How to dissect polar patterns and frequency responses for horns.

[Chris A]

 

[Chris A]

Personally, I don't recommend any "oblate spheroid" throated horn.  As far as I can tell, all of them have issues with either on-axis frequency response (relative to off-axis), or the off-axis polars have to be given up.  Roy has talked about this in private communications...and so has its "inventor" (rather its proponent - Earl Geddes).  Geddes downplays this by stating that he only listens to his loudspeakers off-axis.  If you're talking about horns, why give up anything when you can basically have it all in the K-402?

[DizRotus]

40 minutes ago, Chris A said:

. . . .  If you're talking about horns, why give up anything when you can basically have it all in the K-402?

 

My next "last speakers" would be K-402 based MEHs.   I've heard Claude's, @ClaudeJ1; they're amazing.  In the unlikely event I move to a place with more space for my man cave, that would be considered.  As far as I know, such systems aren't permitted in most nursing homes . . . my next stop.

[jazzmessengers]

@Chris A what is the lower limit that you run your TAD drivers at and what sort of a crossover slope does it use to the Jubilee bass bins?

[Droogne]

@Chris A man... I just realised you are the legend who build that custom K-402 center synergy... Read that post several times months back!

[Chris A]

I cross the TADs with the bass bins at 425 Hz, 48 dB/octave. 

 

You really have to pay special attention to the HF delay when you do this:  it doubles the required delay required in order to make the step response look right when you go from 24 to 48 dB/octave.  You can see the added delay of the lower frequency channel when using steeper slopes.

 

I'm planning to try the Harsch crossover (the presentation by Harsch himself in French is translated by me to PowerPoint below) when I get my measurement rig out again on the Jubs.  It preserves the step response and the proverbial "square wave response" a little better than L-R steep slope, above.

 

Phase Distortions and Time Effects of Audio Systems (Harsch).pptx

 

Chris

[Chris A]

7 minutes ago, Droogne said:

I just realised you are the legend

There's only only legend on this web site...and his initials are PWK.   But yes, the K-402-MEH is the fruit of one of my nightmares...  I like it a lot. 

 

I've been working on getting more built for like 2 years now (...my goodness, has it been that long?).  I'm on the last step before trying out the fabrication of the horns in one piece.  The horn looks a lot like a K-402 but with four extra holes in it from the front side, and a bunch of other stuff on the back side.  It's not a K-402, but I bet the polar plots look very similar...if you catch my drift.

 

Chris

[jazzmessengers]

1 hour ago, Droogne said:

I believe a lot of comparison were made between the Seos 24 and the K-402, but not with the (I think more recent) Seos 30. Not sure. Pair of black painted Seos30 with good drivers (HF200 from faital) would only cost me 1050eu. Still hoping to find a dealer to know the price for the K-402 (incl. all the shipping etc) so I know what I'm up against! To be clear: I'm 100% planning on buying the K-402, but depending on cost I might go for an intermediate. And before you say "that's gonna cost you more in the end", well that's true. But, I also have LaScalas for the rear and side (and center), and if the 2-way is something I like I could move the Seos to the rear/side when I decide to go for the K-402. Seos would be easier to have as a center too due to it's height (10cm). But who knows what I can come up with (rising the couches so the tv height isnt an issue anymore)(K-402 mounted above the tv? with bassbin beneath it, or to the sides?? )(synergy K-402? Not sure I have the skills to pull that off)(Seos as a center between K-402 rears, not sure about timbre matching, but who knows how good it turns out if I'd use the same driver as the K-402 + EQ)(insert random idea)

 

 

 

Personally I would only do a setup where the K-402 sits above the bass bin or horn to get the most coherent point source image.

[Droogne]

3 minutes ago, Chris A said:

There's only only legend on this web site...and his initials are PWK.   But yes, the K-402-MEH is the fruit of one of my nightmares...  I like it a lot. 

 

I've been working on getting more built for like 2 years now (...my goodness, has it been that long?).  I'm on the last step before trying out the fabrication of the horns in one piece.  The horn looks a lot like a K-402 but with four extra holes in it from the front side, and a bunch of other stuff on the back side.  It's not a K-402, but I bet the polar plots look very similar...if you catch my drift.

