ben.

Just sent you a PM, Mike. VPI 16.5 listed at $450 now with the extras. They are $650 new?! Wow. Great machine, though.

1/25 I am seeing if I can raise $2500 by Monday 1/27. I will not be insulted by any offers that will get me there. Bundle them up, make offers, let's see if this can happen. The iron is hot. Hit it now. Let me know what you need to make it happen. Adding some pics and info to end of thread shortly. Note: I will try to keep edits in red to call attention if you are revisiting this. So, shedding my skin. Simplifying. That means no tubes, no horns, no vinyl, no stuff I don't really need to be happy. I want to offer my gear here first, as for a long time this was a community that I felt close to and of which I am still quite fond. I'm located near Buffalo and Rochester NY. Zip is 14067. Please pm, email or post to thread with any questions or anything. Posting some without prices pending evaluation of condition or research. Pics pending, please ask only if you are really interested in a purchase, not curious as my time and resources are limited. Can ship via truck freight at commercial (reasonable) rates. International parcel shipping fine. Pair 70's Khorn bass bins with empty tops. Unsure of model of woofers but play great, Rough cosmetics but not trashed by any means. Can pull apart but don't want to. Very solid. $500 SOLD! Pair Altec 203B horns $400 (4) Altec 290 midrange drivers, (1) 292 Prices vary - pics and details on pg 3! VPI Scout with Benz Glider H2 cart. Very clean. A little wear on the arm from the holder. No issues whatsoever. Original packaging. $1500 with homemade acrylic cover (cracked from shipping but functional) that Thebes sent me years ago. SOLD! VPI 16.5 record cleaner. Barely used, super clean. Original packaging. (2) brand new Disc Doctor brushes and fluid with instructions (I think Allan Songers method, too) $450 SOLD! (2) granite slabs - one thick black w/ flakes - ~70 lbs, one a bit thinner green with lighter marbling ~45 lbs. Nice locally made custom cabinet (modeled after Salamander) with adjustable shelves and lockable doors. Walnut stain on oak I think. Classy. $350 pics added! Juicymusic Blueberry w/ Cream preamp original packaging. $1500 - only due to minor flaw on top of cab. pics in thread! Pair McIntosh Mc30 w/ National Union 350B outputs, Tele and Amperex small tubes. Average cosmetics, amazing sound. $1100 SOLD! Pair Heathkit W5M with cages. Average cosmetics. Unrestored but great working condition. $1100 SOLD! (2) Teac AL-700P chip amps. One NOS, one light use. $? Sony SACD 5 disc changer - have to check model #. $? 800-1000 LPs. Looking for someone local here - I will get a list together eventually, but right now I am hoping to have someone just come look and make an offer for the lot. If I'm going to take the time to make a list, it will be at a point where I'll cherry pick and sell some to pull more money out of the collection than a lot sale. Some high value, some run of the mill. Rock/pop, jazz, some nice classical too. Ikea storage. Audix PH-250 powered studio monitors. Relaxed, unhyped (British?) sound, $200 obo Altec 353A integrated amp. Works great. Was in office system for a while. $850 Pair Altec 605A coaxials. Perfect. No crossovers. $900 Pics added!! SOLD for more on Ebay. Electro-voice Regency III corner horn cabinet. Unloaded, baffle cut for 3-way. Nice shape. $300 obo Beautiful Karlson cabinets. 