m_ms

Myself am very keen on learning about your impressions of the RCF LF21N551 in the SKhorn, but looking forward to a rundown on all 3 units used.

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Had a rather big break-through today with the aid of friend, who helped optimize the MW's. Actually, he deserves sole credit for totally rearranging the delay and other aspects via the Xilica unit in the wake of honing in on an 80Hz (still 42dB/octave Linkwitz-Riley) cross-over that we settled on. The high-pass of the MW's remains unchanged. Also, the MW's remain hooked-up in true stereo mode. He had "fallen in love," as he put it, with the MW's for their "clean, fast, non-signature, hard-hitting bass" that "wholly integrates with the mains" (he uses a pair of Electro Voice TL880D cinema subs in his own setup). He has extensive experience with and knowledge of horn subs, and found the MW's the best horn subs he'd yet heard. Not too shabby..

Sorry for the late reply as well, and thanks for getting back to me, @lilmike. I see clearly were you're coming from with your HPF recommendation for the MicroWreckers. My 8th order BW HPF for the MW's was perhaps somewhat exaggerated, not least in light of my not all that commanding use of them, so today I've dialed it back to a 4th order Butterworth HPF. I believe it actually sounds better this way, but I won't bother any of you with details to describe it. The most I've seen those B&C units move was with a recent Blu-ray showing of Blade Runner 2049 where they "jumped" 2 mm's perhaps during the scene where K's being downed in his hovercraft from a strike of lightning - and that was running the system volume 6dB's hot.. Yes, that's all they move with my typical use, but the SPL could most definitely be felt! The first weeks of use (actually until rather recently) the MW's sounded somewhat lean and lacked impact, but slowly and steadily they're really getting around to it, though I suspect running them in properly will take months. Those rugged cloth surrounds of the B&C 15TBX100'a are quite stiff, and the little they are being worked out from the limited in-use excursion won't see rapid burn-in progress. As is, after finally finding their proper on-the-side-lying placement along each side wall, I'm really pleased with the result; the MW's provide a totally effortless, uninhibited, smooth and enveloping bass that blends in extremely well with my all-horn mains - indeed they seem like a perfect match. I'm surprised they're so informative as they are. The bass is so present, clear and even liquid in a way that makes it extremely easy to follow bass-lines, and they refuse to "solidify" the way I felt the SVS SB16-Ultra did; this is bass that energizes the air, shakes it even, and is more of an enveloping, floating kind. What follows now is a rather lengthy process of fine tuning delay, PEQ, crossover frequency and slope, and subtle changes in placement (from a general outset that won't change). Right now I cross over to the mains at 91Hz 42dB/octave Linkwitz-Riley, and as mentioned above 4th order HPF Butterworth on the MW's. Great design, @lilmike - kudos

Interesting. From my understanding on the subject of high-passing subs a certain degree of slope steepness is needed for it to have an effect (i.e.: to actually be a protective measure to the driver), and going by lilmike's recommendation of a 4th order minimum it would follow that an even steeper slope is advisable. This advice may come in the wake of the relative nature of what exactly needs to be high-passed: horns generally gain from being used within a rather narrow bandwidth, and with a tapped horn both the low- and high-pass section would seem critical; the HPF for protection of a driver unloaded (in free air) below its tuning frequency, and the LPF to quench any looming peaks in the upper band. As is I'm using a 48dB/octave Linkwitz-Riley LPF at 90-100Hz (presently at 100Hz) on the MW's, and a corresponding 48dB/octave Linkwitz-Riley HPF on my main speakers (all-horns). Later I'll try out a 24 or 36dB/octave L-R crossover at 80Hz and see how that fares. The HPF on the MW's is 48dB/octave Butterworth at 20Hz, but I'll try a HPF down to 24dB/octave - slope type unchanged.

