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

[Khornukopia]

It is good to read that you plan to replace all the speakers in your home theater with copies of your New Center design. Will they all be identical, or might the surround speakers use different drivers or port configurations for experimentation? The Jubilee bass bin has 2 twelve inch woofers, why does the New Center need 2 fifteen inch drivers?

[Chris A]

The idea is to use the same configuration all the way around (5 loudspeakers), but the 2" compression drivers in the surrounds will probably be K-69-As that I have on hand.  I plan to pick up a better compression driver for the center.

 

The subject of woofer size is discussed earlier in this thread.  To summarize that discussion, I found that the design really needed two 15 inch diameter drivers in order to have sufficient capacity below the horn's 1/4-wavelength frequency (about 175 Hz) to compensate for the gradual loss of horn gain on-axis.  The horn itself begins to lose directional control at about that frequency (just like the other Klipsch Heritage bass bins--about 100-200 Hz).  So the woofers still get the advantage of horn loading below Fc, but not directionality.  Putting the loudspeaker up against a wall (like a Cornwall) or in a corner (like a Khorn, Jubilee bass bin, La Scala, or Belle) constrains the directionality of the bass bin horns to significantly raise their on-axis SPL relative to without those room boundaries present. 

 

Having those two 15" drivers only raises the cost of the drivers by a fairly small amount.  They are easily accommodated inside the box, and present no other issues related to their diameter, but enable the extended LF performance of the loudspeaker--with no horn folds required.

 

Chris

Edited February 20, 2016 by Chris A

[Khornukopia]

Thanks for the explanation. I think about this speaker design often and therefore have many questions, but some become slightly off topic, or some questions might appear cynical in writing, so I don't ask because I respect what you are doing. I look forward to more progress reports.

[Chris A]

Feel free to ask your questions.  Who knows...perhaps something will change in the design based on a good question that's asked here.

 

Chris

[mark1101]

 

...+ K69 tweeter.

 

The K-69 is a poor tweeter, IMO, as is the K-69-A.  If the diaphragm areas that you're talking about in the coax version are insufficient to make FMD inaudible, I'd say those listening will soon need hearing aids--if in a home hi-fi environment.

 

he coaxial diaphragms also need to deal with the air pressure generated by the MF driver showing up right in front of the HF driver. This causes modulation of the HF unit's coupling, which is a form of modulation distortion. When the two drivers are separated into separate horns, then you don't have that effect.

 

Then I think that you need to reconsider the thread that you're in if you believe that is actually a factor in this design.  I'd recommend you forking a new thread on that rather than now arguing that point at this juncture here.  This thread actually assumes that you've gotten past those kind of arguments and buy into point source performance.  Otherwise I believe that the outcome of trying to make those arguments now will diverge the focus on the current design to the point that this thread will no longer reflect its title.

 

Chris

 

I installed the K69 as my tweeter after trying several drivers that technically out perform it.  After trying several others I returned to the K69 because it was the more CORRECT sounding driver to me.  It brought back the very noticeable Klipsch sound that had departed.  Not sure what your goals are, but mine are to have Klipsch speakers.  A little experimentation with no reference can bring you out to the boonies.

[Chris A]

It brought back the very noticeable Klipsch sound that had departed.

 

I actually don't want the loudspeakers to sound like anything...except perhaps what the original performance sounded like.  I have to say that statement is a bit mystifying to me.  However, I can say that the K-69-A in the current loudspeaker sounds much more convincing than it did in the Jubilee configuration.   That's been a real surprise.

 

Chris

[ClaudeJ1]

 

Instead of 50x50 coverage it's 60x40. and 3 more for surrounds...while I work on my K-402 setup.

 

One of the things that I really can't overstate is the coverage (and smooth directivity throughout) of the K-402s...which is spectacular.  I mentioned this point to my son-in-law, at which point he walked from side-wall to side-wall and also found that the integrated soundstage image was stable and solid anywhere in the room once you get about 2-3 feet from the center loudspeaker.  I believe that he was very impressed.  That's the benefit of having 100 x 60 degree coverage with the front three loudspeakers. 

 

I really can't wait to hear the difference with surround channels once I can replace the present bi-amped Cornwalls with this new multiple entry horn design. Cornwalls don't have anywhere near that kind of even (i.e., no directivity hiccups with frequency) in horizontal coverage. 

