di-pole front horn

[nuconz]

Compression horns are sealed 4th order band-pass (BP) alignments and vented variants are 6th order BPs. Tapped horns are these taken to their logical extreme and while they can perform exceedingly well down low due to their high damping they have little HF extension for the same reason.

GM

so what you are saying is if the back radiation is brought forward then the speaker will no longer function as a "full range" system? but sealing the back of the horn will not alter this?

 

[Rudolf]

Originally posted by GM Hmm, at some point in its response the horn goes omni and dipole comb filtering begins, so how is this different from a driver on a large flat panel?

GM

Even if you only compare the on-axis radiation from the front side with that from the back side, there is ~6 dB difference from 0.1-2 kHz:

An externally hosted image should be here but it was not working when we last tested it.

Simulation with AJ-Horn for FE 103 E. Red is the response of the front side (frontloaded horn). Black is the backside. Simulation as a CB with a front baffle of 17.3 x 27.4 cm and a volume of 2000 l.

I don´t know the mechanics of the off-axis response of a horn, but that should make things only worse. Of course there will be comb filtering, but what about the symmetrical radiation pattern, by which a "dipole" is defined?

 

[nuconz]

no, i meant JohninCR's design and mine
http://www.diyaudio.com/forums/attachment.php?s=&postid=1462509&stamp=1206131492

do you have specs on this?

wonder if the Fostex would work in a push pull arrangement on this design?

wonder how would a simulation of this arrangement appear? and as push pull?

thanks.

 

[GM]

so what you are saying is if the back radiation is brought forward then the speaker will no longer function as a "full range" system? but sealing the back of the horn will not alter this?

I'm saying as damping on the diaphragm increases its HF response is increasingly rolled off and since 'bringing the rear radiation forward' is increasing damping, so goes the HF with the extreme being a tapped horn, though in retrospect this isn't quite true, it would be the simple vented 6th order BP.

With a 4th order BP horn, damping is a function of its compression ratio (CR) and filter chamber volume (Vb), ergo for a max driver HF extension you want no filter chamber or compression, i.e. a throat: driver ratio (St:SD) > 1:1 since a 1:1 creates a filter chamber in the guise of a short resonant tube.

GM

 

[GM]

I don´t know the mechanics of the off-axis response of a horn, but that should make things only worse. Of course there will be comb filtering, but what about the symmetrical radiation pattern, by which a "dipole" is defined?

Sound falls away from it just like on any panel, just that you have to flatten it out to find its acoustic size.

I wasn't aware that by definition a dipole has a symmetrical pattern, only that it is out of phase. I mean not all dipoles in nature are symmetrical, so why should acoustic ones be?

GM

 

[GM]

do you have specs on this?

wonder if the Fostex would work in a push pull arrangement on this design?

wonder how would a simulation of this arrangement appear? and as push pull?

thanks.

Terry G.? and I helped John realize a proper waveguide (WG), but didn't save any details because I figured it would be in one archive or another, so you'll have to email him for the details.

You can make most any alignment work in a WG, but size is the variable that keeps many from being built.

Don't know and not aware of any consumer available software to do it.

GM

 

[nuconz]

Terry G.? and I helped John realize a proper waveguide (WG), but didn't save any details because I figured it would be in one archive or another, so you'll have to email him for the details.

You can make most any alignment work in a WG, but size is the variable that keeps many from being built.

Don't know and not aware of any consumer available software to do it.

GM

so we're probably better off using one of the spawn family double horn designs, then?

 

[MisterTwister]

nuconz, right now I can't say anything meaningful about that design.
once I make enough progress with building that doublesided horn, I'll resurrect my old thread

 

[nuconz]

nuconz, right now I can't say anything meaningful about that design.
once I make enough progress with building that doublesided horn, I'll resurrect my old thread

can't wait to see it dude!

 

[GM]

so we're probably better off using one of the spawn family double horn designs, then?

Don't know, it depends on your performance goals.

GM

 

[nuconz]

Don't know, it depends on your performance goals.

GM

wide bandwidth, image breadth, and SWs off most of the time.

 

[Rudolf]

I wasn't aware that by definition a dipole has a symmetrical pattern, only that it is out of phase. I mean not all dipoles in nature are symmetrical, so why should acoustic ones be?

GM

By and large the "di-pole front horn" works as a U-frame. JohnK, SL and others have shown that the radiation pattern of highly non-symmetrical "dipoles" like undamped U-frames changes from figure-8 (dipole) through (sort of) cardioid to monopole and vice versa - depending on frequency.

I know that (too) many people call any two-point source, which is out of phase, a dipole. But I consider that a bad habit. A "dipole" with a monopole radiation pattern?

May be you will call it nit-picking. Am I becoming old?

 

[Scottmoose]

Probably.

I know what you mean, but I'm with GM on this really. OK, so their polar response won't be symmetrical, & probably looks more like a kind of corrupted quasi-cardioid pattern, but they're still radiating on both sides with no real phase inversion going on. Depends how tightly or loosely you apply the term 'dipole.' And, ultimately, whether it really matters.