shadyJ

If you think the PB16 Ultra sounds bad, you are very lucky never to have been exposed to a truly bad subwoofer. The fundamental performance of it is pretty good, and it's amazing how much clean deep bass they manage to get out of a 15" driver. In conclusion, you are out of your mind.

This has been something I have always wanted to do as well. A real qualitative subwoofer comparison would have to be done outside (or in a room as large as an indoor stadium). Also, as you say, the equipment would have to be hidden. That is the only real way to fairly compare subwoofers, at least with human ears. They would have to be compared using fast A/B switching between the subs as well, at least for complex signal content like regular movie or music content. The problem is, GTG's are all about having fun, not rigorous testing. I wouldn't want to ruin a GTG by insisting on rigorous adherence to a strict testing regimen. GTG's are usually about drinking a lot of beers and seeing how loud some speakers get, and that is fine, but this kind of testing wouldn't work for that kind of gathering. I would want to see if these subs can be distinguished when they are operating well within their linear ranges. SME seems to think that there would be a difference. I don't think there would, but such a test, if conducted appropriately, would certainly serve as good evidence one way or the other. Neither SME or myself would be able to properly participate, because we already have predispositions that a blind test could not overcome. Still, I would love to hear it for myself. I need to secure some kind of grant to do this with.

Ilkka Rissanen and Ed Mullen did a study of IMD in subwoofers and found that subs with low THD also have low IMD. You can read about it here, if you don't already know about it. It is not a surprising result really.

Look at the subject from the perspective of sound pressure waves. As long as the driver is turning the voltage signal into sound pressure waves at a 1:1 relationship, it is a perfect reproducer. Anything else is distortion, whether linear or nonlinear. If you have no linear distortion and you have no nonlinear distortion, you have perfect accuracy. Of course, that is the unattainable ideal, but a very good system can get close. With effort, you can get a very flat response that has insignificant distortion quantities. What difference does it make if that is achieved through a $5k super driver or a $30 buyout driver from parts express? A good driver, when it is operating at nominal levels, can have distortion quantities of 1% or less and so is inaudible. If the frequency response is flat, and it isn't making any mechanical noise like flutter noise, there is nothing else that can distinguish these units, so long as they have the same dynamic range.

Wait a minute, are you saying the subjective and ambiguous term 'sound quality' can't be absolutely defined by a single number?! Heresy!

I was thinking when I looked at all the results that must have been a brutal day of testing or spread out over many days of testing. Heck, I think just testing all the modes of a variable tuned sub is a pain in the ass, and what you tested took many times that amount of work. I hope you wore sunscreen. Anyway, great job, and incredible sub. 130 dB at 30 Hz is insanity! bravo!

I watched a movie recently that had some passages with lots of energy in single-digit frequencies: Hidden. An interesting little movie with some tense scenes. Here is a spectrograph taken at the 51 min mark: My spectrogram only shows down to 10 Hz, but you can see there will be a lot of energy under that point.

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.

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.

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

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

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?

You can actually. It has adjustable brightness, and also an adjustable timer that turns it off after x many minutes.

Unbelievable how picky some people are. Reminds me of this classic Louis CK bit.

Maybe have the coil rest in some ultra-low viscosity, thermal-conducing fluid, sort of like Ferrofluid tweeters. What we need is Ferrofluid subwoofers!

Those measurements look to be quite good. One unusual thing is they go out to 180 degrees off-axis instead of 90 degrees or so, that is a bit weird. That might be Harman's own measurements? They do 360 degrees by 10 degree intervals in their own anechoic chamber on both the horizontal and vertical plane.

Here are a couple computer sound interfaces if anyone cares: MOTU UltraLite mk3 Hybrid: Behringer U-Phoria UM2: Not bad for a $30 USB sound interface!