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Here you see the input screen.

The area called Nd is the place where you click two times and a box comes up. The box can be used to alter the number of drivers Hornresp calculates. The connections are series or parallel. Changing the number from one to two will tell Hornresp that there is a second driver. You know you have been successful when the ND box shows 2S or 2P.

The s stands for series connection.

The p stands for parallel connection.

Mark
 

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Hornresp will automatically add the Sd values together according to the number of drivers that you specify. It will also correct the other driver values.

Any driver within a quarter wavelength of the frequency being reproduced that is beside another driver reproducing the same frequency will act acoustically as one lumped driver. Hornresp models this in the same manner. All the drivers surface areas are summed to become a super driver in surface area and relevant mechanical parameters.

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wave length calculator:

http://www.mcsquared.com/wavelength.htm

example 100 hz wavelength = 3,44 meters divide that by 4 to 1/4 you get 0,86 meters as long as your drivers are this close together or closer they act as one driver at this frequency and below.

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I can say this with a great deal of confidence. If you model your box correctly, then build it as you modeled it you will end up with almost exactly what you modeled. I have been using Hornresp for over 6 years and building boxes for just as long. The simulations are very accurate.

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This is my case, where S3 is right in the middle of the tho holes.
You do realize that the length and the sizing in the box you show are grouped as one lumped parameter by the drivers. They see the entire volume, and port as an acoustical impedance. The dividing of the box into sections is for the sake of computation of flared horn segments. A straight horn could usually be modeled in three sections or less. Driver positioning as discussed before only has an influence on how the port behaves.

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In the Eg field enter 0 volts.

That will allow you to model a perfect driver on your horn . Since your driver has no true physical parameters. I have been doing similar work with planars.
 

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After modelling an OD horn 380 cm long, it's SPL has some ripples. Could I space a second offset driver at 1/4 wave distance from the first to compensate for major dips or would it make problems worse ?
I don't want to use a back chamber but let it radiate free to air.
Thanks a lot, Marc
Don't know if Soho is active.

Your hopping for a filler driver effect if I'm thinking the way your thinking.

The greatest problem is this. There is no way to simulate this in Hornresp, and it will effectively not do what you want in the first place.

Drivers that are within a 1/2 wavelength of the frequency you are hopping to fill in will behave like a compound driver. In other words spacing them next to each other in acoustical terms.

That is why Hornresp is so successful in modeling systems. It treats multiple drivers as a lumped driver having the surface area of the combination.

As for ripple.

You will not hear ripples in use. Room response is definitely not flat, and music tends to mask most of the ripple effects up to about plus or minus 5db. Tests tones played a semitone intervals will to the trained ear display differences. But this generally occurs at differences greater than 3 db.

To get a handle on this the vertical divisions in Hornresp are 5db increments. Plus or minus 2.5db. If you are within this, from personal experience having built many enclosures. Don't worry man!
 

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Marc, you seem very enthusiastic in your pursuit of good sound.

Here are a few things that are not part of what you are trying to do.

Phase describes space and time. Two components. Where something is in space relative to time of the measurement period.

In a loudspeaker the only way this can really cause you problems is if you have two drivers that are wired in such a manner that one driver is moving in one direction and the other is moving in the opposite direction. This not out of phase but actually anti-phase to each other. This will create a null at some frequencies but not all, and is really determined by more things than I care to tackle right now.

Your desire to create an infill is better pursued by cabinet construction lengths than another driver. The second driver idea, while it has it's merits, only has those merits at and above the frequency where the distance between driver "A" and driver "B". Look up a frequency to wavelength of sound calculator, and you will see that there are longer wavelengths for lower frequencies, and shorter wavelengths as you go up in frequency.

Again, if you do your box effectively you will mitigate most of your problems. Make a bend near the 1/2 wavelength of the frequency where you have a problem. But take note of this simple fact. A tapped horn is not a wide band device. two to two and a half octaves in frequency are all that a tapped horn, or tappered pipe type loudspeaker are able to do much with. If you try yo do more you will have a suck out in the middle that you will not be able to fill in.

Octave: 16 to 32 hertz in an octave. 32 to 64 hertz next octave, I think you figured out the next octave is 64 to 128 hertz. These are nice round numbers, actual note for note frequencies are slightly different.

Going up to 500 hertz with a tapped horn will cut you off around 100 hertz on the low end dropping two octaves.

If you are happy with this, then fine! But I really wonder if you have a tapped horn, or a tappered pipe enclosure. I have seen only a handful of true tapped horns posted on the internet. If you want some guidance look up jbell on diyaudio. He definitely knows what he is doing.

And he does a boat load of well designed PA cabinets that have serious usefulness.
 
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