K-402 horn - worth the effort to DIY?

[Invidiosulus]

I assume my LS II measures closely to these, at least the bass bin. After switching in the Kappa 15C for the K33’s, the K55 was bumped up 2.6 dB (calculated).
This was done to more closely match woofer and the MWHL and DE120 at crossover frequency.
Retuned the low pass on sub up to 80Hz and LS is running full range.
Best they have sounded. So far. Plus are really a 105dB efficient speaker now. At 1000 Hz.
I do not notice the hump at 150 Hz. The crossover may be taming that some.
Listen at a good distance and all sound is reflected. Cannot see the speakers. This may tame the high Q spike at 150Hz.
The ported LS does not look very good, compared to stock. Even less compared to Kappa 15C.

Looking back over my notes, or lack thereof, I’m not actually sure if I had any EQ applied on the ported LS measurement.

However, I would keep in mind that it is an actual measurement vs simulation.

Either way, I need to grab my calibrated mic from the studio and run some more curves at the house.

 

[Invidiosulus]

This is a screenshot of the settings offered by Roy Delgado for using a K-510 on top of the LS 1 or 2 bass bins, based on measurements in the anchors chamber at Klipsch.
Of note is the -7dB Q=8 PEQ at 148Hz.

 

[Dave MacKay]

Mine were 'Corner' sims, here's 'Corner' vs 'Wall' K33:

View attachment 3718414

K33 (gray) Kappa 15C (black): The trend is there, get better upper range, lose some bass.
View attachment 3718416

Where does the horn quit? The lowest crossing of Acoustical Impedance and Acoustical Reactance:

View attachment 3718418

Thank you. This is very informative.

From the graphs you’ve shown it looks like the Kappa 15C doesn’t offer enough to justify replacing a K-33.

I appreciate you explaining how we know the frequency at which the La Scala bass stops acting as a horn.

 

[mboxler]

I'm eyeing this...

It's Troy's opinion that the horn mouth angle doesn't need to exceed 71 degrees to minimize reflections back down the horn.

Sabourin Front Horn DIY Plans

The Sabourin Horn is a front horn offering ease of construction for the DIY enthusiast. By purchasing these plans you'll automatically receive by email the zipped file containing all the PDF drawings required to construct the horn. These plans include seven different size variations included a...

josephcrowe.com

 

[mboxler]

I'm eyeing this...

It's Troy's opinion that the horn mouth angle doesn't need to exceed 71 degrees to minimize reflections back down the horn.

Sabourin Front Horn DIY Plans

The Sabourin Horn is a front horn offering ease of construction for the DIY enthusiast. By purchasing these plans you'll automatically receive by email the zipped file containing all the PDF drawings required to construct the horn. These plans include seven different size variations included a...

josephcrowe.com

I decided to purchase these plans to play with. After loading it into Fusion 360, I discovered it was in dozens of pieces. After breaking those pieces into surfaces, I ended up with dozens of surface pieces. I was able to stitch the pieces I needed for the horn only, added curves and an CD adapter. I shrunk the horn down to a 14.5" by 14.5" mouth and a 1.4" throat. This a what I came up with so far.



I've been trying to learn AKABAK to test horns, and this is what I got when simulating the polars



The full-size version may be impractical to print, but...

Many thanks to @DirtyErnie for his help. I probably would have given up on this otherwise.

 

[FastlaneDave]

How big is the full size horn?

 

[mboxler]

How big is the full size horn?

500mm square

 

[DLStryker]

Speaking of the 402.... can someone direct me to where ClaudeJ1 is active? I would like to finish a conversation he and I were having on the K-402 before he parted ways with Audiokarma.

 

[Gigantic]

if you really want to see him talk about how great he is, he occasionally posts at DIY Audio & Audio Asylum in the High Efficiency subform.

 

[FastlaneDave]

New project, approximately 60X40 CD style 2" horn 19.5' X12.5' mouth.

Simulated horizontal polars suggest reasonable CD behavior through much of the intended passband.
Predicted acoustic cutoff is roughly in the low 300Hz region. I am hoping for a usable frequency down to 600Hz.

 

[DirtyErnie]

Dave,
What defines 'usable' for you?

 

[FastlaneDave]

Mike Boxler was good enought to run an AKABAK simulation of the horn geometry for me. This simulation shows the predicted horizontal directivity behavior.

 

[FastlaneDave]

Dave,
What defines 'usable' for you?

"Useable" in this context, it generally means the horn is providing adequate acoustic loading and reasonably controlled behavior at the crossover frequency.

The frequency I am shooting for is 600Hz, though that may be reaching for the stars considering my minmal experience with CD designs.