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

[NBPK402]

Hi
 
I was wondering what you refer to in regard to wiring between your two woofers and the Icepower 125asx2BTL?
 
 
So I take it, that you had your two woofers wired in series and then driven BTL.
 
I don´t know how well you are into your Icepower-amp, so excuse me if i tell you something you already know. I have attached the manual for the Icepower 125asx2.
 
On page 9 there are some Power Specifications, but it doesn´t seem to indicate, that there should be much difference in output-power whether driven with two channels SE and 4 ohm or one channel BTL and 8 ohm!?
 
An other thing that I noticed when studying the manual is, that there is a pin on the signal connector from the DSP-board to the ICEPOWER-board that says "BTL Sync". Page 6. When it is activated it synchronizes the switching-frequencies of the two amp-channels. Page 12. I don´t know how much DIY your amps are, but maybe that is an issue when driven in BTL without synchronization? On my MiniDSP plateamps, the software/dsp-board takes care of that.
 
 
(I own six of the MiniDSP PWR-ICE-125 plate-amps, and have studied the the manual for the Icepower  125asx2, to figure out how I can substitute the Icepower with a small class A amp. There is a manual for the Icepower 125asx2 on the MiniDSP homepage.)
 
Steffen
 
ICEpower125ASX2_Datasheet_1_9 (3).pdf

I was running in BTL mode driving 2 4ohm woofers which was presenting a 8ohm load to the amp (I never drove them in SE mode...I only use XLRs). I added a 2nd amp and rewired my woofers so each woofer was now powered by a single amp in BTL mode. Now if you look at my REW graph you will see how much my bass has increased by adding an additional amp and powering each woofer individually. I am tninking it has to do with the impedance load, and power output the amp is seeing by driving 2 4 ohm woofers versus 2 amps driving a 4ohm load each. I have the BTL pin as per the manual too.

I find it strange in the way they are showing their power output too. I think they flipped the 8ohm and 4ohm spec on the one spot as they show way more power into 8ohm than 4ohm. The amp is spec'd at only 70w into 8ohms at one spec and 200 at another. For 120v it is spec'd at 370w into 4ohm BTL...with no rating at all at 8ohm. I am assuming 8ohm would be 1/2 that and since it would be driving 2 speakers...wouldn't it be giving 1/2 of that 8ohm to each woofer?

Sent from my SM-T830 using Tapatalk

[NBPK402]

Good news, I have the bass back up to where it was and if you look at the was before we added the 2nd amp... I def got a nice improvement in bass by powering each woofer by its own Icepower amp...also it appears the large peak and dip when i used 4" of Roxul all around instead of 2" on the side, floor and behind the mic actually caused the difference. 

[tweakin]

On 5/13/2020 at 6:58 AM, Chris A said:

By the way, the SH-96 horn is 26.5x45 inches and I assume about 17 inches deep (25 inches for the entire loudspeaker box).  I did a little fudging within Bill Waslo's Synergy Calc spreadsheet to approximate the outside dimensions of a dual-flare (straight sided Danley Synergy style) horn that would fit into an approximate box of the same dimensions without the mouth flange of the K-402, which you will see below.  (Note that I haven't built this horn or tested it yet.)

 

 

 

 

 

 

 

Chris

Hello. I don't have and can't really get k402.  Is this what you think is the best option?  Is it worth going even lower than 200hz with a bigger horn?  would be using the 2 15s and 2" compression driver Thanks 

 

I'm very familiar with sh50 and setting up MEH speakers. As well the principles of how they work and what makes them magical. I love what you have done on this full range topic, thanks for that.

[Supersteff]

Hi Tweakin

 

7 hours ago, tweakin said:

Is it worth going even lower than 200hz with a bigger horn?

 

I did ask Chris the same question some time ago in this thread, and Chris did answer it back then. You have to go back and find it your self, I have lost track of where it is, its in the last third I guess.

 

I have decided to build my horns about 53 inches wide, as that is as big as I can accommodate in my living-room. It´s actually about where Chris estimates the (meaningful) limit to be, 60 inches I think he mentioned. Meaningful in respect to your/most living-rooms Schröder-frequency. Directivity-control makes sense as long as the reflections in the room behave like billiard balls, and that is the case above Schröder-frequency, below that frequency room modes (standing waves) are dominating. That is how I understood Chris in regard to size.

 

8 hours ago, tweakin said:

Is this what you think is the best option?

