Horn Honk $$ WANTED $$

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Yet another reasons horns honk is the conical flare rate of the compression driver interfaces at the more elliptical flare rate in the throat of the horn. Now I know this is really a small change but it is down there in the part of the horn where things are very touchy. Any step change is a change in propagation Z which can cause a reflection and make the horn honk. I use a thin matching device there which re-emits the signal from the compression driver into the throat. This has completely removed honk from horns in testing. A soft gasket with a reduced hole size from that of the horn throat. Nothing but good has come from this in practice as far as I can measure.

This may not work on all horns but has worked on the horns I use as in earlier post.
Interesting, sumaudioguy! Can you tell us a bit more about this gasket? Wool felt? How thick? How much smaller is the hole than the throat of the horn?
 
Nothing but good has come from this in practice as far as I can measure.

Could you post before and after measurements??

Here's the normalized CSD

Rob🙂
 

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Felt gasket

Interesting, sumaudioguy! Can you tell us a bit more about this gasket? Wool felt? How thick? How much smaller is the hole than the throat of the horn?

Using 3/16" thick felt ring where the hole is half the area of the throat has worked well for 1" horns. I have not done this with bigger horns.:idea:

As a note, running 10dB crest factor noise through the horn the honk really stands out as its own sound (like a train) and is easily heard. Adding this felt ring has other effects of course but a horn that honks is worthless as far as I am concerned so the overall result was good and the horn still had 1 decade of bandwidth though instead of 1400-14,000 1300-13,000 was the result. For me a small price to pay. Have not tried this on many horns, only 2 but worked both times with not hugely dis-similar results. These were screw on type 1 3/8"-18 TPI compression drivers.
 
Using 3/16" thick felt ring where the hole is half the area of the throat has worked well for 1" horns. I have not done this with bigger horns.:idea:

As a note, running 10dB crest factor noise through the horn the honk really stands out as its own sound (like a train) and is easily heard. Adding this felt ring has other effects of course but a horn that honks is worthless as far as I am concerned so the overall result was good and the horn still had 1 decade of bandwidth though instead of 1400-14,000 1300-13,000 was the result. For me a small price to pay. Have not tried this on many horns, only 2 but worked both times with not hugely dis-similar results. These were screw on type 1 3/8"-18 TPI compression drivers.
Thanks. I've wondered about doing something similar but I've never tried it. Half the area works out to a bit over 1/8" sticking into the throat on each side and that seems pretty reasonable. It would be interesting to compare it to some of the other honk preventers looking at how they do one at a time and if using two or more of them helps even more.

Felt ring at the driver-horn junction.
Reticulated foam inside the horn (and inside the driver's throat?).
Absorptive foam/felt surrounding the mouth.
 
Absorptive foam/felt surrounding the mouth.

I think this one Peavy has a patent on.. (Earl I believe has or is in the process for the foam in the mouth), but the "ring" I've not seen before. I think Peavy's is a moot point for DIY'ers (..and I seriously doubt the patent would withstand scrutiny - people have been using the proverbial "towel on the Horn mouth" for a LONG time.) 😀
 
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Hello,

Some of us introduced the idea that different type of honkiness exist in horns. If we mix all together the different sources of reflections, group delay..., should it still be possible to study separately the different type of honkiness? That's doubtful.

I must confess that, even if I find your method to characterize reflections inside a horn theorically interesting and promising, I failed until now to see any definitive proof of some practical usefulness...

What you should do IMHO, is to take some more time to develop your method and to show "real life" results on different horns in order that some comparison could be done.

My method, like CSD, wavelet or whatever, is also practical than unpractical, it's just a question of what we search and what we see.
For my method, I have found what I hoped to see, not because I analyzed different data like sim's, measures (but I love that), hoping to discover something which led me to this, but because I worked with simples and known acoustics phenomenon.
My method is developed, not perfectly precise but I see on it a lot of meanings because it goes to the source of the problem.

My opinion, it's just a question of reflection, because in acoustic it's often that, plus standing wave and wavelength.
Different type of honkiness are details without meanings for me, thus I don't understand the interest.
I think it's more judicious to focus on the reflexion (the why of my method), standing waves and coupling horn/driver instead of analytical approach without global meanings.
 
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Hello sumaudioguy,

Such compression drivers having a high Q may exist. In that case it more than probable that the designer had for goal to obtain a reduced bandwith and an increased efffciency.