1950's Phillipine Mahogany. 12" cutouts. Average sounding Utah coax installed. Condition good, not mint but nice. $300 obo Pair Altec 9844A flat black. Cosmetics not great, but solid, not trashed. A close second to my Khorns back in the day. Perfect functionally. $950 SOLD! VTC Pro Audio DLMS4080 system processor. SMOKES dbx stuff. http://www.vtcproaudio.com/dlms4080.html $600 3 or 4 Akai M8 RTR with speakers. - offers here. Probably being converted to pres or instrument amps. David Bogen db110 - mono 6V6 integrated. Negative feedback disconnected. $? University/EV Cobreflex mid horn $? University PAH 1" 25W phenolic mid compression driver $? Also some music gear: The Heritage H137TV guitar w/ factory case. Some play wear, awesome sound and overall condition. $1200 G&L Tribute S-500 sunburst/maple w/ factory bag. Indonesian. Nearly no wear, finish chip near trem bar was there from new. Needs nut work but plays and sounds great (intonation off in lower positions). $375 Bill Fitzmaurice DR250a in carpet with neo, Tuba24 in flat black. $600 will separate. 1964 Harmony Meteor. Generic bag. Front p/u needs rewind - Lollar does these all the time. $500 Awesome guitar. SOLD!! 1991 Fender CIJ 51 Precision Reissue. Titanium bridge saddles (originals included), Novak single coil pickup (also I think the Duncan that I bought it with) Super light, amazing instrument. Can send links to recordings done with it. Beautiful pale finish, not yellow. Ash grain shows up really nicely. A keeper. Strung with TI flats. $1000 Godin Kingpin II w/ Tric case in Cognac Burst - nearly no wear, awesome guitar. Strung with flats $800 1967 Vox Pacemaker (tube - only made for a year or so). Average cosmetics, superb sound, killer trem. Liquid, tube rectified sound. Loaded with Weber ceramic or 50s/60s Jensen P10R $800 SOLD!! 197? Ampeg B15N© in custom road case. Loaded with Altec 421A speaker. Perfect operating condition, included custom XLR4-1/4" cables to use a speaker DI or use head with other cabs. Vintage RCA military 5692 pre tubes, Sov 5881 I think for outputs, Weber SS rectifier and vintage 5AR4 included. Can link to recording clips. $1500 Guitar speakers: Weber Alnico Blue Dog 50W, '58 Jensen P12N, P12Q, Jensen P10R, PM12U, Utah (something), Weber Ceramic 15" Michigan, Celestion 12" Century Vintage (neo) pair - 16ohm Weber MiniMASS 50W with 1/4" line out $125 Roland JX-305 Groovesynth - $350 Hughes & Kettner BK200 bass amp with rolling bag - $350 More and updated prices to come. Hit me up and don't be shy about offers, peeps. I'll get on interested pieces first. Also, if anyone has leads or connections for rental housing or employment opps in the Rochester, NY area, I'm all ears. Sales (big corp and small biz), music background. Ben