 

I have followed this for some time now, and there doesn´t seem to be a commercially available horn alternative to the K402, so building a horn based on Bill Waslo´s spreadsheet is the second best option as I see it.

 

I have decided to build my horns in two sections. The primary horn (first expansion) with all the drivers, and a second section (second expansion) for the outer flare/second flare. In that way I can get my horns through the doors in my house, and it will be less heavy to transport! And I can experiment in steps, so that I can start with straight (second) flares and later build som tractrix-like flares. 

 

I hope that helps.

 

Steffen

[NBPK402]

On 11/12/2021 at 2:06 AM, Supersteff said:

Hi Tweakin

 

 

I did ask Chris the same question some time ago in this thread, and Chris did answer it back then. You have to go back and find it your self, I have lost track of where it is, its in the last third I guess.

 

I have decided to build my horns about 53 inches wide, as that is as big as I can accommodate in my living-room. It´s actually about where Chris estimates the (meaningful) limit to be, 60 inches I think he mentioned. Meaningful in respect to your/most living-rooms Schröder-frequency. Directivity-control makes sense as long as the reflections in the room behave like billiard balls, and that is the case above Schröder-frequency, below that frequency room modes (standing waves) are dominating. That is how I understood Chris in regard to size.

 

 

I have followed this for some time now, and there doesn´t seem to be a commercially available horn alternative to the K402, so building a horn based on Bill Waslo´s spreadsheet is the second best option as I see it.

 

I have decided to build my horns in two sections. The primary horn (first expansion) with all the drivers, and a second section (second expansion) for the outer flare/second flare. In that way I can get my horns through the doors in my house, and it will be less heavy to transport! And I can experiment in steps, so that I can start with straight (second) flares and later build som tractrix-like flares. 

 

I hope that helps.

 

Steffen

How do you plan on attaching the flare... I ask this because I am thinking of extending mine to give me the flare all the way to the stock horns flat front outside edge. The only think I could think of was to make a picture frame and route the inside to match the flare, but then where and how do I attach it temporarily? 

[Supersteff]

Hi Ron

 

Sorry, did not sea your post until now.

 

I must admit that I do not have a finished plan for the attachment of the second flare yet, and I am still far from building a horn. I am stil in the planning and preparation, trying to figure out where to start.

 

But if I do understand your question right, you want to extend the tractrix-curve of the second flare all the way out to 90 degrees, and by so extending the whole horn.

 

I think the idea makes sense

On 12/30/2021 at 6:50 PM, NBPK402 said:

to make a picture frame and route the inside to match the flare

You could make two frames, an outer one extending the tractrix-curve, and an other one screwed on from the back, clamping the K402 horn between them? Does that make sense?

 

Happy new year 🙂

 

Steffen

[NBPK402]

On 1/1/2022 at 9:39 AM, Supersteff said:

Hi Ron

 

Sorry, did not sea your post until now.

 

I must admit that I do not have a finished plan for the attachment of the second flare yet, and I am still far from building a horn. I am stil in the planning and preparation, trying to figure out where to start.

 

But if I do understand your question right, you want to extend the tractrix-curve of the second flare all the way out to 90 degrees, and by so extending the whole horn.

 

I think the idea makes sense

You could make two frames, an outer one extending the tractrix-curve, and an other one screwed on from the back, clamping the K402 horn between them? Does that make sense?

 

Happy new year 🙂

 

Steffen

That is a good idea!

[NBPK402]

.deleted

[rickmcinnis]

I do not come around often.  Looks like Chris A has left this project behind which is a shame.

 

What I have found since my last post:

 

Getting the Xilica Solara has continued to be very educational since you can do anything you want with it.  I had tried using a tremendous number of PEQs just to hear what happens and I got a good result but I think it is better when you trim it down from excess.  The thing is you learn something from using too many.

 

I have found that one should measure both speakers together below four hundred Hertz.  You can adjust each speaker separately but get a pretty miserable result when you play them together; if a good result is having the least amount of phase change as possible from the listening chair.

 

You will see what looks horrible when you measure each separately - each channel below 400 Hz is using the same values of EQ so you know each speaker is putting out the same amount of energy.  What you are seeing is the room.  But when combined you can see the correction works.  This is confirmed by listening.  I have gone back and forth numerous times between using this approach and adjusting each channel and the sound of the "stereo" approach is dramatically better every time.  This cannot be ascribed to expectation bias since my expectations were for it to sound worse.

