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DIY in wall speakers?


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#1 of 8 DustinF

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Posted November 02 2003 - 04:28 AM

Just wondering if this is possible.
Maybe using something like the W3-871S.

This will be for rear channels only in a 5.1 system.

#2 of 8 Greg Monfort

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Posted November 02 2003 - 03:47 PM

These don't make much SPL so would have to be paired with at least an 8" to fill in down to the sub(s). The other problem is that they're highly directional in the HF, so a supertweeter would be required to get the necessary fill across the seating area.

GM
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#3 of 8 AllanRW

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Posted November 03 2003 - 02:08 AM

beg to differ.
The 871S is the only 3" that falls off 3db at 25k at 30dgrs off axis.
So tell me were you will need a super tweeter.
As well the super tweeter will fall of at 30dgrs off axis down around 8-10 db is normal for most tweeters.

Al

#4 of 8 DustinF

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Posted November 04 2003 - 07:39 AM

Does anyone think the 871-S would work if mounted onto a piece of wood and placed into a wall?

#5 of 8 Brian Bunge

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Posted November 04 2003 - 07:53 AM

Dustin,

As long as you can mount to piece of wood to the wall I think you'd be fine.
Brian Bunge
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#6 of 8 AllanRW

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Posted November 04 2003 - 08:14 AM

Also make sure you round over the back of the driver hole.The 3" hole even in 1/2" MDF cuts down the air flow around the driver by as much as 50%
Well worth doing.
Scalloping on the 3" Drivers Posted Image

#7 of 8 Greg Monfort

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Posted November 04 2003 - 11:15 AM

>beg to differ.
The 871S is the only 3" that falls off 3db at 25k at 30dgrs off axis.
So tell me were you will need a super tweeter.
As well the super tweeter will fall of at 30dgrs off axis down around 8-10 db is normal for most tweeters.
====
That alone is sufficient to give someone pause to a nominal 3"er's ability to best them. I've auditioned Jim Griffin's and Brian Bunge's ~fullrange TB speakers (dual/single driver) as well as BB's 'straight 9' and my listening experience doesn't jive with this measurement; it would put them up there with ribbons, CD horns WRT off axis imaging/soundstaging, which they don't.

Anyway, WRT a surround app., I'm more concerned about what's happening out at 45-60deg off axis out to 10-16kHz, and a supertweeter capped off at the right point for the room/audience coverage area when combined with the TB's output will yield a more convincing surround sound experience than without them.

You bring up a good point about typical dome tweeters polar patterns though, they're not really suitable for off axis use and I should have been more specific by referring to a piezo, or more expensive compression diffraction, horn, or $$$ ribbon, depending on the budget.

If dome types are used for surround apps, then I recommend either canting the FR one way and the ST the other ~15deg included to get the necessary fill, or use two STs in a bifircated baffle to extend their off axis response.
====
>Does anyone think the 871-S would work if mounted onto a piece of wood and placed into a wall?
====
Sure! I second Al's recommendation to chamfer out the back side of the mounting hole, and of course the sub-box to get the proper Vb/alignment needs to be well built. if you're using the cavity as an IB, then the LF driver will need to have specs suitable to get down to the LFE's XO point ~flat in the available Vb, or ~2.72ft^3 in a typical 8ft wall with studs on 16" centers.

GM
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#8 of 8 DustinF

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Posted November 04 2003 - 11:15 AM

Thank you for the replies. I guess I'll try the 871's and let you know how it turns out.