I can imagine such "specialized" compression drivers to be used in the low-mid and the bass (may be as the Goto Unit bass compression drivers)

Best regards from Paris, France

Jean-Michel Le Cléac'h


You are right of course but please note it when the compression driver is installed on the horn and not the unistalled Q. Yes I have seen about 2 that were that high installed.
 
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Hello Robh3606,

The wavy frequency response with those bumps (several dB) high at
450Hz
950Hz
1500Hz
2100Hz

and the corresponding intermediary holes , plus artifacts on the impedance curve at the same frequencies, plus artifcats at the same frequencies on the group delay crurves, indicate that powerful reflections occurs in that horns.

Best regards from Paris, France

Jean-Michel Le Cléac'h


Here's a group of graphs to look at all from the same measurement. Do we have a honker here?? If so why and what posted measurement is the most useful??
 
Ok Jean-Michel, that adaptor's acoustic discontinuities propably explain the two reflections before 2ms and the reflections between 3 and 4ms.

Seems to be that most likely there is honk in this horn! 😀

- Elias


If you look at a view side of the horn:

http://www.audioheritage.org/vbulletin/attachment.php?attachmentid=5869&stc=1&d=1110049751

You can see that 20% of its total length (32" = 81.28cm)

is a kind of adaptor the length of which is around 17cm.

So there is at a distance from mouth roughly equals to 65cm a visible change in the profile. This means that the difference of path that leads to an interference between the direct wave from throat and the reflected wave from mouth is 1.3meter and this means that we should look for a reflection around 3.8ms. What we see on the wavelets graph are reflections between 3.8 and 4ms so we can admit that there is probably some reflections induced honkyness regarding the RCA horn.

Best regards from Paris, France

Jean-Michel Le Cléac'h
 
Hello Elias,

I used to listen to a quite similar horn: the Yamamura Churchill. Honkiness was not so noticeable.

We have to consider that the Kleinhorn you show (from Linkwitz lab) is a rear horn. The effect of that large horn will mostly be audible in the low frequency (bass + infra bass...). From the low mid to the highest frequency the response is mostly the one of the full range loudspeaker itself.

In fact it seems to me that the perception of honkiness has some relation with our perception of phase distortion (to which I am sensible as more than 10% of the general audience and probably more than 30% of the audiophile crowd).

Here in France we have a lot of large bass horns (half a dozen of them are Le Cléac'h horns of the quasi-cylindrical waves type. Here are 2 examples of those Le Cléac'h bass-horns:

http://www.diyaudio.com/forums/atta...427-jean-michel-lecleach-horns-floor-horn.jpg

Imageshack - dsc30511280x768ac0.jpg

We don't perceive neither phase distortion nor honkiness with those basshorns. From my readings on phase distortion I became convinced that phase distortion is less audible below 250Hz and strangely I believe also that honkiness is not audible below 250Hz or so.

Best regards from Paris, France

Jean-Michel Le Cléac'h




Hi,

Would be interesting to have impulse response of these horns to see if they honk 😀

- Elias
 
Using 3/16" thick felt ring where the hole is half the area of the throat has worked well for 1" horns. I have not done this with bigger horns.:idea:

As a note, running 10dB crest factor noise through the horn the honk really stands out as its own sound (like a train) and is easily heard. Adding this felt ring has other effects of course but a horn that honks is worthless as far as I am concerned so the overall result was good and the horn still had 1 decade of bandwidth though instead of 1400-14,000 1300-13,000 was the result. For me a small price to pay. Have not tried this on many horns, only 2 but worked both times with not hugely dis-similar results. These were screw on type 1 3/8"-18 TPI compression drivers.


Thanks, I will have to find some 3/16" felt to try this.
 
Thanks. I've wondered about doing something similar but I've never tried it. Half the area works out to a bit over 1/8" sticking into the throat on each side and that seems pretty reasonable. It would be interesting to compare it to some of the other honk preventers looking at how they do one at a time and if using two or more of them helps even more.

Felt ring at the driver-horn junction.
Reticulated foam inside the horn (and inside the driver's throat?).
Absorptive foam/felt surrounding the mouth.

Catapult do you have any current builds going?
 
Hello Elias,

We have to consider that the Kleinhorn you show (from Linkwitz lab) is a rear horn. The effect of that large horn will mostly be audible in the low frequency (bass + infra bass...). From the low mid to the highest frequency the response is mostly the one of the full range loudspeaker itself.


Jean-Michel Le Cléac'h

Jean-Michel: That's from Pass Labs, not Linkwitz. BIG diff!
 
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