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Time for me to part with these - I haven't had Klipschorns for about 5 years now and just don't see any projects using these materializing any time soon. Divorce and apartment dwelling are both awesome! :-/ These were built by DeanG using custom ordered Jensen PIO caps to Type A spec. They are as beautiful sounding as they are to look at. Inductor and autotransfomer are factory spec. $400 Paypal and shipped in US. I will happily ship elsewhere at cost. I'll take a check if I know you from the old days.

momma ran off with a trucker, momma ran off with a trucker, momma ran off with a trucker, Peterbilt... Peterbilt... hey guys!

Great post, man! Appropriate for the milestone.

If you violate the criteria for being able to treat it like a plane wave, then of course you shouldn't call it a plane wave. Demonstrating that you can violate the criteria is meaningless. I could create a huge long list of behaviors engineers refer to with "wrong terms" because it makes it easier to communicate what is happening, or what is important. There is always some layer of abstraction going on and you have to make sure you're operating within the same abstraction. Ok, I gotta get this off my chest... d First of all, discarding theory is not wisdom. True wisdom is knowing when the theory is valid and knowing how to compensate when it isn't. If there's anything I've learned in my short year and a half outta college is that the theory is far more valid than I ever thought it was...and way more valid than all the "real world" comments thrown around on the audio forums. In fact, I've been amazed by how the good engineers will be able to know all performance criteria ahead of time easily to within a dB or a few Hz (at least in the electronics world). I'd wager the speaker guys are within a couple dB of their predictions...in fact, at work I've already experienced tweaking in circuits to their theoretical maximums. Of course nothing worked entirely as expected right away, but it had to do with things outside the assumptions of the theory itself....so when those other things were addressed, the theory was hit exactly. If anything, my doubting of theory has become a thorn in my side and I've found myself brushing up on all the textbook equations because they actually work extremely well. Second of all, nothing that I have brought up in this thread (except for my comments about assumptions behind the acoustics wave model) has had anything to do with "books". My comments on time-alignment have all stemmed from personal experience and many years of measuring more systems than I care to count. I'm still learning everyday and keep finding new gotchas and tricks, but it's incredibly frustrating being demeaned as one that lives only in textbooks when I'm trying to share real world experiences. But hey, I get the young guy card all the time so I'm kinda used to it... Those comments had nothing to do with the value of theoretical thought or discourse. I say it because you don't seem to be able to communicate in a direct fashion. Still plenty of points in my argument you're ignoring... Yes you can treat the output of whatever line array in certain conditions as a planar wave. You still seem to overlook the original context, which concerned whether or not sound waves can be "joined or melded together". Electronic time alignment is not a cure-all, because sound waves cannot be "joined or melded together". Over emphasizing its importance is a mistake. My arguments have only been to prove that point. If one could "meld' or "join" sound waves together, electronic time aligment would still work outside of the few points that are on the plane of points where the differences in source-listener distance remain equal. You can't and it doesn't. See, I'm trying to help people understand what's happening and what isn't. What are you trying to do? I'm sorry if you're frustrated because you feel demeaned. I feel frustrated because you're obviously a smart guy but seem unable to communicate effectively in a reasoned argument. This stuff isn't in the shadowy realm of opinion and subjectivity that we normally deal with here. Maybe that's the problem...

You said synergy horns are always better. I provided a case in the real world of a basic horn speaker that outperforms what is available in the synergy horn world. I brought up the footprint to acknowledge that they have two totally different design goals in mind and I would be curious to see what Danley could design in the footprint of the khorn since I think that's a good sweetspot for aesthetics. You can save your energy on the line array data...I've probably already seen what you intend to show, and I'm not at all a fan of the line array approach anyway. You've missed my point twice about why I even brought them up in the first place. What I said was that, in a comparison between "Classic" line arrays, conventional horn loaded, and Synergy horn loaded line arrays are better. I know that you know a Jubilee is not a line array, so I guess you should slow down and read more carefully with regard to context. Once again, Synergy horns were brought up only to illustrate the imperfection of electronic time alignment when implemented in designs where acoustic sources are more seperated. Here it is, copied from a few pages back: "Classic" line arrays using direct radiators are inferior to horn loaded designs since that behavior is strictly linked to array length. Off axis response is a mess as well. Horn loaded designs are better. Horn loaded designs utilizing Synergy technology are even better. google around and you might start to see where I am coming from. Hop a plane to Buffalo and I'll prove it to you and buy you dinner afterwards. Please tell me why you brought up line arrays if I have indeed missed your point. I thought it was in an attempt to prove that sound waves can be joined or melded together.

Better depends on the application. The 2-way Jub outperforms the Synergy horn in regards to polar response. However, the design goals are very different. Could a synergy horn be modified to come closer or even better the Jub performance? Probably. But then the Jub could also be redesigned to have even better polars too. Given the footprint constraints of the Jubilee, I don't think one could design a Synergy horn that would yield better performance...although I would love to hear Danley's best attempt within that footprint. I guess what I'm trying to say is that I see the two design approaches as different tools intended for slightly different purposes. In a home environment, we don't need 150dB SPL and a true stereo configuration really only has one sweet spot anyway... Ok, again with the, "Better depends on the application." Then off on a tangent... What does the Jub/Synergy comparison have to with it? This little tangent you brought into the argument led to an equally tengential comparison of "Classic" direct-radiating line array with horn loaded designs. Then bringing up the footprint... stay with me for a few sentences at least! If I can find the energy to bother with it, I'll post a couple images from EASE-Focus that will show you why there is no application where a decent direct radiating line array outperforms a decent horn loaded system. Unless your application requires all kinds of energy sprayed around the off axis area, and also requires large amounts of acoustic energy be spent to get any kind of directivity in the first place. But hey, you brought it up... Your last sentence I completely agree with - once again, I only brought up Synergy tech to illustrate a point. If you want to revisit any of my other challenges to your logic that you've yet to respond to, feel free.

