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Chris A

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

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On 6/9/2020 at 5:49 PM, rick mcinnis said:

For anyone wanting 4 x 8 Baltic birch in the Atlanta area  - SUWANEE LUMBER is Suwanee - close to Buford - is selling the sheets for $57.00. The price was so good I thought they were confused but it is the good stuff.

 

They don't list it on their website. I will have to give a call.

 @Dave A  Dave, where do you get your BB? I am probably in between... have to check the maps.

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21 hours ago, Negatron said:

@rick mcinnis How far off the floor are you running them as vertical...mine are about 13" off the floor.

 

At the moment in my rudimentary temporary system they are 35 inches off of the floor since I have them on top of my Edgar SEISMICS which are being used, believe it or not, from 40 Hz to 460 Hz.  The EDGAR 75 Hz horns I had used for years and had driven me crazy for years my Atlanta audio friend Greg Monfort said why not use those - the JBL 2242 is more like a midrange than a bass driver.  I initially laughed and then a year later, once this project had begun, I though WHY NOT?  So I gave them a try and that is how bad those 75 hz horns were - a great feeling of relief was experienced.  Now there are facing the listening chair and have had the back chamber reduced substantially so they really are a 50 hz horn and not a 50 hz horn with a closed box for the first octave.  They sounded much better with the smaller back chamber and with plenty of EQ, though not as much as you might suspect, they blend in the K402s surprisingly well.

 

Last night I toed them in more and they disappeared.  No question - vertical works better in my room.

 

When I get the enclosures made for both MEH and the RYTHMIKs they will be 24 to 25 inches off of the floor which I think will be fine.

 

21 hours ago, Negatron said:

 

 

 

 

 

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Marvel,

 

I had to call them to get any information.

 

They're very nice people.  

 

Their main business is fancy woods which have market prices like Red Snapper!  I figure this is why they do all pricing on the telephone.

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Chris A,

 

Forgive me for not looking back - but did you ever try the TAD 4002 in your MEH?

 

Since cutting holes in those horns will be a week or so away I am wanting to make sure I am thinking correctly.

 

I know I have asked this before but you will have to forgive me since my Mother was born in Missouri.

 

The driver you are using in the MEH has no internal throat as far as I can see. I have never held it so I am not sure.  There is no question the TAD 4002 has the snout which is approximately about the same as the internal throat of the JBL 2441.

 

It seems you are in disagreement with everyone else about FROM where the ports are located.  All of the folks at DIYAudio say that the port distance is from the phase plug and you say where the phase plug is located has no bearing - that the entrance to the horn is all that matters.

 

Was wondering if you had measured the MEH with the TAD installed?  I see measurements for the K691 and the BMS - both of which do not have any internal "horn" so not comparable to the TAD or my JBLs.

 

If I understand your previous response you made it sound like this does not make any difference but this is at odds with what everyone says at DIYAudio - not that that makes it right but I do not want to cut holes in those horns that might need to be filled.

 

There is a minimum of two inches from phase plug to exit of the JBL and I would imagine the TAD to be about the same.

 

I need your help as you well know.

 

THANKS and take care,

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On 6/10/2020 at 9:03 AM, DizRotus said:

 

That is a good price.  If I send you the money will you buy a couple of sheets and mail them to Michigan.  On second thought, that won’t work.

Wish I could!

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Here is a photograph of a plot of the JBL 2441s w/TRUEXTENT diaphragms at my listening chair with the mic 90 degrees.

 

You will have to believe me that I intended the vertical divisions to show they are 2 dB.  12 dB smoothing is used.

 

I find this method of measuring and adjusting to have a better correlation with what I hear.  When I adjust at one meter it sounds terrible at the chair in my room.

 

 

IMG_0034[1].JPG

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Here is a picture to allay all concerns of whether I actually have these things!

 

Sitting atop one of my Edgar SESIMIC subwoofers turned into lower midrange horns by the xilica.  Amazing how much better this gigantic ungainly thing sounds compared to Edgar's last horn the 75 Hz horn.  Obviously forward facing with the restrictor plate removed and the back chamber about 1/3 the volume - maybe even less than that.

 

The 402's look like some kind of mutant MARTIN LOGAN.

 

The idea is to have the 402 MEH on top of a box housing a RYTHMIK woofer - will put the 402 about 23 to 26 inches above the floor instead of 39 inches at the moment.

 

 

IMG_0032[1].JPG

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On 6/15/2020 at 1:31 PM, Marvel said:

 

They don't list it on their website. I will have to give a call.

 @Dave A  Dave, where do you get your BB? I am probably in between... have to check the maps.

