15" Woofer Choice for K-402 based MEH

Part Express lists the Delta 15A 8 ohm at 9.56 cubic feet VAS. Not as much as the 11.35 Kappa 15A 8 ohm but more than the Kappa 15A cast frame at 5.92 cubic feet. Interesting that you heard a big difference. I'll be using the same Klipsch KPT-305 boxes Chris used. I believe he stated the design is relatively insensitive to back chamber size. Not sure if that's only with the Crites woofers he used which appear to have even higher VAS in the spec listings I found
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Glad to hear CRITES is still around. Last time I tried to go to the website it looked like they were giving up.

I followed Chris A's lead and built a pair of these using the CRITES woofers.

I do not think there is a best way to make the holes in the K402s but I found mistakes are easily corrected using JB WELD and sheets of card stock.

If you go too far tape some card stock on one side of the horn and fill with JB WELD. When it dries you can sand it to the shape you desire.

I went too far wih two of my holes and this did the job.

One does get nervous cutting into those expensive horns - though they are worth every penny. No need to fret - they are fixable though it does take time for the JB WELD to fully dry and one application is never enough.

I made my holes right at the corners of the horn. I then used LOTS of JB WELD to make a larger plane for the woofer plate to be set against.

On the side of the plate facing the woofers I made a very large transition area to the holes with the edge of the hole very thin. AS close to a knife edge as baltic birch would allow.

Obviously the transition area is limited to the area facing the center of the woofer.

This advice was given by the great GM to whom I am ALMOST as grateful as I am to Chris A for loudspeaker of a qualiuty I never thought I would own.
Thanks for that Rick! Very encouraging to know mistakes can be corrected. Did you listen/measure before and after any of those mods beyond what Chris had done? Specifically before and after cutting the transition areas? I don't think he did much along these lines judging by the pics showing his MEH and the thickness of the ports.

Have any pics of your "larger plane for the woofer plate to set against"? and what did you use for a plate/mount? (Edit: oh you said "Baltic Birch" how thick?) How did you attach the plate/mount to the horn?
Wondering if Acoustic Elegance really would give lower distortion and better articulation? I get down to 30 hz, so I’m not looking to get lower, just looking to get tighter and more articulate sound.
FYI/FWIW, etc., way back when, this was one of my primary goals, winding up with the Altec 515B and the 416A a 'ballpark' 2nd best with both having ~the same Fs, both with very high Vas, though the 515's was ~35.5% lower and the 515 having a ~74%! lower Qts, so implies to the first approximation that the stiffer, lighter the cone, the lower the Vas, Qts, the more 'snap', 'articulation', 'heart attack fast' transients, etc., the better and in lieu of the AlNiCo VS ferrite motors; today my choice would be Nd, which can go down to at least 0.1 Qt (if an option) Vs the AlNiCo's (presumably) ~0.17 lower limit.
This advice was given by the great GM to whom I am ALMOST as grateful as I am to Chris A for loudspeaker of a quality I never thought I would own.
A note at this juncture: thanking Tom Danley--and to a similar degree, Roy Delgado (Klipsch) is probably more on target. My prototype MEH was based on their contributions::

Tom, for his amazing MEH designs that are now known as "Synergy Horns", and

Roy, for his surprisingly good full-range K-402 horn with nearly constant directivity and extremely neutral sound.

As far as the quality statement that Rick mentioned: with the above two individuals noted, I can now concur with his comment about sound quality. Rick, I also know that you've done a great deal of work dialing yours in and using quality drivers.

For those that haven't heard a large, dialed-in, full-range MEH like the Danley SH-96 or the K-402-MEH in a home-sized listening room, I can only say that you have a treat waiting for you--a very surprising one at that.

Chris A
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Of course, Chris A is correct and no slights were intended.

I was mainly addressing the construction aspects. Danley and Delgado did not help me build the loudspeaker though they would never exist without the great contributions of them both. They are the firmament on which the project rests.

Without Chris A's contributions I would have never dreamed of doing this. He laid it out such that one knew the direction to go in. I was not aware of the K402 at all for that matter before his posts here which led me to that Klipsch site that does not seem to appreciate his efforts, sadly. I assume the posts are still there and those must be fully digested before proceeding.

I added what little I knew as some accountingish refinements - but the basics are Chris A's recommendations.

MA04 - that is all I can keep in my head - I will see if I kept some photographs of how I assembled mine,.

They are larger than Chris A's. I built my own cabinets since the cabinet he used was not available when I got my horns.

I used 3/4 inch baltic birch for everything. Multiple layers for the back and the baffle - what little baffle there is.