 

Chris

Are there some back side pictures? Or is that a trademark secret?  Synergy horns do look quite spectacular as center speakers! They have everything on would need (good match with LCR and massively reduced height). Would it be possible with a K55/K77 combo? Or would that require a lot of extensive calculating? Planning on selling the LaScala II I already have and spend the money on a custom center, but I'm really not convinced of any design I have come across.. They are all too high or just dont perform well. Was gonna try out a sort of center using the K55/k77 I have with the woofers from the Heresy I I have (as in, decouple the K55 and K77 in the Heresies, lay them on their side so they are as low as possible and then use those 2 cabinets with the other K55/K77 combo on top of it). If it performs well I was planning on building a double 12" cabinet with some Eminence woofers. 

[Droogne]

15 minutes ago, jazzmessengers said:

 

Personally I would only do a setup where the K-402 sits above the bass bin or horn to get the most coherent point source image.

haha I know! I know those are garbage ideas soundwise, but wouldnt it be "cool" to have a full jubilee setup with the tv "wall mounted" to the front of the Jub bassbin. Problem is that would only allow like a 22" TV which is not even a real tv size . Plus the tv would be placed way too low. 

 

Again I have been thinking about all sorts of ridiculous ideas (MF/HF horns placed between 2 flanking LaScala bins etc) but placing a 65" tv on a speaker, while keeping the center of the tv at an eyesight height is near impossible.

 

EDIT: the true solution to my problem is building my couch riser near-field subwoofer! I'm waiting on the project till I have actually moved in (my rentlord is complete a**hole who is already 3 months late on our contract. Have been building my whole setup since June but as I live in temporary setup with 0 place for any decent size speaker I'm restricted to using my headphone only.. my 65" OLED, Chorus II, LaScala II etc have all been sitting in boxes for over 5 months which gives me all the time in the world to look up more ways to upgrade, without actually having my setup in place. I know.. not the best way to go about it but oh well.) 

[Droogne]

19 minutes ago, Chris A said:

There's only only legend on this web site...and his initials are PWK.   But yes, the K-402-MEH is the fruit of one of my nightmares...  I like it a lot. 

 

PS you shouldnt be so humble  PWK might be thé legend, doesnt take way any bit of the awesomeness of your build!

[Chris A]

16 minutes ago, Droogne said:

Are there some back side pictures?

Here's one of the prototype using a modified K-402 horn with MDF woofer mounting pads, a K-69-A compression driver (that I had on the shelf), and two Crites 15" cast frame woofers:

 

 

19 minutes ago, Droogne said:

They have everything on would need (good match with LCR and massively reduced height). Would it be possible with a K55/K77 combo? Or would that require a lot of extensive calculating?

The calculations are really easy: 1/4 wavelength axial distance from the on-axis throat entrance to the off-axis ports at their crossover frequency.  For the K-55/K-77 handover at 4 kHz (as low as I'd take the K-77 tweeter), that would be about 0.85 inches.  The throat of the horn would also have to reduced farther from 2 inches to the diameter of the K-77 throat. 

 

In other words, it's probably easier to use coaxial drivers, like the 8" coaxial from Faital Pro that Danley uses on their SH-69 for instance if you're trying to do a 3-way MEH design.  Then the tweeter/midrange ports could be built into the same horn adapter with separate midrange and tweeter ports in the adapter to the big horn.  This makes the tweeter/midrange driver interference issues disappear.  The woofers and through off-axis ports would stay where they are on the big horn.

 

You could also do a 3-way and just use a BMS 4592ND coaxial driver with dual ring diaphragms, then the problem would disappear altogether.  It would look just like above, except the apex compression driver would have two sets of electrical leads instead of one.

 

Chris

[Droogne]

16 minutes ago, Chris A said:

Here's one of the prototype using a modified K-402 horn with MDF woofer mounting pads, a K-69-A compression driver (that I had on the shelf), and two Crites 15" cast frame woofers:

 

 

The calculations are really easy: 1/4 wavelength axial distance from the on-axis throat entrance to the off-axis ports at their crossover frequency. 

 

Hmm might be easier to try out a synergy with the 2-way HF200 I was gonna try out. That way I could do something like your build. Would it work with PH2380 horn, or is this one to small to support low frequencies? 

