m_ms

Not using my set-up at "war volumes" (I like that expression), nor in any pro use settings, and there are different factors at play with my system compared to yours that would have me prefer the particular cross-over choices (slope/type and frequency) I've made between the mains and subs. That being said I wouldn't go with a gentler slope, by rather a steeper one - if you can. In my set-up I find there's a "plateau" or leveling of virtues or qualities if you will with a 36dB/octave Linkwitz-Riley slope between the mains and subs. Lower than that and the sound starts becoming a tad too placid (loss of energy and firmness), and higher than that the sound becomes a bit high-strung or tensely wound-up. 30dB/octave L/R is close, and with some music perhaps preferable, but overall I prefer the "energy coherence" of the 36dB/octave L/R slope. I use a 20Hz 4th order BW HPF on my tapped horns, and they're crossed at 78Hz. Would love to cross higher than that, but though I've yet to try out crossing in the 95-100Hz region more thoroughly (which may be preferable with my mains), I fear it'll challenge the upper range cleanliness of my TH's. Actually a friend of mine may try out building a pair of Othorn subs to augment his all-horn mains (WE 12a replicas made of wood), and should he not be too pleased with the pairing (I somehow doubt that), the Othorns may find a way to my setup - an exciting thought.. I guess in your case I might try out a 105-110Hz cross-over with a 36dB/octave L/R slope and see how that works..

Essentially, isn’t a tapped horn exactly that - a 6th order BP?

Heard a bunch of those KS28's at a Rammstein concert earlier this year, and I must say the sheer wallop and physical presence they delivered was rather astounding. In a some 50,000 ppl stadium we sat about the furthest away from the stage we could, in the upper balcony, and yet the bass pounded in a manner almost beyond belief. It mayn't have been great bass per se, but it sure as hell was physical, dense and loud! Btw, I thought the KS28's housed BMS drivers?

Would a Danley DTS-10 get there? EDIT: Of course, the DTS-10 is likely beyond proposed budget..

Interesting impressions - much appreciated. The Skram appears to be one heck of a sub (and the Othorn as well), and I'd also like to have a closer listen to the Danley's. Regarding named perceived differences between the Skram and Othorn (grunt vs. growl, if you will), I'm wondering whether the more pronounced rowdy character or "growl" of the Othorn is at least partly explained due the driver being more exposed at the mouth? The way you describe it though doesn't make it sound as if the Othorn is sonically akin to a typical direct radiator (i.e.: if we accept there is any such typicality to the sound of a direct radiator), and moreover I've heard other people speak of the tapped horn sound in ways quite similar to yours (something about a combination of presence, smoothness, a certain visceral feel, and even a touch of "warmth") - impressions I can relate to via my own tapped horns, though it may at first glance sound like any capable, well integrated sub regardless of topology.. Interesting also that the Skrams appear to be more impactful (alive?) in the upper end of their range compared to the Othorn and how this is explained (simply caused by a rise in the frequency curve in the upper range?). I've always imagined the Othorns were good to some 125Hz.

Good idea with the systematic study. A friend of mine has implemented a 48dB BW HPF at 20Hz on his six 15"-loaded FLH's (tuned at 25Hz), and that sounded pretty decent to me, but other than not having heard a lower HPF slope on his setup I don't know the variables that would affect the outcome differently compared to my own setup. I've never really understood the meddling with audio content that would impose HPF; leave that to the end user. Lately I've found a tendency among studios/mixing facilities to limit ULF content in Blu-rays/UHD's (certainly from Disney, added to a low reference level), and while the impact of this is less audible in my own setup (with the latest 18dB BW HPF 17-18Hz extension is all I'll ever get), though still easily audible, I presume it's an entirely different matter with your sub setup and extension down to ~5Hz(!). It's a shame also that IMAX theaters are the only commercial cinemas to hit in the vicinity of 23Hz, but I wonder the type of HPF they're using. A bunch of Skrams/Skhorns/Othorns in a commercial cinema would be fun, and high-passed at some 25Hz would offer a significant gain in extension over the typically used dual 18" ported cabs.

If your use of 12-24dB BW HPF (or mostly 18dB) is implemented in the context of the subs having to endure your test-bench trials, then I take it the slopes being mentioned are sufficiently protective. I may try out 12dB BW and see whether it's advantageous in terms of sound quality, but I'm not sure it's a good idea with tapped horns if they unload more severely below tune compared to ported subs or a 6th order BP iteration like the Skrams? As is 18dB BW HPF is preferred here over 48dB BW. The overall presentation just appears to be more cohesive.

Maybe this has been brought up at an earlier juncture, but is the driver in a Skram unloaded below tuning frequency similarly compared to a tapped horn or ported enclosure to necessitate a high-pass filter, and if so what's the proper/sufficient slope and type to use here - Butterworth, 2nd to 4th order? 7th or 8th order slope HPF are oftentimes considered too steep, but why? It should follow they offer better protection of the driver while "eating" less dB's down to the cut-off; to my ears a steeper HPF (like 8th order) makes the low-end appear slightly more extended for this reason, but perhaps also a bit too distinctive. I'm back to a 3rd order BW to see how that fares..

Can you elaborate on the "low growl" aspect of the sound of the Othorn, and how it differentiates the sound of the Othorn compared to other subs you've heard? Is this something that makes the Othorn sound different compared to the Skram, even though you deem them to be "equal" to each other in the low-end performance?

My assessment of the Skrams-sensitivity was with a pair of them in mind (like, emulating a single SKhorn), so that would have them hover in the 100dB territory. Sorry I wasn't clear about that. Really, I'm a blundering novice on these matters, so @Ricci and others would be much better fitted to answer your questions, but I've also had my thoughts on the Othorn vs. Skrams and what to choose here if one were to venture in that direction (I'm very happy with my pair of MicroWrecker tapped horns of @lilmike, but am intrigued nonetheless). Initially I got the crazy idea (but still relevant, I believe) that since my main speakers are all-horns it's better to use a horn variety to augment them below 80 or so Hz instead of using direct radiators (hence my choice of the MW's), but with the Skrams I'd be willing to make an exception (i.e.: hidden driver, a very slight horn-loading(?) of the front side of the driver-cone; ported on the backside, a bad-ass 21" driver w/massive power handling, high-ish sensitivity, relatively wide and clean bandwidth). If I'm not incorrect the Othorn is build around the B&C 21SW152, and therefore it's perhaps the best choice (apart from the IPAL) compared to other, cheaper alternatives. The Skrams however appear to be very well equipped with the cheaper B&C 21DS115 (or other), is a less complex build (from what I've read), perhaps a cleaner upper band performance, a slightly smaller footprint, and optional lower-band extension via port blocking. It would be most illuminating listening to them side-by-side, but Ricci already elaborated on a comparison of the SKhorn vs. Othorn, which should give one an idea in regards to the Skrams vs. Othorn performance. I believe I'd go with the Skrams (a pair), but either choice I'm sure would be awesome. If you only need to go to 70Hz upwards the supposedly cleaner upper band of the Skrams may not be relevant.

So, in the case of your initial and specific request aimed at the Skrams it's not really about movie playback capabilities as such (a different inquiry altogether, it would seem), but simply whether they kick a** from 30-120Hz with a suggested (and, it seems, fitting) driver, the B&C 21DS115-4. From what I'm able to assess the Skrams do exactly that; being 25-120Hz monsters at a relatively modest physical size, not least in light of them being fitted with a 21" driver, close to or more than 100dB sensitivity and hitting 25Hz quite comfortably. For your purpose I'd leave all ports open, or close no more than one per cab. Traits on paper that, if it weren't for my MW's, I'd have a pair build to my own setup in a heartbeat. EDIT: more fittingly you may consider poster @dgage's advice of either not being in the need of the Skrams, or use them solely with, say, 2 ports open. Personally I'd go with the latter option

I suspect the Skrams are as good for movies with the B&C 21DS115-4 as any other fitting driver 21" driver in this cab, the variable here being the number of ports being blocked and how this affects extension. I'm guessing, but for movie playback (and music playback in general) it seems a good compromise is blocking one of the four ports for a reasonable balance between extension and output/response smoothness in the lower octaves.

Have you thought of comparing running just the one SKhorn against the two Skrams? I know, they're differently configured placement-wise, but that's the point; getting to know what this does to the performance. Using all three of them, do you run them all in mono? Stereo content below 100Hz has created some heated debates on whether there really is stereo information this low, but if it was my own setup I'd connect the Skrams in true stereo and the SKhorn in mono.

Wow, that looks to be one sonically mean, massive wave-front hitting whoever's sitting here in the sweet spot.. 🤪 What's the chosen low-pass of the Skrams, and do you use any high-pass filter on them?

So no port noise - I guess that figures given the stated venting area, but just wanted to be sure. Air velocity I take it can be quite violent through the ports with designs as capable as this, and with longer-throw 21" drivers that can shift a lot of air. I'd assume your answer re: the speculative question on a comparison between the MW and Skram. My guess is the Skram will be even more visceral-sounding than the MW, and with a single blocked port go almost as deep. I'm extremely happy with my MW's though, and with a 7th order (8th order alternatively) low-pass at 80Hz they're no audible effects of any higher band anomalies. They could possibly be crossed higher if it weren't for the sidewall placement but instead flanking the mains (in a bigger room). The Skram seems to be able to low-pass without issues at 100Hz or even above, with the potential advantages that follows here, so with its other likely traits that certainly makes it a serious contender for a future build. A main concern of mine is integration with the mains. The MW's integrate, for all I'm able to assess, more or less perfectly with my mains, certainly not something I'd want to miss out on..

