gnarly

Thanks for replying Chris, Glad to hear that was the type info you were looking for.... A big capability i forgot to mention is Presets (or what Q-Sys terms "Snapshots'). The Snapshot capability allows changes to however many selected & altered settings you choose in the schematic. A Snapshot Bank can hold 24 presets, and each bank can do something entirely different. I think 6 banks are allowed if sky's the limit. For instance, banks could be used simply to vary para EQs, or shelving filters for house curves, etc. Or for switching xover orders, and types. Or even from switching between FIR and IIR xovers and IIR processing. The reason I'm bring this Snapshot capability up, is unlike other processors I've owned, where changing Presets is essentially a global operation that causes a reload and a service interruption, the Q-Sys Snapshot implementation has all the various 'presets' loaded into the one design, and ready to simply switch between. It allows instantaneous switching without glitch or tick, even accommodating multiple FIR file changes instantly and silently. I've found it to allow A/B testing for things like quick comparisons / polar measurements of Xover frequencies and slopes. And comparing whatever order linear phase xovers to the same order IIR xover, all other things the same. I've seen in the Xililca XP/XD Manuals, they speak of 'Presets within the Device Only'. I'm hoping/curious this is along the same lines as Q-Sys Snapshots, with similar broad capabilities in what can be altered on the fly. Do you use them much?

I'll try Chris, and please let me know if i'm providing the info requested, or not. Q-Sys is a processor design program, that compiles the process design onto Q-Sys Cores. Cores are the term for various hardware processors, all running Linux. They range from small Core 110f's, to giant enterprise Cores. FIR is implemented by either choosing FIR HP and LP filters options, at chosen dB/oct slopes, or by loading into Q-sys custom filters made with other software (ala rePhase, or any of the commercially available programs) The stock IIR xover can go to up 6-way, but that can be expanded. Stock parametric EQs can be be 32 bands per channel, and again expandable (if ever needed ) Assortment of band pass, all pass, shelving filters...all kinds of functions .... Anyway, just begins to scratch the surface in terms of design flexibility. here is a screen shot of the schematic design I'm current running on a a pair of syn7's Every block or control in the schematic is available for real time adjustment, and live monitoring. here is a few of the blocks blown up ( from a different design it think) Point is....everything is available to adjust or monitor in real time. A PC connect to a Core and all is available realtime. The Cores can also run standalone, without any PC/Mac connection. There really isn't any third party software involved, other than our usual measurement software, for figuring out what to do. If you are into FIR, a FIR generator program is needed. I like FirDesigner for automated work, and rePhase for manual. Q-sys accepts wav or csv FIR files. It has been amazing to me how much my general understanding of audio processing has grown because of this type processor. many times, i simply run electrical level transfer functions, learning how xovers and EQ's work, etc. You can even imbed dual channel FFT analyzers into the schematic to test block components, as well as putting simple RMS or peak meters anywhere. Sorry if i sound oversold....but i am 😀 I'd kill to see/hear how the Xilica Solaro works 😀

Xilica rocks ! The Solaro series looks super duper !! i would love to try it, but the used market for it doesn't exist, and even for the lower spec Q-Sys stuff that i use, the new price of Q-Sys is prohibitive for me. Open architecture processors like the Solaro are where it's at, imo. Heck, even Xilica says so ! They offer so much; i would gladly chose a lower spec open architecture processor than the highest spec conventional fixed I/O processor (in terms of the usual audiophool specs). Big world, getter bigger 😀

Here's a page of processors that Fulcrum Acoustic provides setting for their speakers. I've found it a good place to check what's out there in pro land. https://www.fulcrum-acoustic.com/support/processor-configurations/ The BSS BLU series might be of particular interest, like this BLU-160 https://bssaudio.com/en/product_documents/blu160datasheet-pdf I believe it runs 48/96k...but not sure if FIR can run at 96k. (it's open architecture like discussed below) I use a Q-Sys Core 110f, but it's 48k only. I put channel counts, input types and connections, output types and connections, processor functions, FIR capability, AD/ DA of sufficient quality, ease of use, design flexibility, and so on above 96k. 96k would be the tie breaker for me, all else equal....otherwise not than important (for me) One additional biggie...and a must for me since moving to Q-Sys...is an Open Architecture processor. Their incredible flexibility....the configurations that can be easily put together, tuning experiments, etc, not to mention their network capability ....are all simply mind boggling imho. Oh, processors like the Core110f and the BLU-160 tend to trade used on ebay for around $1250. They are pretty robust, I don't worry about used.

