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

[Don Richard]

I love OVERKILL, don't you?

 

Anything worth doing is worth overdoing.

 

IMHO.

[Khornukopia]

There is only one K-402-Based Full-Range Multiple-Entry Horn for us to read about, so the comments about somewhat comparable speakers owned by forum members whose opinions we trust gives me a frame of reference that enhances my interest in the New Center speaker.

 

This design does stir up a lot of questions and I enjoy reading everybody's comments, but I respectfully agree about keeping the thread on topic, and I hope that none of my posts have been too far out of line.

 

The K-402 horn and driver combo available at American Cinema Equipment comes with the K-69. Is this the HF driver used on the New Center?

 

In my e-mail exchange on Monday with Spencer, I asked his permission to post his reply on the forum and he said yes, but to omit the price of the K-402 / K-69 combo, as it is subject to change, but someone else had already posted their copy of his reply, price included on the Tads and 402 thread.

 

[Chris A]

The K-402 horn and driver combo available at American Cinema Equipment comes with the K-69. Is this the HF driver used on the New Center?

 

I'm using a K-402 with a K-69-A presently.  I might switch to another compression driver if budget allows: I'm looking at using a TAD TD-4002 or, even more interesting, a bi-amped dual-diaphragm BMS 4592ND (i.e., the full-range version).  Those last two types are premium compression drivers that have extremely clean HF performance.  Whatever happens, I can recommend the K-69-A (or similar P.Audio BM-D75 Series II driver at about $170US) as solid performers.  The B&C DE750 is also a nice driver (about $300US) - which I believe is also available on a K-402 assembly w/stand as an option--it's also been called a "K-69".

 

Note however that I'm not disappointed in the K-69-A at all.  In fact, I'm amazed at how well everything sounds relative to when I used the K-69-As in my Jubs.

 

Chris

[ClaudeJ1]

 

I love OVERKILL, don't you?

 

Anything worth doing is worth overdoing.

 

IMHO.

 

Don, you don't "overpost" like some people, but what you have to say is always worthy of noting.

[juniper]

 

The K-402 horn and driver combo available at American Cinema Equipment comes with the K-69. Is this the HF driver used on the New Center?

 

I'm using a K-402 with a K-69-A presently.  I might switch to another compression driver if budget allows: I'm looking at using a TAD TD-4002 or, even more interesting, a bi-amped dual-diaphragm BMS 4592ND (i.e., the full-range version).  Those last two types are premium compression drivers that have extremely clean HF performance.  Whatever happens, I can recommend the K-69-A (or similar P.Audio BM-D75 Series II driver at about $170US) as solid performers.  The B&C DE750 is also a nice driver (about $300US) - which I believe is also available on a K-402 assembly w/stand as an option--it's also been called a "K-69".

 

Note however that I'm not disappointed in the K-69-A at all.  In fact, I'm amazed at how well everything sounds relative to when I used the K-69-As in my Jubs.

 

Chris

 

Chris if you want to borrow my 4002's  you are welcome.... you are just moving progress forward, a great thing! The BMS driver I have heard, it can be spooky, yet was soft in the two systems I heard, but I like it a little hot in some areas of the spectrum, and it could have used some eq for my tastes. I like piano to sound like a piano, and strings to sound like strings.... then I look for recordings that sound balanced and good with my space, system and lowly gear...  There is nothing like a point source speaker...

Edited January 27, 2016 by juniper

[Chief bonehead]

 

 

 

 

Note however that I'm not disappointed in the K-69-A at all.  In fact, I'm amazed at how well everything sounds relative to when I used the K-69-As in my Jubs.

 

Chris

 

And in 5, 4, 3, 2, 1......here's deano!!!!

[Chris A]

Hi Roy!  Glad to hear from you.

 

Well...no negatives intended above, just a comment on the difference in sound that seems to draw attention to the strengths of the compression driver.  It's actually quite startling.  Perhaps some of it is due to the fact that this is such a strong center between Jubs that I'm hearing soundtracks and surround music as it was intended...for the first time.  Perhaps its because it also fills the center room (anti-node) positions with LF at least an octave below that what anything else that has stood in that spot performing center duties, including the immediate predecessor JuBelle. 

