First post: Full range column surround?

[crapitecture]

I've been working on a design for a rear surround speaker for my HT setup. Linkwitz's and M&K's upward firing column surrounds have intrigued me and should work well for the way my room is set up. The speakers will be on either side of the couch, which is against the wall. I want a very diffuse sound so they aren't placeable, especially since they'll be so close to the sitting area. I also liked Cyburg's Needles, but wanted the smallest footprint possible. I'm interested in trying a completely minimalist approach: one driver, no xover.

I've researched several drivers looking for one that would offer a fairly smooth off-axis falloff in the upper end and a decent enough extension down low to integrate with a sub. I'm leaning toward the TB W4-654S.

I've modeled the project with winisd, and came up with a ported design that should get down to 50hz @ -3db. Attached is a sketch of what I'm contemplating.

Questions I have:
1. At 36" they are at ear height, should they be taller and if so how much? Temper that with the fact that I don't want them over 5' for aesthetic reasons.

2. Could this work with a TL design? What would be the benefit of doing so.

3. I've read some discussions regarding ports directly behind the driver, will this be a problem with this design?

4. Are there other inexpensive drivers I should be looking at.

Finally,

Thanks for sharing your knowledge, I have learned so much since stumbling on to this site.

[Bob Brines]

Originally posted by crapitecture

1. At 36" they are at ear height, should they be taller and if so how much? Temper that with the fact that I don't want them over 5' for aesthetic reasons.

Since you are nearly 90 degrees off axis to your up-firing surrounds, it doesn't make much difference how high they are. You will be getting most of the energy bouncing off of the ceiling.

I use up-firing surrounds in my HT setup. I like the results.

2. Could this work with a TL design? What would be the benefit of doing so.

This IS a TL design. Any time you have the height of your BR more than twice the width, assuming the depth is in normal proportions, you will get some quarter-wave modes. Your design is of the normal proportions for an end-loaded MLTL. WinISD won't have a clue as to how to handle this. You will need something like MJK's MathCAD worksheets.

3. I've read some discussions regarding ports directly behind the driver, will this be a problem with this design?

Since this is an MLTL anyway, I don't see an issue here.

4. Are there other inexpensive drivers I should be looking at.

What are you using for your mains? You want a similar sound for your mains and surrounds. I use either Fostex FE167E's or Lowther DX2's for mains and FE167E's for surrounds. Another consederation is the efficiency of the surrounds compared to the mains. Make sure that your receiver can balance the mains and surrounds.

The W3-654's should be OK for surrounds. They need a notch filter if used for mains. You will have to decide if you need a filter for the surrounds. If the surrounds are placed against a wall, you will not need to consider a baffle step filter.

Bob

[crapitecture]

Thanks for the information. I guess I better go back and remodel it with the Mathcad worksheets to see if this will work.

My mains and center are NHT SuperZeros, I'm in-between subs at the moment. I'm contemplating putting together one of the Rythmic units or creating stereo subs that will act as stands for the SZ's.Do you think the TB will be compatible with the NHT units?

[Dick West]

Do you think the TB will be compatible with the NHT units?

People mention that ALL speakers in a 5.1 HT setup should have a similar sound or timbre. I would go even further and state they should all have similar crossovers.

The space effects of surround sound are mostly based on phase differences, or phase shifts. If the front speakers use 2nd order crossovers with the phase of the tweeter reversed (as is often the case) and your surrounds use a different speaker with a different crossover without the tweeter reversed, or maybe even a full range speaker, the sound in the room may not "gel."

My home experiments a few years ago confirmed the need for all speakers to have the timbre but to also have the same crossover to derive the best surround sound.

My $0.02. . . .

[Bob Brines]

Continuing what Dick West said, your best bet is to locate another pair of Super Zeros and then mount them facing up.

Bob