A K-402-Based Full-Range Multiple-Entry Horn

[Chris A]

He's also more than halved his IMDs.

 

Uhmm...not in the case of the dual diaphragm BMS driver.  All that happens when one uses another horn and driver assembly is that you lose the point source capability.  What you are experiencing when you do that is something else--not actually in the recordings.

 

When I heard the BMS4592ND on a K-402/KPT-KHJ-LF, it was clear to me that there were remaining FR issues that needed careful re-EQing, and probably phase mismatch issues in the crossover region introduced by the passive crossover network.  Roy also remarked that this driver probably needed more than just a passive crossover and low-Q re-equalization that was used in order to get it sounding the equal of a TAD. 

 

This driver's integration of two ring diaphragms into one assembly is a superior design solution, even more so than the TAD 4002--in terms of eliminating FMD and holding material costs down (i.e., eliminating the requirement for beryllium diaphragms).  However, the price of getting performance equal to the Be-diaphragm drivers seems to be bi-amping are careful EQing/setting of delays and phase.  I've seen where this last step was not done properly--in fact, all attempts to use this particular dual-diaphragm driver using the available BMS passive crossover ($49US) seem to fall short.

 

But I do understand the sensitivity to the sound of modulation distortion and the need to want to minimize it...just not at the expense of point source performance. 

 

If your choice of music doesn't generally include classical, acoustic jazz, non-electric blues, world music, and many other music genres that preserve the subtleties of unamplified acoustic music performance...then the loss of point source capability becomes very much less audible--in my experience.  However, once a hi-fi recording of any of these identified genres are played, the realism of the point source effect is like turning on a light--it's a dramatic enhancement to the music reproduction experience.

 

Chris

[ClaudeJ1]

 

If your choice of music doesn't generally include classical, acoustic jazz, non-electric blues, world music, and many other music genres that preserve the subtleties of unamplified acoustic music performance...then the loss of point source capability becomes very much less audible--in my experience.  However, once a hi-fi recording of any of these identified genres are played, the realism of the point source effect is like turning on a light--it's a dramatic enhancement to the music reproduction experience.  

 

Yes, I have found this to be the case, since I mostly listen to Jazz, instrumentals and vocals, without sacrificing the enjoyment of all other forms of music..........other than the system's superior resolution making some really bad recordings intolerable.

 

It's pretty amazing when you think about a triangular horn that is less than 2 feet deep, with a 29x29" mouth, that's reasonably flat from 40hz-18Khz, and sound like a single driver with electrostatic resolution. BTW, per Tom Danley's advice, I listen without the grilles. I'm glad you found a way to integrate this type of sound into a Klipsch K-402, since that horn provides the best platform I know of for further exploration, both sonically and aesthetically (wood version).

Edited January 29, 2016 by ClaudeJ1

[Chris A]

Aesthetics have value, for sure, but should not override acoustic performance.  There may be a way to significantly enhance aesthetics without resorting to all-wood construction with its attendant construction difficulties, material and machining costs, and acoustic performance issues related to horn material requirements. 

 

But that's just a little down the list of my "things to do" presently: first things first. 

 

By the way, the comments about point source imaging of these type of horns pervade all posts that I've read on diyAudio and elsewhere.  It's the major effect that I believe is the most popular and well known characteristic of multiple-entry horns, by far.

 

Chris

[ClaudeJ1]

By the way, the comments about point source imaging of these type of horns pervade all posts that I've read on diyAudio and elsewhere.  It's the major effect that I believe is the most popular and well known characteristic of multiple-entry horns, by far.  

 

 

If you consider that PWK made all of his Symphony recordings with a pair of spaced omni microphones, which are point sources, it only makes sense to do the playback with point sources.

 

I didn't think to ask him at the time, but when I mentioned Blumlein co-incident microphones to him, his comment was "too much Mono component," which I thought strange, since the 2PH3 speaker array he championed since the Bell Labs days introduces a mono component in the center channel. This is something I did for a few decades, with a La Scala between two Khorns using PWK's resistor box and an extra amp, but with an amazingly STRONG and precise phantom channel from Synergy Horns, my "wall of sound" is perfect, even with 18 foot spacing, without a center. Mine is strictly for HT, which is mostly voice channel for movies and some concerts on Blue Ray or DVD. I'm about ready to go back to 7.1 from 6.1 since I have more speakers and need to make a change in the position of my rear sub.