 

Chris

 

While I do believe your observations, I have experienced a more restricted horizontal coverage keeping all the direct sound off the walls until many many milliseconds later in the room in my own as well as the best space I ever heard (Artto from this group), so I have yet to prove out what your are speaking of here, but I intent to do so this year as I build Synergy mid/woofers into 402 wood clones.

[Chris A]

A little experimentation with no reference can bring you out to the boonies.

 

I have Jubilees on either side whose timbre must integrate with the center.  No problems there (with TADs on the Jubs and K-69-A in the center).

 

I've found that a certain "sound" is usually correlated to the loudspeaker's frequency response plot: when you correct the FR, the timbre sounds more neutral.

 

Chris

Edited February 20, 2016 by Chris A

[NBPK402]

The idea is to use the same configuration all the way around (5 loudspeakers), but the 2" compression drivers in the surrounds will probably be K-69-As that I have on hand.  I plan to pick up a better compression driver for the center.

 

The subject of woofer size is discussed earlier in this thread.  To summarize that discussion, I found that the design really needed two 15 inch diameter drivers in order to have sufficient capacity below the horn's 1/4-wavelength frequency (about 175 Hz) to compensate for the gradual loss of horn gain on-axis.  The horn itself begins to lose directional control at about that frequency (just like the other Klipsch Heritage bass bins--about 100-200 Hz).  So the woofers still get the advantage of horn loading below Fc, but not directionality.  Putting the loudspeaker up against a wall (like a Cornwall) or in a corner (like a Khorn, Jubilee bass bin, La Scala, or Belle) constrains the directionality of the bass bin horns to significantly raise their on-axis SPL relative to without those room boundaries present. 

 

Having those two 15" drivers only raises the cost of the drivers by a fairly small amount.  They are easily accommodated inside the box, and present no other issues related to their diameter, but enable the extended LF performance of the loudspeaker--with no horn folds required.

 

Chris

Chris, I don't know what you are looking for in a driver, but I have 3 spare EV DH1a drivers i am going to be selling...let me know if you are interested in any or all.

[ClaudeJ1]

Chris, I don't know what you are looking for in a driver, but I have 3 spare EV DH1a drivers i am going to be selling...let me know if you are interested in any or all.

 

If they have original diaphragms, the DH1A driver is very good. I preferred it over my JBL 2446 drivers when I had both. Roy Delgado tested my DH1A drivers in the Anechoic Chamber in Indy and told me that was an excellent driver. It was also the driver used by John Pope to convince Paul Klipsch that tractrix horns were superior to exponential horns. It's also the best bang for the buck in the used market, FYI.

[Khornukopia]

The Tannoy dual concentric coaxial driver loudspeaker is called a point source design and they do sound good, but when I did a casual A--B afternoon listen session a few months back with a pair of passive K-horns in the same room, I still liked the K-horns better. I was actually comparing several amps that day, not speakers. Maybe I'm not keen enough to appreciate the Tannoy, or it could be my personal bias, but now that I know how you guys like your point source multiple entry horns, and that I might need to get one or more myself, I am wondering why is it that more speaker builders don't utilize dual concentric, coaxial drivers on their direct radiator designs? For hypothetical example, a Cornwall cabinet with a single Radian 5215 physically time aligned point source coaxial woofer-tweeter?

[Chris A]

I am wondering why is it that more speaker builders don't utilize dual concentric, coaxial drivers on their direct radiator designs?

 

There isn't much space within a dual-concentric driver of the Tannoy type.  It's difficult to do well and I'm sure the compromises must be made due to those space limitations.  That also drives up costs and tooling complexity,and it forces the companies to make their own drivers--something that is problematic for most companies from an investment and tooling standpoint.  It also isn't visually impressive to look at what appears to be a woofer in the middle of a box.

 

...when I did a casual A-B afternoon listen session a few months back with a pair of passive K-horns in the same room, I still liked the K-horns better.

 

This isn't a mystery.  The bass of Tannoys typically aren't horn-loaded, so they suffer from the same modulation distortion (FMD and AMD--mostly AMD) like the difference between a Cornwall and a Khorn.  Additionally, it isn't clear whether the horn-loaded HF unit is actually time aligned to the bass cone or if it suffers phase misalignment due to its passive crossover network--somewhere between 90 (low order crossover) and 360 degrees (higher order crossover) of phase misalignment.

 

If you were listening to the Westminster Royal--which is fully horn loaded, you were listening to a back-loaded horn, something that cannot be time aligned any better than the physical layout of the horn vs. the direct radiating woofer cone--which is 11 feet closer to the listener's ears than the backwave. 

