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Chris A

Nearly Full-Range Multiple Entry Horns (MEHs)

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On 5/3/2021 at 12:12 PM, Chris A said:

I

 

 

....There is a lot more head scratching going on when the horizontal horn dimension is less than 35-40 inches (the actual mouth size--not the horn flange size)....

 

I

Well at least my 1003b horns are big enough at about 40 inches - now just to figure out where to put the woofers....🤔1003b2.thumb.jpg.3fa53db464e766d354d8ef59c6bcd4b3.jpg

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I am working in a 2' (approximately) cube MEH. It will be using my EV DH1A driver and most likely a pair of Emminence Kappa 15C woofers (same as my k402 MEH). Hopefully it will compare well. I am planning on it being built out of 2 layers of 3/8" bendable plywood, but we might do it out of kerfed plywood. Time will tell as to which is easier, and less expensive to build (I do not want this to get more expensive than a k402 or the only benefit will be size). I might also build a sub to go under each cube to get down low for movies too. It would most likely be a seperate box custom folded horn...with the MINI on top.

 

Sent from my SM-T830 using Tapatalk

 

 

 

 

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22 hours ago, NBPK402 said:

I am working in a 2' (approximately) cube MEH. It will be using my EV DH1A driver and most likely a pair of Emminence Kappa 15C woofers (same as my k402 MEH). Hopefully it will compare well. I am planning on it being built out of 2 layers of 3/8" bendable plywood, but we might do it out of kerfed plywood. Time will tell as to which is easier, and less expensive to build (I do not want this to get more expensive than a k402 or the only benefit will be size). I might also build a sub to go under each cube to get down low for movies too. It would most likely be a seperate box custom folded horn...with the MINI on top.

 

Sent from my SM-T830 using Tapatalk

 

 

 

 

 

Sweet project !

Please post how you end up laying out and cutting  the curved plywood, to get it to match together in the flared corners.  This is so hard for me to visualize how to do.

I've had a heck of a trial and error process time with my attempts at any kind of curved secondary flare / horn walls.

Are you using the Bwaslo spreadsheet for starting design?  

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  Sweet project !

Please post how you end up laying out and cutting  the curved plywood, to get it to match together in the flared corners.  This is so hard for me to visualize how to do.

I've had a heck of a trial and error process time with my attempts at any kind of curved secondary flare / horn walls.

Are you using the Bwaslo spreadsheet for starting design?  

 

I made a fullsize attempt out of mdf a few years ago, and I will mount the compression driver like I did on my previous attempt. Now the previous attempt did not have the flare extension, but I did a mockup out of bendable 1/8" plywood that had the contours cut and they matched up fairly nicely. We will see how this one works out. I have attached an image of the rear of my first attempt.

 

I have a k402 that I made a copy of the curvature of the short side of the horn with bendable plywood, and kerfed mdf. All 4 sides of my horn will be the same size so modeling off of one side should work. I am awaiting some 3/8" bendable plywood now I am planning on forming 2 pieces together for a 3/4" thick horn. Hopefully I will have the pieces ready by the end of the month. I only made the template to go from the flange for mounting the compression driver to the flat area on the mouth of the horn. I think I will have a picture frame style piece made that can be added to the front for the flat area. I am also thinking of making the pucture frame part flat on the backside, and curved to match the horn contour on the front...if this makes sense.

 

2nd image is the contour of the k402 short side template for bendable plywood.

 

Sent from my SM-T830 using Tapatalk

 

 

14b33141a64881dcab7ed8e231721831.jpg

 

e43014426593cf58c7ccbf679b3a2fe9.jpg

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On 5/4/2021 at 3:31 AM, Chris A said:

Yes, I'm aware of the limitations of some listening room sizes to handle them.  "Cheap" is another issue, not related to acoustic performance.  That's a barrier to entry for some DIYers that are severely budget constrained.  But when you look at the cost of a new pair of Cornwall IVs, I think the cost of the K-402s isn't quite so bad.

 

If that's all you can handle, then that's it.  The listening room itself is the limitation.  However, I would also point out that I've seen many people state that they can't handle the width when what they are really saying is that they don't like the visual width in their room.   I try to go with the acoustic performance first.

 

This actually works quite well (I use AMT-1s on top of Belle bass bins currently as my surrounds in my 5.2 array, and they are outstanding).  Using K-402-MEHs and/or Jubilees, doesn't really constrain where the listener is located, however--anywhere from sidewall-to-sidewall in multichannel music mode (LCR). 