 

The interesting thing is that this center is not corner loaded--in fact, far from it.  I have it on my agenda to listen to it in the corner--very soon...

 

Chris

[Chris A]

Want to drop in for a listen?

 

[Stevenarrow]

 

The K-402 horn and driver combo available at American Cinema Equipment comes with the K-69. Is this the HF driver used on the New Center?

 

I'm using a K-402 with a K-69-A presently.  I might switch to another compression driver if budget allows: I'm looking at using a TAD TD-4002 or, even more interesting, a bi-amped dual-diaphragm BMS 4592ND (i.e., the full-range version).  Those last two types are premium compression drivers that have extremely clean HF performance.  Whatever happens, I can recommend the K-69-A (or similar P.Audio BM-D75 Series II driver at about $170US) as solid performers.  The B&C DE750 is also a nice driver (about $300US) - which I believe is also available on a K-402 assembly w/stand as an option--it's also been called a "K-69".

 

Note however that I'm not disappointed in the K-69-A at all.  In fact, I'm amazed at how well everything sounds relative to when I used the K-69-As in my Jubs.

 

Chris

 

 

 

wow, that BMS dual diaphragm looks very interesting.

[DrWho]

Is there a reason you're considering bi-amping the coaxial BMS driver? You know there is a passive xover option for it, right? I remember the acoustic summing was so good I couldn't tell where each driver stopped/ended in the measurements, but then I'm not sure if I was looking at phase back then or not.

[Stevenarrow]

Is there a reason you're considering bi-amping the coaxial BMS driver? You know there is a passive xover option for it, right? I remember the acoustic summing was so good I couldn't tell where each driver stopped/ended in the measurements, but then I'm not sure if I was looking at phase back then or not.

Is the passive XO an option from BMS?

[Chief bonehead]

Hi Roy!  Glad to hear from you.

 

Well...no negatives intended above, just a comment on the difference in sound that seems to draw attention to the strengths of the compression driver.  It's actually quite startling.  Perhaps some of it is due to the fact that this is such a strong center between Jubs that I'm hearing soundtracks and surround music as it was intended...for the first time.  Perhaps its because it also fills the center room (anti-node) positions with LF at least an octave below that what anything else that has stood in that spot performing center duties, including the immediate predecessor JuBelle. 

 

The interesting thing is that this center is not corner loaded--in fact, far from it.  I have it on my agenda to listen to it in the corner--very soon...

 

Chris

it has been an interesting read.  i experimented with something similar but it had too many drawbacks.  i preferred another method.  but that doesnt mean that what you are hearing is perfect for your situation and application!  and i may take you up on your offer to come listen.......

[Chris A]

I see some on-axis SPL flatness issues with the stock BMS 4592ND and its supplied passive. I assume that the acoustic phase inside the driver s okay since the two diaphragms are within 1/4 wavelength at the crossover frequency (I believe).  The only thing left to look at would be the electrical phase shift of the passive crossover itself.

 

That's the only reason why I'd bi-amp - to flatten the response and correct the phase if that crossover is a typical Butterworth low-order network (probably second order = 180 degrees of phase shift HF to LF).  At the crossover frequency they selected, phase and amplitude are extremely audible.

 

Chris

[Chris A]

...and i may take you up on your offer to come listen..

 

Shoot a PM when you've got a date in mind.  Schedules here are open.

 

Just ran the new configuration in a corner after EQing it flat again.  The harmonic distortion plots vis-à-vis the Jub in the other corner is very interesting...as in "you gotta see this".      So are the phase and group delays. 

 

I might have to swap out the K-69-A with a TAD to capture relative impulse performance.  I haven't settled on a dual tone comparison test yet.