 

I can't wait until you go "full tilt boogie" when you do a stereo version of your New Center for the flanks. You will be even more amazed.

Edited January 29, 2016 by ClaudeJ1

[Shiva]

Quite a few pages on this speakers attributes. How about a nice quality video recording of it in action.  

[ClaudeJ1]

Quite a few pages on this speakers attributes. How about a nice quality video recording of it in action.  

There is nothing to see beyond the photos and it would be subject to the audio portion of the recording anyhow, which doens't do the speakers any justice.

[ClaudeJ1]

Aesthetics have value, for sure, but should not override acoustic performance.  There may be a way to significantly enhance aesthetics without resorting to all-wood construction with its attendant construction difficulties, material and machining costs, and acoustic performance issues related to horn material requirements.    But that's just a little down the list of my "things to do" presently: first things first. 

 

Of course. Maybe I will end up getting enough intestinal fortitude to cut holes in my 402's, which now have TADs, instead of making wood copies for that purpose. Maybe a Rosewood veneered box around them would be good enough. Meanwhile, I have all sorts of great synergy and Unity horns to "suffer" with until I decide what I will do later. 

[kg4guy]

https://www.facebook.com/patrick.ortiz2?fref=photo

 try this just scroll down .

Edited January 29, 2016 by kg4guy

[NBPK402]

https://www.facebook.com/patrick.ortiz2/videos/10207892871059658/

 

Video of those DIY Synergy horns in the link .

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[mark1101]

 

This has proven to sound much better than the coaxial setup on just the 402.

 

Mark, by doing this, you have further separated the acoustic centers of the drivers beyond 1/4 wavelength, thus negating any point source effect that might have even partially have existed.  It is that point source effect that is the subject of this thread.

 

I'm aware that there are different tastes in music reproduction.  In this case, I can definitely say that my tastes strongly diverge from yours. 

 

YMMV.

 

Chris

 

 

Absolutely, I agree.  Otherwise the whole world would only buy Danley products.  While you can show the unmatched benefits of the point source sound system from an engineering standpoint.........you have to actually listen to it as well.  I absolutely prefer what I just stated (which also includes steep slope networks), and it makes me wonder if I would prefer Danleys at all. (I also think your project is still very cool and impressive.)

 

In fact, after JC brought me those K69s to replace the BMS tweeter section..........I bought another pair for my MCM setup the following week.

 

This is what I spoke of when I said it takes a long time to decide whether a change is better FOR YOU, or just different.  I had other more expensive higher performing drivers on my 510s (several different ones) and when I returned to the K69s............the Klipsch sound came back.  I had diverged too much looking for better performance.

 

But on the Danley thing...........next Saturday JC and I will be at Danley sound labs,  Its 45 minutes from my house, and I should have done this long ago.  I'll be hearing it all for myself in a week.

[DrWho]

Interesting that you're using K31s in Hornresp.  I actually thought that driver was obsolete and unavailable

 

I was using the K31 since that's what is in the Jub LF. I was trying to do a model comparison between Jub LF and Crites K402 to see if anything popped out in your real world comparisons between the two. I have no idea how accurate Edgar's hornresp model is, and we know hornresp has its own issues too, but overall I think the model comparison is interesting.

 

Speaking of drivers, that Crites woofer is surprisingly good at keeping up the LF energy. I've been cranking a lot of drivers through your K402 model in hornresp and a lot of them exhibit really early rolloff....even though they may model similarly in a sealed or vented alignment. I'm trying to figure out a variable to look for that indicates that kind of behavior to help narrow the driver search (right now I just pump everything into the model). I actually haven't found anything that does better in the low end than the Crites woofer (or K33). The K31 performs really well on the 12" side of things.