And this has to be said clearly: thank you, @lilmike, for taking the time answering my endless questions and supplying free plans to a TH that by all accounts appears to be an excellent design

Can you elaborate a bit on the "ringing" - how is this noticeable? Btw, @lilmike at an earlier juncture advised me to use a HPF at 20Hz for the MW's, "minimum 4th order," so 24dB/Octave at least. Question is whether his recommendation entailes an implicit upper limit for the slope used..

How can the HPF slope here be (too) "extreme"? Is it potentially detrimental? Certainly my assessment as well. My line of thought is why you'd bother sending info to the MW's they can't reproduce anyway, so might as well keep the HPF for music as well as for watching films.

Would like some views from you guys on the matter of a high-pass filter, and whether it's really necessary in my case with the MW's? Well, I've just applied a 20Hz 48dB/Oct HPF just to be sure. I take it this is more a measure relating to distortion than protection of the drivers per se, being that I can't see myself going beyond SPL's of 110-115dB's (short bursts, like from watching Blu-rays). Playing a scene from "Ready Player One" towards the end (of the game) is some "doomsday device" being set off, resulting in some very low-frequency rumbling as the destruction unfolds. In this scene, at my usual playback level, the excursion of the SVS driver was clearly visible, but playing the same scene with the MW's at the same SPL I can't see the driver move at all, apart from very small cone vibrations - quite impressive. Perhaps the frequencies here are sitting in the vicinity of the tuning fs of the TH.. OTOH, many Blu-rays contain frequencies indeed much below 20Hz - at full level - so if the MW's don't produce much worthwhile information below 20Hz anyway I don't see any reason for them to work, unloaded, with infrasonic information. That's certainly the argument in favor of using a HPF here.

They're alive! That is - it's still a very early sound-draft, so to speak. There's a lot of optimization in the wait, and so any impressions may only tell you so much. I won't be able to supply measurements anytime soon (I know you guys crave seeing them data), but I hope they'll land eventually. I had no success with the removal of the fan of my Crown Macro-Tech 1200; from the bottom of the amp we were able to safely pull off the fan from its spindle/axle, but when I fired up the Crown this way, with speaker load, it turned very hot quickly, and not soon after shot down one of the channels. So, the fan went back in, and properly fan-cooled one barely registers any heat on its chassis, if at all - even when cranking the MW's a bit. So, with the proviso of a noisy background level from the Crown fan, B&C drivers that aren't yet run-in, and no elaborate optimization other than crude level-matching with the mains and a preliminary HPF/LPF at 90Hz, here're some early impressions: The MW's in my particular setup are a different animal compared to the SVS SB16-Ultra, that's for sure. At first I found them surprisingly "civilized" or delicate even, and after switching polarity in one channel found a more satisfying (but not altogether) level to match the mains. They still sounded a bit recessed, in a way, as if not really kicking into gear. I've since had them playing a good many hours for the last two days, and yesterday while seeing "Mission: Impossible - Fallout" on Blu-ray I noticed how they suddenly started loosening up and subjectively gaining in volume level. This tendency has continued throughout today with a fuller, more tactile sound, so much indeed that I needed to re-calibrate their volume. Compared to the SB16 the MW's provide a noticeably smoother and more "liquid" presentation of the lower band, and a livelier mid-bass. Moreover the bass from the MW's is much more wholly immersive, like an omni-presence. What's interesting is hearing how the bass of the MW's can truly sound like the lower registers of an instrument (like strings), where the SB16 sounded congested by comparison and more obscured "bassy." There's indeed an obvious thickening of the bass from the SB16, from my recollection. The MW's have more roar and texture in the mid-bass to mate more seamless with my mains, while subjectively rolling off earlier in the lower bass compared to the SVS, but this is a bit tricky to assess. With up-beat techno material the SVS had more emphasis on the lower bass to the point where you felt it to stumble a bit, whereas the MW's are more agile with no drag, more impactful and yet fuller sounding, but with more emphasis on the mid-bass. There's no sense of the MW's lacking in the lower bass as such, where there's the sensation of them shaking the air very effectively, but I suspect the SVS to dig a little deeper. Pics later, and more impressions to come as the optimization process kicks into gear..