 

Chris

[Chris A]

So the results of the corner-loaded tests relative to the Jubilee are....(drum roll, please)...harmonic distortion is not different for the multiple-entry K-402 and the two-way Jubilee at 90-100 dB SPL at 1 metre. All harmonics are generally below -50 dB from the fundamental from 60 Hz to the crossover frequency. Below 70 Hz, the multiple-entry K-402 actually has slightly lower harmonics than the Jubilee bass bin, corner loaded at above-stated SPLs.

 

Bentz, I found an EQ anomaly around 300-500 Hz that I corrected - it wasn't delay or phase.  In fact, the overall phase spread and excess group delay of the New Center below 500 Hz is much lower than the Jubilee.  I've got to re-run some sweeps to clean up all the plots, since I corrected the EQ after I had it in the corner.

 

Overall, I'm extremely impressed with the performance of this New Center - either as a center loudspeaker or in the corner going head-to-head with a Jubilee in the other corner. 

 

"Wow."

 

Chris

Edited January 29, 2016 by Chris A

[mark1101]

Is there a reason you're considering bi-amping the coaxial BMS driver? You know there is a passive xover option for it, right? I remember the acoustic summing was so good I couldn't tell where each driver stopped/ended in the measurements, but then I'm not sure if I was looking at phase back then or not.

 

I have been running those BMS 4592ND coaxials for most of 2015.  I have used the passive crossover it comes with on the K402.  It was very good on the 402 as a coaxial driver.  A little tricky to EQ as it is a very hot driver.

 

I have since added a 510 atop the 402 and I now use an ALK ESN at 500 / 5800.  I am just using the mid driver on the BMS and have a K69 on the 510.  This has proven to sound much better than the coaxial setup on just the 402.

[Chris A]

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

[DrWho]

Below 70 Hz, the multiple-entry K-402 actually has slightly lower harmonics than the Jubilee bass bin, corner loaded at above-stated SPLs.

 

Just for clarity, you're talking about THD here? Not IMD?

 

The 15" drivers start off with ~1.7x more Sd, which means a 12" driver needs 4.5dB more gain from the horn for matched SPL with the same cone excursion. Of course there are the motor linearity differences between the drivers too.

 

Below are some interesting plots. The amplifier voltages are set so that the drivers are receiving 1W into their Re (the Crites woofer has a lower Re than the K31).

 

This one shows Edgar's Jub LF model with K31 versus the Crites woofer offset on the K402:

 

Here are two K31s as direct radiators versus two Crites drivers as direct radiators:

 

 

Also of interest is the SPL of the system with 1mm of Xmax...Jub LF with K31:

 

Max SPL with 1mm of Xmax: K402_Crites:

(Note that Hornresp forced the scales to change between the two Max SPL plots.)

 

 

And then 1mm Xmax SPL of the sealed systems....

K31:

 

Crites:

 

 

 

 

Granted these are simulations, but I think some general ideas here are applicable. We're seeing the expected 4.5dB difference between the 15" and 12" drivers in the sealed 1mm Xmax SPL.

 

On the horns, the Jub LF is very comparable to the K402 at 100Hz (both 127dB). 200Hz and above the K402 is 5dB better. Below 100Hz, the Jub LF is ~5dB better (ignoring the peak at 65Hz).

 

In terms of the loading provided by the horn, the Jub LF is providing 10dB more gain below 100Hz than the K402, 5dB more at 100Hz, and then they're the same above 200Hz.

 

 

In other words, the Jub LF is a "better horn", but the 15" driver on the K402 is providing an equal excursion advantage over the 12" on the Jub LF. Theoretically we could put 15" drivers in the Jub LF (if they fit) and be 5dB better at every frequency.

 

 

 

All that to say, I'm not entirely surprised that the THD numbers are similar. However, it is interesting to me that the distortion below 70Hz is better on the K402 system. We do see that the measurements of the khjub are ~3dB down lower than the model when we get below 100Hz.

(https://community.klipsch.com/forums/storage/3/761352/khjub.PDF)

However, we see a similar drop in output on the K402 model too - which seems to be a common theme with hornresp.

