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


Chris A

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Looks like the EVM is smoother and a better match to a TAD if one were to cross at 600 Hz., but even at 450 hz. with 4th order L-R filter, it's got 2 db more output at 300 Hz. Since PEQ boost at the higher frequencies does not add any appreciable IM distortion, I don't think either is a bad choice.

 

I'd be curious about my favorite 15" woofer, the Eminence Kappa 15C.

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Dual 15 inch Eminence Kappa C.GIF

 

Ask and you will receive....two Eminence Kappa 15Cs.

 

Chris

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Edited by Chris A
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  • 2 weeks later...

I got a new multi-channel power amp a few months ago and was so happy that my audio system upgrade was finished.

Then this thread on the K-402 Based Full Range speaker appeared and caused me some imaginary stress as I wondered how to fit another pair of large horn speakers in the room while still keeping the 4 K-horns. After two and a half months of careful consideration, I decided to move my rear surround Cornwalls out to the garage, fabricate another pair of "false corners" to enable moving the front K-horns to the back of the room (none of the actual room corners aim at the listening position), thus giving me space for a new pair of front speakers. As soon as I had this plan, a forum garage sale ad for Brazilian Rosewood Klipschorns suddenly popped up, just moments after I had mentally created an opening. Well, now I have 6 Klipschorns and a La Scala center channel in my 7.2 system.

This has caused a slight detour to my purchase of point source multiple entry horns, but I am still interested in the K-402 based design and specs, and look forward to reading more about the New Center speaker.

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This has caused a slight detour to my purchase of point source multiple entry horns, but I am still interested in the K-402 based design and specs, and look forward to reading more about the New Center speaker.

 

Nice detour, but I can't overemphasize the phase coherent approach and new found micro detail and clarity of multiple entry horns, however and whoever creates them. They simply sound better than anything else I tried.

Edited by ClaudeJ1
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Here is the New Center with two K-31 12" woofers  (same woofers as in the Jubilee bass bin):

 

Multiple-Entry K-402 with two K-31 12inch drivers.GIF

 

Chris

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Edited by Chris A
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  • 4 weeks later...

You can decide--first the dual Crites 15" cast frame woofers:

 

And the dual EVM-15L

 

 

 

 

Chris

Based on the curves, the smoothest from 60-600 Hz. is with the EVM-15L. Which was the original driver for my Quarter Pie horn. It seems to be good for more than one type of horn.

Edited by ClaudeJ1
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I think that most of the above woofers will work well in this design.  I don't believe that Hornresp is going to tell you how it actually sounds, but only gives a relative indication of the power response, which is useful but not the determining factor in which woofer to select for your use.  Bentz mentioned that he was thinking of crossing at a higher frequency (between 100-200 Hz), so dual 12" woofers would probably work well - and saving a few bucks on drivers. 

 

Once I get another multiple entry horn or two to play with, I plan on enlarging/elongating the woofer ports on at least one of those horns to see if the resulting efficiency increase offsets the loss of horn area.  I believe that something like a further doubling of the woofer port area might help out a bit.  That performance trade really isn't modeled very well within Hornresp, but the Beranek horn formulae clearly shows an increase in speaker efficiency with decreased compression ratio.

 

Chris

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....the Beranek horn formulae clearly shows an increase in speaker efficiency with decreased compression ratio.

 

Not to get too far down a rabbit trail, but I wonder if the total efficiency of the system is really the variable we're trying to optimize....and what I mean by that is efficiency calculated as Electrical Power delivered by the amplifier divided by the acoustic output power. This is what Beranek is calculating (if we're thinking the same equation).

 

The reason I say that is because the electrical output power of the amplifier doesn't dominate the distortion of the entire system. It seems like the dominant distortions are driven by the motion of the mechanical components, like the suspension, diaphragm, motor, and even the air. The power dissipating of the driver usually doesn't matter either - certainly not in a home environment.

 

What if we had a system where the electrical input power requirements were higher, but the cone excursion was less for the same SPL?

 

In other words, I think we want to maximize the mechanical efficiency of the system....basically looking at cone excursion versus acoustic output. In hornresp, you can see what I'm talking about by running a MaxSPL calculation. Enter the specs for a fake driver that has very little cone excursion, but a crap ton of electrical power and you'll see a red line indicating excursion limited output. It's really only at the high frequencies where power handling is the limiting factor, but size of the horn isn't as limiting for the HF as it is for the LF.

 

 

 

So all that to say.....do you see an increase or decrease in cone excursion when you decrease the compression ratio? Efficiency may be higher, but what is happening to the total distortion of the system? Maybe the larger throat has less distortion? Beranek gives us some calculations for that too (just to get an idea for order of magnitude).

