Anyone else excited for this Borresen subwoofer?!!!

The DSL Matterhorn, as per the video, is actually a very large tapped horn which means both sides of the woofer cones are used for pressurization, so that the back wave of the cones build up down through the expanding horn path to the bottom of the container, and from there the horn path goes into a 180 degree turn to continue back towards to the container opening where the combined wave from both sides synchronizes with the front wave of the woofers at the "mouth." This is not what the Borresen sub is doing (i.e.: it only uses the front wave of the cone, added to the fact that it’s not horn-loaded), and the "velocity" rethorics to me reads more into merely creating a combined pressurization through the slot at the front. Lot of yada yada and hifi sensationalism if you ask me, but I actually like the approach being the multitude of smaller woofers will combine and act like a single, larger woofer, which to me is preferred route vs. several smaller, and spread out woofers.

Correction: presumably I was incorrect about the Borresen sub principle and it only utilizing the front wave of the woofer cones. They look to be mounted in a folded-baffle design (a so-called "RiPol" after Alex Ridtahler, short for Ridtahler Dipole) that radiates both front and aft in a directional pattern - i.e.: the backside of the cones "shoot" into the open-to-the-back dual chambers - and thus necessitates a free-standing position. Inherently low efficient, but by all accounts (very much dependent it seems on accurate positioning) delivering a very clean "coming from nowhere" bass, also very suitable it appears in conjunction with planar/ESL main speakers. Interesting principle for a number of reasons, but less so for my requirements in particular. Sorry about the confusion.

@deep_333 wrote:

All technical and sensationalist jargon aside...the simple ability to delay the mains, very easily accommodated in the multichannel or pro world to make life a whole lot easier...but, a freaking rarity in purist hifi.

The buzzwords here are "purist hifi" and "analog," but as poster @mijostyn points to delay can be done in the digital domain (the non-purist approach, god forbid), even more accurately and expansively with a separate, quality DSP unit that can also be more sonically transparent than most analog solutions (not least omitting the passive crossover), and if the same DSP section affects the whole frequency range actively the inherent delay of the unit affects the different driver sections equally.

What’s considered "purist" in the Borresen way or general sense of audiophilia is usually only so in a limited context (i.e.: analog vs. digital), and so I’ll glad incorporate quality digital where it makes a lot of sense, apply a purist oriented approach elsewhere and try and see the forest for the trees more clearly.

@m-db wrote:

I had one of Tom’s tinnitus inducing Tech 7 ServoDrive belt drive horns with the band for a few weeks. Brought it in the house and ran the source through the Velodyne’s Rap EQ preset, OMG!

I read of those, allegedly they were SPL-beast (and then some) but according to sources also somewhat unreliable?

I hate to criticize anything I haven’t actually listened to at home or at least on a familiar system.

Good point.

On the other hand there were some phrases coming from Mr. Borresen that triggered my yada whada? too.

Yeah, the sub principle at hand at its core certainly isn’t unique, it appears, though hardly widespread in use either. I’ve heard similar rhetorics from Borresen and others with more or less grandstanding notions, and yet the physical framework where speakers go, as usual, is stunted. One can only do so much from a restricted outset.

As a Double Bassist a single or 6 pack of -6dB sub-bass systems just don’t go low.

Perhaps a physically more all-out open baffle tower sub system would be the way to go (multiple 12" woofers or bigger), albeit taking up more space into the heights and without being SPL- or extension-monsters all the same..

Paul McGowan of PS Audio on dismissing servo-feedback in his custom upgraded IRS V bass towers:

https://youtu.be/1OdkRiwmYbE?t=101

Subwoofers from the outset of what are actually physically accommodating designs is the purist approach audiophiles don't want or know how to talk about, because it's inconvenient from the perspective of interior decoration and spousal approval, i.e.: the sheer size of such designs, as well as an area relegated to lesser importance - also in regards to the use of amplifiers and DSP section. What's so hard to comprehend about that?