To think that I once considered the Gjallarhorn, though only briefly because of its monstrous size (this thing would have never gotten up the stairs to our 2nd floor apartment, both due to its shape and weight), fairly limited upper band and out-of-production driver. Speaking of which (i.e.: the driver) I'm hoping the B&C unit will do well in the MW's. It's never been tested in this tapped horn before, though it models very well. Hoping to get the MW's up and running Sunday or sometime next week.

Sound like beasts. What's the in-room low corner from a pair of those, and how big is your listening room (in square meters)? Not that I believe it's really necessary, but I plan on applying a HP-filter at about 18Hz for the MW's. What's the opinion on this from you guys - do I need to bother with a HP-filter if I don't go past 110-115dB max. in my listening room? My reason to go with a HP would be to keep distortion at bay, rather than protection of the driver per se in my particular setup. The B&C driver does have limited Xmax, so it might be a good idea..

But you got 4 of those 21" subs, right? Are they sealed? Don't know why I never realized how big the MW's really are when crawling through my listening room measuring them out for placement options. There's something about seeing those solid surfaces for real that blows away one's idea of size formed from a measuring tape. I've thought about that myself: what does @lilmike have in store for us to come when the biggest, current creation of his is a "LilWrecker"? 😲 A Mega-iteration would have to be an extension of the house..

That was certainly "Plan B" hoping that the errors wouldn't affect performance severely, but that's not a desirable option when the outset is going "all in" and fuzzing over single millimeters. Fortunately it didn't get to that

1206 x 608 x 768mm's (H/W/D).

Construction quality of the building is likely the primary reason for the neighbors not being rattled out of their minds, indeed, added to (fortunate) inventory layout of my neighbors homes and how they relate to the placement of my listening room. In other words: luck is also a factor here, I guess. Had a near DEFCON 1 moment earlier this evening. Being that I need a rack build over the on-the-side-lying MW between the main speakers I thought I would just manually measure out the height of the MW, and somehow surprised by the number I saw was later horrified when my measurement didn't correspond to that of @lilmike's orig. Sketch-Up drawing. I was devastated, panicked, made more measurements, all of which were off - what the hell would all this effort be worth with a pair of huge, heavy bass horns with a likely misaligned horn expansion?! I was shut down for over an hour - close to weeping even. Desperate I contacted Simon Mears (who made the CAD-drawings from Mike's orig. plans, and is also the man behind my main speakers), and he gave me the height spec from his CAD drawing: some 1206mm's. Hey, this corresponded precisely with my own actual measurement, which veered off from what I thought should be about 1170mm's. Another measurement from Simon as requested from me of the horn mouth, and that fit my measurement to the mm as well. I then divided Simon's measurements in mm's with those from Mike in inches, and got 2,54. Blood went to my head again - I had used the crude 2,50 as a conversion value from US inches to mm, and with the correct 2,54 value all actual measurements were spot on down to the damn millimeter. Now I was even closer to weeping - the day's small miracle!

Two pics of the MW's in my listening room, only partly unwrapped (and not oil-finished). I also placed the B&C driver in one of them just for fun. The Uccello main speakers aren't small by any measure, or so I thought.. The plan is for one of the MW's to be placed on its side between the Uccello's, and the second MW against the rear wall behind the listening sofa. We'll see how that fares. After the clear oil finish the MW's should attain a light-golden appearance not too far from the mains. I like the look of good, "naked" quality ply.

Haha, what a great reply from your wife As I just replied to Ricci, the MW's may prove a challenge re: neighbors. But so far they've been very tolerant. Good answer. Indeed Denmark is a small country. I know of one in the whole of this country (Norway, different matter) - yes, only one who's using horn subs in his home setup. I'm sure there're more of them out there, but I bet they're far between. The one I do know has an awesome all-horn setup (all-horn from top to bottom is even more rare): 4-6 FLH's (can't remember how many exactly) with a 15" Fane Colossus driver in each that extends to 25Hz, and paper horns from Inlow. All active. Subs take up some 4 square meters total volume. Impressive..

