How to dissect polar patterns and frequency responses for horns.

[Chris A]

2 hours ago, Droogne said:

What would the effect be if you'd add some regular front firing bass bins beneath the MEH center? Would it be impossible to integrate? Or wouldn't there be any real additional effect?

It's not an integration issue, but rather a sound quality issue.  One of the things that you've probably yet to experience is a center loudspeaker with fully horn-loaded bass, i.e., without reflex ports.  The following article written by PWK is one that I keep handy for these instances:  http://assets.klipsch.com/files/Dope_760600_v15n6.pdf.  The short story is that if you go to the trouble to have horn-loaded bass in the front corners, you don't want to mess that up using direct radiating bass in your center.  In fact--and this is something that few people have actually experienced--I find that there is really a need cleaner bass in the center loudspeaker--not worse or even as good as the flanking front L-R loudspeakers. 

 

The reason why this is so seldom experienced by audiophile listeners is due to the difficulty in getting good, extended, horn-loaded bass in a center loudspeaker.  But once you hear it, you'll never want to go back to direct radiators, in my experience.  The K-402 MEH does that better than any other loudspeaker that I've heard--in fact it has potential usable extension down to 30 Hz (about an octave lower than a La Scala or Belle, and slightly lower than a typical Khorn bass bin) without incurring significantly increased distortion.  See the following on-axis frequency response and phase plot of the K-402-MEH when placed in a room corner:

 

 

This means that the K-402-MEH also will serve extremely well as a

 

1) corner-horn loudspeaker,

2) center loudspeaker, or even as

3) an extended capability surround...assuming the required space exists in-room--about the size of a La Scala II as a surround loudspeaker.

 

I've found that using only a center K-402 MEH dramatically lessens the required bandwidth of subwoofers to below 40 Hz and their distributed room placement.  There are quite a few listening rooms which have very few acoustic modes below 40 Hz to deal with via multiple subwoofer room placement.  The front (L, C, R) + surround channels themselves can provide most of the deep bass output, leaving only about one octave of infrasonic bass to be covered by the subs (below 30 Hz).

 

Chris

[Khornukopia]

On ‎11‎/‎25‎/‎2017 at 8:29 AM, Chris A said:

I stumbled across a captured phantom view drawing from some time ago of how to fix a bifurcated bass bin horn mouth (i.e., dual source diffraction) this AM.  Some guy in New York City area ("Levan Horn") did this to an existing design:

 

I don't have one to experiment with, but adding a nose piece and some wings to a Belle could be an interesting project.

[Droogne]

3 hours ago, Chris A said:

It's not an integration issue, but rather a sound quality issue.  One of the things that you've probably yet to experience is a center loudspeaker with fully horn-loaded bass, i.e., without reflex ports.  The following article written by PWK is one that I keep handy for these instances:  http://assets.klipsch.com/files/Dope_760600_v15n6.pdf.  The short story is that if you go to the trouble to have horn-loaded bass in the front corners, you don't want to mess that up using direct radiating bass in your center.  In fact--and this is something that few people have actually experienced--I find that there is really a need cleaner bass in the center loudspeaker--not worse or even as good as the flanking front L-R loudspeakers. 

Well I'm using a LaScala center (which costed more than the fronts together) because I wanted a sound as clean as possible  I already though the direct firing were a bad idea! Only height appropriate horn loaded bass bin I ever found was the EV TL4025 (http://electrovoice.com/binary/TL4025_Engineering_Data_Sheet.pdf), but it's huge (depth and width wise). I long thought about using direct firing because they looked like the only option for the height problem. But  it does feel like stepping down, instead of upgrading.. so Ive finally settled for the MEH als the only real option (and till recently  an intermediate with a cheaper one). All thanks to you  

Quote

The reason why this is so seldom experienced by audiophile listeners is due to the difficulty in getting good, extended, horn-loaded bass in a center loudspeaker.  But once you hear it, you'll never want to go back to direct radiators, in my experience.  The K-402 MEH does that better than any other loudspeaker that I've heard--in fact it has potential usable extension down to 30 Hz (about an octave lower than a La Scala or Belle, and slightly lower than a typical Khorn bass bin) without incurring significantly increased distortion.  See the following on-axis frequency response and phase plot of the K-402-MEH when placed in a room corner:

