The effect of placing the horn on the outside of the Speaker cabinet

[cl_ng2003]

I own a pair of Flamenco speaker. The 811 horn is placed inside the custom cab.

For long, I have been considering placing the horn over the top and outside the flemenco cab to achieve a better sonic effect. I would be interested to know from anyone that the benefit of external horn placement, and the secret to achieve the correct phasing. Has anyone tried this before for a Flamenco? should I consider blocking the vent opening inside the speaker cab where the horn used to locate?

[cclark65]

It would be easy to remove the horn and just set it on top to test it, and you could easily screw a piece of plywood in where the horn was for testing. If you don't like the sound, put it back, and you have lost only a little bit of time, but aquired the answers you are looking for.

And please be sure to post your results!

[GM]

I don't remember this speaker, but anytime you increase the distance between two sources, then the further away you need to sit before they sound like a coherent source. The ideal is to have the horn/LF center to center (c-t-c) spacing no >1/4WL at the highest frequency, which obviously is impossible with an upper limit of ~20kHz, so butting them up against each other in the vertical plane is the best you can do, then use a XO that 'points' the upper driver's response down somewhat, which is what Altec, etc., normally did.

When top mounted, optimizing the phase response through the XO's passband and tilting the horn as required to blend at the 'sweet spot' yields good results: http://www.soundpractices.com/images/phase.pdf

If the design is one where the vent is part of the horn opening, a reduction plate is required to get the desired in-room reflex tuning. If there is a separate vent(s), then the opening will need to be tightly sealed off and possibly the vent lengthened to offset the increase in net Vb. That, or stick some bricks/whatever in it to make up for the horn's displacement.

GM