@ Steffen, good stuff. I'm pondering the same compromises. @parlaphone1, the thing about Amir's phase video that doesn't any make sense to me.... .....is that his key point appears to be, that by the time direct sound and all the room reflections reach the ear, phase has become a jumbled mess and can't matter.. Seems to me, by that logic, the same should be said about frequency response....as we all know how jumbled up it gets too. Plus, how about outdoors... where there are considerably fewer and weaker reflections to mess things up. Does phase matter then? My ears say a resounding yes. So no, i don't buy it.

Yep, cheers for lower pattern control. Ime, lower pattern control is what allows the quality of indoor listening to approach that of outdoor listening. Another yep, it's been clear from the start that the Hyperion picts looked like the SM-60f horn, and that the speaker is a morph off existing products rather than a clean sheet design. And I saw in the other thread mentioned, that Tom said someday he might like to redesign a SH-50 for home use. Big question in my mind though ......Do you think the home market can really accept the size it takes to get lower pattern control? There doesn't seem to be any way to get around Keele's pattern control formula......making large size mandatory I'd be surprised to see DSL make a clean sheet home-use Synergy for 200Hz pattern control.....unless maybe it was a 90 deg design for use in corners, like you've been using. (That would kinda go against the narrow SH-50/60 pattern preference seen to date, though.) I'm very interested in the AXI2050 for a MEH too. My only concern with it, is how deep a horn will it take to use it down to 200Hz. Well, that and its weight. The dcx464 loads to 300Hz fine...with the me464 horn .....which adds depth with a diffraction slot. My guess is the Axi will need depth too, like with Celestion's Big Red Horn prototype..https://celestion.com/our-news/see-the-celestion-big-red-horn-on-display-at-pro-light-sound-with-the-axi2050-axiperiodic-driver/ It will be late summer before i can get back to speaker building/testing. I hope by then to have seen some Axi builds to learn from ....

I've meant/tried to respect your desire to keep this thread about your 'K-402-Based Full-Range Multiple-Entry Horn'. I guess when you quoted me, when you brought up TomD's post about ports in corners, it seemed like an invitation to discuss that here. Maybe it would have been better raised/quoted in the "Nearly Full-Range MEH' thread ??? Anyway, I completely agree with your assessment of the benefits of lower pattern control (and lower loading). And i like the idea of expanding the size of the K-402 a bit to do so. That was the design goal of my 'syn7' version that tried to copy the K-402's flares, albeit larger in size. It has 225 Hz horizontal control by Keele's formula, and is 21" deep, mouth to throat. best, mark

Hi Chris, I was really glad to see that post of Tom's. It comes right when I've been exploring port placement and sizes, in another in-depth round of prototyping. The "low pressure zone" in the corners..... I'm thinking i can take a 1/4" measurement mic and stick it through 1/4" holes in the horn, located in a corner and in the center, equidistant from the CD. This will be on a horn alone with no ports it it. Seems i should be able to measure a SPL difference to get a sense of the low pressure zone effect. Make sense to you? Any suggestions? I'm particularly interested in this for the use with smaller mids, to go along with larger low drivers....like in a traditional Danley Synergy. I'm guessing port location for small mids, may be considerably more critical to the CD's response, since they are so close to the CD. When going straight from a CD to larger cones (12"s, 10", etc), I've measured horns without ports, and then again with ports, for both corner ports and centered. Similar to what Tom described doing.. but by measured, I mean mag and phase, on and off-axis. Like in the Nearly Full Range MEH thread These larger cones, whether ports are in the corners or the center, have required the ports be about 6" inches from the CD. I simply have not measured any significant advantage of corner ports over centered ports. Neither port location, that far out from the CD, seems to effect CD response all that much. Mouth termination has had a consistently much greater effect on CD response. One big caveat to all that........ those comments are based mainly on horizontal polars....vertical polar experience is much more limited . i hope to explore verticals more with this new round of prototyping . And i must say, the idea of using small mids is intriguing, even when i can go straight from a CD to larger cones. My gut says the tighter the acoustic packing, the greater the synergy effect. I'd like to tighten up the physical spacing of the 2-300hz to CD xover range. And then also, using small mids would allow putting the larger low cones further out in the horn for lower loading. (I currently have to keep the low ports within about 6 inches to be able to reach the CD.