 

That plot looks amaaaasing. When I suggest some extra bass bins for beneath the MEH I wasnt really looking for a deeper response, but rather about middbass headroom. As you explained above, that option is a step down. However, would a LaScala bin for the lower bass (beneath 200hz) give that. You talked about this sort of combo (as a different model with smallers woofers instead of the 15"ers.). It wouldn't change my plans a lot, as I have the LaScala bass bin already, and I'm definetely building a "regular" MEH for my center like you did, so I can just try it out and see if I like it more than the regular MEH. However that would mean losing lower end, which is not such a problem as I'd be using them in home theatre, but it would be nice to have. Could you combine the MEH with (1 or even 2) LaScalas (a vertical or horizontal tower) and have the MEH cross the total full range, and have the LaScala bins give an extra bump in the 200-50hz range (because of its polar control up to 200hz)? The HF200 has huge output, but I'm not sure what it's relative to the 15" ers in the MEH. Would the extra 50-200hz range add something, or would it not really amount to anything? 

Quote

This means that the K-402-MEH also will serve extremely well as a

 

1) corner-horn loudspeaker,

2) center loudspeaker, or even as

3) an extended capability surround...assuming the required space exists in-room--about the size of a La Scala II as a surround loudspeaker.

Only thing I see being a problem is budget. Crazy though: MEH height channels lol. How much does the MEH weigh? Par chance less than 40kg (90lbs)? 

Quote

 

I've found that using only a center K-402 MEH dramatically lessens the required bandwidth of subwoofers to below 40 Hz and their distributed room placement.  There are quite a few listening rooms which have very few acoustic modes below 40 Hz to deal with via multiple subwoofer room placement.  The front (L, C, R) + surround channels themselves can provide most of the deep bass output, leaving only about one octave of infrasonic bass to be covered by the subs (below 30 Hz).

Having the need for fewer subs would be awesome, my setup is in my living room and my brother is really forgiving (so not WAF but BAF?), but having that huge horn loaded sub is already a pain in the but  with a LCR MEH I could maybe sell that sub and replace it with a pair of smaller sealed 18"ers for the ULF (or convince him let me have an othorn) in the living room  

[Chris A]

1 hour ago, Khornukopia said:

I don't have one to experiment with, but adding a nose piece and some wings to a Belle could be an interesting project.

I agree.  The nose would have to be fairly well veneered to match the presentation of the Belles, I think.

 

I think that a nose applied to MWMs (assuming anyone has the space to do it) would be a fairly spectacular addition, not only improving the polars on the top end, but also extending the bass cutoff by a small amount on the low end.

[Droogne]

@Chris A, as I have almost most definetely chosen for a MEH in the near future I might start looking for some of the parts  Will probably just use the HF200, but might go with 20AT (as the difference in price is negligible when compared to total cost), but if I can maybe decide on a few good woofers I might look for them on local second hand sites. The eminence kappa 15"ers are good choices normally (don't remember the specific one), but would there a benefit by using something more "high end"? 

[Chris A]

I didn't see any significant correlation to woofer cost and higher fidelity in the MEH in my analysis during the design stage.

 

It's just like PWK's fully horn loaded loudspeakers: once you find the right T/S parameters for the job, it makes little difference if you put a pair €100 woofers in or €1500 ones, the sound quality is basically unchanged because of the acoustic transformer action of the horns.  When you take away the need for long throw diaphragms (like those used in direct radiating loudspeakers), the need to spend a lot on the woofers evaporates. 

 

It's much better to put your money on the compression drivers to get the best quality you can afford for reproducing the last octave: 10 to 20 kHz. That's why the BMS 4592-ND is of interest: there are actually two drivers built into one compression driver case--one that crosses over at ~6-7 kHz (the tweeter) and the other midrange diaphragm that goes from that 6-7 kHz tweeter handover band down to as low as 300 Hz crossover to the woofers.

 

Chris

[Droogne]

3 minutes ago, Chris A said:

I didn't see any significant correlation to woofer cost and higher fidelity in the MEH in my analysis during the design stage.