 

At the end of the day the driver excursion will be the same between all these different drivers, but I like the idea of not minimizing the amount of EQ needed to bump up the low end - which ultimately comes down to power handling and thermal non-linearities.

 

I've also found that having the extra LF extension capability in the center loudspeaker position is a big deal.

 

I agree with you wholeheartedly here.  I've come to the point where I don't even bother with surround sound unless all the speakers are identical....including the surrounds. I think there are several factors there, but I'm with you on not limiting bandwidth solely for the sake of MD. I think a big part of that is phase coherency on sounds that pan around the various channels.

[Chris A]

Thanks Mike--the modeling is very helpful.  It will of course address the first question that anyone will ask of the design: "...is this the best driver to use?"

 

The EQ actually increases the THD in those frequencies, since you boost not only the main frequencies of interest but also the harmonics at the same time by equal amount.  That's the limiting factor that I've found for EQ boost: % harmonic distortion of each harmonic.  The good thing is that the harmonics start out so far down with the current design (generally less than -50 dB above 60 Hz.  Room gain apparent does the exact same thing as EQ boost: it boosts not only the fundamental frequencies, but also the harmonics.

 

The second and third harmonics are typically not big issues in terms of audibility of the resulting modulation distortion products because of the masking effect of human hearing: this masking effect also comes into play to mask the lower order frequency sidebands when listening to phonograph records. 

 

Fourth order and above harmonic distortion is generally directly audible, so it's those to pay particular attention to.  The best news is that those products are -50 to -70 dB below the fundamental as-is (something like 0.5% to 0.03% distortion for each harmonic).  That's the reason why I believe this design works as well as it does.

 

Your comments on surround sound identical performance are extremely perceptive, IMO.  I think that the points that you make are conveniently forgotten by those that want to sell you "surround" dipoles/bipoles that are generally much lower performance speakers whose amplitude, phase, harmonics, coverage angles--the lot--don't match the front three loudspeakers.  THX and Dolby I believe try to mention that, but are typically not followed by the loudspeaker manufacturers and the buyers, unfortunately. 

 

I can tell you that the closer that you get all surrounding loudspeakers in terms of their performance and time delays to the listener, etc., the more spectacular the performance using full surround-sound music.

 

Chris

Edited January 29, 2016 by Chris A

[ClaudeJ1]

But on the Danley thing...........next Saturday JC and I will be at Danley sound labs,  Its 45 minutes from my house, and I should have done this long ago.  I'll be hearing it all for myself in a week.

 

Make sure you try the BC 415 sub, heck you'll be impress with the TH-112! 

[DrWho]

Hmmm, I've never seen EQ increase distortion when measured at the same SPL. Are you saying the harmonics increase because the SPL at the frequency you're measuring has also increased? I have definitely seen that.

As far as room / boundary gain, that has always lowered distortion in my experience. That's free energy that otherwise wouldn't be arriving at the listening position. One could argue that harmonics are benefiting from the gain too, but that would net an equal relative level, not increased. Are you keeping the SPL the same when measuring?

I think this is partially why distortion is so hard to compare. What variables do we hold constant to represent true apples to apples? One of the realities of our systems is that their frequency responses aren't ruler flat, and we listen to them with these "voiced" curves. Comparing same SPL distortion may not be truly representative because in practice they won't be matched. It then comes down to which design decisions we're trying to inform. A couple dB ripple here and there is quite normal / acceptable, but sometimes 1dB can be the difference between 0.05% THD and 10%.

[Chris A]

Are you saying the harmonics increase because the SPL at the frequency you're measuring has also increased?

 

Yes.

 

 

As far as room / boundary gain, that has always lowered distortion in my experience.

 

There is actually a mild relative lowering of HD at frequencies below the room's calculated Schroeder frequency, but nothing dramatic.  I think that the modulation distortion (i.e. dual tone tests) show disproportionately lowered levels by moving from quarter space to eighth space. I know that I had to fairly significantly reduce EQ boost below 200 Hz (i.e., about 100 Hz above the Schroeder frequency for my room).  That says that the total cone motion is much, much less to reproduce the same SPL at those frequencies.