That's very decent extension from a box of this (relatively) moderate size, housing a 21" driver, and sporting a sensitivity in the late 90's or around 100dB's? Impressive engineering/design, Mr. Ricci. If blocking one of the 4 vents, would honest 20Hz or even slightly lower be achievable in-room? Continuing, will port noise with 3 open vents be a non issue below 120-125dB's (or even higher), with a pair of Skrams? Any preference between drivers such as the B&C 21DS115, Lavoce SAN214.50 and RCF LF21N551? Here in Europe the B&C 21DS115 comes some 50 Euros cheaper compared to the other two alternatives, but overall performance seems comparable. Being even more expensive than either of those drivers, would there be any uptick in using the B&C 21SW152? The IPAL I'm sure will add a few dB's more output. (EDIT: effectively you did answer above question earlier in this thread:) If one were to compare a single Skram with a single MicroWrecker tapped horn (with a 15" B&C), how would that go about? The Skram I'm sure will have perhaps some 10dB's extra output from, say, 30 or 35Hz to 100Hz, but will it feel more visceral at the same SPL? A 21" driver has roughly twice the radiation area of a 15" unit, but the 15" driver in the MW is fully horn loaded (i.e.: as a tapped horn at least), whereas the 21" in the Skram isn't (it seems there's a slight horn-loading in the Skram?). That is to say: the force multiplier via the horn-loading of the 15" in the MW is bigger than any such of the 21" in the Skram. At least this would make a comparison on a driver-to-driver basis difficult, I'd say. Sorry for this speculative question - I'm just curious..

I would expect that too. How low would you estimate they go, honestly - 25Hz? What drivers are you using - the B&C 21WS152, 21DS115, or..? Your "avatar" pic would seem to suggest the B&C 21DS115.. Btw, do you have any of the ports blocked (oh well, not according to the picture you supplied)?

I believe you've made your point (i.e.: referring to your (earlier) multiplied post) Seriously, you may be right. Maybe what I should wait for are some measurements to see how the Skrams "behave" compared to the SKhorn.

Looks like the SH50..

Holy cow, you should be doing alright with this setup That's like - four 21" drivers in a fairly limited space..! Have you done any comparisons between the two Skrams and the single SKhorn, I mean simply by listening to them?

Me neither, but likely you better Anyway, won't derail this thread any further with the ShyHorn. Interesting sub though..

Apparently it is a horn - I've asked. Sensitivity is 98dB's.

Off-topic (not sure whether a new thread would validate my inquiry; this thread seems the one to most closely resemble its "madness"-level): have any of you guys heard of the Norwegian-developed "Shyhorn" subs? They're fitted with a 24"(!) Precision Devices PD.2450, and take up some ~28 cubic feet (i.e.: 800 liters). I've seen some measurements (if I recall correctly they're to be found via below build-thread link, with written text in Norwegian), and it appears they load fully to 14Hz and extend cleanly to over 150Hz - quite impressive..! I can't quite figure out the specific horn profile used, and what the sensitivity rating is (I'd assume no higher than 95dB's, certainly not above the driver's rated sensitivity), but the horn mouth is located just above the tilted P.D. driver. https://www.hifisentralen.no/forumet/mitt-anlegg-og-billedtra-der/92723-ivaols-hjemmekino.html

One of the benefits of tapped horns in regards to THD and power handling, from what I can understand, is that the driver has excursion minima at the tuning frequency, whereas FLH's have excursion maxima here. Does that mean that FLH's are loading the driver at higher frequencies and possibly even over a broader range compared to TH's, and does it therefore follow that FLH's have less excursion over the midbass area compared to TH's? Reading up on the subject it's not always clear to me whether a (fitting) driver used in a TH is totaling less or more excursion in its operating range compared to a driver in a FLH. Off the top of my head it seems having excursion minima at the tuning frequency will "bleed" - i.e. have similar influence into higher frequencies as well (contrary to frequencies below the tuning fs), though to a lesser degree. I'd therefore wager excursion control is more important at lower frequencies, where excursion demand is higher, and that TH's, overall, sport less excursion than drivers used in FLH's - is that correct? I'm assuming the Skram/SKhorn behaves similarly to a TH in regards to excursion characteristics at the tuning frequency? Perhaps how the driver is loaded in a design is only of academic interest where overall performance envelope and sound quality goes, and that upper band limitation with TH's is a more significant marker in regards to THD when used close to the performance ceiling. In any case the SKhorn/Scram seems to be a very neat "compromise" combining fairly compact size, extension, SPL capabilities, and upper band cleanliness. Slightly off-topic perhaps: I've sometimes stumbled over the expression "enclosure interaction," and how horn variants that sport very little enclosure interaction are desirable. What's to be understood with 'enclosure interaction'?

@Ricci Good looking (and likely performing) single-build of the SKhorn - anticipating measurements/testing. Do you see yourself returning to Tapped Horns or even Front Loaded Horns with future builds? Does the SKhorn (singles or not) sound like TH or FLH's with similar tuning frequency - seeing that it houses its driver hidden inside the enclosure, or how would you describe it sounding different? /Mikael