Very welcome. 😃 Apologies if i went into overload zone...I've had speaker building/tuning as at least a half-time hobby, for about 6 years now. 30+ boxes of all kinds of designs......and counting !

Hi again Alanhuth, More 2c on reciprocity.... I probably should have only mentioned it as a technique for sub placement. It works for me, but my main speakers have more directional control than most, and I can pretty much point them at listening position anywhere i want to put them, and get very good response from midrange up. So i use reciprocity to find where the main speakers works best, only in the upper bass range, say 100Hz to maybe as high as 300Hz. For subs, I think it totally works for anyone, who has the flexibility to put the subs where they want. (8 out of 10 times, corners have been hard to beat ime) The best mic position translates back to speaker position, as simply the place where you want the speakers acoustic centers to be. Which means which particular drivers in the speaker, which frequency range, you are using the reciprocity technique for. For subs, it's obvious, for main speakers, its the woofers or maybe low-mids. The hardest part in all this, is having a real time measurement program, where you can see the screen as you move the mic around. Solve that, and it's a heck of a lot easier to move a mic around than move speakers around ! The easiest way would be with an RTA, like REW's, as they are real time. They give a blended room & speaker response, albeit at the expense of ignoring the time domain. Due to RTA's ignoring the time domain, and circling back to your original question about sequence, my very first steps with any speaker are your E&F....tuning frequency response, phase, and timing. I try to do this in as quasi-anechoic setup as possible (which means outdoors off an elevated deck for mains, and out on the driveway for subs. Lol). That way, when i move the speakers into the room, I know it's all about room interaction, and am more comfortable with simply using an RTA then. Hope i made some sense....

My 2c... G. Use omni source room excitation if available, and level RT 60 across the spectrum with acoustic treatments as best as possible. A. Figure out Front speaker placement. I like the reciprocity method. Put a Front speaker at listening position, and move mic around in possible speaker locations to find smoothest response. G. With Front speaker placement determined, use room treatments to diminish early reflections. A. remeasure to see if early reflection treatments and an even RT 60 hold up well , or beg slightly different speaker placements/acoustic treatments. D. Use reciprocity method for finding primary sub placements. B. MSO if desired, again with reciprocity technique. E, F, .. depends on how far you want to go. Personally, I like doing E&F independent of the room...ie, as anechoic as possible. And with FIR to achieve both flat mag and phase. C. not for me. Too much correction to too narrow a location.

Pt2. The reason for all the plate experiments has been to try to improve polars as they get wider. I've been happy enough with round port response within +/-20 degrees. I imagine some folks are wondering why not just put the ports in the corners (off-axis) like usual, but I need to use centered ports to be able to build synergies with top and bottom mounted woofers. This makes construction so much easier, as the top and bottom panels can be used to seal the woofers in. It also is a big weight saving box design. It's probably worth reminding though, that this strategy does require a CD that can reach straight to the woofers, without any small mid-ranges. Anyway, the best wide angle 'horn alone' polar matching has come from smiley face ports. Good call Steffen 😀 Here is horn alone vs smiley, at 30 and 45 degrees. The traces match much nicer against the CD than the round ports do.. But within the +/-20 range of excellence for round ports, smiley is not nearly as good. So, I'm like, what if I put the two together, smiley and roundy, sized to keep area the same... Like this lower plate... top plate fell off...damn tape haha...but at least shows the 7" open hole under the plates Here is the polar graph for this combi-shaped plate. So far it's the best overall compromise i think. I need to compare verticals against the simple round hole, to decide if it's worth the extra build effort. Hoping so, really 😄 If nothing else, I hope these two posts help encourage folks to try MEH ports, anywhere they want to try them !.