 

Welcome to the forum!

 

Chris

Chris,

Sorry for the delay. Thanks so much for your comments and encouragement. 
 

In reviewing other posts, I see that K402’s are “only” 39-40” wide. For some reason, I was thinking they are 46” or more. That error in thinking adds up for an LCR set. (Well at least 18” or so less than I thought). 
 

I will keep reading all the various threads. A wood K402 set would be very interesting. My AE 15” subwoofer would only need to cover the very lowest organ pedal tones and concert bass drum notes. 
 

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14 hours ago, NBPK402 said:

I made a fullsize attempt out of mdf a few years ago, and I will mount the compression driver like I did on my previous attempt. Now the previous attempt did not have the flare extension, but I did a mockup out of bendable 1/8" plywood that had the contours cut and they matched up fairly nicely. We will see how this one works out. I have attached an image of the rear of my first attempt.

 

Sent from my SM-T830 using Tapatalk

 

 

 

 

 

 

NBPK402,

would you describe the sound characteristic of your first MEH attempt?

I was following that project hoping to maybe one day do somethinng similar. How is it different to your ears than MEH made using K-402 horns, and what made you go further with MEH explorations?

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On 5/4/2021 at 10:39 AM, Chris A said:

 

 

So the answer is that the horn needs to be perhaps 32-35 inches wide x 19-21 inches tall to fit my "full-range MEH" criterion. 

 

Chris

 

Now we're getting somewhere good, at least the bass player in me thinks so. That's about the size of a 2x12" cabinet, maybe a small 2x15", and might stack up well. What is the efficiency of your New center, in the 1w/1m numbers? I have an addiction to vacuum tubes, which can make it hard to keep up.

 

Great discussion, thank you all.

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NBPK402,
would you describe the sound characteristic of your first MEH attempt?
I was following that project hoping to maybe one day do somethinng similar. How is it different to your ears than MEH made using K-402 horns, and what made you go further with MEH explorations?
I wish I could...it was 4 years ago and we only had time to listen to it once, and all we had done was cross it over at 500hz. Also we used round ports instead of oval ports. All I can remember is it sounded better than a modified La Scala except at one frequency which it seemed strange (which we were thinking was around the crossover frequency).

Sent from my SM-T830 using Tapatalk

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Posted (edited)
21 hours ago, NBPK402 said:

I made a fullsize attempt out of mdf a few years ago, and I will mount the compression driver like I did on my previous attempt. Now the previous attempt did not have the flare extension, but I did a mockup out of bendable 1/8" plywood that had the contours cut and they matched up fairly nicely. We will see how this one works out. I have attached an image of the rear of my first attempt.

 

I have a k402 that I made a copy of the curvature of the short side of the horn with bendable plywood, and kerfed mdf. All 4 sides of my horn will be the same size so modeling off of one side should work. I am awaiting some 3/8" bendable plywood now I am planning on forming 2 pieces together for a 3/4" thick horn. Hopefully I will have the pieces ready by the end of the month. I only made the template to go from the flange for mounting the compression driver to the flat area on the mouth of the horn. I think I will have a picture frame style piece made that can be added to the front for the flat area. I am also thinking of making the pucture frame part flat on the backside, and curved to match the horn contour on the front...if this makes sense.

 

2nd image is the contour of the k402 short side template for bendable plywood.

 

 

 

Thanks for posting this description and the picts 😀

So on this new build you are working on, with all 4 sides equal, I gather you are planning on the same H vs V, correct? 

If so what degree angle pattern ?

 

I think I might be able to pull off a flared square pattern with the bendy board;  60x60 etc.  It's the different angles that melt my mellon, 90x60 etc.

The picture frame style has worked well for me, although i've tried to make the secondary flares removable, and it's been harder than expected to keep the joints from resonating when driven hard.

 

I very much share parlophone1's questions. 

Extremely curious how you compare your DIY's to the K-402's, and your motivations behind the DIYs.

Thx again.

 

mark

 

edit:

ps....i now see you posted to parlophone1..

 

Edited by gnarly
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4 hours ago, DirtyErnie said:

That's about the size of a 2x12" cabinet, maybe a small 2x15", and might stack up well.

It turns out that the Cornwall cabinet is about the right size for a slightly smaller (but still full-range) MEH than the full K-402. The K-402 horn itself can be accommodated inside the Cornwall box, with perhaps a small amount sticking out on the front (like Ron's [NBPK402]) or back, (like a Khorn or La Scala K-55/K-400 midrange) to get the full 17.5" depth of the K-402 horn.  The compression driver depth (whatever that happens to be for your application) would attach to the horn throat, and increase the depth of the total stack by that amount. 

 

So you can say that the K-402 is actually a 36" x 21" horn...with extra mouth flanges that make it easy to seal against a box mounting.  If you don't need or use that flange, then the full-size K-402 is 36" x 21" x 17.5".

 

4 hours ago, DirtyErnie said:

What is the efficiency of your New center, in the 1w/1m numbers? I have an addiction to vacuum tubes, which can make it hard to keep up.

If you are thinking about trying passive crossovers and mono-amping...I think that designing and implementing a correct passive crossover that EQs properly, etc. will take much more effort than the DSP crossover/bi-amping solution.  The effort to build a "correct" passive for any controlled directivity horn loudspeaker is non-trivial. 

 

Note that PWK built collapsing polar midrange horns (a.k.a., a "pattern flip" midrange horn) in order to avoid having to put EQing (low-Q notch filters) into his passive crossovers because DSP crossovers weren't really available back then.  DSP crossovers have really become the preferred approach in terms of affordability and really superb performance within the past 10-12 years.

 

Chris

 

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If we're talking about musical instrument use, a little strangeness and 'color' in the sound is generally part of the appeal to most speaker systems. Everything between your hands and the crowd's ears can be thought of as great big coloring crayons.

The efficiency and frequency range would be much more important technical factors.

 

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32 minutes ago, DirtyErnie said:

If we're talking about musical instrument use...The efficiency and frequency range would be much more important technical factors.

 

If you're looking for raw SPL output for live sound, I'd recommend Danley's offerings as they offer robust PA levels of output and generally (such as many in the Synergy series...except the SH-96) arrayability, as well as road ruggedness.  [One Jericho per side of a stage is said to be sufficient. See https://www.youtube.com/watch?v=AkrZplo9xgM, replacing 11-box line arrays on each side.]

 

But for home hi-fi use, the loudspeakers we're talking about in this thread are much more suited in terms of their design requirements...and affordability.  

 

Chris

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You're not wrong there.

 

I'm still curious about db/1w/1m, though.

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29 minutes ago, DirtyErnie said:

You're not wrong there.

 

I'm still curious about db/1w/1m, though.

Can safely say, therein lies the 

complete understanding of the anechoic chamber from whence we are all here. Anything less is just a guesstimate. The effeciency is a rightly standard, that has of yet, been the standard. An apparatus with software will not get you all the way.

Billy

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7 hours ago, DirtyErnie said:

I'm still curious about db/1w/1m, though.

Here is the raw response of the woofers in the K-402-MEH, SPL and phase response (i.e., very close to the MEH variants discussed in this thread):

 

K-402-MEH woofers only (No EQ).jpg

 

and the high frequency (TAD TD-4002 channel) raw response on the same K-402 horn:

 

TAD TD-4002 on K-402 (No EQ, no Xover FIlters), 1 m on-axis SPL Phase.jpg

 

Where do I select the output SPL to calculate sensitivity? One kHz?  Bass bin frequencies?  Here is a quote from another audio forum:

 

Quote

Loudspeaker sensitivity is a measure of sound pressure level at a given distance when a specific sinusoidal voltage is applied across the loudspeaker terminals. The sound pressure level at the given voltage, say 2.83V, has to be inspected across the entire audio band.  Looking at frequency response, it is easy to see that for a constant voltage input, sound output varies with frequency.  It is easy to impress with this number by taking the peak in the loudspeaker frequency response and stating it as the loudspeaker sensitivity.  Unfortunately, this does not help anyone understand how loud the speaker will sound to the average listener.  Making all things fair, it is better to find the average SPL from 300Hz to 3kHz representing the mid-band of a typical full range loudspeaker. 

 

So , using that method, the voltage sensitivity (not power) is artificially boosted by about 8-12 dB.  I find that the idea of using a single number for sensitivity, and not using power, but RMS voltage input from the amplifier, further points to the uselessness of the measure.  Loudspeakers are current-drive devices, not voltage driven (which is a common misconception). And in this case, a single sensitivity number isn't valid, because I'm bi-amping (actually tri-amping in the case of the dual-diaphragm BMS 4592ND presently).  So each channel has its own SPL response. 

 

I think it's a little better just to post the SPL response at a certain RMS input voltage for each driver on its horn.  Then the customer (a hypothetical, in this case, since no one here is apparently buying anything) can make the final decision.  The above measurements are apparently -13 dB for the high frequency plot (and unknown for the woofer channel--likely close to 0 dB), down from the 2.83 reference voltage that is usually reported, and would be extremely loud in my listening room, and would in fact annoy my neighbors if I tried testing it outside at that drive level.  I think it's easier to let the reader figure it out for themselves, since the measure itself has no real meaning except as a poor guide to the efficiency of the loudspeaker (which should be the measure, but has to be reported as a function of frequency).

 

I can say this:  the subjective sensitivity of the K-402-MEH is about the same as the Jubilees on each side (reportedly "105 dB/1m" loudspeakers).  If I didn't use the DSP crossover to extend the bass response of the center K-402-MEH (because I can...and the difference is spectacular in-room listening), their subjective sensitivity for the bass channel only (since I'm bi-amping) is within ~3 dB of the Jubilees.

 

Does that answer your question?

 

Chris

 

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Pretty well, yes it does.

Most of my playing history was struggling along with scrounged-up tube amps into cabinets at least 5dB less efficient than what the guitar player had. Mostly, it was cool to have the grinding tone of a maxed out Bassman 100, but there was no options or headroom.

 

Wish I would have had a pair of these in '99. Maybe they'll go on the project list.

 

Thank you for humoring me.

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Posted (edited)
5 hours ago, Chris A said:

Here is the raw response of the woofers in the K-402-MEH, SPL and phase response (i.e., very close to the MEH variants discussed in this thread):

and the high frequency (TAD TD-4002 channel) raw response on the same K-402 horn:

 

 

Where do I select the output SPL to calculate sensitivity?

 

 


 

5 hours ago, Chris A said:

Here is the raw response of the woofers in the K-402-MEH, SPL and phase response (i.e., very close to the MEH variants discussed in this thread):

 

K-402-MEH woofers only (No EQ).jpg

 

and the high frequency (TAD TD-4002 channel) raw response on the same K-402 horn:

 

TAD TD-4002 on K-402 (No EQ, no Xover FIlters), 1 m on-axis SPL Phase.jpg

 

Where do I select the output SPL to calculate sensitivity?

 

 

 

 

 I'm taking off on a tangent....but it does address the question...

Hope is ok...

 

 

Raw driver published sensitivity specs are surely useful for initially laying out a speaker design.  

And raw measurements of the driver(s) in a cabinet let us see what efficiency gain(s) the design provided.

After that,  just as you showed with the varying responses, a single sensitivity number no longer has any meaning.

 

If we assess sensitivity with processing in place, i think we get a more useful, real-world metric.

I feel all that really matters with sensitivity,  is for the leveled-out intended use, of the bandwidth in play.

 

If nothing else, the processed response curve allows a better visual judgment call of sensitivity, because its levels out erroneous peaks.

 

And best, when processing is in place that includes xovers, each driver section can have its sensitivity objectively measured, with no judgment call whatsoever.

 

One technique is to use pink noise, and measure SPL-Leq (time averaged SPL), and a rms voltage average at the driver terminals, over the same identical time interval.

This measures an integration of all frequencies' contributing sensitivities.  (Time averaged, SPL and rms voltage, are needed because pink noise measurements bounce around a little.)

 

A little math turns whatever is measured into SPL at 2.83v/1m for 8 ohm nominal db/1w/1m;  or use 2.0v for 4 ohms nominal db/1w/1m; etc.

REW can handle the SPL-Leq measurement; relatively inexpensive DVM's can handle the rms voltage average.

Highly recommended technique....no more BS or guessing..😃     

 

Heck, even eyeballed 'nominal' impedance can be traded in for an objectively measured average impedance.

Simply measure average current at the driver terminals over the same time period as the SPL-Leq and rms voltage average. 

An honest, accurate, dB/1w/1m can be derived.

 

I've only talked in the context of DSP mulit-ways, but it seems the averaged measurements would work for a passive speaker just as well.

The key in my mind, is how to achieve a real-world integration of sensitivity across the full spectrum of operation.