You are close enough to make the trip. Nashville Plywood and last time I bought a month or so ago I got 25mm 4' x 8' for $77 a sheet. You better have a big husky guy to help you move it though. 60" x 60" x 25mm was $54 last time I bought and they have it from 6mm up to I think one size above 25mm. If they are selling that cheap in Atlanta I wonder if prices are headed down here. I thought $77 was a real deal.

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Just ordered a 3/4" BB 5x5 sheet cut in half from Makerstock for $60 and $15 shipping to my home.  It was a bit difficult to place the order as their automated shipping calculator kept saying that the 60x30 or 30x30 pieces I was choosing couldn't be shipped to my address but C.S. Amy helped me out.   Will report how that works out...

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On 6/16/2020 at 9:10 AM, rickmcinnis said:

Here is a photograph of a plot of the JBL 2441s w/TRUEXTENT diaphragms at my listening chair with the mic 90 degrees.

It's better than no measurement at all. 

 

Can you post the reverberation time plot for that same measurement, and perhaps the Filtered IR plot (with Schroeder Integral)?

 

Chris

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There is no question your process is scientific and mine is pragmatic. Needless to say I look at this project as way to learn more about these things you know and I do not.

 

Wanted to show that the 2441 with the Be diaphragm can get to 20kHz.  There is not an exciting phase plot from eleven feet away.  With the whole system playing it is a stair step shaped thing that drops like a rock above 1000 hz - writing from memory.

 

I will go take some more measurements and post the filtered IR.  I never save any of the stuff since changes are fairly constant.

 

Take care,

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10 hours ago, rick mcinnis said:

There is no question your process is scientific and mine is pragmatic.

Actually, I think it's closer to the other way around.  Articles have been written as well as "room correction" firmware programs implemented on the subject of recognizing and subtracting out non-minimum phase room distortions, and introducing the resulting "house curves" that then become necessary to introduce into the process when taking the measurements farther away in room than 1 m--that are simply not needed if taking the measurements at 1 m and correcting to flat response. Toole also talks about this.

 

Chris

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I now realize I do not know how to do the reverberation time plot.

 

Here are a few more bad photos.  I should attach the REW file and will tomorrow.

 

Must admit I have no idea how to interpret the IR.  

IMG_0037[1]__1592491405_73.82.152.46.jpg

IMG_0046[1]__1592491360_73.82.152.46.jpg

IMG_0048[1]__1592491314_73.82.152.46.jpg

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On 6/3/2020 at 1:47 PM, Delicious2 said:

Setup2:

The very same K-402 and TAD-4002 samples mounted in a KPT-305 box (securing the full mouth flange at all 12 factory drilled mounting points) 

 

I have a picture frame of quarter inch thick wood bolted to the K-402 mouth flange. Its purpose is decorative, but maybe it also adds a little bit of stiffness. The effectiveness would probably be relative to the SPLs in the room.

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Posted (edited)

Hope it is OK to show some progress pictures.

 

If I have misunderstood the purpose of this thread and what I am posting is not what is intended please let me know.

 

Got the baffles made - the long side of the horn has much less "length" than the side Chris A used - turns out to be much tighter than I expected.

 

The baffle is the width of the CRITES woofer.  

 

To come in close contact with the horn required some table saw gymnastics.  One ends up with an area that is, maybe, 3/8 inches thick at the mouth so I made pieces to fit aside the woofer.

 

A length of square tubing will be used to clamp the woofer down on the side near the mouth.

 

I tried to take a picture of how close the piece fits to the horn but the photograph doesn't tell you anything.  It fits very closely - I think some kind of material of about 1/8 of an inch would make it very dead and fill remaining gaps.

 

The baffle board with the lines is with the horn shape and the driver circumference.  I am hoping this means that I can get ports away from the suspension.  I figure I am going to place the ports as close to the mouth as I can.

 

By the way the MORTITE blobs are very effective at quelling the hollow sound when tapped.  Obviously this will not be ised with the baffles in place!  Though I will use this on "top" and "bottom".

 

Baffles will be affixed  by two bolts at the throat and bolts and two turnbuckle at the mouth.  the excess length of the baffle will be used to attach the baffle to the box.

img_0060__1593448865_73.82.152.46.jpg

img_0059__1593448798_73.82.152.46.jpg

img_0062__1593448730_73.82.152.46.jpg

img_0061__1593448583_73.82.152.46.jpg

Edited by rickmcinnis
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As far as I'm concerned you've got the point of this thread completely Rick!  Have to admit I don't get yet what you're doing with the "tablesaw gymnastics" but I appreciate that you're trying to evolve the design beyond Chris' initial build and paying close attention to fit and vibration control.  Keep the pics coming!

