audiholics measured and reviewed the sub already

http://www.audioholics.com/subwoofer-reviews/svs-pb16-ultra-subwoofer/measurements

I thought Ricci did the measurements for their subs

That's about what I expected. Can't wait for Josh to test the new Cap1400