http://www.aes.org/e-lib/browse.cfm?elib=8194 There are other references to shifting acoustic centers in the literature...I spent a while searching, but couldn't find any of the specific articles that I originally read. However, all horns (to my knowledge) have shfiting acoustic centers with frequency and angle of measurement. It seems like it's not fully understood why this is the case, but my theory is that the wave velocity isn't the same everywhere in the horn... As far as the synergy concept, take a look at how the polars bounce back and forth between the various drive units. Also, you should try doing your string experiment with all the different throats in the horn... For the record, I'm not at all a fan of line arrays. However, the reason I brought it up is to point out that there is merit to calling the wavefront of a line array a planar wave when it in fact is not by an overly specific definition. There is criteria to where it behaves like a planar wavefront and under those conditions it is completely acceptable for an engineer to treat it as such. Engineering is not science... I'm not trying to be nit-picky or dance around or whatever, but it is very difficult to communicate when we're not speaking the same language... And also for the record, I'm also a fan of the synergy horn concept, but it doesn't change my opinion on time-alignment in a 2-way system... Well, I'm not going to pay to download the paper so you can prove whatever point you are trying make. But I appreciate you actually reponded in somehwat of a linear fashion to the conversation. This: "This paper describes recent experiments regarding the acoustic center of a horn. It is generally believed that at low frequency a horn's acoustic center is located at the mouth and that it moves with increasing frequency toward the throat. A computer model and acoustic measurements are used to test this hypothesis on an array of similar horns." actually makes sense. This actually doesn't contradict any arguments I've made, though. The imperfection of electronic time alignment in systems we are talking about remains. I'm not trying to plug Synergy technology - I brought it up as way to try to explain to you the shortcomings of electronic time alignment. Anyway, a situation where the acoustic centers shift towards the throat is a lot simpler to deal with than having acoustic centers that are much further apart to begin with, since the acoustic centers in a Synergy horn would be more or less on the same plane and therefore easily corrected even with properly designed passive network (since the corrections are in the phase domain). These corrections will remain more effective out in space, again since the acoustic centers are more or less on the same plane. The situation become more complicated as one moves left to right with a more typical multi-element design, since the difference between arrival times changes as you move about, and the electronic time alignment falls apart as you do so. This is my point, which I think many have gotten but you for some reason continue to obfuscate with tangential arguments. Yes, there are conditions where the output of a given line array will be behave as a unified wavefront, but the simple fact that you can change the angles between cabinets to change that behavior chould prove (even to an engineer) that the sound is not magically glued together. Again, semantics matter. Using the correct words allow normal human beings to communicate, not just guys with the same degrees. Again, put down the books, Mike.

I didn't (and don't) mean to put you on the spot. I was merely curious as a technical background was coming through as I read what you have to say. I was presuming you were an engineer, like DocWho (meaning, I was presuming you were an EE verses some other kind of engineer). Not at all. Just trying to be respectful of the forum. Thanks, though!

I'm not sure. My experience with Khorns is with '76 models using original AA and Dean-built Jensen PIO type A networks.If you buy the gear right and can sell it for about what you have into it, money isn't an issue outside of short-term cash flow. Time? The value of time is up to you. I think it would surely be illuminating. If I were to do it, I would set up the crossover with no delay and mostly listen that way for a few days (occasionally adding the delays to time align for the ideal listening position), then reverse that - listening primarily with the delays in place, occasionally removing them. Then you know what you've got in your room and can make a reasonable judgement based on your perceptions and priorities. My hunch is that it would make a slight but noticable improvement to electronically time align the Khorn, compared to the same crossover with no time align. I also have a hunch that I would prefer it with my type A networks, though.

Cool. I'm glad you tried it. I think what you did is perfectly fine. You now have an idea what time alignment actually does and sounds like. I think your conclusion makes sense, too. The best results are possible when digital correction is not required (which is from about 400Hz on up in the Jub).And no, I didn't know there were Jubs in the Buff. Anyone I might know from the old days? pm if more appropriate. - thanks.