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I should have my center channel cabinet tomorrow. I also have some dynamat type material I am thinking of using to damp the cabinet. I will post up pics of the MEH as soon as I install the drivers, horn. and wire it.

Sent from my SM-G935V using Tapatalk

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Got the turnbuckles and bolts to attach the panels and found I ordered turnbuckles that are one-half inch too long.  Suitable ones to arrive Wednesday from McMASTER CARR.

 

Hope they will accept the too long ones in return.

 

About to get serious about assembling the cabinet.

 

The pieces are cut.  I am going for a bit of overkill since one would rather go too far than not far enough - the front frame is 2.25 inches thick - 3 layers of 3/4 inch plywood - back panel two widths.

 

Tried some 1/8 inch natural rubber matting for sealing the baffle to the horn - too thick - so I have ordered some  0.30 inch material which should be about right.

 

The baffles against the horn sides - even without the tension from the turnbuckles - seriously deadens the walls. Even without the rubber - I figure the rubber will make them as dead as practicable.

 

Making pieces for the top and bottom of the horn which will be padded with MORTITE and then pressed against the horn - hoping I can use the "rigging" to make this easy - I figure a piece of wood perpendicular to the "top pieces" will make this easy using the bolt and the turnbuckle as one side of the clamp.  I have found the MORTITE, by itself, does a great job of damping, but there is the danger (not likely but who wants to take the chance?) that it could fall off.  Plus I figure some gentle pressure would only make it better.

 

Another thing - I would have liked to epoxy the baffle to the horn but then I would never be able to remove the CDs.  The woofer almost touches the throat flange and the baffle is up against the bolt for the CD.

 

The table saw gymnastics refers to chamfering the mouth edge to match the flare of the horn.

 

I had to run the blade high and at a angle (different heights and different angles to achieve this.  Don't think the saw liked this that much; keeping the board straight in two dimensions was the gymnastics part.  It is not perfect but close enough that the gap left after using the rubber sheet will be easily filled with (yes, you guessed it) MORTITE.   The fellows at ADVENT said the MORTITE sealer was part of the ADVENT loudspeaker sound.  At age twenty I was following the Pied Piper of audio - Harry Pearson - so I had to have Double ADVENTS.  Of course, I could not afford anything better.

 

I continue to be astonished (I use the word seriously) at how good the K-402 sounds.  Simply incredible compared to my INLOW horns which made it impossible to return the Edgar's salad bowls which I used for over ten years. 

 

So now the only problem is deciding where to put the holes.  I worry that i am missing something because i usually am.  Chris A says 5 inches from the screen.  I am not sure if screen was used in a general sense (always 5 inches from the screen) or just an easy way to illustrate his installation.

 

Here is the BMS driver

087157d661.jpg

The screen is right up front - but on the JBL, and I suspect the TAD 4002, if similar to the 4001, the screen is 2.75 inches behind the front of the driver.  Using my memory for the 4001s since I sold them years ago.  It was over two inches, though.

 

Should I, also, have my ports 5 inches from the screen or from the front of the driver?  This would place them almost at the throat of the horn.  Though this position would put the ports in a more center of the cone position.  The vertical mounting does force the ports to be very close to the suspension if they are placed further "down" axially.

 

I read over the Unity patent again and there is the suggestion that the area where the ports are located should be the same area as the ports.  This would not be the case if I used the screen as a reference point.  Of course, 5 inches from the mouth does.

 

So hoping for a little MORE reassurance before I make the holes.  I know I keep going on about this but I want it to be right

 

Would a Forstner bit work on the ABS?  

 

I will post a picture of the baffles tightly coupled to the horn Thursday.

 

Thanks for the help and encouragement.

 

 

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Today I got my center channel cabinet. I had to abort the side wood pieces that the woofer pads were mounted to, and drill mounting holes through the horn to the woofer pads. I am using silicone between the horn and the woofer pads plus the screws. I grabbed the horn driver to see if there was any play and there is zero(I can literallylift the rear of the cabinet off the ground via the horn driver with no slop). I am still going to line thebhorn and cabinet with a dynamat style material with one thin layer and 1 real thick layer to also help provide additional sealing for the cabinet.

My wife liked the cabinet, but when the big black horn sticks out she doesnt... I might need to try the wood grain film that another klipsch k402 user used. I need to find out where to get it and if I can get it in Mahagony. 012c25bdf7d2bc77031cb5856fbbcc8d.jpg

 

Sent from my SM-T830 using Tapatalk

 

 

 

 

 

 

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14 hours ago, Negatron said:

My wife liked the cabinet, but when the big black horn sticks out she doesnt... I might need to try the wood grain film that another klipsch k402 user used. I need to find out where to get it and if I can get it in Mahagony.

 

Sent you a PM.

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