Acoustic Horn Design – The Easy Way (Ath4)

[gedlee]

I can't find it. Do you have an idea which patent it would be? - Meyer Sound - Patents

Maybe it wasn't a patent, because it was cited as prior art in my patent as "Meyer Sound Laboratories Specification Document for Model UPA-1A" Whatever that is. Hope you can find it.

 

[mabat]

"High frequency horn - modified radial with foam lens"

That's all I can find. But it seems to me as something quite different though.
1989

 

[gedlee]

Yea, that's it. The technical document described the use of foam in the throat. You can see it in that picture. Apparently not worth patenting!?

 

[aragorus]

Has anybody tried to use VACS to display the measured data?
I can't really get it to show what I want....
When I import my raw .wav impulse responses and specify the angle offsets in order to create a polar it seems like the on axis measurement has a lower amplitude than the off axis ones. As if it interprets the amplitude data the other way around.

 

[bmc0]

Make sure the WAV files are not normalized on export. In REW, there's a checkbox in the export dialog: "Normalize samples to peak value".

 

[aragorus]

I'm using HolmImpulse and I have made sure they are not

 

[aragorus]

I think it's something to do with the units.
VACS expects sound pressure, and is getting dBFS

 

[Brinkman]

Yea, that's it. The technical document described the use of foam in the throat. You can see it in that picture. Apparently not worth patenting!?

Iirc, the foam was to keep insects out of the CD due to use in outside environments.

 

[aragorus]

So I plotted the fft of the impulse responses from HolmImpulse in Matlab and it seems like HolmImpulse is normalizing, or perhaps I'm missing something'


EDIT: There is a .info file with every measurement where it is specified how much the data is scaled

Data_Amplitude = 0.0036298722639196415

 

[gedlee]

Iirc, the foam was to keep insects out of the CD due to use in outside environments.

That's not what the literature claims. There is already a "bug screen" on the drivers.

 

[mabat]

Finally, I can measure exit angles like a human

 

[mabat]

Now it's perfect -

 

[aragorus]

That is sooooo nice! Good invention Mabat!

On a side note, I just managed to finally import the impulse responses into VACS. Here is a plot of 1" driver on a rectangular horn 370x290mm crossed to a 12" woofer.
I got to figure out how to window properly and find a better place to measure.

 

[Brinkman]

Yea, that's it. The technical document described the use of foam in the throat. You can see it in that picture. Apparently not worth patenting!?

That's not what the literature claims. There is already a "bug screen" on the drivers.

The UPA-1A uses/used the MS-1401A compression driver. Go to this link, picture 4: 403 Forbidden

Those drivers are made in-house so technical details on them should be scarce. But I don’t see a bug screen.

 

[turk 182]

Now it's perfect -

so are all driver exits a flat line...? a may stand corrected but to my recollection some drivers if i am not mistaken are designed with a exponential curvature from the phase plug on out, so how does your jig deal with that?

 

[turk 182]

and as i don't have the sim software to analyze it i've wondered what the effect of starting with a short exponential expansion coupled to OS or anything else turns out like.

 

[pelanj]

I wonder if planar drivers (like e.g. Heil AMT) emit a planar wave that would benefit from a nice horn. Or this one Order the GRS PT6825-8 Tweeter - SoundImports that was used in Joseph Crowe's Sabourin horn. I wonder how this would perform with optimal horn (waveguide) expansion. Maybe we need the option for rectangular throat to try out

 

[mabat]

so are all driver exits a flat line...? a may stand corrected but to my recollection some drivers if i am not mistaken are designed with a exponential curvature from the phase plug on out, so how does your jig deal with that?

I've never seen a driver like that.

and as i don't have the sim software to analyze it i've wondered what the effect of starting with a short exponential expansion coupled to OS or anything else turns out like.

I suspect it would beam too much at high frequencies, especially for the bigger throats.

 

[airvoid]

Here’s one, the 5551 ring radiator; albeit part of a coax.

 

[TNT]

It really looks straight.

//