Håper det er greit at jeg spammer tråden din litt Hornlyd, siden det er her mye av hornpraten foregår for tiden.
det lukter både trau og K-402 og 2384 i nesa mi
Hadde vært kult å prøve noen waveguider av denne størrelsen óg om man først er på det kjøret. For min del blir det ikke aktuelt før ungene flytter ut eller jeg bygger på huset, men jeg kan jo sitte her og drømme mens dere tråkker opp løypa.
Disse er bygget for Radian 1,4" Be. Wooferne er 15", så på øyemål ser hornet ut til å være rundt 120 x 75 cm. Heftig!
Kommentar fra eier Paul Wright:
All of the usual tweeter flares were evaluated in HornResp…Exponential, Tractrix, LeCleach, OS, Spherical, Conical, etc. Excessively narrow top octave response quickly eliminated all of the classics except OS, Conical, and very high “T” Hypex. The more promising tweeter profiles were exported to AxiDriver for detailed comparisons with custom profiles, including hybrids with standard throats tangent to various mouths. In the end, a continuous elliptical curve from throat to mouth provided the best overall match with performance goals favoring low diffraction and clean impulse response.
Vertical simulations in LspCAD, and HornResp were straightforward and processed nearly instantly. The time sink was AxiDriver which, even at low resolution with an i7 processor, typically took nearly half an hour to run. 1/48 octave simulations usually ran overnight. Since “the operator is the optimizer” it is easy to see why it took so long! (Note: ABEC appears to be a multi-threading evolution of AD so it runs much faster…but I had already endured one painful learning curve with AD. If you’re simulating your own waveguide profile from scratch, consider ABEC.)
All three channels share WG mouth sizes with different directivity achieved through differing depths and profiles. Listeners are below room center so, to help align acoustic centers with minimal room intrusion, the upper and lower woofers are slightly different. It took, literally, months of simulation before all of the WG designs were acceptable.
The weakest link in all of this is vertical directivity of the tweeter WG. The vertical dimension limits vertical pattern control at LF and achieving the desired aspect ratio (extremely narrow vertical by wide horizontal) would require an exceptionally wide and deep WG. Subwoofer mounting requires flat surfaces, but I was unable to identify a high-performance/low-diffraction tweeter profile with angled flats as the mouth termination. Unfortunately that results in tweeter WGs 4’ wide rather than 7’. At a listening distance of nearly 15 feet, mitigating LF tweeter floor bounce must be a task for Acourate.
Horns scale with frequency, but real drivers don’t. Several physical prototypes, some of them full-size, were built to validate plans before final construction began. The final tweeter “prototype” was built to become the center channel…and it did…whew!
TWEETER WAVEGUIDE DESIGN:
The idea of loading drivers with the maximum available HxV mouth area comes from pro sound. JBL has done it for years and still does , including the Everest and M2. Tweeter WGs more than a wavelength in all dimensions combat pattern flip by providing reasonable polar control into the region of crossover overlap. “Super-sizing” also reduces diffraction since the HF signal largely leaves the walls before reaching the mouth. A further benefit of size is lower driver distortion through improved acoustic loading via more optimal radiation resistance.
Freedom to choose any part of any ellipse provides great design flexibility. With a smooth continuous sweep from throat to mouth, the ellipse can be stretched, tilted, or offset to adjust performance trade-offs. By definition, diffraction “bumps” are avoided. Here, the long axis is the listening axis; the exact curve plotted in Excel with performance modeled in AxiDriver. Maximum SPL output and directivity was traded for smooth directivity and clean impulse response…sharp rise with very quick settling time. (Impulse response speaks, literally, volumes about real-world performance.)
The compression drivers used here have a negative 7 degree exit angle so, thanks to an engineering drawing from the driver manufacturer, phase plug output was included in the WG sims. For the converging/diverging CD/WG interface, a near-conical throat provided the most compact impulse response. With a tip-of-the-hat to Earl Geddes, a 1.5” cube of open cell foam absorbs diffraction generated at the driver-throat interface. The small block of foam is so effective at reducing destructive interference in the throat it actually increases output at 20kHz by more than 2db.
Hadde du ikke noe adapter ringer på M2?
Dette ser jo veldig bra ut [emoji108]
Estetisk synes jeg nå OMF sitt oppsett ser bra ut. Har ikke han 2384?