 

Is the Crites woofer really that much more linear than the K31? Would impressions change if there were a better K31 replacement?

 

 

It's really interesting to me that Roy said he tried this approach but didn't like the compromises. Perhaps it's a MaxSPL thing for Cinema? What else is left to measure between the two? Maybe the Jub LF intermods are better?

 

I'd be interested in seeing a two-tone measurement with 60Hz and 400Hz since that seems to be a good range in favor of the Jub LF and keeps the sidebands within the bandwidth of the system.

[DrWho]

 

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

 

 

He's also more than halved his IMDs.

 

I get the impression that Mark really likes dynamic music - and also wanting things to be huge and in your face like a live concert. He even stands up with a beer in hand while listening. I think there's a photo somewhere showing that

Separating the acoustic centers like that is certainly going to make the sonic image "taller" or "bigger" or whatever.

 

Different goals perhaps, but I think some of the benefits that he's getting in the tradeoff are universally experienced.

[Chris A]

Interesting that you're using K31s in Hornresp.  I actually thought that driver was obsolete and unavailable--as in you can't buy it from Parts Express (PE), etc.  The K31 is an interesting driver--I've not found anything that approximates it, although my search was a cursory one.  I do remember why Roy used it in the Jub bass bin--it was small enough so that the two horn mouths of the bass bin could be rotated closer together, thus increasing the frequency at which the two horn mouths begin to interact with each other (about 210 Hz for the present Jub bass bin, IIRC, which is pretty low, still).  That's a consequence of choosing a "W" section bass bin design--very narrow polars on its upper FR.

 

You've investigated some Interesting Hornresp simulations using the 12 vs. 15 inch drivers, and K33s.  I'd like to point out that the choice of Crites cast frame woofers was not made on the basis on exhaustive Hornresp simulations, but rather on its perceived supply availability vs. typical 15" woofers that I saw from PE. Clearly other woofers can be used and I'm sure that something like a K31 12" woofer would have good performance--assuming you are planning to cross over to a good horn-loaded subwoofer below about 60 Hz or so. 

 

Otherwise, the only downside of the Crites woofers in this design that I can see is that two of them cost $300, delivered...which in the scheme of things is a small burden, indeed.  The upside is that the Crites woofer has a ~6 mm Xmax, which I believe is useful for applications where you might not have a crossover to a horn-loaded sub. There aren't any issues related to space limitations using the dual 15s.  I don't see the reason to use something smaller, other than the marginal decrease in cost. 

 

I've also found that having the extra LF extension capability in the center loudspeaker position is a big deal.  I wouldn't have believed it but my listening room benefits greatly from having that extra extension in the center position. I haven't traded that out with a higher frequency high pass filter in order to limit modulation distortion (MD). I find instead that having that extra extension there is much more useful than worrying whether it is creating a bit more MD.  This is probably also related to the different psychoacoustics of having a 5.2 array instead of just stereo.

 

Roy's comment puzzled me too.  I wish that he would elaborate a bit more.  It's got to be related to the much higher average SPL that is seen in cinema service.  I'm actually seeing no real downside currently to the multiple-entry design for home hi-fi, only advantages in placement flexibility, its dramatically reduced size over the K-402/KPT-KHJ-LF configuration, its ability to lower the listening axis in-room to something approximating head height, and its much better integrated midbass performance/listening advantage, as well as cost and frankly--aesthetics.  I might modify my opinions a little after doing dual tone (MD) tests, but currently my ears tell me that the multiple-entry design is a winner in all those trades.

 

By the way, I'm investigating the relative harmonic distortion performance because MD is dependent on those harmonics: if you can control the harmonics, you're also controlling at least some forms of MD, especially when looking at the higher order harmonics which typically aren't masked by human hearing when they get turned into MD.  The fact that the K-402-based multiple-entry design can match the Jub bass bin in those terms is a big finding, and for me, a big surprise.  I didn't expect that performance.

 

Chris

Edited January 29, 2016 by Chris A