 

But the harmonic distortion levels didn't reduce by the same amount...relative to the fundamental frequency boost reduction. 

 

One of the realities of our systems is that their frequency responses aren't ruler flat, and we listen to them with these "voiced" curves.

 

I personally try to make the resultant FR curves as flat as I can within the limits of the crossover PEQs (with slowly rising LF SPL below ~200 Hz).  I've found that it sounds a lot more neutral/realistic to me when I do.  That was a result of an exercise that I did in-room about 1 1/2 years ago for all 6 channels (including subwoofer) as suggested by Greg Oshiro.  He was right--a lot more than I believed he would be.  Toole and Olive have also written that subject. 

 

A couple dB ripple here and there is quite normal / acceptable, but sometimes 1dB can be the difference between 0.05% THD and 10%.

 

That, I've found, is really the difference between minimum phase (MP) EQing and non-minimum-phase (NMP) EQing.  I avoid the latter like the plague.  You can clearly see it in the distortion plots when you try to boost the NMP room modes and other acoustic reactance-dominated frequency response dips. 

 

Chris

[ClaudeJ1]

I have been using "Room EQ for dummies" for several years in my 6-8 channel setups in various rooms. It's called Audyssey, and the higher up the Audyssey product scale I went, culminating with XT/32, the flatter and better (more resolution( the sound got. Listening to Jubilees with both passive and active Xovers, designed by Roy, in the same room led me to believe that they were awfully close in performance and that other variables, like one's listening room, were far more important than tubes vs. solid state or active vs. passive, once the anechoic curves were matched up as close as possible in the Xovers. So, for me, ROOM EQ has been far more impactful than anything elses, even on Unity and Synergy horns.

 

Mostly it has been an exercise of miking technique more so than anything else. BUT, the better the room was, and the better the speaker to begin with, the better the job at making things sound good from Audyssey32. In doing magnitude responses after the fact, for example, I found that I had to reverse the polarity on all 3 of my subs to completely eliminate a deep notch at 40 Hz. which, upon listening, I was totally unaware of.  I now have the best/flattest, but elevated bass I've ever had below 70 Hz. and had to turn the gain down to compensate. Also, when one does a 20 to 20K sweep, moving the mike an inch or two from either side of center changes the curve in a very different way from 100 Hz. on up. AND it seems that Audyssey is programmed to use the Fletcher-Munson curve or the later ISO one. Plus, my receiver has a variable loudness compensation curve so things sound good at all levels, but I prefer 85 db or so at my sweet spot.

 

That being said, I'm not exactly sure how they use all those extra data points with their FIR methods, since they work in the both the time and frequency domain and we are NOT allowed to control the magnitude response curves like we can with other tools, like the Dirac stuff and their competitors.

 

Long live DSP's!

 

But the better the speaker and room, the more believable the illusion of 3D sound from 2 speakers becomes AND that translates also to 5, 6, 7, 9, or 11.1,2, 3, or 4 surround.

Edited January 30, 2016 by ClaudeJ1

[ClaudeJ1]

But then manufacturers cannot sell more and more speakers and equipment if this starts to be believed about 2 channels.   

 

INdeed. But to take full advantage of modern recording and mixing technologies, especially movies, we need more channels. It still boils down to the quality of the recordings in concert with the playback system. So far Blue Ray movies and concerts are IT for me, but I would be happy if all producers used the full capabilities of a redbook CD, which is still good enough of a playback medium standard after 33 years.

 

For those of us reading this thread, I'm sure ALL of our systems are better than most recordings. It's shameful, but it's true. We have digital medium resolution and signal to noise ratios beyond our analog amplifiers, 135 db DR, yet the stupid producers insist on designing music with a 2 db dynamic range slammed up as close up as the high bits will allow with rolled off bass, so they can win the loudness wars on the crappiest radios. 

 

Having Unity/Synergy horns reveals all the variables involved in with the production of music media, good or bad, better than anything before it.

Edited January 30, 2016 by ClaudeJ1

[Chris A]

But then manufacturers cannot sell more and more speakers and equipment if this starts to be believed about 2 channels.