 

It's just like PWK's fully horn loaded loudspeakers: once you find the right T/S parameters for the job, it makes little difference if you put a pair €100 woofers in or €1500 ones, the sound quality is basically unchanged because of the acoustic transformer action of the horns.  When you take away the need for long throw diaphragms (like those used in direct radiating loudspeakers), the need to spend a lot on the woofers evaporates. 

Aight, I'll stick with the eminence woofers then  

3 minutes ago, Chris A said:

 

It's much better to put your money on the compression drivers to get the best quality you can afford for reproducing the last octave: 10 to 20 kHz. That's why the BMS 4592-ND is of interest: there are actually two drivers built into one compression driver case--one that crosses over at ~6-7 kHz (the tweeter) and the other midrange diaphragm that goes from that 6-7 kHz tweeter handover band down to as low as 300 Hz crossover to the woofers.

 

Chris

Well only problem I have with that is that it would just not stay affordable if I'd want to try to match my speakers. The faital HF200 looks like a very nice and recommended driver for the K-402, and it's affordable enough to use in all speakers. The BMS would be too expensive for this. And if I would ever to decide to upgrade the drivers in the LCR (so keep the surround etc all HF200 and only upgrade LCR as to keep the change in timbre match as minimal as possible), I would probably go for something even more high end (TAD? JBL with Be extented diaphraghm, Be Radian drivers etc). But upgrading those drivers would be even after upgrading the amps for my LCR. Probably not for a long time, but when the times comes I'll definitely love some guidance in picking some good amps (when going SS I'd probably go for something like the Emotiva XPA6 Gen 3)

[Chris A]

By the way, the prototype K-402 MEH weighs about 125 pounds--the weight of a La Scala I.  If using the lightest weight K-402 horn, i.e., the most recent version, subtract 10 pounds--to arrive at about 115 pounds overall. 

 

If using a DIY horn--the one I'm working on--add at least 20 pounds.  If using TAD 4001 drivers, add 15 more pounds.  This would bring the weight up closer to the La Scala II's 175 pounds. 

[Droogne]

11 minutes ago, Chris A said:

By the way, the prototype K-402 MEH weighs about 125 pounds--the weight of a La Scala I.  If using the lightest weight K-402 horn, i.e., the most recent version, subtract 10 pounds--to arrive at about 115 pounds overall. 

 

If using a DIY horn--the one I'm working on--add at least 20 pounds.  If using TAD 4001 drivers, add 15 more pounds.  This would bring the weight up closer to the La Scala II's 175 pounds. 

haha well never mind the MEH height channels then  maybe in an ideal situation one could mount them, but my situation isnt that (although if you'd use 2 wall mounts you could get there hypothetically.). Not that it really matters, I dont really know a situation where I would ever want to pump over 3k in a pair of height channels. (although a smaller version with smaller woofers and a higher cutoff (100?) integrated into something like the K510, if at all possible, would be something cool to design)

 

And if you don't me asking, how far along are you with the DIY horn? Dont want to pressure you or anything, especially if you have more important things on your mind, but it looks a cool project. How are you modelling the horn? A replica of the K-402, or a more "self-invented" design? And what is holding up the project? Are you having some design struggles, difficulties in the DIY construction part, or just time? How is it looking so far? Any results? 

[Chris A]

Well...the pattern looks very similar to a K-402 from the mouth side--except for the four woofer off-axis ports, of course.  The rear of the horn is much different--with woofer mounting surfaces and reinforced horn side walls included in the differences.  The horn material isn't black ABS: it can be clear or most any clear or opaque color, with the possibility of other decorative embedments possible.  There is a fair amount of latitude in the material acoustic properties available and filling materials that can attenuate structural vibrations.

 

The mold is about 90-95% complete: the rear reinforcing structure is very near completion.  A full day or perhaps two at reasonable fiberglassing temperatures should be enough to complete.  After that, assuring the sealing and preparing the mold, then pouring the first part (about 35 pounds of resin) will follow. 

 

Much trial-and-error in the mold design was required in order to accommodate the unique shape of the MEH assembly.  The mold itself is unique in construction and materials.  That is the only part of the design that I don't intend to share. 

 

The geometry of the off-axis ports in the horn was verified using the prototype for acoustic measurements, and was simulated using Hornresp--but only very coarsely.  They proved to be on the mark in terms of their placement and size.