I was concernd about the sealing of the woofer plate to the horn. I have my horns oriented vertically since horizontal would have been awkward in my room. Also, when I look at photographs of the giant ALTEC speakers with the horn vertically oriented I figured I could not go wrong. I did listen to them as horns before making this decision and they did sound better in my room this way.

There is more curvature on this side of the horn which required shaping the woofer plate to fit flush.

I made the speaker so it would be simple to take apart - I did not glue the woofer plate to the horn. I used heavy duty hardware - turnbuckles to hold both plates to the horn. I like the idea of the pressure exerted against the walls of the horn.

From the start I knew i would use my RYTHMIK subwoofers with them. I have four of them in the room - two of them act as the base for the MEHs. I made my own cabinet to fit under the gigantic satellites.

My room is long - I did not think the internal woofers would load the room to my satisfaction. And they do not. The REW measured distortion for the MEH vs the RYTHMIK is a no brainer. I do not know how accurate these distortion measurements are. In addition there is the suckout around 100 hz that cannot be cured with EQ in a sonically attractive way. Luckily the RYTHMIKs will go that high and with four of them the cone excursion is minute. This is the weak point of the system but one is not made aware of this shortcoming when listening. Needless to say I would have preferred a lower crossover point for the transition.

I wish a different woofer would change this but I doubt it.

I would change out the woofers if someone knew of one that was better. Due to what GM wrote I would like to try a ND woofer.

One thing to remember in choosing a woofer is you do not have all of the room in the world. Sixteen inch ALTEC woofers will not fit.

The CRITES are probably a very good compromise considering cost, size and performance. But like any audio kook I would love to know of a better solution!
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Eminence Delta 8ohm wired in Parallel (red trace) beats out the Klipsch K-33 4ohm also wired in parallel (blue trace) in the 40-80Hz range by a bit in my new K402 MEH.
I would change out the woofers if someone knew of one that was better. Due to what GM wrote I would like to try a ND woofer.

One thing to remember in choosing a woofer is you do not have all of the room in the world. Sixteen inch ALTEC woofers will not fit.
Yeah, where space is an issue and extreme eff. isn't required, then at a glance the lowly/~dirt cheap 8" MCM 55-2421 in multiples (4 = 15") seems a viable option.
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Eminence Delta 8ohm wired in Parallel (red trace) beats out the Klipsch K-33 4ohm also wired in parallel (blue trace) in the 40-80Hz range by a bit in my new K402 MEH.

I have also started building my MEH, making the k-402 horn out of birch plywood. Considering I live in Europe there would be a fair amount of shipping cost and clearance to get two pairs of 15 inch Crites woofers at my front door.

The Eminence Delta are locally available here, but I'm wondering if there are any drawbacks compared the Crites?
Because the FS is 40hz on the Delta and 26hz for the cw2615..
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The Crites woofers are not critical. When I chose them for the prototype, they were simply an alternative to the K-33 woofer, which at the time I wasn't sure that I could get in future MEH builds and at a reasonable price. I recommend just plugging in your candidate woofer T/S parameters into Hornresp to see the relative simulated power responses. Note that the real on-axis SPL response that I got from the woofers/horn in quarter and eighth space loading was really different than the sim'ed power response I used at the time (with possibly an error in input data, IIRC). First the woofer input screen, then the approximate TAD 4002 compression driver input screen (two input screens are necessary for a two-way MEH within Hornresp).



and the two woofer power output screen simulation :


Here is the actual on-axis SPL response measured at 1 m in quarter space (back touching a wall):


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There is also the issue of choosing a nominally 8ohm woofer (such as Eminence Delta) over a 4ohm (Crites). Chris was directing me towards 8ohm choices when I was building my MEHs and he could run out exactly why. Something to do with running the 2 in parallel rather than series and ending up with a nominally 4ohm load on your amp vs 2ohm.
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Yes, that's right, Mark. That slipped my mind. Thanks.

Wiring two 15" woofers at 8 ohms impedance in parallel gets you ~4 ohms net resistance, nicer for the bass amplifier channels to drive at lower average voltages. I currently drive my Crites in series (8 ohms net impedance).

Old-ish thread I know. Just FYI, I have a customer that built these k402-meh and purchased some Celestion ftr15-3070E from me. He said the bass response was night and day better. I just messaged him as I remember he had some measurements. If I get them I'll post them. If memory serves, he ws using an Eminence N314X but was debating the Celestion Axi2050. I'm a dealer for them all. I do have more of those Celestion woofers available if interested. Plug them in to the program and see how what it spits out. I'll have a few of the K402 arriving in a couple weeks also, which will be up for grabs if anyone is debating this project. This is what got me going back down this rabbit hole... I'm a hopeless SpeakerAddict ;-)
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