 

 

I've spent a little time on this subject.  It seems that when you get to something like 5-6 surround sound channels horizontally, like an ITU 5.1 configuration, you've really reached the point of diminishing returns.  Adding extra channels doesn't do very much to further the experience.  Toole in his book references a series of research papers that point this out, some of which are available on-line.  Having a center channel is useful for two main reasons that I've found:

 

1) speech intelligibility (for television and cinema), and

2) for locking in the center image for those that are not sitting directly in the sweet spot (which means basically everyone in a room that has more than one person sitting in it). 

 

The center channel is also, by far, the most difficult to get right.  Once you do, the sound experience typically expands the whole surround sound experience into a much more realistic presentation.  I find that most people never really get to hear a proper center channel experience since they are using loudspeakers that, almost as a rule, aren't up to the task (I'm probably talking about most center loudspeakers on the market).  I've found that out first hand--not by reading white papers or believing it vicariously through others' experiences.

 

I received a relatively recently recorded BD set of Beethoven's 9 symphonies (described above).  During the playing, I noticed that the sound was a little thin.  (The default audio setting for these discs is stereo.)  Once I realized it and changed to surround sound, it was a dramatic change. The experience came alive in the room--which was using the New Center, I might add.  I can't even begin to describe the difference, but we re-watched that symphony performance in its entirety again and was literally awed all the way through.  There is no comparison to the stereo version on the same disc--it just isn't in the same league.

 

Unfortunately, I don't believe this is a common experience with typical consumer surround sound systems.  Only a fraction of that experience is typically achieved, and many issues typically remain due to the compromises accepted (not the least of which are controlled directivity).  This implies that there is a threshold in terms of surround sound quality that enables a complete surround sound experience.  It's unfortunate that the bar is actually that high, but that's been my first hand experience.

 

The point is this: simply adding relatively cheap loudspeakers in multiplicity around a typical home listener doesn't achieve that effect.  It apparently takes more than that--in loudspeakers and room acoustics (The electronics used make very little relative difference outside the quality of the electronic crossovers used, I've found.)   And stereo actually sounds dull and flat in comparison. 

 

 

It isn't as easy as buying and installing a system from the store, running a canned firmware program in the preamp to take out the slack/set it up, then pushing "play".  Stereo still does pretty good in comparison to this level of performance, until you get to a certain threshold of implementation at which point surround sound far exceeds stereo in terms of realism of performance.

 

Chris

Edited January 30, 2016 by Chris A

[ClaudeJ1]

It isn't as easy as buying and installing a system from the store, running a canned firmware program in the preamp to take out the slack/set it up, then pushing "play".  Stereo still does pretty good in comparison to this level of performance, until you get to a certain threshold of implementation at which point surround sound far exceeds stereo in terms of realism of performance.

 

I agree with this statement. However, it is still highly dependent on the source material, which is my biggest complaint in the industry right now.

 

I heard Sting's trumpet player Chris Botti, live in concert in a 1500 seat venue. I also bought his Blue Ray Concert and it was almost as good as the live show, in some respects, better on my system.

 

BTW, I actually bounce my Super Heresy surrounds off the walls (the 6th rear channel is the only surround that is pointed at my head and has little effect.

 

This "sound bounce" creates a larger effective source of sound, and a broader dispersion angle, which is something I learned in photographic lighting as well as experiencing Bose 901's decades ago,  before a Cerwin Vega amplifier blew them up (a fitting ending for a bunch of over driven mid range speakers with a smiley face EQ box).

 

I had Unity horns doing that duty for a while and I may go back to that with an different bounce angle, since those TD-1s are so narrow in their dispersion, but a bit more efficient than my Super Heresy's which I really like.

Edited January 30, 2016 by ClaudeJ1

[Chris A]

Any pics of the rear?

 

Chris I expect he is interested to see how the mid/bass drivers on the side of the horn look.

 

This is very interesting and a cool idea. The walls on the 402s look pretty thick, or is that the mounting plate for the woofers showing?

 

Don,

Somewhere in this he mentions some 3/4 inch mdf to mount the woofers.

Bruce

A  rear view of the horn itself with drivers attached: