Jump to content
The Klipsch Audio Community
Chris A

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

Recommended Posts

Second note to Chris A,

 

In my unhumble opinion you have never (or I missed it which is likely) explicitly showed your ports.  You have described them and I would agree there is enough there to get the idea, but a more explicit drawing from you would make many of my question even more unnecessary!  The pictures were not as illustrative as one might wish for. Don't get me wrong I am not complaining and KNOW you have supplied a great amount of information about this.  But for those of us without your engineering abilities we are not able to go from conceptualize to realize as easily as you can.

 

I look at DANLEY's ports which are long and slender - I figure the length gives one some wiggle room for the crossover.  That is why I am thinking of longer and narrower.

 

Since the CELESTION can go lower I wondered if one could take some of the load off of the woofers in the area where they are least effective.  Needless to say both drivers are at their least effective parts of their respective ranges.  Compromise is required and trying to find which direction is the best compromise.

 

I would never ask you to disassemble your speaker but it would have been instructive to see how you handled the ports on the woofer side.  I have assumed you went for a 45 degrees conical shape which is what I am planning to do.

 

Take care,

Share this post


Link to post
Share on other sites

By the way, the reason why I made the comments in the last post is to communicate to others (perhaps beside yourself) that are either currently working on or planning to work on K-402-MEHs.  It just isn't that complicated.  I don't want others to think that it is complicated.  It's not.

 

2 hours ago, rickmcinnis said:

...I wondered if one could take some of the load off of the woofers in the area where they are least effective...

Here is a raw output from the prototype K-402-MEH that I've used as my center channel loudspeaker since January 2016.  The fall-off in output above 450 Hz is due to the reflection wave from the throat of the horn (the returning acoustic energy that is emitted from the off-axis woofer ports that cancels the acoustic energy being emitted toward the mouth of the horn).  I'm struggling to understand what you mean by the above quoted text:

 

New Center - Woofers Only RAW No EQ.png

 

Note that there are two 15" woofers in the cabinet, and these were sized to provide plenty of capability to the bass response--even down to very low frequencies.  You can read the -3 dB point of the following SPL response plot (16.5 Hz) of the K-402-MEH in the center position (EQed flat), elevated above floor level by over a metre, back touching the front wall...as well as the phase response:

 

K-402-MEHwithDanley-StyleCrossoverFilters.jpg

 

Chris

  • Like 1

Share this post


Link to post
Share on other sites
3 hours ago, rickmcinnis said:

One has to find out for themselves.

Can I make a suggestion:  perhaps you can find out and then report the results.  You can include the response and harmonic distortion plots, too, and perhaps a picture of the amplifier innards with external capacitors.  I believe that your comments before you actually try it with your (admittedly esoteric) amplifier configuration are a bit like "making the sausage" instead of "tasting sausage".  If I'm not conversant with what you're currently doing (and why), then I'd also fear that most others are not following along, too.

 

It helps to keep things as simple as possible at first, then layer on the more complex cases later.  In that type of course of action, I'd also recommend also trying a more garden variety SS amplifier first that does not require such provisions (and issues).  KISS works really well, I've found.  After establishing a working baseline with run-of-the-mill configurations, then reporting on more esoteric component use (i.e., your First Watt SIT-1 amplifier that requires a very large capacitor on its output channels) afterwards.

 

3 hours ago, rickmcinnis said:

Still would like to know if you are using the first order slopes within the XILICA or only PEQs.

I've used it both ways.  Surprisingly, it doesn't make any difference in the output SPL/phase response, harmonic distortion, as well as the off-axis polars, etc. with the MEH design (which is not true with a multiple-horn loudspeaker like the Jubilees on either side).  The difference is in the acoustic summing that takes place within the horn/waveguide itself within the MEH.

 

3 hours ago, rickmcinnis said:

If I set the crossover higher (obviously) I could get a less extreme acoustic slope order and that is something I will try before I assemble the MEH.

Trades on the crossover point center frequency are okay.  I think you have yet to acknowledge that there isn't any audible difference if using Danley-style crossovers in an MEH.  There is no lobing, so increasing the  overlap of drivers in the "interference band" has no effect in the output sound quality or measured distortion.

 

3 hours ago, rickmcinnis said:

...There are lots of pieces!...

I find that there are very few pieces, actually, much fewer than trying to use multiple horns and passive crossovers.

 

3 hours ago, rickmcinnis said:

Since my temporary setup with the Edgar Seismics as lower midranges/mid bass are much happier with the 300 hz crossover it was good that the CELESTIONs allowed this.

I can see that--but I will recommend listening to those Celestion compression drivers at that lower crossover point.  My experience has not been good trying to use metal or ring radiator diaphragm (poly material) compression drivers of any make or type below ~400-450 Hz.  I find that it's easy to hear the difference during the upsweep measurements using REW.  The human hearing system can pick up very small differences in distortion levels under upsweep conditions.

 

3 hours ago, rickmcinnis said:

Getting those 18 inches JBLs to go higher up in frequency requires lots of boost.

Using 18 drivers above ~300 Hz will probably require phase plugs inside the horn-loaded cabinets in order to avoid driver-based cancellations due to the diameter of the cones themselves.

 

3 hours ago, rickmcinnis said:

I know you posted a raw response curve but i cannot find it.  Would you mind posting it again along with your current XILICA settings for the CRITES?  I would be very grateful, AGAIN!

I've posted the raw response of the K-402-MEH woofers, above. 

 

I'll have to look around for the Xilica settings that I used.  I experienced a hard drive failure this spring that wiped out my measurements from the past three years (which I apparently failed to back up to my backup external hard drive.  However, I did manage to back up all the music tracks that I demastered--yea! 

 

I've also got a USB port issue with the Xilica (yet again). I have to again replace the USB connector in the Xilica. (Good thing I bought a bag of those--I keep inadvertently running into the cable when taking measurements and damaging the cable and USB connector in the Xilica...bummer.)  I have to take the time to put the system offline to do that--and I find that I'm spending all my available time listening to the system since I made the latest crossover changes in April 2019.  I just finished demastering the first 6 The Alan Parsons Project albums over the past couple of days and the sound is too addictive to stop listening to them presently.  Note that I've found that those bass bin settings are so sensitive to room placement, etc. that they're not transferable to other installations, etc., so I don't bother to post them for that reason.

 

Chris

  • Like 1

Share this post


Link to post
Share on other sites

@rickmcinnis Did you make your ports 10 to 1 compression...if so I do not see how you could change the size now without patching. On mine I used a 45 degree router bit to chamfer the woofer side of the woofer mounting plate. We chamfered down to about 1/8".

 

Sent from my SM-T830 using Tapatalk

 

 

 

 

Share this post


Link to post
Share on other sites

I sure wish I could hear the Alan Parsons albums demastered...one of my favorite groups. Have you listened to the 5.1 versions too?

Sent from my SM-T830 using Tapatalk

Share this post


Link to post
Share on other sites

I can post these recently demastered albums (i.e., I redid my demastering from 5 years ago when I first was learning to demaster--in "whole cloth" fashion) on the Google drive account.  They're really nice to listen to now-especially since I got the system dialed in so much better in terms of phase response.

 

I don't have any of these albums on multichannel.  I checked the DR Database on the Eye in the Sky album, and it was more than 4 dB lower in dynamic range than the stereo versions that I've acquired over time (i.e.,  the first CD versions from the 1980s have significantly higher dynamic range).  So I'll probably pass on the multichannel version since 4 dB of dynamic range is a lot of difference.  I know that the Eye in the Sky multichannel disc won some sort of award last year.

 

Chris

  • Like 1

Share this post


Link to post
Share on other sites

Pm sent... I have Ammonia Ave, and Eye in the sky in 5.1. One of my Elvis Costello albums shocked me at the dynamics one night. I was just using my phone to measure SPL.

Sent from my SM-T830 using Tapatalk

Share this post


Link to post
Share on other sites
Posted (edited)

Chris A,

 

My horns have more pieces due to my configuration.  In addition I want to dampen and strengthen the horn so that means four panels for the top and bottoms.

 

Of course, it is not anywhere near as complicated as a corner horn - but then I would never attempt to build one of those.

 

I, too, have found no difference between using the first order slopes and not using them at all.  I appreciate your confirmation.  I just go with, in my temporary situation, with what works best.

 

I hope that I am only two weeks away from discarding the SEISMICs and having the K-402s working.  My comments about my using the SEISMIC are just for fun since it is most assuredly not a serious project.  Just to get me by - but it has been surprising how decent it is.  I have to have something to listen to so it was a relief that this was listenable.

 

Taking the CELESTIONs down to about 300 Hz with a first order and two PEQs allows 1.5% THD at 400 Hz where it is at its worst.  I will certainly try it with higher crossover points once assembled.

 

When i say the "load" off of the CRITES - I mean their need to go as high as yours are going - which is quite impressive.  The question is which driver sounds better in the octave below and above 500 Hz..  All the while I would not want to cut holes based upon a supposition which is why I posed the question to you to give me your thoughts.  I know you do not KNOW my situation but you certainly know what you are doing and you have done this so we are dependent on you and your knowledge gained from experience which is the best knowledge of all.

 

I know you are correct that I am making this to be far more complicated than it should but then I have two horns to cut into and I think this is what makes me overly cautious.  I know it would not be that hard to fix an error but I think I hate the thought of having to take the things apart. And times two.

 

When i get everything ready for assembly I will just cut holes in the horn.  In the interim, in preparation, one wonders about all sorts of things.  

 

If anyone wants a pair of SIESMICs they are free for the taking!  

 

 

Edited by rickmcinnis
stupid sentence

Share this post


Link to post
Share on other sites
Posted (edited)
On 8/21/2020 at 4:05 PM, NBPK402 said:

One of my Elvis Costello albums shocked me at the dynamics one night. I was just using my phone to measure SPL.

 

Which one?  I have listened to the 24/96 versions and they are all much better than the standard ones.  Speaking of the "classic era" from MY AIM IS TRUE to TRUST.  After that it got to the point the records were very uneven - a couple of great songs and the remainder McManus's throwaways.

 

My favorite EC is GET HAPPY which is probably the worst recording but it sounds very good in 24/96.  

 

As far as dynamics go - NEW LACE SLEEVES on TRUST is pretty impressive.

 

To add: NORTH is a very well recorded record and I have a soft spot for PAINTED FROM MEMORY.


 

 

Edited by rickmcinnis
addition
  • Like 1

Share this post


Link to post
Share on other sites
On 8/14/2020 at 8:29 PM, Chris A said:

Well, the answer may surprise you...

 

I run the natural response of the woofers and then compression driver, after flattening the SPL response of both sections individually.  Then I look at the natural crossing point of the two.  In the case of the BMS 4592ND, I believe that was 550-600 Hz. 

 

I use first-order crossover filters (effectively) to take out the 90 degree lead of the woofers to the compression driver.  Voila! Time alignment.  When I did this (and stopped trying to tell the compression driver and the woofers where to cross using the crossover and PEQs), all the performance measurements got better and it sounded better.  I simply trim off the response of drivers that is not needed using attenuating PEQs in order to keep the crossover interference band SPL response flat. 

 

Chris

'THE FORMULA' for JUBILEE tuning's : (May I add, after TUNING the room first !)

 

…run the natural response of the woofers and then compression driver, after flattening the SPL response of both sections individually .

 

...take a look at the natural crossing point of the two. 

 

use first-order crossover filters (effectively) to take out the 90 degree lead of the woofers to the compression driver.

      

                                         Voila! = Time alignment. 

 

stop trying to tell the compression driver and the woofers where to cross using the crossover and PEQs.

  

trim off the response of drivers that is not needed using attenuating PEQs in order to keep the crossover interference band SPL response flat. 

 

Thank You, brotha CHRIS !

  • Like 1

Share this post


Link to post
Share on other sites
20 hours ago, rickmcinnis said:

I know you are correct that I am making this to be far more complicated than it should but then I have two horns to cut into and I think this is what makes me overly cautious.  I know it would not be that hard to fix an error but I think I hate the thought of having to take the things apart. And times two

Well, this thread serves two purposes (at least): the first is to document the experiences of building and dialing in/measuring the MEHs, and the second is to convey to others considering building this amazing sounding loudspeaker--that it isn't really as difficult to build and dial in (using a DSP crossover) as a typical box-type loudspeaker. 

 

So my comments above on the difficulties encountered were to clarify that those that are considering their own MEHs that it is really simple--assuming that you own a $95 calibration microphone and a computer.  I dare say that if a pair of these were put into the same room as other loudspeakers (and I'm not going to "go there" by identifying any others), that the K-402-MEHs would, well, let's just say..."do really well". 

 

______________________________________________________

 

I would hope that Klipsch (consumer division) itself would try out this configuration and listen in a home hi-fi--sized listening room. I think the configuration would blow away any competitors in the market.  And at the prices that Klipsch pays its supplier of horns (probably significantly less than $290 per horn), this is a no-brainer for those looking for Jubilee sound quality (at least) in a package that is 1/3 the volume and 1/4 the cost (and price to the consumer).  The price of good DSP crossovers that can do the job is now at $200 (USD) for a pair of MEHs, and the net performance of them after dialing in would eclipse the in-room performance of anything that Klipsch currently produces exclusively for the home hi-fi market (without exception).

 

The K-402-MEH works well elevated above floor in half space, i.e., touching the wall behind it.  It also picks up 15-18 dB of low bass gain if placed in a room corner...like a Jubilee or a Khorn.  So it has the flexibility of placement that the other two loudspeakers really don't have (unless large false corners or bass bin wings are added and taking up a great deal of space).

 

I've found that for my center channel needs, the K-402-MEH also serves as its own subwoofer due to the two 15" woofers enclosed, and has consistent polars all the way up and down the audible band, and flat phase response (within ±90 degrees) from 100 Hz to 20 kHz.  I've posted those in-room REW measurements on this forum. This is a good deal.

 

Chris

  • Like 1

Share this post


Link to post
Share on other sites

Chris A,

 

Meant to have given my condolences for your hard drive failure.  That is a great loss to you and all of us here.

 

Hope there is a forensic guy who can get most of it back for you.

 

It would be great if KLIPSCH would offer the MEH but then I could not afford it and I would probably have plenty of quibbles with how they handled certain aspects.

 

All of the thinking (?) that goes into these projects is good for us in many ways.

 

Had to mow the yard yesterday evening.  Tonight I am going to see how low a crossover I can get with an acoustic first order slope. More of an academic exercise than anything.  I know one thing to do that will require a very surprisingly high frequency first order setting within the XILICA for my current settings within the temporary setup..  Already I am using 1100 hertz to keep from having massive reductions in level in the 700 to 2500 Hz range.

 

One's instinct is that a first order acoustic slope would be best but I do not doubt once everything is connected together that will not be the case.  Only reason my curiosity is aroused is whether there could be a good reason to bring the ports a littel closer to the mouth.

 

The way I see it  - getting the ports closer to the throat is good for the woofer's high frequency extension but that getting the ports further away from throat allows less interference between woofers and CD.   I know I am NOT going to get it right but luckily this is a forgiving arrangement - but might as well try to get it as close to DANLEY right as possible.  Without PEQ we would be out of luck!  

 

Will post results tomorrow.

 

Will punch holes in one horn this weekend.  Have one set of cabinets almost finished.  Need to get them installed to have room to perform the finishing on the second set.

 

Sine my ports will be much closer to the suspension than in your situation I am thinking longer narrower ports than yours are called for.  I wonder if the longer port aloows for more fudging since they will then be in a wider range of the frequencies of where the horn is working.?  Uh, oh, there I go again!

 

One last thing I have assumed you removed the extra thick gasket from the CRITES woofer.  I have removed them completely to use Mortite.  I love MORTITE. Get a little less volume - actually surprisingly less.

 

Thanks and take care,

 

 

  • Like 1

Share this post


Link to post
Share on other sites

 

 

 

 

   

One last thing I have assumed you removed the extra thick gasket from the CRITES woofer.  I have removed them completely to use Mortite.  I love MORTITE. Get a little less volume - actually surprisingly less.

 

[

 

Do you get any slapping with the woofers being closer to the mounting pad? I was thinking of actually adding a little space qith my Kappa 15Cs. How much clearance would the Mortite give me?

 

Sent from my SM-T830 using Tapatalk

 

 

 

 

 

Share this post


Link to post
Share on other sites
2 hours ago, rickmcinnis said:

Meant to have given my condolences for your hard drive failure.  That is a great loss to you and all of us here.

Well, it's a loss, but probably not a great one.  I lost my measurements from April 2017 to April of this year.  That includes the detailed measurements on my Danley SH-50 and the ESS AMT-1 drivers.  But I still own all the loudspeakers, etc., so once I repair my Xilica USB port connector, I'll be back in business again to capture them again.  That HD drive is dead, however.  I'm thinking the value of the measurements lost aren't worth the cost of forensically retrieving the data via HD recovery service (which is what it would require since the lead-in track is trashed).

 

I need to try to double stack my AMT-1s on the surround Belles (since I'm not using my Khorn bass bins/AMT-1 in the much smaller bedroom/office (13.5' x 12') that I use for storage.  I think that angling the second AMT-1 upwards (i.e., leaning it backwards) to approximate an inverted J-shaped line array will give better coverage plus a little shading of the vertical coverage to the AMT-1s.  I'm thinking that I'll need another miniDSP 2x4 HD in order to control the shading and delay properly.  I'll advise on that project when I get some round tuits.

 

2 hours ago, rickmcinnis said:

It would be great if KLIPSCH would offer the MEH but then I could not afford it and I would probably have plenty of quibbles with how they handled certain aspects.

Can't talk about this subject here--it's bad manners, I believe. I'm working on a solution.

 

2 hours ago, rickmcinnis said:

All of the thinking (?) that goes into these projects is good for us in many ways.

You're right.

 

2 hours ago, rickmcinnis said:

Only reason my curiosity is aroused is whether there could be a good reason to bring the ports a little closer to the mouth.

2 hours ago, rickmcinnis said:

Sine my ports will be much closer to the suspension than in your situation I am thinking longer narrower ports than yours are called for.  I wonder if the longer port aloows for more fudging since they will then be in a wider range of the frequencies of where the horn is working.?  Uh, oh, there I go again!

You can do this.  Just note the effects of this on woofer off-axis loading ("cone tilt").  The off-axis polars will be affected at a higher frequency. Long, thin off-axis ports will also elongate the off-axis polar coverage effects in frequency.  (Those long ports on the Danley Synergies that you've talked about are for those using four woofers per loudspeaker rather than two woofers like the present K-402-MEh configuration.  They did that because each woofer only has one port in the SH-96, etc.)  Also, using four woofers is probably a fair bit of overkill for home hi-fi needs.

 

2 hours ago, rickmcinnis said:

The way I see it  - getting the ports closer to the throat is good for the woofer's high frequency extension but that getting the ports further away from throat allows less interference between woofers and CD.

Yes. The off-axis ports need to be in the right place, and be the right size and shape.  I found that Hornresp provided enough information in terms of woofer on-axis SPL response to place them in the right place.  Experimentally, it worked out.

 

If you move the woofers too close to the throat, you'll have to make their port sizes too small, and you'll seriously affect the efficiency of them if those ports are too undersized.

 

2 hours ago, rickmcinnis said:

Without PEQ we would be out of luck!  

Based on my (now lost) SH-50 measurements using REW, the K-402-MEH woofers have a much flatter response than the SH-50, and the midranges in the SH-50 are almost not necessary--probably they're only there because Danley needed them to hold the phase growth down using passive crossovers.  If he was using DSP crossovers only and was using the loudspeakers at home hi-fi levels (rather than PA levels), I think he would have avoided the midranges altogether.  The midrange drivers only cover just over an octave of bandwidth in the SH-50--hardly worth the effort to put them in.  Danley pays a great deal of attention to phase response.  So do I, now, after hearing the difference.  This is the difference between the Unity horns from Sound Physics Labs, and the Synergy horns from DSL--flat phase response.  And the listening difference is startling.

 

2 hours ago, rickmcinnis said:

One last thing I have assumed you removed the extra thick gasket from the CRITES woofer.

No, I didn't.  Again, I think you're obsessing over "mouse meat" issues.  If you're using 18" woofers, you'll probably need to create a frustum of a cone phase plug to reduce the self-cancellations due to the diameter of the woofer cone itself.

 

Chris

Share this post


Link to post
Share on other sites

Chris A,

 

I am only using 18 inches woofers that are in the EDGAR SEISMICS as a temporary setup while finishing my CHRIS A K402 MEH.

 

I am using two of the same CRITES woofers you specified for each channel.  As soon as these things are finished the SEISMICS will be put in the garage for someone to take away and if not one wantes to take them away they will be sewn into pieces and thrown away.

 

I removed those gaskets and tested it against my baffle and the woofers would have to move a long way to contact the baffle.  With corrugated paper I would think if allowed to move further than that they would be seriously distorting.  

 

I know I will have to take the things apart at least once to correct for incorrect assumptions.  Hope this is not one of them though it would be an easy one to fix.

 

NBPK402 - I doubt your woofers have this double gasket since CRITES says this is something they do differently for use in some replacement situation.

 

Chris A - I must admit to being a devotee of Colin Chapman and racing car designers who do not pick and choose where you lighten a part - you lighten every part as much as you can - which is how I look at this project.  Not that I disagree with you that one can tilt at windmills but always looking for the cumulative effect.  So every piece is given scrutiny and one tries to make it as good as they can.  

 

Of course, you have real experience with this but I must admit I had assumed you had removed some of that gasket if not all of it.  

 

From the beginning I have been concerned about the higher frequency response of the woofers so all of that folklore kept running through my head.  Your raw graph is all the more surprising if those measurements were made with those double gaskets used.

 

This weekend I will make holes in the side of my left channel K402s.

 

Thanks Chris A for the caution about those long SINGLE PORT holes.  That does change everything.  I suspect my ports will look as close to yours as i can make them.  

 

I had the best intentions of showing you the raw response of those CELESTION CDs today.  I have been listening to them with the response leveled off to make the top octave flat.  The amount of attenuation required should give one a tremendous amount of dynamic range from 600 to 4000 hz.

 

One last conceptual question - Do you think there is any value in giving the drivers a 6 dB per octave slope?  Not too hard to get one octave below 350 hx with a slow slope and I guess if you used 500 hz as the nominal crossover point you could get a 6 dB per octave slope for almost two octaves.  Here i am speaking about measurements i made one meter away from the face of the horn.

 

What is interesting and I know you do not have much interest in my measuring at the chair but I find it interesting.  One thing is the slope becomes much more steep  - almost an acoustic fifth order Butterworth slope while maintaining the same crossover frequency but with a hump at the crossover frequency before falling off - so almost getting a Chebychev .  looking slope. Knowing as little as I do about this kind of thing I find that very interesting.  Also when both speakers are playing together the slopes become sharper still - again, at the chair, and my chair is about 2.5 meters away from the front of the horns.  

Share this post


Link to post
Share on other sites
On 8/28/2020 at 4:22 PM, rickmcinnis said:

I suspect my ports will look as close to yours as i can make them. 

If you want to move them closer to the throat to raise the throat-bounce frequency(ies), that's probably a reasonable thing to do.   I don't believe that they need to be reduced in size if you're only moving them a half inch or so closer (i.e., from 5" from the leading edage of the off-axis port to the horn throat entrance...to ~4.5" for the same data (i.e., the plural of datum), thus raising theoretical the first bounce frequency from ~680 Hz to ~755 Hz, etc. 

 

On 8/28/2020 at 4:22 PM, rickmcinnis said:

Of course, you have real experience with this but I must admit I had assumed you had removed some of that gasket if not all of it.

I just found a picture--it's a single gasket:

 

1378148364_IMG_3003cropforgasketview.thumb.jpg.eceb7c0fa785848f7a836e1d03ded2a0.jpg

 

On 8/28/2020 at 4:22 PM, rickmcinnis said:

Do you think there is any value in giving the drivers a 6 dB per octave slope?

I use an additional out-of-band attenuating PEQ or perhaps two to cut the out-of-band driver levels to the compression driver (high pass), and I use additional attenuating PEQs on the first two woofer response peaks above the effective crossover frequency (the crossover frequency is about 550 Hz currently).  I have attenuating PEQs at ~1300 and 2200-2300 Hz, wherever they show up.  I use enough gain on those attenuating PEQs to keep the bass channel roll-off curve pretty much constant above 550 Hz.  (I don't remember what I used.)

 

On 8/28/2020 at 4:22 PM, rickmcinnis said:

What is interesting and I know you do not have much interest in my measuring at the chair but I find it interesting.  One thing is the slope becomes much more steep  - almost an acoustic fifth order Butterworth slope while maintaining the same crossover frequency but with a hump at the crossover frequency before falling off - so almost getting a Chebychev-looking slope. Knowing as little as I do about this kind of thing I find that very interesting.  Also when both speakers are playing together the slopes become sharper still - again, at the chair, and my chair is about 2.5 meters away from the front of the horns.  

The problem with measuring further back is that the non-minimum phase in-room reflections clutter the measurements.  You can't do anything about those (and shouldn't) unless you're into "head in a vise" listening rooms.  I'm not...

 

If you look at Toole's book, he'll show flat on-axis response at 1-m or closer, but a tilted response (downward as frequency increases) if measured further away from the loudspeaker.  This is the "listening window"...as he puts it.  I see this using Dirac vs. REW measurements (i.e., Dirac measurements taken at the listener's positions, and REW measurements at 1m).

 

You can stick your head into the aperture of the horn and still hear a balanced presentation (as Danley has claimed several times in the past).  The effective minimum listening distance for the MEHs happens to be "zero" because of that phenomenon. I can detect no lobing.

 

Chris

  • Like 2

Share this post


Link to post
Share on other sites

Rick if still have and want to get rid of the 18's I will take them. I can come anytime but would like to see the Meh's with the ports cut. Thanks, send me a PM if you like.

Share this post


Link to post
Share on other sites

A report on the cutting of the ports on the first horn.

 

First thing - is the first time you do anything don't be surprised if you mess it up.

 

I sure did with my first hole.  I was so excited to see if I could do it I made the hole 1/2 inch away from where it was supposed to be.  What an idiot.  Now I am having to fill in the area with layers of JB WELD.  Not hard to fix just time consuming.

 

Second set was a little better but still requires so JB WELD.  I am using a Forstner bit.  I found with this hole that trying to go all fo the way through is NOT a good idea.  Too much heat and the material that was removed is very hot and sticky and will stick back to the horn.  Good thing for grinders!

 

The third hole - I was getting much better by this point and by the fourth I had got it.  Now to hope I remember what I learned when i do the second horn.

 

So what I learned - a Forstner bit can do a great job - I got the DIABLO brand at Home Depot.

 

Significant heat will be generated.  Stop drilling at intervals to let the heat subside and to move the scrap out of the way.  Wish I could remember the word for that stuff!

 

If you do remove the bit from the piece, and this is NOT a bad idea be extremely sure you have replaced it into the hole correctly.  This is what I did not do well on my second hole.  It is easier to get it wrong than you might think.

 

I found a jig saw blade using a set of VISE GRIPS as a handle makes a much betterr tool to cut away the triangle that one of those hack saw blade holders.  The hack saw blade is much too limp.

 

The good thing is that you cannot ruin the horn unless you do something completely consciously destructive so no need to fear cutting into them.  Not to say I did not fear cutting into them all of the months I have owned them.  Nothing like DOING IT to get over unfounded fears.

 

I made my holes with a two inches bit with the distance between enough to give the needed area.  My ports are at the opposing wall.  I am confident with the JB WELD I can add material to the horn, this along with good old MORTITE will result in a good deal.

 

After making your first hole - I made my first hole INSIDE the horn - but after seeing what happens on the outside wall I made a new guide to allow making the rest of the holes from the outside which is vastly easier to do.  There is no way to make the hole closest to the throat without an angled head drill.  I just made my first hole closest to the mouth and used that as a guide.

 

So getting closer to hearing them - would almost be there if I had not been such a dumbass!

 

I have a removable back for my cabinets.  The back will rest against a 3;.4 inches flange made with 2 x 4's.  I read over the weekend that Frank van Alstine, always a source of good sense and good ideas recommended modelling clay that never dries for such a duty.  Have some of that on order.  I think it will work as well as MORTITE but not be as difficult to separate the panels as I hope it is NOWHERE near as sticky as MORTITE.  I will know in a few days.

 

I will be using the recycled rubber floor matting on the outside side panels of the boxes.  I will use this same material on the inside of the back and thought I would try the GREEN GLUE along with a minimal number of screws to attach it.

 

Chris A there is no question the K402s sound great with your head inside them - it is amazing that this is so.  i used to be one who sat as far from my speakers as i could and now I realize that was telling me everything I needed to know about my loudspeakers.  I figure with the MEHs as close as you can will be the best and be able to maintain as much of that phase linearity as possible at the listening chair.

 

Better get back to work ...

 

 

Share this post


Link to post
Share on other sites

Wreote the above at work and had to stop.

 

One thing about my chair response is that my high frequency response increases.  Now this could be since I am not measuring the K402 in its center - a littel bit below - they are sitting up really high in the air and my copper tube is not long enough and it is not that important at this point.  In MEH configuration I will be able to measure at the center.  The SEISMIC cabinets are 35 inches tall and, as you know the K-402 are mounted vertically.  Tall imposing thing!

 

I believe that with the MEH the response at one meter will  not be anyhwere near as diminished as it has been with a speaker with drivers VERY far apart - voice coils easily thrity inches away from each other.

 

I have not posted anything of real usefulness because there is no way to post an REW file here - they are too large and my pictures are useless.  I tried to email them to you, but again, they are too large.  I hope I am missing something and there is a way to do this.

 

One thing I found while measuring at 1 meter which goes along with what you have expanded upon to us from Danley's suggestion (!) to never use a filter with a man's name.  I greatly appreciate his male chauvinism in this respect.  I can just see more craven folk having to insert the obligatory "man or woman's name" in its place. But, what I found was that with no first order filter I got the expected for the greatest part of the range from 100 to 20,000 Hz a straight line at 0 degrees.

 

Then I used a 100 hz first order slope and zero degrees phase became a much larger number.  I went up 100 Hz at a time till 600 hz and by then the line remained just as straight as it was, from memory, but close to -1000 degrees.  When i would use the PEQs to get the response I wanted using no added filter, as you have stated, there is no phase growth to speak of.  So my feeling is that we should not use the first order filters in the XILICA unless one has no other choice.  

 

Will be interesting to see what is required with the woofers.  Maybe that shift will be useful?  Only measuring will tell.

 

I know what filters I need will be different from yours - I am not interested in copying them but It would be interesting to see your approach.  I think I am approaching this as you have since I have tried to use your advice along with the fact I had been trying this many months ago on a whim but with my old system, not the kooky one with the Seismics which actually have some phase linearity the old system did not display the goodness.  It shows me in hindsight that many of the things we have done traditionally were bandaids for hopelessly flawed systems which is how I would describe my system when it contained to horrendous EDGAR 75 Hz horn.

 

What Danley said in the old DIYAudio post was the purloined letter.  It was right there for all to see but from what I have read Chris A was the only person to see the beauty of it and put it into practice and of course bring it to our attention with his measurements.

 

Thanks again, Chris A.

 

Now to work on those holes.  By the 2way if I said I was going to make them smaller I made an error.  Mine will be as close to 1/10 Sd as possible.  I will err on being a little bit large instead of the other way around.

 

Take care,

 

Edited by rick mcinnis
correction
  • Like 1

Share this post


Link to post
Share on other sites

You should be able to find some freeware online to resize your pics to a smaller size so that you can upload. There are also online websites that you can upload your images too, and then it resizes to uour desire. Then you just download the new file and upload here.

Sent from my SM-T830 using Tapatalk

Share this post


Link to post
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.
Note: Your post will require moderator approval before it will be visible.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.


×
×
  • Create New...