Hi Steffen, hi all, I've has some real run with these plate-overport experiments the last few drizzly days. Long story short, I've tried many new things: smiley face, tear drop, vertical and horizontal open slots (without pizza pan), and a combination of s smiley face and a round hole. Also remeasured my existing syn7 with 2.75" round centered ports, under the exact same testing conditions, . Syn7 has the same sized 90x60 horn, that the test horn does. Probably the first graph to show is the benchmark....the CD on the horn with no ports at all. dcx 464 with 500Hz hpf, and xover at 3.8kHz. All graphs reflect full tuning; flat mag and phase response with linear phase crossovers. I settled in on just taking 0-45 deg horizontals, due to the amount of data being collected. So I think that's as good as polars can stay, after adding ports. Next, to show what damage 2.75" centered round ports over the woofers do to the CD's response, are comparisons against the curves above at 0, 15, 30, and 45 degrees. Easy to tell which is which, as the woofer ports push response down to 120Hz. 0 deg first. 15 deg 30 deg 45 deg As you can see, the round centered ports do very little harm to polars, until around 30 degrees. To keep this post from getting too long, i will stop here and continue with a Pt2

I think i get what you are saying...not sure, but the idea to me has been that the "acoustic notch" from the CD to mid ports, gets spread out in time more with larger ports, due to a greater distance span. The preceding exchange is why i used a frowny face. I think it maximizes the port-to-CD distance-spread variation. I kinda quit trying to think about wave front shapes, hasn't helped me make better sound. Happy to , my #1 rule is OBSERVE MORE, think less...... That said, i kinda tried this before, albeit in wood. It sucked. So I'll just spin the frowny plates 180 degrees. Will be too far away from throat, but if it looks at all promising, I'll remake duct tape smiley closer.

Here's a current project that is exploring different port shapes in the center of top and bottom horn walls. On-axis ports! Meant ror traditional conical syn/meh's; and ones that use a single sized driver to bridge between CD and subwoofer. In this case, there is a pair of 10"s crossing at 500Hz to a dcx464. What you're looking at is a couple of air bake pizza pans, cut to lay on top of 7" diameter holes in the horn, which are centered over the 10" cones. I duct tape over the plates holes, to try different port shapes. The small holes, for what ever area is exposed, match the freq response of the same area completely opened, surprisingly quite well. I began the project by putting the plates over existing round hole synergies to see if the correlation was good. Had to pass the smell test, to get started ya know . The small holes caused about a dB and a half loss on the cones lower end response on the syn7 (for which i posted polars on on the K-402 MEH thread) So far, pure circular ports were marginally bested by vertical slots. Horizontal slots weren't as bad as expected. The frowny faced ports are the best yet. By best, I mean polars hold up the best after tuning. All non-taped, uncovered port areas, have been the same, 1/10th Sd. I have a couple of 22 gauge steel sheets coming, that I will cut the frowny face slots into. Seems worth a try already, because the polars look pretty good to me, especially for a test horn without secondary flares. Here's 0-45 horizonal in 15 deg increments. Red, green, blue, brown in order. Psy smoothing used, as that seems to be the norm here..

That's such neat work you're doing !! Awesome to have such tools and the knowledge how to use them. Oh, also looking forward to your dcx/me464 findings....

Hi, thx for asking.. Currently have 3 DIY variations that are all close to the same, but with different H-V patterns, and a different pair of low-mid cones. They all use a bms 4594he or b&c dcx464 coax CD to reach down to the low-mid cones, crossing in the 5-600Hz range. They all high pass at 100-120Hz, for use with a sub. All are about 48" wide, and have detachable secondary flares for mobility. Here's a pict of them.... Left is 75x50 with 8" Beyma 8mc300nd's. It needed reflex ports to reach down to 100-120Hz. Center is 90x60 with 10" Faital 10pr300's. It uses the same top and bottom, centered port location as in Left. No reflex ports were needed. The secondary flares are curved, kinda quasi-tractrix. Right is 60x40 with 12" RCF mb12n405's. Traditional port locations. This one is a real beast in terms of max SPL.

Chris, my apologies for sounding discourteous.....I had felt that way about your post, and my reply back lacked grace. I see the reasoning for separating threads. And besides, this forum is labeled Technical Modifications, which I take to mean modifications to Klipsch products. All good 😃

That's simply not true...that amplifier power isn't a factor today. In fact, a little math will show most home audio lacks sufficient amp peak power to fully reproduce subwoofer transients. And please don't hold me (or anyone else) accountable for not having read all the K-402-MEH posts or other related threads. Besides, whos to say those posts have to be agreed with 🙃 I don't see there was a topic shift. The discussion was sealed vs vented subs, and how they compare. Relative power requirements are often discussed in such comparisons. And within the context liberty of having compared two drivers to one, it sure doesn't seem like a big topic switch to me. Honestly, you seem to be the argumentative one.... i hope you can see your comment sure has riled me up !

That's a great depiction of the discussion we were having. And the results mirror the simulations, as well as electrical filter transfer function measurements I've made. The sealed BW3's impulse is a bit better than the vented BW5. Not a lot, but definitely better. Here's a test i forgot i made a year ago, that also supports sealed being ultimately best. Green is sealed with a Linkwitz transform in place, I forget exactly what hpf filter was used. Low pass was linear phase. Blue is vented with a BW3 hpf. Not sure why i didn't lowpass it like the sealed, guess cause all i cared about was looking at the low end. Oh, forget that Smaart says 'Phase' on top graph, it's Group Delay. Smaart toggles back and forth, phase and GD, but panel title doesn't change. Clearly there's more GD with the vented, but a good part has to be the different hfp orders. I'm sure it would look closer if I'd used a BW1 hp. Those subs btw, are about 175L vented, and 110L sealed. Have them running right now playing around with getting a B&C dcx/me464 setup working. Honestly though, my ears aren't golden enough to hear the differences in the sims or measurements, between those two subs. Heck, which one is sitting on the floor makes more difference, i think. I do know the vented will play considerably louder before pushing my amp into clipping. I put each box on a channel of a QSC PL-380 amp, 1500W per channel @ 8 ohms. (Drivers are 8 ohm)

Sure, of course. I assume a hpf is a mandatory component of a bass-reflex. Not sure what you are saying here regarding the importance of cone area to sound reinforcement, as it's a plain given that more drivers, more boxes any type, equals more sound. And for live-sound its a 98% given that conventional subs will be bass-reflex, not sealed. By conventional, I mean not horns. Agreed. Tis why I only use complementary linear phase xovers....to eliminate even 2nd order (electrically) One thing i still want to impart, is my experience with the sealed's final acoustic order, when response-matched to the bass-reflex. (Different cabinet sizes for sure, but single driver comparisons are the context that make best sense to me.) (And same driver in both.) I found after bringing the sealed's low-end freq response up to match the bass-reflex f-3 response, final acoustic order was not much different from the bass-reflex. Reason being: Paragraphic boosts altered phase /raised group delay substantially, (albeit without excursion problems if constructed carefully ) A series of shelving boosts which didn't warp phase so bad, unfortunately had no limit on how low they boosted and could cause thermal problems...requiring a hpf just like the bass-reflex. Both EQ techniques for bringing up the bottom, took away the sealed's natural second order advantage . I'd add: If you want the lowest extension possible, then bass-reflex is the way to go. If you want lower end extension with less amp power required, bass-reflex is the way to go. If you want the very best with no constraints, get as many sealed as it takes to get the f-3 response you want.....without needing any low end boost.

Gotcha now. Appears both of were a little surprised by simple misunderstandings in communicating. I still don't understand though, why the choice of hpf (passive vs active) to the main speaker would have anything to do with whether to use bass-reflex or sealed. I think getting all the low-end extension possible is the biggest reason for using bass-reflex in MEHs. And DSP just makes it easier. Is there any Danley SH-series Synergy that doesn't use BR ports for its woofers? I don't know of any.. Did you see the Hyperion picts? Looks like the dual 15" sub drivers are BR too, no? It's really cool you are getting full low-end extension using dual 15"s on the K-402 horn. Big woofers on a big horn work ! Someday I want to try 15s" or 18"s on traditional straight-sided conical MEHs.

Hi Edgar, must say the comparisons you showed don't make sense to me. The root.....Why would i want to compare two drivers to one ? Cabinet volume isn't a good reason. I can build a 170L quality 3/4" BB box for under $100, or even two lower volume boxes (for sealed) for only a bit more $. Each driver costs 5 -7X that..... so dollar wise, I clearly want to get the most bang per driver. Excursion much below f-3 isn't a good reason, because once response is >6dB down, response is gone imo.. Maximum SPL surely isn't a good reason, as that's simply a function of how many drivers. The impulse responses appear to be simple Butterworth electrical filters, intended to replicate 2nd and 4th order acoustic responses, ....no? Like i mentioned earlier for single-driver/sub-type comparisons, after you level response to the same f-3, the sealed and vented impulses ( phase traces) look very similar. Of course multiple drivers can eliminate processing needs for sealed, other than having to attenuate the heck out of the high end. But what's the point in that. Usable bandwidth imo, is a function of flat response, that starts from f-3. IOW, all the extra SPL of the 2x sealed blue trace in your SPL comparison is a so what, ....it's unusable. Bring the blue trace down level to the green at 100Hz, then which one do you want ? Still need that low end boost with sealed, huh? 😃 Really, the only way your comparison makes sense to me, is if i were truly box volume constrained....(and not $ constrained at all)

Hi Chris, first, may i say yes to a possible prior question regarding my name.... my name is gnarly, mark100 on DIY, and Mark Wilkinson on prosound forums. Thought I'd add a few thoughts re bass-reflex since I've used them at home (and for live sound). For home, I've built sealed, bass-reflex, and push-pull slot load (PPSL) subs, all using the same 18" driver(s) for comparisons. I chose the BMS 18n862 based off of Josh Ricci (data-bass) getting very good results using it, in both sealed and vented DIYs. The sealed was certainly the easiest to build and get great results. A no brainer really. Adding EQ to the bottom was a bit trickier than first appeared. I ended up using a Linkwitz transform ala the miniDSP route. The tricky part was xmax increased fast, given the gain it took to flatten response to as low as I wanted, 30Hz. But as long as I keep the sealed at reasonable SPL, it is simply super. Then I built the bass-reflex. Hornresp led me there, but it definitely still took some trial and error with port area and length, to get to 30Hz and keep port velocity within bounds. Must get right, takes work, but once accomplished, it rocks. Requires so much less amp power than the sealed, and sounds just as good to my ears. Interestingly, I found the phase traces / group delay of the bass-reflex, and the sealed after the necessary EQ to get to the same f-3 response, were very similar. Something we don't normally hear about. Oh, i've never encountered anyone using a passive high-pass for a bass reflex to prevent it from overloading below tuning. Come to think of it, I haven't heard of anyone using anything but active for bass-reflex....but I'm less in tune with home audio than live sound on this. Your post about folks using BR because they continue to use passives took me by big surprise. I'll abbreviate any comments about the PPSL subs other than to say the motivation behind them was purely for cabinet vibration reduction, and the hope of needing less extensive internal bracing. Happy to say it worked awesomely! Opposed subs is the only way I'll fly anymore. I've noticed the prelims on Danley Hyperion indicate dual opposed subs, covering 14-45Hz. It also appears he's probably going bass-reflex from the pict...as it looks like there's a hole in the bottom of the cabinet, hence the funky bottom plates and feet.

I'm taking off on a tangent....but it does address the question... Hope is ok... Raw driver published sensitivity specs are surely useful for initially laying out a speaker design. And raw measurements of the driver(s) in a cabinet let us see what efficiency gain(s) the design provided. After that, just as you showed with the varying responses, a single sensitivity number no longer has any meaning. If we assess sensitivity with processing in place, i think we get a more useful, real-world metric. I feel all that really matters with sensitivity, is for the leveled-out intended use, of the bandwidth in play. If nothing else, the processed response curve allows a better visual judgment call of sensitivity, because its levels out erroneous peaks. And best, when processing is in place that includes xovers, each driver section can have its sensitivity objectively measured, with no judgment call whatsoever. One technique is to use pink noise, and measure SPL-Leq (time averaged SPL), and a rms voltage average at the driver terminals, over the same identical time interval. This measures an integration of all frequencies' contributing sensitivities. (Time averaged, SPL and rms voltage, are needed because pink noise measurements bounce around a little.) A little math turns whatever is measured into SPL at 2.83v/1m for 8 ohm nominal db/1w/1m; or use 2.0v for 4 ohms nominal db/1w/1m; etc. REW can handle the SPL-Leq measurement; relatively inexpensive DVM's can handle the rms voltage average. Highly recommended technique....no more BS or guessing..😃 Heck, even eyeballed 'nominal' impedance can be traded in for an objectively measured average impedance. Simply measure average current at the driver terminals over the same time period as the SPL-Leq and rms voltage average. An honest, accurate, dB/1w/1m can be derived. I've only talked in the context of DSP mulit-ways, but it seems the averaged measurements would work for a passive speaker just as well. The key in my mind, is how to achieve a real-world integration of sensitivity across the full spectrum of operation.