When I used the SVS SB16-Ultra over the entirety of my ownership of it (i.e.: about a year and a half), I had not once received a complaint from the neighbor above or below. And believe me, I've watched countless Blu-ray films and given them a good run, music as well. I know, compared to you guys and the subs you're used to this may equate to iPhone-levels, but still. It even got so far that I wondered why my neighbors didn't complain, so I asked them to their faces, several times: "Have my watching films and listening to music ever bothered you?" Their answer, repeatedly: No, no and no. Color me surprised. I see you're already on your way to the keyboard wanting to let me know 2 MicroWreckers vs. a single SB16 is like comparing a ship cannon to a bebe gun. Granted, I may invite hell and flynders here with the MW's - I hope not. Oh, btw. - the MW's were safely transported to our 2nd floor apartment. The cabinet maker and I fought for it, but we succeeded. Now I only need to sand the edges a bit, and apply a clear oil. Then comes the mounting of the drivers. And did I say the MW's are huge? Heavens..

It would be interesting nonetheless to do a comparison between a MW and a 24" sealed sub From what I can read here and there the magnifying power of something like a tapped horn is in the vicinity of factor 3 (or even more), so a 15" in a TH would roughly equate into two 18" direct radiating units or thereabouts? Reading through the big "Danley DTS-10 "Super Spud" DIY kit"-thread though it's quite obvious the DTS-10 sports a different kind of overall sound delivery and impact compared to a series of 18" DR's (poster 'MKtheater' in particular provided a lot of intel in the form of actual listening impressions here), which points to the tapped horn itself as something that leads to a distinctive bass imprinting (which, perhaps, could also be said about direct radiating solutions, so not to hand a "character-baton" to TH's as such). On a side note I saw my completed MW's today (at the cabinet maker's workshop at a local theater), that is: one of them only needed some clear oil and finishing touches around the edges, while the second one had just been assembled today and was still wrapped in clamps. What dawned on me though when I finally laid eyes on them "in the flesh," so to speak, was their sheer size. Holy freakin' moly - they're huge..! 😱 I've measured out these things at home to plan for their placement, but nothing prepared me for the solid surfaces of these when I finally saw them for real. Subjectively they look something like 50% bigger than I'd imagined. A lighting technician from the theater came by as the cabinet maker and I stood there looking at the (almost) finished MW, me still in amazement, and wryly asked: "Isn't one of them enough?" Having now been confronted with the sight of these I hesitated a bit, then replied: "Ooh yes, certainly going by the sheer output this will be able to produce, but.. " and then followed a less than convincing speech, possibly because I now felt it to be quite hilarious, about smoother room respons with 2 differently placed subs (or more) and all that jazz. Needless to say the lighting technician seemed skeptical about my explanation. With a smile on his face the cabinet maker then followed with the question "For how long will you be allowed to keep these, and at what cost?" We just laughed Tomorrow they'll be transported to our home, a second floor apartment. More to come, if we'll survive the endeavor of getting them up the stairs..

Finally some pics of the assembly process. The MW's of @lilmike are finished on Wednesday.

Oh well, the ever-delayed two MicroWrecker's of @lilmike will now see completion (dare I say it?) on Wednesday. Pics - a few, at least - should start rolling in Monday or Tuesday. The main reasons for the delay are: an extremely busy cabinet maker (working at a theater with some big productions just about to premiere), and that the CNC-cut panels had two of them, the driver panels, with a wrongly aligned driver hole cut-out (driver panels have been re-cut). Fortunately everything else fits perfectly, and the assembly has slowly started up (to speed up from Monday). A few days ago we double-checked the fit of the holes for the driver bolts. Speakon terminals will by mounted at the bottom tilted back panel. 13-ply birch looks great. Initial pic of the B&C 15TBX100 on the driver panel for screw hole mark-up, and two CAD-pics of the MW attached.

