Driver configuration...

[Jonny Hotnuts]

I am building surrounds for my home theater (limited program materiel, not for music applications).


Nearly every speaker design I have seen that utilizes multiple identical drivers always puts them in a vertical array with tweeters centered.

Is there any reason why I should NOT use the second examples configuration and make the speakers overall height a few inches less and keep the same width?

I am concerned that with the relatively close seating position the taller configuration will have some noticeable separation. I also have plenty of width but my height is limited; shorter would be better from a build standpoint.

(Both examples use the same drivers and are monopole)

-I already own the drivers.

Already started to make a router template to flush mounting the PITA truncated frames.

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

Thanks for any advice.

~JH

 

[AllenB]

To some degree, and over some range the vertical stack will reduce ceiling reflections and less so for the horizontal. This is probably not a bad thing. Keele has some good information regarding the behaviour of lines.

The frequencies where this happens is going to change the benefit, where higher frequency reflections might be broadly said to affect clarity and lower frequency reflections become troublesome with regard to being modal with the room.

The shape of the lines radiation may be of some concern if you cross at a high frequency.

 

[Brian Steele]

How about this configuration?

With one tweeter instead of two, you avoid the HF lobing problems.

 

[Jonny Hotnuts]

Brian, that is a good idea except I already own the drivers and are all configured to be 8-8-8 ohm as are my passives.

I would have to buy 6 new 8ohm tweets and then have 12-4ohm with no home!

~JH

 

[AllenB]

I'd have no problem using 4 ohm tweeters if that's all you had (and I would), but if you want to use them in pairs then maybe you could experiment with their spacing, although as close as possible would be the best by default.

I'd measure their lobing to make sure you get a useable response in front, and if you also got some useful nulling toward the ceiling then that might be interesting.

 

[Jonny Hotnuts]

I'd have no problem using 4 ohm tweeters if that's all you had (and I would), but if you want to use them in pairs then maybe you could experiment with their spacing, although as close as possible would be the best by default.

I'd measure their lobing to make sure you get a useable response in front, and if you also got some useful nulling toward the ceiling then that might be interesting.

I am building the speakers in a 3 piece configuration where there is a common housing, the enclosure for the 8" and a separate and removable enclosure for the mid/tweeter sections. -This will allow me the ability to remove the mid/tweeter section from the housing and reconfigure the arrangement without starting over (or even removing the housing/8" from the column).

I figure Ill be building a few mid/t sections before finding one that works with my room.


Would it also be advisable to build all 4 of the mids together and as close as possible (Peerless 830987) and put the tweeters together (mounted above, below or side) as apposed to having the tweeters in the middle separating the little 3"?

Thanks for any advice,

~JH

 

[AllenB]

Your first option is more conventional, and I think Brian's suggestion maybe shows promise for a number of reasons. I think you want to ask yourself why you are using multiple drivers to begin with.

If it is to control directivity then I think that at least the first reflection from each wall should be considered separately with what frequencies you want to withhold, and what radiator height/width is required to do this, as well as blending between the bands.