I work for a PA manufacturer (not Danley). My main responsibilities are US sales and support for our line array division. If you're more interested in more detail, PM me as I don't want to be seen as promoting our products (not I think anyone here is gonna drop 50K on a line array anytime soon).I don't know about the stereo imaging thing - that gets into perceptual matters that I think I "get" but can't speak to with any real knowledge.

I understand what you mean by this (especially since you referenced Danley earlier), but I would suggest that what you call perfect alignment isn't necessarily better. It depends on the specifics of each situation. I'm not trying to knock Danley at all, but the marketing propaganda would have one believe there was no other way... Well, it is marketing. I can't disagree about that. But I do disagree that there is a better way out there. Please describe to me a specific situation where digital correction of acoustically seperate sources works better in any way than the Synergy Horn solution. If I can't refute it, I'll send it to Tom. He's a lot smarter than we are. I could have worded that better....I was trying to say that other approaches can be just as good, not necessarily better. For what it's worth, the idea behind the Synergy horn seems to me to be a lot better than how it actually shows up in practice...and I hate to be one to say that when I know I couldn't do any better. Nevertheless, take a look at the CLF data posted on the website. Another thing about horns is that the acoustic centers shift with frequency and the angle at which you're measuring from the speaker. It's just another form of time arrival offsets present in the off-axis...I don't think Danley's horns are immune to this behavior. What about the CLF data? Stop talking about what things seem like to you and say something. Tell me about those other approaches. I'm putting effort into proving these points - stop dancing and pony up. What you say about acoustic centers shifting with frequency doesn't make any sense and betrays a complete lack of understanding of the Synergy design. Please explain how I'm wrong here.

In your classic pro sound line array, you've got a lot of direct radiators....if the sound from each driver decays 6dB per doubling of distance, then why does the output only drop 3dB per doubling like a plane wave? Are the engineers wrong for calling that "combined wave" (or whatever you want to call it) a "plane wave"? Then Danley's synergy horn concept is impossible. The implication is that there is a problem anywhere but that point....I don't agree with that conclusion. It 'can' certainly introduce problems off-axis, but in a competantly designed system it shouldn't be an issue. Ok, Mike. I see that you disagree but you don't answer my questions leading you to prove your points. I've countered each of your statements with logical, fact based replies and will continue to do so as long as I have patience."Classic" line arrays using direct radiators are inferior to horn loaded designs since that behavior is strictly linked to array length. Off axis response is a mess as well. Horn loaded designs are better. Horn loaded designs utilizing Synergy technology are even better. google around and you might start to see where I am coming from. Hop a plane to Buffalo and I'll prove it to you and buy you dinner afterwards. Regarding the joining of sound waves, I don't relly know why you are not getting the point. The Synergy horn concept does not join sound waves. It arranges them so they act like a single acoustic source. The output of the various drivers arrive at the same time because they are originating from the same horn, not because they have been adhered to each other in some way. You simply don't understand this and I don't know why. It's simple. Do the string thing. Just do it. If the sound waves were "melded" they would stay together as you moved off axis. They don't. They are discrete acoustic events and act that way. I'm not implying that there is a problem other than the point where arrival times are aligned, I've said it over and over. Do the darn string experiment. It's simple.

I understand what you mean by this (especially since you referenced Danley earlier), but I would suggest that what you call perfect alignment isn't necessarily better. It depends on the specifics of each situation. I'm not trying to knock Danley at all, but the marketing propaganda would have one believe there was no other way... Well, it is marketing. I can't disagree about that. But I do disagree that there is a better way out there. Please describe to me a specific situation where digital correction of acoustically seperate sources works better in any way than the Synergy Horn solution. If I can't refute it, I'll send it to Tom. He's a lot smarter than we are.

