# DIY Sound Bar



## greglett (Dec 10, 2006)

Hi,
I am attempting my first speaker build ever. The speak will be a sound bar with just LCR speakers.
The width will be 60". 

I spoke with someone at PE and the suggested using three full range drivers. I want to keep this as simple as possible and that was their suggestion. Below is a link to the suggested driver.

http://www.parts-express.com/pe/pshowdetl.cfm?&Partnumber=299-276

I forgot to ask if they were shielded and it doesn't state that.


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## bambino (Feb 21, 2010)

I don't believe that is a shielded driver as looking at the motor gives me that clue. I'm not sure though if that needs to be a concern these days with flat panel TV's that would need to be answerd by someone in the know, it's been awhile since i've needed to worry about that.


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## Anthony (Oct 5, 2006)

Agreed, that is not a shielded driver, although I also agree that it might not matter. If your flat panel is an LCD, it definitely won't matter. Not sure on Plasma, though.

Good luck and keep us posted.


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## greglett (Dec 10, 2006)

Anthony said:


> Agreed, that is not a shielded driver, although I also agree that it might not matter. If your flat panel is an LCD, it definitely won't matter. Not sure on Plasma, though.
> 
> Good luck and keep us posted.


Currently I have an LCD but I plan on getting a Plasma.


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## fbov (Aug 28, 2008)

I have a pair of these in my car, along with their NLA bigger brothers. They're not a bad speaker if you're looking for a straightforward first project as the crossover's already done. You just build the box. 

They are not shielded, and that's fine unless you have a CRT. Sounds like you don't. 

They are not flat; the tweeter sticks out (7/16" per PE), so you'll need to plan some clearance to any grill cover. I fitted some stock metal surface grills, but it's in a car; living rooms are different. 

By the way, all those specs listed between the power handling and the physical dimensions ...
(Le: 0.53 mH *Impedance: 4 ohms *Re: 3.03 ohms *Frequency response: 74-20,000 Hz *Fs: 74 Hz *SPL: 89 dB 1W/1m *Vas: 0.37 cu. ft. *Qms: 3.19 *Qes: 0.80 *Qts: 0.64 *Xmax: 2 mm )
... include everything you need to model the low frequency response of the driver in an arbitrary box, so you can do your own optimizations. I have some box simulations at home, or I can point you to the software if you want to dive into it yourself. It's just a spreadsheet.

Since you build the box, you have to design it, too. If you currently have or plan to add a subwoofer, a simple sealed box will likely work well; if these speakers are all you've got, you might want to use a port to increase low frequency output. Both are easy calculations once the data's entered and you become familiar with the simulations. Or I can give you dimensions that work. Your call. 

And by the way, pictures are good, once you start making sawdust...

HAve fun,
Frank, who will check back eventually..........


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## greglett (Dec 10, 2006)

Hey Frank,

Thanks for the input. I already have a powered sub that I will use.
Simplicity is the key here so that's god about the drivers. I will build the 
box, but I don't think I understand the calculations that are needed
to "model the low frequency response of the driver in an arbitrary box"

The width of the box has been determined 60". I plan on separating each driver
in it's own equally sized compartment. The debt and height of the box will be as small as possible
to accommodate the drivers. I plan on putting some stuffing into each compartment.

I guess the big question now is optimizing the response, how exactly is that done?


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## fbov (Aug 28, 2008)

I almost remembered to grab the file from home, so in its absence, I recreated it. Attached are 4 predictions for sealed boxes varying from 5L to 20L. I looked at vented options as well as sealed, all at 1/2 rated power. 

First off, this driver has a 2mm Xmax. Whether that's the physical limit of travel for the voice coil (Xmech), or just the limit that maintains the coil in the magnet gap, its the limiting factor in your box design. On the FR charts, the red diagonal line is the speaker SPL at Xmax, and you see that all exceed Xmax below 150Hz. The predicted F3 is in the upper right corner. As the box gets bigger, F3 reaches lower, but the gap to the Xmax line increases meaning less power will be needed to exceed Xmax. 

I won't show any vented options as they're all far, far worse for Xmax

With a sub, you only need an F3 around 80-100Hz, so any of these will work. Personally, I don't listen very loud, so I'd go with 10L as that takes 6W to Xmax, but yields 97dB predicted SPL at that power. Keeping in mind that these are steady state limits, actual program material won't be close to this RMS power level. I'm driving mine with 20W in ~15L enclosures and it's not a bad match. 

With a 60" external length, 6" height and 3/4" construction, 9" depth yields 3 equal partitions of ~10L each, so it looks like it fits!

BTW, the simulations are done with Unibox, available here:
http://www.pvconsultants.com/audio/frdgroup.htm

Have fun,
Frank


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## greglett (Dec 10, 2006)

Thanks Frank.


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