Kyle

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Access hatches are huge. Plenty of room.

awe

Sorry if this was asked, but how do you mount the drivers?  Does that rear access hole allow you to get screws all around or does the top come off some how?

Ya maybe the saying should be: there is no replacement for [sensitivity] 

Hello Kyle.  I have heard about you from Josh but never had the pleasure of talking with you.  I guess this is a close second.

 

I think quite a few people have written their PHD on that subject!

 

Just a speaker  

 

Don't get me started on that one.  The truth of the matter is at very few times are we going to tax the port compression on a properly designed subwoofer.  And the times when that does happen we usually have program material that masks the effect in the first place.

 

And the difference between no problems from a port at any time is the difference between a realistic enclosure size and a not so realistic enclosure size.

 

Twin 18 with an 18 inch diameter port.  Wow.  A genuine phallic idol to vent gods if there ever was one!

Hello! I'm the lurker of this forum, lol.

Indeed, very good points. I'm often amazed how bad a subwoofer can sound with a sinwave at full volume (capability) around port tuning, but put music into it and it just seems to work and the distortion seems to subside

The real question is how many more db can you get out of a driver + amp if you increase the box and or port port and the art of the whole process becomes the design trade offs. The double 18 box I spoke of is very huge and very impracticable. A few dB loss here and there for a subwoofer half the size might add a lot of value to most people.

The Plus/2 was awesome too, I loved that sub.

Old school subs for the win

I'm starting to wonder if the Old PB12-Ultra/2 could compare to this thing. Does anyone have one? Its going to have a power disadvantage with that 1k bash amp, but I think it could be a cool battle

I never like giving up sensitivity, even in sealed tbh

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

I'd like to see the PB13 with that new 1.5k amp

:\

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

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!

^ 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 :\

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.

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.

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.

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.

Agreed.

 

I gotta say how much I love this place, btw. We are all bass driver nerds. Nobody gives a shit about the subwoofer as a whole. We're just interested in the important bits. Awesome.

lol, you mean to tell me you're not caught up in how you like or dislike the front LCD panel like they are over on avs?

My ball park guess is that these will put up about 4dB on the 13.5" Ultras perhaps with a bit better extension to boot.

 

About the 8" coil. Kyle is right the first concern is getting a spider system that will support large excursion in a linear manner with so much of the area taken up by the huge 8" former. It's not impossible though. Why use an 8" coil? Well it does provide better centering with the spiders to prevent a long former from cantilevering during large excursions. Also you can get higher motor force with that much coil in the gap and larger heat dissipation surface area. Both can help improve power handling and reduce thermal compression and parameter drift at high power. Some downsides typically would be increased moving mass, cost and perhaps higher inductance. Just because the coil is a larger diameter doesn't necessarily mean that the coil is more massive though. For all we know it could be a relatively short winding height with a single layer edge-wind. Something like a 3" diameter, 3" tall winding height, 8 layer coil, could have more wire mass even though the diameter is much smaller. Those are fairly common in big car audio subs. We don't have enough info to tell for sure. I would assume that SVS's engineering team used the large diameter for centering, improved thermal dissipation, marketing purposes (hey why not?) and higher BL and weighed the tradeoffs versus more normal coil sizes. Their engineering has been quite good so I assume there are solid reasons for it that make sense as per their design goals.

exactly correct. I would also add one more interesting feature. A disc magnet like this generally yields a 2x fold advantage in B captured in the motor compared to an outside ring. Typically you would jump on that, but because of the surface area limitations of the coil ID, disc magnets need to be neo. And even then they have very quick limits with 4" or even 5" coil constraints. An 8" coil opens up that diameter quite a bit and seems to even allow an ordinary ceramic magnet to be useful. This magnet stack may only be ~7.9"" or so in diam., but it might be similar to a 10 or 11" ring magnet. something similar to the LMS Ultra in terms of B. Its just a rough guess...

The nomenclature is still a little silly... "Groundbreaking smartphone app"  

if it was an 18, they would list 18. I don't get the logic of that. And 18" frame is about 18.5" OD.

Yes interesting indeed, excited to see how they perform. The sub looks damn good too!

8" coil... wow. My main concerns with big coils is they cut into overall spider displacement. going forma 3" to 8" coil, one would need to increase the spider by 5" OD to maintain that capability. So if you had a 10" spider, you would need a 15" spider. I don't see how that fits on a 16" speaker. Perhaps they have a special long throw spider that works more like a surround?

Very cool. Is this driver neo by chance? I know back before Steve left SVS he was working on the new 16" driver but it was radial neo I think. Not sure if this driver inherits any of that idea or not. With an 8" coil, I'm guessing not... it might be a good fit for a neo t-yoke disc magnet.

Extremely interesting impressions on your room treatment experimentations. 

 

I want to share a little discovery I recently noticed that is sort of disturbing. I moved into a new place, and the bedroom acoustics are exceptionally bad to the point of almost unlistenable. It was so ridiculous that somehow there was a huge dip near the crossover between the mid and woofer and it was better to invert the polarity on the woofer in that bedroom. It was subjectively and objectively better (the dip was gone). That made it better, but the speaker still sounded much worse compared to the old room it was in (and the old room's acoustics weren't that great). I didn't get more time to tinker with the sound to deal with the room acoustics.

 

However, it didn't take too long (a week or two) for me to get used to the sound and find it sounding good! It didn't sound amazing, or even great, but it was a positive impression instead of a very negative impression like when I first moved in. It seems like our ears are highly adaptable, and I can't trust my own ears! I hope you have some way of comparing against a reference to reduce the effects our ears could have in adapting to a particular sound after long exposure. 

I have a similar problem. For some reason my speakers get more quite only after 2-3min of turning them on. I mean it seems to be 10 to 15dB drop without fail. The other interesting piece of information in my room is that my wife often walks over to the stereo right before it gets quite. I'm wondering if these two facts are related in some way.. hmmm.

That old freezer is about to become DB's top rated LLT.

 

Any day now.

haha

Ya. me wonders about the cheap liquid cooling options for PCs these days and how they might work on motors...

they are probably not nearly big enough but the idea seems interesting