I think this is becoming more of a semantic argument, or maybe I'm not understanding what you're trying to say. If two waves satisfy the criteria to be treated as a single wave, then I would have no problem calling them melded together, or even treating them as a single wave. In classic acoustics, they are always two discrete waves, but classic acoustics also makes quite a few other assumptions that fall apart in nature. I've seen two different waves in a wave table turn into a single wave given enough time. I think it has to do with the effects of particle velocity within the medium. I should reread my textbook to verify, but I'm pretty sure acoustics assumes an average of zero particle velocity due to wave propogation, which I don't think is necessarily true...and might explain for some of this behavior. I don't understand what you're trying to say about a wave propogated by a horn versus a woofer. It is a semantic argument. We're not writing poetry here. If you use words that don't accurately convey the facts at hand, those facts are obscured.If the sound from the woofer were to join with the sound from the horn and behave as one, they would exhibit the same characteristics and properties. We both know that's not true. The woofer's sound will obey the inverse square law, decreasing by 6dB per doubling of distance. The horn's output will not, instead losing 3dB of intensity per doubling of distance. This is a bit of a simplification but I'm running out of ways to explain... This semantic distinction is important because if you don't understand it, you can't understand the inadequacies of digital correction as proven by the string experiment. You cannot join or meld sound waves. All you can do is get them to arrive at a chosen point together.

lol, I am well aware of that Sounds like I failed to communicate though....the emphasis was supposed to be polar steering, not destructive interference. I said it doesn't relate to the polar steering effects that happen in the xover passband. If you're talking about time-aligning rear speakers in a HT, for instance, then I would argue that it doesn't matter that much, but I would also agree that it could only be correct for a single point in the room. and polar steering like you describe works how? By using destructive interference to your advantage. My original point about relating to time alignment was meant to illustrate how the unavoidable compromises in digital time alignment become more serious when you consider it in the context of a stereo system.... which is what we are talking about.

Please elaborate --- you should be able to acheive perfect time alignment without acoustically aligning the sources. The cure (delays in the crossover) will tend to create other problems. BTW if you get things perfectly aligned the speaker will become much more directional and lock in at one listening position. Go back and read what I wrote describing the experiment you can easily perform with string. Try it with a three-way example and you'll see why digital correction is not perfect.

ben: Pardon my ignorance. Can you explain acoustically aligning the sources? Is that like physically aligning the drivers or digitally aligning the signals? No need for a pardon!I'm talking about getting multiple drivers to act as a single acoustic source - digital correction is the problem since it leads some people to believe that it is actually correcting the mis-alignment completely. Tannoy does it with their dual concentric approach (similar to coaxial designs). Danley does it better (why? cause it's horn loaded!) in my opinion with his Synergy solution. http://www.danleysoundlabs.com/pdf/danley_tapped.pdf Skip down a couple pages for the Synergy info.

Does time alignment matter? Yes. Is it critical in a home listening environment? Maybe. Is there any way to get it perfect without acoustically aligning the sources? No.

I should dig up the original research, but the rough rule of thumb I picked up along the way that was derived from many dozens of measurements is that 10x the inter-driver spacing is generally far enough away to treat it like a single wavefront. What happens is that as you move further and further away, the angle between the two sources becomes smaller and smaller until at infinity it looks like a single point source. At an infinite distance, it does "join together" into a single wavefront. Obviously we can't get infinitely far away, but we're only dealing with a finite range of frequencies, so there is a finite distance where phase cancellation from moving around becomes inaudible. With every speaker I've brought outdoors, there is a very definite point where the sound instantly changes and starts sounding more clear. Roy claims this gelling of the sound happens when all of the polars start overlapping completely, which might explain why the Jubilee gels much sooner than the Khorn (even though the acoustic centers should be rather similarly spaced). I haven't had a chance to dive into the original research to see if Roy's explanation correlates with the data. I think it's a bit more complicated than just overlapping polars and inter-driver spacing and I would support that with the observation that the wavefront of the K402's has the shape of a wavefront that is actually further away than it really is. In other words, it's almost a planar wavefront through the majority of its passband and I think that helps bring the gel point in a bit. One thing I would love to do, but haven't had the chance to isolate just this one variable, is to see if time-alignment changes the point at which the sound gels together. I actually don't think it will make much of a difference, but I would like to try it out to know for sure. I would also like to change the tilt of the various drivers to create more/less overlapping of the polars...I don't think this will make much of a difference either unless the polars never overlap (so I don't think moving in the point where the sound overlaps will always bring in the gel point). You're confusing the subjective perception of acoustic behavior with physical facts. Just because two wave fronts arrive together, it doesn't mean that they have joined and are behaving as one. Sound waves simply don't work that way. Answer me this, Mike. Are the waves emitted from a direct radiating woofer melded with the time-aligned waves from a horn going to stay joined together or will they behave differently? They may sound coherent but are still seperate in the physical world, aren't they?