 

I continue to think it is quite impossible to use these as full range speakers unless you only listen to small scale stuff at low volumes if there is any low bass in the recording at all.

 

One can only pump so much air through those ports and I never forget Romy reminding people trying to get a horn to work above and below its cutoff is a BAD thing.  Imagine trying to EQ the 402 between 400 and 2000 Hz.  No better than to try to fill in that area where the horn cuts off and where you are hearing the box loading.  This was the problem with the EDGAR Seismic woofers.  The discontinuity is obvious and not conducive to high quality audio.

 

They have to be the largest mini monitors ever made but the soundfield they throw is beyond the capabilities of any mini monitor.

 

Alone they are not low distortion devices for the bottom two octaves.  As the horn unloads around 150 Hz the distortion rises rather dramatically as one descends.

 

Below 150 Hz I am using four of the RYHTMIK 15 inches woofers in the corners of my room.  I have found something very interesting.  One must play around with the phase of each woofer to find the smoothest phase before proceeding with EQ.  It iwll not be what you expect it to be.  One must measure with all woofers on.  I have found with my setup that the four woofers create their own low pass crossover.  I am using no low pass crossover at all.  I am suing a a few PEQs to refine my slope.  Phase "rises" as one gets to 20 hz but flattens out from there to 100 Hz where it takes a 180 degrees dip - nothing unusual there.

 

With four of these the cones barely move even with low frequency material and the room is loaded immediately.  And when the signal goes to zero the cones follow suit.

 

No named crossover slopes anywhere in this system.

 

I have a big spike in group delay around 240 Hz which I cannot remove. Yet.  I think it is a room anomaly.

 

At the chair my phase change is zero from 1k to 20KHz.

 

It is simplicity to get flat phase with the mic close to the speaker.  You can get that with about any EQ settings.  I figure the real key is getting the best you can from the chair - yes, it is a sweet spot but one can sit to either side and enjoy music.  Sitting behind is even better.  For me audio is a singular pursuit since I know no one who enjoys listening to music. But it has always been that way.

 

The better one has the system the more obvious it is that there is a distinct change in sound when the polarity is switched.  Who knows what is right but I know there is usually a setting which sounds best to me.  The more difference there is the closer I figure I have come to something good.

 

The Celestion drivers are EQed individually.  I find the left channel requires about 0.14 mS delay in the left channel for the above mentioned phase change - flat group delay from 1K to 10K.

 

I kept going back and forth between using lots of boost for the top two octaves or tremendous attenuation for the 100 to 2000 Hz range.  I continue to think a balance is best between the two.  With 20+ dB attenuation the filters become unpredictable.  I am using lots of boost at 20K with very low Q for a broad boost.

 

I do not doubt this is what gives me the very flat group delay at the chair since the HF becomes directional but that is a good thing.  I would like to hear Delgado's "phase plug" which looks nothing like any phase plug I have ever seen - a miniature ALTEC sectoral horn - which would give better dispersion but at what cost only an audition would answer.

 

One has to assume the key to getting this quality is the controlled dispersion of the K402.  The sense of space surrounding each element being reproduced is psychedelic.  It is unlike anything I have ever heard.  The speakers always sounded really good but as I have learned more about how to use the EQ the sound has progressed to the almost unbelievable.

 

I was reading about the gymnastics B&O preformed with their $100,000 dollars speaker to control dispersion and to good effect from what I have read.  I bet doing it the way Delgado and Klipsch did it with the 402 would be superior.

 

I wonder if the 300,000 dollars Wilson Chronosynclastics or whatever outlandish name they have can do what these things do for a fraction of the cost.  Of course those things must have some charming qualities for those with lots of money to spend and a great need for big expensive boxes to adorn their listening room.

 

When one has to pump so much energy into those little boxes it is no wonder exotic materials are needed - along with that crossover/group delay generator - low sensitivity high power amplifier audio is the wrong path for music in my unhumble opinion.

 

Wish there were more people giving these things a try but I guess DIY is losing steam these days.

 

Basically another love letter to the K402 and to Chris A's transmogrification of it into something even more extraordinary.

 

 

 

[tomas2012]

Greetings,

Are there detailed build plans for the K-402 MEH? 

 

Cheers! 🙂

[Marvel]

Welcome tomas!

 

You can start at the beginning of these 60 plus pages. Chris no longer posts on here, but still has an account and may answer if you message him.

 

He's moved to the diyaudio forums, in the multiway section. His username is Cask05.