[Duke]

I will probably be making a post in the "Industry Talk" circle to discuss the benefits of well-controlled radiation patterns, and any such post would be incomplete without including SP Technology loudspeakers.

I want to make sure the information I post is accurate, so I've been reading SP Tech's website - and I've come away a bit confused:

What exactly are the radiation patterns for the waveguide on the Timepiece and the Continuum?

I find what appears to be conflicting information on the website.  From the "Dispersion" page (accessible under "Theory"):

"Sound is radiated into the environment with a constant 120° horizontal angle of dispersion from 900 to 10,000Hz. This means that as the frequency varies, the area that is "illuminated" by the driver remains the same over a 120° arch symmetrically and directly in front of the waveguide."

Later on, from the same page:

"A 90° dispersion angle is ideal for achieving this while still providing a very wide listening area."

From the "Specifications" page on the Timepiece:

"HORIZONTAL DISPERSION +/- 45° - 900Hz to beyond 10kHz(standard -6dB Beamwidth Limits)
VERTICAL DISPERSION +/- 30° - 900Hz to beyond 10kHz(standard –6dB Beamwidth Limits)"

From the "Specifications" page on the Continuum: 

"HORIZONTAL DISPERSION +/- 45° - 900Hz to beyond 10kHz(standard -6dB Beamwidth Limits)
VERTICAL DISPERSION +/- 15° - 900Hz to beyond 10kHz(standard –6dB Beamwidth Limits)"

And finally, here's a link with a good image that we can eyeball:

http://www.4sptech.com/version2/introduction.html

Now it looks to me like the waveguide is axisymmetric, so I don't understand the vertical pattern narrowing as described in the specifications, unless that refers to narrowing in the crossover region only due to driver interference patterns.

It sounds like the preponderance of the evidence supports a 90 degree horizontal pattern, but eyeballing the image that waveguide looks wider than it is deep, which would be consistent with the 120 degree pattern.  However this could be an optical illusion. 

Can anybody clarify this for me?

Thanks!

Duke

[Aether Audio]

Duke,

Glad to hear from you!   How ya been?  Hope to see you at RMAF.

Regarding the waveguide...first and foremost - forget the website...it's totally hosed.  Specs are typo-ed in a couple of places and also screwy as the result of changing from the waveguide/tweeter combo used in the old 2.0s to the system were using now.  I'm terrible at staying on top of documentation - you should see me books!   We have a new site in progress and all will be clarified.

For now, 120 degrees horizontal and vertical depends on what you're measuring.  You are correct though, I was including the suckout off axis at X-O.  Half the time I can't figure out what the "protocol" for dispersion specs are supposed to be in the first place...-6dB referenced to what?  Our waveguide isn't a perfect CD anyway, so where do you call it? 

So... in the new site I'm just going to post curves.  Anyone that cares and understands can derive the spec from them based on their interpretation of protocol, and those the don't know most likely don't care anyway.

Oh yeah, the waveguide flares and looses control below about 1KHz.  At X-O (600Hz for the TP - 700Hz for the Continuum/Revelations) we're looking at half pi radiation on up to where the waveguide starts kicking in and narrowing it down to 120 degrees.  They're certainly not Summas, but I didn't design the guide primarily for radiation control - that was just a spin off. 

As you know, if we wanted to control radiation that tightly the thing would be a lot deeper.  My main concern was diffraction, signal alignment and reduced tweeter excursion.  Radiation is what it is.  On the other hand, if we were doing PA work diffraction and signal alignment would then take a back seat to dispersion.

In other words...all that matters is what it sounds like.   Hey...look at me... I'm an audiophile!

Take care my friend
-Bob

[Duke]

Thank you very much, Bob.  You told me exactly what I was looking for. 

My waveguides lose it below about 1400 Hz, so I crossed over a bit higher than that.  I gotta tip my hat to you for being able to successfully cross over below the frequency where the waveguide is unloading - that can't have been easy!  How'd you do it?  No - wait, you'd probably have to shoot me if you told me.  Never mind.

By the way, your new Mini looks killer! 

Earl has discontinued manufacturing the Summa, but it will re-appear as probably the top model in a line of speakers offered by a new company called Audio Intelligence.   Earl is the designer.   I don't know what his distribution channels will be, so don't know if I'll be able to carry them or not.

Will you be at the Rocky Mountain Audio Fest?  I'll be in room 1100, and if you're there I'll come see you.

Very best to you and your company,

Duke