And then when you time-align along an axis that intersects the listening position, now you've got a lot of seats covered within that plane - or at least very close to it. I don't think that is at all related to time-alignment through a crossover... ============================== The worst case scenario for a system time-aligned along a forward firing axis is the spot directly above and below the speaker, since that will be the point of greatest time-differential. If you xover at say 190Hz with two omnidirectional devices, and the acoustic centers are ~3ft apart, then you've got 180 degrees of phase rotation due to the propagation difference. If the design goal is a controlled polar response, then having acoustic rejection directly above and below the speaker is actually beneficial to keeping the wavefront firing only forward. If you xover at a higher frequency (say 400Hz), then the 180 degree rejection node moves forward (at 400Hz, I believe it would be 60 degrees away from the forward firing axis). In the real world, the HF is generally getting wider on the polars and the LF is generally getting narrower. If the wavefront of the LF never overlaps with the HF, then there is no time-arrival difference because only one drive unit is propogating off into that direction. On a slightly different note, let's say your HF loses vertical pattern control before it loses it in the horizontal (which is often the case). If you can xover low enough to where the vertical polars of the LF are wide enough, then you can use the vertical propogation difference to create phase cancellation and tuck the vertical polars back to where you want them to be. I could see this being much more advantageous if the LF bin was starting to clover-leaf in the vertical (since that allows the forward wavefront to stay tight). If the polar response of both the HF and LF are identical, then the system polar response doesn't change. Btw, the same physics behind the polar steering I'm describing also apply to systems that aren't time-aligned. The problem there is that the polars at the xover frequency get kicked off in crazy directions. And if the delay is beyond just one cycle, then the polars change dynamically with the input signal... The point I'm trying to make is that it involves 3D behavior and the time arrival differences behave differently based on the size of the wavelengths in question. The nice thing about a crossover between two drive units is that the region of overlap is relatively small and easy to deal with. Full-range line arrays with several different units gets a lot more complicated...yet they still steer the polars quite well (provided there's no air turbulence). Mike, I know how destructive interference works. you have a knack for making things sound more complicated than they are - always loved that about you. My point about adding a second speaker was intended to illustrate that getting one speaker assembly time aligned is one thing - it provides you with a finite area where time alignment is retained, Add the second speaker and your listening area is much more restricted if you want to stay in the area that is time aligned. How does that not relate to time alignment?

Actually, I think we cross electronically on the bass bin about 450 and pickup on the HF driver about 380. I don't know how that translates into acoustic crossover. (looking at my RACE file and low out is Linkwitz 24/450hz and high out is LR24 380hz) We're using the K69, not the B&C drivers. The only person that I'm aware of that has the B&C driver is Bob Riff. Everyone else has (or started with) the K69 and a handful of guys have now gone to the TAD 4002. Someday when Mr. Budget and I are smiling with each other, I'll fork out for a pair of TAD's as well. A definate increase in sound quality/clarity. Perhaps so, but tell my ears that what they are hearing isn't a coherent "bubble" of sound The crossover that low is even better, then. Wonder what the K69 actually is... My point stands that it must be light years ahead of the poor old drivers PWK used to such great effect. As far as what you're hearing, what I've been trying to do is help you understand what it is you're hearing and why, so when you give advice it's rooted in reality and not conjecture so as not to confuse matters further. I know you're trying to help and it's really cool that you are so generous with others to expose them to new gear and help them improve their systems, but some of the conclusions you come to are not logical. One of the things I'm trying to make clear is that the coherent bubble of sound you're hearing has more to do with the fact that you're hearing the bulk of the sound from one source, not the fact that you are time aligned around 400Hz. Try changing your delay settings a few milliseconds - see if it makes it all fall apart or if it still pretty much hangs together. Then you're actully learning things. You've got everything you need to stop guessing.