 

Chris

[Droogne]

4 minutes ago, Chris A said:

Well...the pattern looks very similar to a K-402 from the mouth side--except for the four woofer off-axis ports, of course.  The rear of the horn is much different--with woofer mounting surfaces and reinforced horn side walls included in the differences.  The horn material isn't black ABS: it can be clear or most any clear or opaque color, with the possibility of other decorative embedments possible.  There is a fair amount of latitude in the material acoustic properties available and filling materials that can attenuate structural vibrations.

 

The mold is about 90-95% complete: the rear reinforcing structure is very near completion.  A full day or perhaps two at reasonable fiberglassing temperatures should be enough to complete.  After that, assuring the sealing and preparing the mold, then pouring the first part (about 35 pounds of resin) will follow. 

 

Much trial-and-error in the mold design was required in order to accommodate the unique shape of the MEH assembly.  The mold itself is unique in construction and materials.  That is the only part of the design that I don't intend to share. 

 

The geometry of the off-axis ports in the horn was verified using the prototype for acoustic measurements, and was simulated using Hornresp--but only very coarsely.  They proved to be on the mark in terms of their placement and size.

 

Chris

Love what you do man! I just discovered your big post about this on the DIYAudio forum (http://www.diyaudio.com/forums/multi-way/307156-range-synergy-kit-questions-10.html) so I'll be reading through it during my breaks. I see you already have a few people lining up I'm kinda getting convinced that it might be better idea to skip the K402 MEH and get one of yours. Would love to buy one (or 3, or 5 haha) from you. I see you already have a few people who are first in line (after your 5 new ones ofcourse)(What are you doing with the old MEH?). Would it be able for me to get in that line? Like officially If so, could I get a (rough) price? 

 

Thanks for being you man haha, learning so much, and hope to get some your craftmanship into my home someday!

[No.4]

Chris, forgive me if I missed this in this thread or the one on DiyA but what are you planning on using as a material for the horns? Polyurethane? Another exothermic? Fiberglass resin layup? Very curious as I have done some small scale casting with polyurethane using high definition RTV for the mold. There are some very cool materials out there now for casting, always like to “hear” about someone’s process.

[Chris A]

There is a range of options available for the material used, as I alluded to above.  Cost is usually a constraint--as some materials cost significantly more on a volume basis, and stability of large cast sections becomes an issue thermally in a mold of this size.  Structural stiffness and internal damping are also relevant properties in the finished parts.  The type of material that I use for my personal needs and what is used for some else's needs may not be coincident (assuming that I am ultimately successful with my own parts to begin with).  The mold itself is good for various thermoset casting materials, unlike large injection or compression molding presses that must use one type of thermoplastic molding material, notably ABS (Acrylonitrile Butadiene Styrene).

[Chris A]

The structural materials that I've considered include polyester, vinyl ester, epoxy, and acrylic. Polyurethane is flexible--even high durometer formulations.  In the sizes that the present horn has, material compliance would be detrimental.  However, it's a good material for mold making but very expensive on a volumetric basis.

 

Chris

[Droogne]

@Chris A, semi related to something I heard you say about the future of your 5xMEH setup and subwoofers, it maybe even has something to do with polar control, not sure. You were talking about raising the MEH from the ground by putting a sub beneath it, I think a horn (like the othorn?). Just some questions:

 

1) Is there any specific reason for this? Would this couple them in kind of a way? Or is it just because the corner placement would be ideal for both the MEH as the sub (without having any relation between in the specific sound)., OR just because it's a space saving option?

 

2) Are there any kind of "requirements" for having a front speaker on top of a sub? Both same type? Specific crossovers? 

 

3) Would the sub use the LFE channel, or be a lower extension of the MEHs? Like a 3 way. 

