Another Unity Horn

[gedlee]

Very odd that the driver would have that much of an effect. I don't find this in general. In fact, once EQ'd a TAD 2001 and a B&C DE250 are almost indistinguishable on my waveguides. Maybe I'll dig up that data and post it.

I think that you know that the Summas originally used the TAD 2001 and the 15" woofer (forgot the model #, 124b or something like that). When compared to the same system using B&C drivers, the results were nearly identical. What's the point of using mega-buck drivers when the system design dominates the sound.

 

[Patrick Bateman]

Very odd that the driver would have that much of an effect. I don't find this in general. In fact, once EQ'd a TAD 2001 and a B&C DE250 are almost indistinguishable on my waveguides. Maybe I'll dig up that data and post it.

I think that you know that the Summas originally used the TAD 2001 and the 15" woofer (forgot the model #, 124b or something like that). When compared to the same system using B&C drivers, the results were nearly identical. What's the point of using mega-buck drivers when the system design dominates the sound.

The difference reminded me of a demo I heard at CES, using a supertweeter. The demonstrator took the supertweeter out of the mix, and the difference was quite audible. Of course I know this could just be "the power of suggestion."

Having said that, I've consistently preferred speakers that have output beyond 20khz.

Last night I measured my BMS 4540NDs on the OS waveguides I built for my car in 2006, and there's output beyond 20khz.

http://www.diymobileaudio.com/forum/diy-mobile-audio/60146-creating-perfect-soundstage.html

Also, if anyone is following this unity horn thread, it's basically moved over there. When I started this project I couldn't decide if it was going in my car or my house, but I bought a pair of Summas in the meantime, and that basically sealed the deal.

This is definitely a car project now.

 

[Patrick Bateman]

Hi Earl

“As in any horn the HOM bounce off the walls. The fact that they are straight makes no difference. If a sound wave on its way down the horn encounters any "aberation" such as another driver or such, then it will diffract off of said aberation. The diffraction will then bounce off of the walls creating a wave that travels not down the horn in a straight line but angular to the axis bouncing off of the walls.”

Yes I am familiar with this, a 2 inch driver on a wide angle horn, a compression driver with a typical ring type phase plug, all these can typically produce interference in the horn.
The mid hole / throat shape also cause a mode to appear in the Kit version of the unity horn at 4Khz too.

On the other hand, if one has a simple conical horn driven at the apex with an acoustically small dimension point source, there is essentially no way for anything but a partial spherical patch to radiate. To do else wise, would require the horns walls to be at something other than perpendicular to the direction of propagation or vise versa.
That condition doesn’t exist if the source is at the apex and is acoustically small (too small for the origin to have directionality on its own).

In other words, I would contend that if one drives a simple conical horn from a point where the horn is less than about 1 / 4 to 1/3 wl across, that HOM’s of any significance, can’t be produced or radiated. Sure you might be able to present that throat area with a complex phase but the distance between the phases is so small they all sum.

You can’t produce a complex radiation pattern in space or have directivity without a minimum acoustic size.
In practice, if one has a source which already produces a diverging wavefront which is “near enough” to the angle of the conical horn it attaches to for the frequency and size, that the conical internal horn in the driver is simply an extension of the outer horn you see.

I speak in black and white here, obviously the math for all this doesn’t reach asymptotic “zero” at these points rather, that for practical purposes, the effects go away.


I can measure up to 20 feet high, 2 or 3 meters is no problem.
My turntable has clicks at 2.5, 5 and 10 degrees, would 5 degrees be better instead?
Do you want from 0 to 90 degrees, half or full circle?
Hey, I’m not saying they will be as nice as yours but I am curious how they would look on your visual’s and willing to take the data. I will do this after the trade show next week.

Best,
Tom

Hey Tom,

I did some polar measurements of a "unity clone" using a Geddes style oblate spheroidal curve. The measurements are almost freakishly good. I was shocked!

Here's a pic of the polar response of the midranges mounted to a 72 degree x 108 degree elliptical OS waveguide. This is with no crossover, and no EQ. Note the response doesn't waver a bit, all the way down to 200hz. Even in the high frequencies, there's no weird humps on or off axis.

Compare that to this measurement, which uses the same midranges, on a waveguide of comparable size. This waveguide uses a different curve, it's not OS.

You'll note that it's only maintains directivity for an octave and a half, and in the rest of the range the beamwidth varies dramatically. In the upper frequencies the beamwidth widens, and in the lower frequencies it narrows.

Here's the kicker. Both waveguides are about 12" x 6" wide, and they were measured in my car. Looks like the OS is able to "mate" with the dash, but the other curve doesn't.

 

[aceinc]

Y'all might find this interesting;

First Unity horn prototypes ever made by Tom Danley! - eBay (item 110428819765 end time Dec-25-09 11:43:48 PST)

 

[Patrick Bateman]

I built another Unity horn last night, this time with a JBL 2470 (about $200) and a Peerless AV woofer ($15.)

Info is posted here; measurements will be coming soon.

http://www.diyaudio.com/forums/mult...aveguides-psychoacoustics-10.html#post2015060

 

[kees52]

Hi Patric

I have a idea to make a synergy horn who can go together with a tapped horn who is ready to build now.

I have 4 visaton wsp26 s bass 10 inch, and it work very well IF I am right.

Do you now a good learncourse about this horns? I am amp man, but want also learn some about horns.

I have seen that finding a back closed mid loudspeaker is not easy, I have then get a open one and make a little enclosure behind the mid as replacement for the closed one,
the viston mid who was closed has high qts because of the small enclosure formed.

I did see that for bas there are two holes per speaker but one hole is open to the back is this needed for use the back energy of the woofer?.

thanks

kees

 

[Omholt]

Old thread.

Did Tom ever send the measurements data to Earl?

 

[gedlee]

No

 

[djk]

What say you about this hybrid horn?

Looks interesting.

 

[Omholt]

No

Ok. That's surprising.
Would really like to see better data of the Synergy horn.