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That's what I'd like to understand a bit more: port size trades on the woofers in a multiple-entry horn of the profile of a K-402.  There is a price for having the ports too small and a different price for enlarging them too much.  I'd like to understand more what those trades actually are on the offset woofer ports.  I'm really not trying to get more efficiency out of the woofers+horn but rather see if the response smooths out a bit more.  The trade will involve midbass power output vs. power output around the horn/driver fc, I'm sure.  The question is: how much is the midbass performance affected?

 

Danley's Synergy Horn designs keep the total woofer area to port area--a little different than just compression ratio--at about half of the current design of this thread, but DSL is using a reflex porting design in its bass band to do that, clearly done to increase their efficiency on the low end.  They're also using passive crossovers, which is a requirement driven by their business base of selling to the PA loudspeaker market, which also puts their overall design at a distinct disadvantage in order to smooth and "boost" the low bass performance via overall lowering of the speakers' efficiency.  This requires the dumping of even more amplifier power into the passive network or increasing the reactance that the single amplifier channel must drive.  They're up against a rock and a hard spot on both sides of that trade.  Using an active crossover instead doesn't require that trade-off.  I also prefer not to use reflex ports...but simply to get the woofer compression ratios closer to conventional bass horn practice.

 

Chris

Edited by Chris A
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Chris-

I started reading this fascinating thread at 3:00 am while honoring my 67 y.o. BPH bladder. I haven't yet read the entire thing, but I find it fascinating.

Are you at all tempted to replace the Jubilees with two more of these? If so, would a Danley-style TH be helpful, if not needed?

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I'm currently trying to replace the Jubilees with more multiple-entry K-402s...and also the surround Cornwalls, for a total of 5 channels. I've currently got two TH-SPUD clones in the front corners, one behind each Jubilee.  The advantage of the TH subs is form factor.  Conventional front-loaded horns wouldn't be able to be co-located behind the Jubilees.

 

With the multiple-entry K-402 design, the situation is changed, in that I could accommodate two conventional horn-loaded subs of the right dimensions to serve as risers for the multiple entry K-402s fronts on each side.  However, I'm not currently dissatisfied with the SPUDs, so they'll stay.  I've found that having the subs co-located with the fronts gives me added coherence to the bass coverage.  Having the centerline of the horns lower toward the floor is also an advantage in my room--I'll be able to move the TV down to rest on top of the center speaker, as well moving the other channel centerlines down toward the floor for the remaining four channels.

 

The multiple entry K-402s are interesting in that they have much more lower bass output than the former center Belle or even the surround Cornwalls, so they fill in the bass much more evenly around the room.  It's like having more subs--although their bass extends like Khorns--but not really any deeper.  This is a very nice and unexpected benefit of the dual 15" woofers in the multiple entry horn design: the elimination of having to have multiple subs scattered about the room for most music reproduction.  Their overall bass output sound (i.e., tight bass) is much like the Jubilees, unlike vented boxes like the Cornwall or the other KPT-series vented boxes.  The multiple-entry K-402's midbass output is far superior to anything else that I've heard, IMO.

 

Chris

Edited by Chris A
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I've currently got a plan to do it without having to chop up KPT-305s but if it doesn't pan out, that could be something that I'd be interested in.

 

Chris

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Using an active crossover instead doesn't require that trade-off.  I also prefer not to use reflex ports...but simply to get the woofer compression ratios closer to conventional bass horn practice.

 

 

I agree with this notion. Having lived with both sealed and ported Danley designs, and hearing SH-50's at home, Artto's house(in his amazing sound room), and at Danley Headquarters (not the best setup for home emulation), there seems to be somewhat of a "resonance" type sound that is subtle, but has been present in unequalized listening. By that, I mean, no room/speaker EQ (like Audyssey, Acourate, FIR devices like DEQX, etc). Even then, the acoustical properties of group delayed port output, even when cleaned up, might persist.

 

That type of thing appears to be absent in the sealed TD-1 designs. My next step is to remove the simple passive network of this older design and use Tom's PEQ settings with my Yamaha rack and tri amp the things.

 

Then we shall see.

Edited by ClaudeJ1
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  • 1 month later...

Hi Dean.  I'm still working the design which requires a bit of planning and a little trial-and-error as it turns out.  The outside temperatures here are an issue since early May--which affects mfg processes.  I also lost my father a couple of weeks ago after a debilitating illness, so there are now many things to do as a result.

 

I expect to be on this effort more centrally in the fall (October) when the outside temperatures are better for material working times, and have a swamp cooler in the working area for air turnover and temperature control. 

 

Chris

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