[ClaudeJ1]

3 hours ago, Chris A said:

Personally, I don't recommend any "oblate spheroid" throated horn.  As far as I can tell, all of them have issues with either on-axis frequency response (relative to off-axis), or the off-axis polars have to be given up.  Roy has talked about this in private communications...and so has its "inventor" (rather its proponent - Earl Geddes).  Geddes downplays this by stating that he only listens to his loudspeakers off-axis.  If you're talking about horns, why give up anything when you can basically have it all in the K-402?

I agree wholeheartedly with this, which is why I still have K-402's with TADs as my Reference horns as well as Danley Synergy horns (kept 6 after owning, literally, two DOZEN in the past 4 years). Also, I should mention that I'm only about 30 minutes from Geddes' house, but I have never been there. When I was still a kid, I heard him speak at a Detroit AES meeting the year before I bought Khorns, back in 1976,  when he was still at Ford Motor. He was showing all kinds of curves for different alignment but I was turned off when I asked him which ones he had BUILT and he said NONE. Recently, I Emailed him about his Waveguides, and have watched his You Tube presentation about room modes, recorded in his living room. He's a brilliant mathematician type, and has a great, scientific understanding of transducer behavior, but his arrogant air is at least double the intensity of his IQ, which is forgivable, I guess.

[Chris A]

His contributions to the state of the art don't seem add up to the all the attitude, I'd agree.  But he has some ideas (including ones he's patented) that actually do stimulate other ideas that I found are more useful, I've found.   [I also might have to deal with him in the future, so I'll be nice and just leave it at that...]

[Chris A]

1 hour ago, Droogne said:

Would it work with PH2380 horn, or is this one too small to support low frequencies? 

That horn has a slot in it that discourages its use above 4 kHz (i.e., a 2" slot spacing).  I'd recommend something like this horn instead if the K-402 isn't in your solution space:

 

https://www.ebay.com/itm/11-x-17-ABS-2-Bolt-On-Long-Throw-Horn-90-x-40-For-Many-2-Exit-Driver-/331676072699

 

Chris

[ClaudeJ1]

33 minutes ago, Chris A said:

His contributions to the state of the art don't seem add up to the all the attitude, I'd agree.  But he has some ideas (including ones he's patented) that actually do stimulate other ideas that I found are more useful, I've found.   [I also might have to deal with him in the future, so I'll be nice and just leave it at that...]

No doubt. We should all be nice. I don't think I was being otherwise in mine and others' impressions. He has made many positive contributions to Audio, no question. The other opinions and observations that seem negative are pretty minor league in comparison to all the positive science created and other contributions. I'm a fan of his work also, which I left out.

[Droogne]

4 minutes ago, Chris A said:

That horn has a slot in it that discourages its use above 4 kHz (i.e., a 2" slot spacing).  I'd recommend something like this horn instead if the K-402 isn't in your solution space:

 

https://www.ebay.com/itm/11-x-17-ABS-2-Bolt-On-Long-Throw-Horn-90-x-40-For-Many-2-Exit-Driver-/331676072699

 

Chris

It might be good to try out a synergy horn first DIY with something cheap like this  Shipping is 2,5 times the actual price though .. Would something from P-Audio (those are very cheap over here)(http://www.paudiothailand.com/pac/index.cfm/products/high-frequency-horns/) or from Autotech be suitable for this little try-out project? 

 

PS, back to the subject. Just out of curiosity (I'm becoming more and more convinced that I wont be spending anything more than like 200-300 on horns/pair as a temporary replacement for the K-402). Can you explain the pattern control of the bass bins some more? How do you have to look at their pattern control? Does it have to go down to their lower crossover, or upper? And how do you match it with the HF/MF horn? Pattern control down to their crossover is enough right? 

[ClaudeJ1]

2 minutes ago, Droogne said:

pattern control of the bass bins some more

An oxymoron at best considering the wavelengths of bass.

[Droogne]

7 minutes ago, ClaudeJ1 said:

An oxymoron at best considering the wavelengths of bass.

:s , I have been trying to not trip and fall (aka making stupid remarks) but I'm talking about things I know literally nothing about  let me rephrase! What does Chris mean with:

 

"If the bass bin polars match the horn/compression driver polars in each axis (horizontally, vertically), then the loudspeaker will sound very good.  If there is a mismatch in polars at the crossover frequency then it will sound not as good in-room."