 

 

The design represented in this thread (the New Center multiple entry horn) is different...

 

1) it doesn't require special co-axial drivers...which are expensive and difficult to optimize.

 

2) It's fully horn loaded--front horn loaded--with full time alignment.  It also doesn't suffer from modulation distortion (in an eight-space corner loading or even quarter space wall-floor loaded configuration).

 

3) It uses a much better horn profile (modified tractrix) for much better directionality control vs. frequency.  It doesn't have the severe HF roll-off at increased listening angles that you will find exponential or hyperbolic horn profiles.

 

4) It has more bass reserve/authority (time aligned) due to its increased relative woofer area.  This improves transient response.

 

5) The use of an active crossover with this design smooths in-room response and flattens phase significantly vs. the typical passive crossover-only designs used by most Tannoy owners.

 

Etc.

 

Chris

[Khornukopia]

Some bass reflex cabinets have flared port tubes to minimize turbulence. The Klipsch Reference Premiere speakers use Tractrix geometry on the port tube ends for "the most efficient, fastest air transfer from the cabinet". Is it conceivable that flaring, or rounding over the edges of the woofer port holes on a multiple entry horn (or a Klipsch horn-loaded woofer chamber throat) could benefit the speaker's performance?

[Chris A]

Port flaring only minimizes what most would call "port chuff".  The geometry of the ports inside the horn are a different story than just bass reflex porting.  There the trade off is between horn radiating area and providing sufficient port area to keep the port chuff down to inaudible levels and to smooth the response.  Since there is horn gain present in the ports inside the horn, much less air is required to produce a certain SPL than if the port was located outside the horn.  So ports inside horns can be smaller.

 

If you look around at off-axis ports inside all multiple entry horns, you might notice that the none of the ports are flared inside the horn.  The reason is that the horn surface area and horn surface profile is much more important to preserve than the flaring of the port, which is operating much more efficiently inside the horn.

 

Chris

[ClaudeJ1]

If you look around at off-axis ports inside all multiple entry horns, you might notice that the none of the ports are flared inside the horn.  The reason is that the horn surface area and horn surface profile is much more important to preserve than the flaring of the port, which is operating much more efficiently inside the horn.   Chris

 

The Danley SH have a chamfer on the inside all around. 

[Chris A]

That's another story: on the woofer side of the port, all ports are typically tapered.  So are the ports on the "New Center".

[mustang guy]

I've noticed that discussion has died down.  

 

The K402 debacle where the price jumped $1,000 really ticks me off. I feel like buying one, making a mold and manufacturing them in carbon fiber to sell to personal friends here. Who wants to buy the diaphragm for $700 that's worth at best $200. 

 

If the re-seller was charging $285, then he was paying ~$142.50, which means they cost ~$71.25 to make.  If I am way off base, then I am sorry. I wouldn't even be saying any of this if the horns would be made available to some of us on a case by case.  How else is anybody going to build Chis' center?  This could be the best DIY build on these forums since Claudes QPie.

 

Klipsch, if there is a way to make this happen, it would be GREATLY appreciated. We are your Guinea pigs.

[Khornukopia]

In all fairness to Klipsch Corp., the price difference was $800. each and for the extra money, the customer would also get the K-69 compression driver and the heavy duty, adjustable (I presume) horn mounting bracket/stand. But I do not need the bracket if the K-402 is going inside a cabinet and I would like to use a different driver, so I did not buy the K-402 horns as planned last month, not just about of the price, but because I don't need the extra parts. I am not unhappy with Klipsch for their prices, I just don't want the unused parts.  As I study more about the multiple entry horn designs though, I find a certain appeal about the specs of the 31" wide by 21" tall Danley SM-96, because if I bought some of those, I could still keep my beautiful 31" wide Klipschorns in the room and use them as speaker stands.

[PrestonTom]

We are all looking for a great deal on a pair of horns. That low price being tossed around was quite exciting. I understand the disappointment. 

However, let's not lose sight of the fact that the K-402 is a very, very good sounding horn. Even at the price being charged, it is still  a good deal. 

[Khornukopia]

I was joking about using my Klipschorns as speaker stands, I would actually use a shelf above them. Even if (the not yet acquired) multiple-entry horns sound really good, having Rosewood Klipschorns is to own a masterpiece by a great artist, so I can't imagine letting them move out of my house.