 

I might be interested in placing a DIY sub beneath my fronts  (because of the way my listening room is positioned, and because I also need to raise my fronts) , in which case I would model the cabin to be a drop in "extension" of the fronts (so it's a steady foundation and looks nice). A horn sub would be ideal, but I'm looking for a couple of subs to take me down to the lower frequencies (sub 20hz) and I was thinking about doing this with front firing sealed ones. A horn sub that goes down this low is too expensive, and too big (although if you perchance know about a design that can do this, and which is maximum 2ft deep and 2,5ft. high, I'm happy to hear about it!). Any reason why not to do this kind of combo? (let's say I have a full LCR MEH for this hypothetical). Maybe some acoustical reason why not or just because of the same principle as explained above by PWK ?  (distortion wise) 

[Chris A]

55 minutes ago, Droogne said:

You were talking about raising the MEH from the ground by putting a sub beneath it, I think a horn (like the othorn?). Just some questions:

 

1) Is there any specific reason for this? Would this couple them in kind of a way? Or is it just because the corner placement would be ideal for both the MEH as the sub (without having any relation between in the specific sound)., OR just because it's a space saving option?

There is a requirement to get the centerline of the loudspeaker up to about 1.3 metres (~50 inches) off the floor. 

 

If you're going to do that, it makes sense to fill that air between the bottom of the loudspeaker and the floor with something.  Additionally having truly "full range" frequency response capability co-located at each of the five surrounding loudspeaker locations is a big plus in terms of low bass coverage in-room to avoid the effects of room modes.  It simply makes sense to integrate low bass capabilities with the surround loudspeakers. 

 

1 hour ago, Droogne said:

2) Are there any kind of "requirements" for having a front speaker on top of a sub? Both same type? Specific crossovers? 

From the standpoint of distributing low bass injection into the room at differing points in the room (like Geddes's subwoofer method), it's simply advantageous to use the locations of the five surrounding loudspeakers to place them in-room.  You could also place one subwoofer in a corner, one at mid-wall, and one somewhere else in-room and achieve approximately the same result.  SO there is no "requirement" for co-locating the subwoofers with the loudspeakers, only the opportunity to do so.  It eliminates other dialing-in issues if it can be done.

 

1 hour ago, Droogne said:

3) Would the sub use the LFE channel, or be a lower extension of the MEHs? Like a 3 way. 

If you integrate the subwoofer frequency response with the surrounding loudspeakers, then you'd treat each channel as a single loudspeaker, and the LFE would inject into the array at each surround channel using "full range" loudspeakers and no subwoofers.  An AVP or AVR will do this for you...handle the LFE content in movies and the crossover point to the "infrasonic bass" channel at each loudspeaker to basically eliminate the separate subwoofer concept. 

 

This subtle shift in thinking affects the entire subject of full-frequency coverage...which tends to treat subwoofers as "something different".  They're not, but they need to be located in places to negate the effects of room modes--something that in most listening rooms is important at 200 Hz or perhaps even higher frequencies.

 

1 hour ago, Droogne said:

Any reason why not to do this kind of combo? (let's say I have a full LCR MEH for this hypothetical). Maybe some acoustical reason why not or just because of the same principle as explained above by PWK ?  (distortion wise)

If you're limiting the bandwidth of the subs to one octave or so (and you would in the configurations that you've illustrated above), then you might be able to get along with direct radiating subs for the bottom octave below 30 Hz.  They would be limited in terms of absolute loudness--which is important for subs due to the equal loudness curves, but unless you're a big pipe organ fan (...like I am...), you probably won't hear any difference using the DR subs, which you'd mostly hear/feel on movies.  The size of your room and the number of subs-distributed across the room's front wall should be taken into account in terms of "filling up" the room's modes.

 

Chris

 

[Droogne]

10 minutes ago, Chris A said:

There is a requirement to get the centerline of the loudspeaker up to about 1.3 metres (~50 inches) off the floor. 

 

If you're going to do that, it makes sense to fill that air between the bottom of the loudspeaker and the floor with something.  Additionally having truly "full range" frequency response capability co-located at each of the five surrounding loudspeaker locations is a big plus in terms of low bass coverage in-room to avoid the effects of room modes.  It simply makes sense to integrate low bass capabilities with the surround loudspeakers. 

 

From the standpoint of distributing low bass injection into the room at differing points in the room (like Geddes's subwoofer method), it's simply advantageous to use the locations of the five surrounding loudspeakers to place them in-room.  You could also place one subwoofer in a corner, one at mid-wall, and one somewhere else in-room and achieve approximately the same result.  SO there is no "requirement" for co-locating the subwoofers with the loudspeakers, only the opportunity to do so.  It eliminates other dialing-in issues if it can be done.

