[DIY] Horn on Polish speaker - STX

Nice horn for the bedroom.

Just wanna point out one thing, you should always use t-nuts and panhead/crosshead bolts to hold the driver to the baffle; because screws don't hold well in the screw hole, especially if you need to take the driver out for any reason.And t-nuts and panhead/crosshead bolts keep an airtight seal around the driver wheras screws can wiggle loose from the bass vibrations and air pressure behind them.

 

Edited by ToXiC

What did you use to make the plots other than hornresponse? Looks really usefull.

If you look at the efficiency, phase response and driver excursion plots you'll see straight away the tell-tale signs of a BP hybrid. It's not a black/white destinction, but this is definitely more hybrid than horn.

What's the benefit of putting a substantial flare on what appears to be a port?

I'm guessing it's the same as horn loading a driver.  The horn acts to couple the accoustical impedance output of the cabinet (the port) to the lower impedance of the outside world (free space) thus increasing efficiency.

I've been playing with sims of horns similar to HD15 and this while trying to design my own 15" horn (see other topic).  As you increase the front chamber volume you lower the resonance of the driven resonant system which is then loaded with a horn.  The effect seems to be to allow the box to play lower at the expense of efficiency and high frequency performance (as with BP).  I'm guessing transient response will also suffer.

[RAMBLING ALERT!!!]

The problem with hornresponse is, that it cannot model systems accurately (at LF anywways, higher up it's off by a bit->lots anyways) that break the asumption of a planar wave, i.e. the real life wavefronts have a curvature to them. At LF it is a resonant system acoustically similar to a 4th order Bandpass and some people model the proper size for the front chamber like a BP in WinISD/similar before adding the non-constant-cross-section port.

The other effect is a 1/4 wave resonance which can be seen in the excursion plots. The returning wave (it gets diffracted at the mouth or often a little in front of it, esp in stacks) meets the driver in phase at 1/4 and helps it along to more excursion. If you were to look at a detailed Waterfall plot you'd see that this energy trails the rest of the system (which starts acting more and more like a horn depending on mouth size and to a lesser extent horn geometry, i.e. the exact flare isn't that important) and helps the driver to more excursion than what it would have been capable of in just a sealed box (even more so at high volume levels)

Yes and no. While the effect on loading might be rather small at LF, higher up you can get yourself less loading that what would have been possible (i.e. if the flare is too steep you might loose on loading in the middle or get a nice resonance midband or you might have yourself a nice 4th order bandpass with a really strong resonance higher up in stacks).