Acoustic Horn Design – The Easy Way (Ath4)

[mabat]

Thanks. No I don't, but you should be able to easily reproduce the shape anytime.

Now it would be interesting to see the horns measured in an (rounded) enclosure for how much of it is caused by the horn itself and how much by the improper termination. For example the slight widening between 2 - 5 kHz should not be there according to the infinite baffle simulation so I wonder if it is related to a particular termination.

- From these plots it seems that the time window was quite short, wasn't it. I guess that data below ~3 kHz are not very reliable.

 

[jzagaja]

It was named d99: width 357mm, height 282mm, depth 125mm, coverage 90x80.
Can print rounded baffle. R= 5cm?

I've used 2ms gate for polars and 1.5ms for raw plots.

Qestion remains can we minimize second pulse in slot waveguide by using rounded slot end. Will make sketch.

 

[mabat]

Why would you want a coverage wider than ~90 deg in the first place?

But I agree that for the smaller speakers it might be advantageous. You can easily modify this A9 for a wider coverage...

 

[mabat]

I've used 2ms gate for polars and 1.5ms for raw plots.

Yeah, that's quite short. You can see that the truncation of the IR has still an obvious impact on FR below about 3 kHz, meaning it's not reliable there.

 

[jzagaja]

Plus problem with RME Babyface, it has stronger impact.

 

[onni]

Here you are. I requested elliptical design from Dr. Keele for direct comparison. Do you remember that black elliptical data?

That A9 seems very promising!

How far do you have to boundaries? 4 ms gate should be easy to achieve in almost any room.

/Anton

 

[mabat]

To be honest, I wouldn't expect such a strong reflection in the diffraction horn. I believe this is really not a typical behaviour, or is it? That would make them hardly usable at all. Despite of that, people seem to use them, still. What's going on here?

 

[jzagaja]

Dr. Keele writes it is normal and minimum phase, easy to eq.

 

[mabat]

OK

 

[mabat]

Could you also show (or upload) the IRs for the two horns, say the ones for 10 deg?

 

[jzagaja]

Below impulses and spectra. Second pulse in Dr. Keele's waveguide makes response with 6dB nulls, in A9 it is less pronounced.

 

[mabat]

So it's the mouth reflection and that is mainly caused by the abrupt termination in both cases. The reason why it is less pronounced on A9 might be the narrower beamwidth (i.e less energy reaching the edge).

- You would need to add some roll-back (or an enclosure) to get rid of this.

 

[jzagaja]

Can attach JMLC roll-back if you like. Do we see any benefit of slot other than wider directivity control of 2" throat?

 

[mabat]

It's up to you, I don't mind
I don't know, I have no practical experience with any 2" horn. I have some 2" drivers but haven't ever really tried them.

- If you want, you can try a shallow variant of A9 (120 x 120 deg, 50 mm deep). See what you get.

 

[jzagaja]

That A9 seems very promising!

How far do you have to boundaries? 4 ms gate should be easy to achieve in almost any room.

/Anton

Almost, with small baby

 

[mabat]

A9S

 

[jzagaja]

Waiting for bigger variable intensity version

 

[mabat]

Much deeper A9 -

 

[turk 182]

looking at those two i can almost hear the difference....sorry to much scotch today...

 

[mark100]

Impulse that goes up/down middle axis each measurement.

Aah, of course..duh

I've never seen that float with the babyface pro, but i don't use Arta.
Here's the analog loopback impulse I get ..looks perfect to me..