Acoustic Horn Design – The Easy Way (Ath4)

[mabat]

I measured HF1440 directly with the 460-36:
https://www.diyaudio.com/community/...-design-the-easy-way-ath4.338806/post-7427264
https://www.diyaudio.com/community/...-design-the-easy-way-ath4.338806/post-7426470

It could probably make a very nice sounding system but I haven't tried yet.

 

[Olombo]

Misunderstanding: the hf1440 in a Athex with conical throat extension (not meaningfull for 1.4" exit driver). Anyway in the 460 a bit curvy but after some eq may be good

 

[mabat]

Yeah, the extended version turned out to be so interesting that I want to study it a bit deeper now. The HF1440 doesn't seem like a good candidate, but who knows, maybe it's still worth a try...

 

[mefistofelez]

Hi Marcel,

There's really a great potential in using large-format drivers at their phase plug exits, even if radiating e.g. through a 1.4" aperture.

Can you please clarify- do you mean to use the 1.4 in driver directly at the horn sans the throat extension, or with a throat extension?

I am asking as I have two drivers, a phase plug of which terminates at the front face of the driver.

Kindest regards,

M

 

[camplo]

There's simply something to the "full-bodied" reproduction from one driver. You won't hear that very often.

1.5 a/b Ratio at the mouth, Cutoff; 150hz F3, with the mouth height no bigger than 700hz.

 

[mabat]

460-36 + Selenium D2500Ti-ND with an extension starting at the phase plug exit.

 

[mabat]

Just an attempt - harmonic distortion at 1 Vrms. I don't have a calibrated setup but this could be ~96 dB SPL@m for a conservative average estimate of 105 dB/2.83V.

The second set with the mic a bit farer away, seems consistent:

I see no reason why not to use this down to around 600 Hz...

 

[mabat]

With the microphone at the mouth (looks like the mic is still doing fine) -

 

[mabat]

0.5 Vrms, i.e. 6 dB SPL less (probably reaching noise limits here):

 

[TNT]

...

I see no reason why not to use this down to around 600 Hz...

One is perhaps that if you are really picky, you would like the distortion creating fundamentals below 600 to be at least say 20 dB down - that requires a quite steep filter... to obtain perfection, one need margins... wide, preferable....

//

 

[mabat]

Measured with an active HP filter at 600 Hz (FusionAmp "HP2", Q=0.7).

a) 12 dB/oct:

b) 24 dB/oct:

Seems to me that even 12 dB/oct would be still fine.

 

[TNT]

OK - 4th is about 5 dB better than 2nd at 500Hz - and looks good with filter - thanks!

Still - 1% 3rd at 500.... had been nice to keep below 0,1%...

//

 

[mabat]

It's already around 50 dB below fundamental...

 

[TNT]

Yes + No

//

 

[mefistofelez]

I am asking as I have two drivers, a phase plug of which terminates at the front face of the driver.

Yeah, but unfortunately the driver is 1.5 in.

Kindest regards,

M

 

[mabat]

The 2" driver I used (PA-D99) also has 1.5" at the phase plug exit. You can try to make an extension for the 1.4" throat of the 460-36 as I did. It doesn't seem to matter much -

 

[mabat]

BTW, it's possible to buy the sole diaphragms+coils for (e.g.) the D2500Ti. What could one expect when clamped this between two rubber rings? Wouldn't there be some advantage over the stiff surround for home use? That's what I intuitively feel but maybe it's not a good idea (?) so it's not even worth a try.

 

[mabat]

Distortion with the PA-D99 @ 1 V (SPL not calibrated):

This is a big difference compared to a 1" driver. The nice thing is that the radiation pattern is virtually the same.

 

[mabat]

@0.5 V (roughly 95 dB/m?)

 

[And1]

Hello Everyone,

if have a little problem with the ath 4.8.2. – maybe anyone can help me 😊
I try the demo1.cfg example.
When „reading bem_mesh.geo“ the program is freezing:

When i use gmsh v.4.6.0, i get some errors but the abec project is created … But whats the Problem?

Best Regards

Andreas