@deep_333 wrote:

Paul’s vid describes the free lunch that he got with initial use of crappy drivers. How about this....Get the low distortion high excursion bells and whistles driver. Now, stack/integrate several of them so they don’t have to move as much for said spl level. Now, add servo control on top of it...it is incremental. It could all be overkill at normal listening levels, but, maybe not, because it is still the highest distortion component in the chain, relatively speaking.

It’s interesting to note that, with the knowledge and experience of being a servo-feedback designer himself (for the bass system of the IRS V’s), Paul is expressing how "everything is a compromise," and that - it follows - includes the servo-feedback circuit itself. What’s entailed in this specifically isn’t made clear, but it touches upon the aspect of a more purist oriented approach where, with a physically more all-out sub system, one can avoid "compensating measures" like servo-feedback, EQ-boosting and other. With the scenario you’re suggesting (i.e.: low distortion high excursion bells and whistles driver in stacks) the need for servo-feedback circuit will by all accounts be lessened, and so when will the insertion of such a circuit itself be deemed a larger, negative influence than the positive ditto it’s supposed to create? From my chair it appears that what Paul implies is that this is the very reason for them having omitted servo-feedback in their driver and amp upgraded sub towers, because servo-feedback wouldn’t have the desired, positive effect here when all is said and done.

As to the negatives of larger subs and the compromises that may or may not be involved here, structural integrity/enclosure resonances is the one area that is usually addressed. The important question to ask then, to me at least, would be to which degree subwoofer enclosure resonances of a certain magnitude would be an actual impediment in the reproduction of music, not least compared to the contribution of mechanical noise/distortion coming from smaller, direct radiating and inefficient woofers working much harder; would you rather have a capacity strained* small sub setup with more or less inert enclosures, or a capacity unlimited, larger ditto with what is still structurally sound cabs (i.e.: built with interlocked, CNC-machined and Baltic Birch multi-layer plywood, and heavily braced)?

From experience I can say with absolute certainty that, in each and every case, I would choose (and have chosen) the latter option. It’s no contest, period. How many have actually made an informed decision based on experience with both options? Close to none, because the by far most common scenario is that few even considers large, efficient subs for reasons we know all too well, and thus the only frame of reference to go by for most is that of smaller, inefficient subs.

On a related note, I have some coupled cavity speakers, i.e. the physical bass drivers sit inside and are cavity coupled to external radiators (Acoustic filter/ clean bass). One might argue that it is a unnecessarily complicated design. But, the free-er lunch there was that you didn’t need very expensive drivers trying to hit a price point (the expensive driver that may or may not hit a performance requirement just because you kept spending up the wrong tree). I know because i also owned a cost no object conventional speaker design from that same designer...a few different ways to do these things/clean it up, i suppose.

My quip would be: there’s no free lunch with smaller sub designs.

The good thing working with large, efficient sub designs is that of being dictated design appropriate woofers. Either you use them, or performance will be severely impacted (and who’d want that?) - that’s the deal. With tapped horns, like I use, there are very specific woofer requirements and a relative small specs-"window" to accommodate, or else the design won’t perform as intended. Like, too little motor/magnet force and the horn isn’t properly resonated; too much and the air pressure will be too compressed at the throat section and thus also not resonate the horn properly. Too light and non-rigid a cone is an issue as well, also because a cone too flimsy would simply be ripped to pieces with the uneven pressure built-up at the front side of the cone in the throat of such a design.

Build and board material quality is also important here. When the woofer cone really starts moving in tapped horns (and it takes a lot in domestic milieus) the pressure built-up inside the horn path can be so severe that the enclosure cracks open due to the immenses air pressure forces created inside (remember: the single 15" woofer per cab of my tapped horns is force multiplied at the mouth into the equivalent of two 18" direct radiating woofers). In reality such sub designs are built to withstand SPL’s at full tilt, why they’re rigidly built for that very reason - i.e.: design dictated.

*When are subs capacity strained? When there’s not enough if any notable headroom to speak of at the max. SPL one desires. What’s sufficient headroom? From my chair, no less than 10-15dB’s, preferably +20dB’s.