Of course.

Looking forward to that indeed 😎 Truth be told I'm absolutely clueless as to what awaits me with the MW's. My last sub was a single SVS SB16-Ultra - no slouch by any means relative to its size, and quite musical - so I take it I'm in for a change, safe to say, with a pair of horn subs each fitted with a driver the same size as the one used in the SVS. Overall impact comes to mind here.. 😬 I did contemplate adding a second SB16, which I'm sure would've made for a very good result, by why not try something altogether different (and more powerful) while you're at it (I'm rather drawn to pro-style sub bass), for what will amount to the same-ish sum of investment? Further off topic (sorry, Mr. Ricci): have you ever heard Danley's TH-50, and if so how did you like it? I know the MW's are inspired by it (as is the Ghorn, I guess), so maybe some impressions of the TH-50 would give me a slight bearing - if indeed this model is anything to go by in relation to the MW's. Yeah, 25Hz Ricci-measured response from the SKhorn could well turn out to be quite sufficient with movies when all has been said and done with the contribution of room gain. I do have concrete walls in my listening room, but hardwood floor and a ceiling material I'm not aware of (my guess is some kind of plaster), so what that does for room gain I couldn't say. If memory serves me correct you're using a total of four 21" units (sealed?) for your subs, right? Using only little imagination I take it those could potentially level your home at "full tilt" or war volume as well? I believe a pair of MW's with the B&C 15TBX100 (which per lilmike is mechanically limited in the MW at about 600 watts) could hit 130dB's with 400 watts, so perhaps in the same ballpark compared to your setup

Got it - re: whether the SKhorn is a horn or not. It's impressive what it does with a relatively limited size, and split up in two has a form factor that would suite my environment quite well. The measurements look excellent too. I'd use it with the B&C 21DS115's to shave off some expense (instead of the siblings 21WS152 or IPAL), perhaps also to deliver a slightly smoother measured response (?), but only because I'm under the impression this unit wouldn't compromise overall performance too severely (certainly not for my use); otherwise there wouldn't be any point in building them. But as it is I won't be building them - at least, not anytime soon Right now my focus is getting to implement the two MicroWreckers, which are planned to finally be finished by next weekend (I know it's not a build by Ricci, but might still deliver a build-threat here when they're finished). Exactly; while not completely sure - because really, how deep does 25Hz feel? - my gut feeling tells me the SKhorn would be slightly lacking with movie-playback, at least some of them, while being potentially better in the opposite end of its operating range compared to the MW. That being said I won't deny horns intrigue me the most (as I'm sure is quite obvious by now), and one of the technical reasons for my preference for TH's over FLH is excursion minima at the tuning frequency, while offering better extension for a given horn size (my listening space is limited, after all). I'm sure the SKhorn is an awesome sub - even without being a horn What fascinates me about horn bass though, and where I feel it differs to the sealed and ported designs I've heard (haven't heard 6th order BP iterations), is a distinctive smoothness or buttery liquidity even. I'm thinking it has to do with very little smear/good transient ability, high-ish sensitivity and ease. With the bass heads lurking around here and an experience far exceeding mine I suppose I should eat up my preconceptions and accept that other principles than horns can provide great bass, but is it the same as horn bass? That I'm not convinced of. For now I'm hoping the MW's will integrate well with my all-horn mains with an 80-100Hz low pass. That's an interesting solution that I'll keep in mind, mixing the SKhorn with a more depth-capable solution for movies, but it would hardly be manageable in my current listening room. Maybe at some point I'll realize giving up extension below 25Hz is the most acceptable compromise with the SKhorns only - we'll see. The M.A.U.L however - good Lord. LOL! Or was that Darth M.A.U.L.? That's one mean beast I'd never dare getting my hands dirty with 😲 I mean, 250 kg's?! But, down to 15Hz - job done in that department.