 

 

 

 

 

Edited by gnarly
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Thanks for posting this description and the picts 
So on this new build you are working on, with all 4 sides equal, I gather you are planning on the same H vs V, correct? 
If so what degree angle pattern ?
 
I think I might be able to pull off a flared square pattern with the bendy board;  60x60 etc.  It's the different angles that melt my mellon, 90x60 etc.
The picture frame style has worked well for me, although i've tried to make the secondary flares removable, and it's been harder than expected to keep the joints from resonating when driven hard.
 
I very much share parlophone1's questions. 
Extremely curious how you compare your DIY's to the K-402's, and your motivations behind the DIYs.
Thx again.
 
mark
 
edit:
ps....i now see you posted to parlophone1..
 
I think the curved flare can be made removable...I would french the screw holes just a bit, and make the horn 3/4" thick at least at the part the curved flair would attach. I believe it will be 60 degree for the horn pattern.

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The current status of loudspeaker specifications (in my opinion) isn't terribly good-especially if applied to fully horn-loaded loudspeakers. 

 

I'd add that the reason why a lot of people prefer the sound of horn-loaded loudspeakers--those measures (modulation and compression distortion levels) aren't even mentioned  in their specifications--relative to direct radiating loudspeakers (fully horn loaded loudspeakers effectively have zero modulation and compression distortion relative to direct radiators, and virtually no one understands or remembers this point). 

 

The efficiency of horn-loaded loudspeakers isn't well suited to voltage sensitivity measures, and as Mark(?--Gnarly) has pointed out, nowadays each channel needs to be EQed flat to compensate for controlled directivity horn efficiency swings over their passbands. 

 

That's why I don't like to use sensitivity ratings since I don't use passive crossovers in my setup any more--everything is bi-amped or tri-amped, and EQed (very carefully) to flat response on-axis at 1m. The typical sensitivity ratings of loudspeakers is not actually measuring the bass bin channels in their measurements, only assuming that the bass bin channel has enough woofer diaphragm area (or bi-amping) in order to keep up with the midrange/high frequency drivers.

 

So the whole subject of loudspeaker efficiency becomes a bit subjective even though objective measures are being used.

 

In general, the MEHs that I've had my hands on have efficiencies that vary between 2-20% on the bass channels (i.e., on the same channel, same MEH, as a function of frequency), and between 4% and close 100% on the high frequency channels. If using midranges, the efficiency varies between 3-50%.  You can see this by the number of drivers used on the high frequency, midrange, and woofer channels in the Danley SH-96 (which is almost the same dimensions as the K-402-MEH, and has the same horizontal and vertical coverage):

 

2619651027_f27f0151a7_b.thumb.jpg.4a41154ae1c057409dff544129fdcefe.jpg

 

The SH-96 is a fixed PA loudspeaker (not arrayable) that is used mostly as a center stage loudspeaker (or one each on the side of the stage).  It has 90 degrees of horizontal coverage and 60 degrees vertical coverage in order to cover the full audience in a PA or music reinforcement application. The SH-96 uses 11 drivers...not because it needs all those drivers for home hi-fi duty, but because it has to play at 133 dB continuous (music power) output to full audiences in large auditoriums and outside venues--without boundary gain.  Danley very conservatively rates this loudspeaker at 101 dB/2.83 V into WHOLE space (no boundaries close by--as if elevated far above ground level outside). 

 

If that same loudspeaker were rated into half space, it would jump 6 dB in sensitivity rating, another 6 dB if in quarter space (e.g., wall/floor interface) and another 6 db in eighth space (full corner loading).  So it is 101 dB /1 m @2.83v elevated far above ground, and nearly 118 dB/1m @2.83v in a room corner.

 

The K-402-MEH needs to play at much less overall SPL than that.  It can use three drivers (a good 2" compression driver and two 15" woofers) instead of the one 1.4" compression driver, 6 compression midranges, and four 15" woofers of the SH-96.  If you need the MEH to play louder at the same input power, add drivers.  Of course, this isn't what I need at home, so for me, three drivers are more than "good enough".

 

Chris

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I think, for my alleged purposes, your three driver arrangement would be much more suitable, maybe bass-reflexing it would be an option to look into, once I get the time...

Most of that 'great tone' from the Classic Rock era relied on abuse of amplification and reproduction systems, and Danley's definitely engineering his stuff to avoid that.

 

Wish I would have had two pair of EV Sentry IV back then, but those days are gone.

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