 

If you integrate the subwoofer frequency response with the surrounding loudspeakers, then you'd treat each channel as a single loudspeaker, and the LFE would inject into the array at each surround channel using "full range" loudspeakers and no subwoofers.  An AVP or AVR will do this for you...handle the LFE content in movies and the crossover point to the "infrasonic bass" channel at each loudspeaker to basically eliminate the separate subwoofer concept. 

 

This subtle shift in thinking affects the entire subject of full-frequency coverage...which tends to treat subwoofers as "something different".  They're not, but they need to be located in places to negate the effects of room modes--something that in most listening rooms is important at 200 Hz or perhaps even higher frequencies.

 

If you're limiting the bandwidth of the subs to one octave or so (and you would in the configurations that you've illustrated above), then you might be able to get along with direct radiating subs for the bottom octave below 30 Hz.  They would be limited in terms of absolute loudness--which is important for subs due to the equal loudness curves, but unless you're a big pipe organ fan (...like I am...), you probably won't hear any difference using the DR subs, which you'd mostly hear/feel on movies.  The size of your room and the number of subs-distributed across the room's front wall should be taken into account in terms of "filling up" the room's modes.

 

Chris

 

 

As always, sublime answer! Don't think I have any questions left in me... Only that if/when I go MEH I might just make a 8x 18" layer below the LCR with a few others spread around the room. Troubles for later.  For now I'm putting my money into 2-3 smaller 15" subs to better fill the room. Depending on how everything goes that might be extended to a 4th beneath the couch (VNF,  but also very good to help with room modes I thought). Good to know there is no inherent problem with the front firing, fitting in an othorn into my room would be a tough sell ! Maybe as a down firing coffee table  

 

What subs were you thinking about? 

 

 

[Droogne]

@Chris A

 

As a temporary situation I'm gonna use my LaScala rears as center front and back (so 6.1 instead of 7.1 on the ground). I wasn't planning on building top bins for them, but I I'll need to ,if I want to put my tv on top of it. Brings me to my question: would it be so terrible to put the mid/high horn next to the bassbin, instead of on top of it? Would be almost the same distance, but in the horizontal instead of vertical plane. I know we talked about something similar, but I can't seem to remember if it's just "not ideal", or really a no-go. 

[Chris A]

1 hour ago, Droogne said:

...would it be so terrible to put the mid/high horn next to the bass bin, instead of on top of it? Would be almost the same distance, but in the horizontal instead of vertical plane.

This really depends on the crossover frequency.  I wouldn't do that if you're crossing much higher than  something like 250 Hz.  The typical 400 Hz crossover frequency of the La Scala is actually a little too high to avoid introducing lobing issues, but the lobing may be partially mitigated by using shallower slope crossover filters, if the drivers can support those extended frequencies, or steeper crossover filters and all-pass compensation if not.  It also depends on the listening distance from the listeners to the center loudspeaker.  If you're farther back than 3-4 metres, you're probably okay.

[Droogne]

37 minutes ago, Chris A said:

This really depends on the crossover frequency.  I wouldn't do that if you're crossing much higher than  something like 250 Hz.  The typical 400 Hz crossover frequency of the La Scala is actually a little too high to avoid introducing lobing issues, but the lobing may be partially mitigated by using shallower slope crossover filters (i.e., 6 or 12 dB/octave), if the drivers can support those extended frequencies.  It also depends on the listening distance from the listeners to the center loudspeaker.  If you're farther back than 3-4 metres, you're probably okay.

Ok it seems like I'll have to test it  making a temporary stand wont be that hard. Makes me wonder about people putting their tweeter next to the mid horn instead of one top. Doesn't that have a similar effect?

 

PS I have the option between a 3-way LaScala (original parts on the PH2380) with active crossover, or my passive K510/HF200 combo. I'm not really sure about the specs of the cross, but  this is what Steve (Steve Bedard that is), had to say about it: "

 "It's a Crites 500Hz crossover. It is a simple design, much like the traditional Klipsch crossovers. Gentle 12Hz/Octave slope. Use of Klipsch autoformers and Sonicap Capacitor."

 

Would you suggest the 3 or 2 way for the center/fronts? I could also use the heresy as a center between the 3-way LaScalas for best coherence.