Building an enclosure for In-walls

[Ceruleance]

What are everyone's thoughts on building an enclosure to house an in-wall speaker. The way ebay works it may be cheaper to get an in wall speaker with drivers that match my front soundstage and then build an enclosure for it. I move my system very often and rent, so actually installing in-wall speakers is not an option.

Let me know what you think.

Oh, please no "Uh, it's not designed for it, so don't do it "
responses. This is completely obvious, I want to know the actual drawbacks

[RuSsMaN]

Drawback, albiet possibly minor, will be low-end response. If the in-wall speakers are truely designed as infinate baffle.

Not saying it couldn't work, but what is the budget, and what are you trying to match (on the front stage)?

-Russ

[Ceruleance]

I want CMMD (ceramic metal matrix design) drivers to match those of my infinty interludes. (Polk's Tri-Lams sound crappy with them ) I want bipolar/dipolar rear surrounds, which i thought i might be able to make out of a set of some cheap bookshelves. Currently the in-walls with CMMD are too high, but i think the price could come down drastically, as the current outdated inwalls sell for like 30 bucks a pair.

This all may be null and void as I bought Fosgate Audionics SD 180's yesterday and I am waiting for their arrival. I have no idea what they will sound like, so who knows.

The only bipolar/diploar speaker with CMMD that infinity has ever produced is the Alpha 25ES. There are very few of them around and I absolutely cant find them for less than $400, which I think is too much to pay for a surround speaker, especially one that only handles 125 watts.

I am also trying to find a pair of Interlude IL10's that I can drill holes in and mount on the wall, but I am waiting till I can get a pair in Maple, for less than a benjamin.

[gidrah]

You might be able to build something with either a large enclosure or something that left the back open. The front baffle would need to be relatively large and preferably not have equal distances across the front.

[Ceruleance]

do in walls work well suspended with no enclosure?

i.e. just fix them with a bracket so they are hanging in mid-air 6 inches from the wall

[gidrah]

but to make them sound their best your gonna need a front baffle of some sort to stop the front and back waves from intereferring/canceling one another.

[madmax]

If it helps, the enclosure a wall provides is about 2.7 cubic feet. 14.5" X 3.5" X 7.7'. If it is a woofer designed for infinite baffle then the area doesn't matter so much but you still need to separate the sound as gidra suggested.
madmax

[Ceruleance]

aha, this is making more sense, thank you.

If I were to mount the speaker perpendicular to the wall, wouldn't I have in essence, a Di-pole speaker? (sound radiates in two directions, out of phase from each other)

[burdette]

Originally posted by Ceruleance
If I were to mount the speaker perpendicular to the wall, wouldn't I have in essence, a Di-pole speaker? (sound radiates in two directions, out of phase from each other)

Not really... you'd still be using only a single driver, and it wouldn't be loaded in any way at all (i.e. no volume of air behind it).

You may be able to build a workable enclosure. The first thing I'd do is contact the manufacturer of the speaker and try to get some T/S parameters for the driver - that would give you the best chance of designing a decent enclosure. If you can't get the information, then you're just going to have to punt. 2.7ft3 is a large box.. much larger, I'd wager, than anything you want to have in an apartment for surrounds. Example.. a cabinet 30" high by 15" wide by 10" deep (internal). Also, I don't think it practical to try to use a baffle large enough to try to simulate an IB alignment. You could maybe get a quasi-IB alignment if you use a sheet of plywood....

What specific in-walls are you considering?

[Ceruleance]

infinity ERS 110 / 210

[burdette]

If you want to, contact Infinity, and try to get to a technical person past customer service. Specificaly ask for Inifinity Design or engineering. Ask them if you can get any of the T/S parameters for the mid/woofer. If they balk at that information, ask them outright about a box size. They MAY be helpful.

Also, if you really really want to do this, the T/S parameters can be measured. I can't do it.. don't know if anyone on this forum can.. but I'd think we could find someone at the PE or HT forums that would do it for you if you removed and shipped him a driver.

Per your original post... the drawbacks are that if you use a box that is not appropriate, the speakers (at least the mid/woofer) will sound like ****. Those speakers don't look like they have a port, which means a sealed box.

If you've the time and the shop, build a simple MDF box about the size you're hoping for .. the size you'd like to work with in your room (I assume pretty small). You can then experiment with amounts of stuffing and decide if you can get to a sound you like.

On the positive side... there is no way that Infinity can guarantee what volume enclosure these speakers will have for any given particular application. A particular internal wall location in my house could easily have smaller or larger volume than one in yours due to a variety of things (2x4 studs vs. 2x6; wall height; wiring; holes through to other spaces; insulation; etc). Therefore, I'd think.. I'd hope.. that Infinity designed them to work reasonably well within a zone of volumes. That is a good thing. However, even an internal wall volume on the small side is going to be quite a bit larger than a small box just large enough to hold that system (and I assume you'd want it pretty small to use as a surround given your circumstances).

I think you need to decide how much you REALLY want this. If you really really do.. then I think the first thing I'd do is build a small 'surround sized' enclosure and mount a speaker, experiment with the amount of stuffing, and see what you get.

EDIT: the FIRST thing I'd do is call Infinity. If you get T/S parameters, you're in business.

I love this sort of stuff, so if you decide to proceed I will assist in any way I can.

[RuSsMaN]

Great advice Mark.

You've got me thinking of doing a big, ugly plywood IB with some 5.25" fr's I've got laying around.

[burdette]

Check these out, Russ.

http://www.pesupport.com/cgi-bin/config.pl?read=126668

You wouldn't have to go with the froofroo colors... and they could easily be larger. These are RS 8" full range... there are a lot of projects on the PE forum using the 10-for-$5 Pioneer 4" full range. You could build a pair of 901s!


Hey, thank you for the music connection. Shaun Mullins' kind of music is the reason I own good loudspeakers. You can hear his fingertips scratch on the strings... I think my wife will really like this also. (I have to go back now and listen to all the evens.)

[RuSsMaN]

I bet it's the best $10 he's ever spent.

Heres another cool IB link:
http://member.nifty.ne.jp/Jiya/ehtml/sp.html#GSP

Scroll that one for a minute or two....

[Ceruleance]

Thanks for your help guys.

My conclusions:
1. There is a lot of work involved in getting it to sound right
2. I dont mind doing this work, but my main goal is cost vs. performance, and so it's all going to depend on how cheap the CMMD in walls get over time. as of now a pair is going to set me back $160, if they get down to the price of the previous, now outdated ERS series, I will definitely pick up a pair and try it out for $30
3. Mainly, I was just thinking out loud and interested about the possibilities, more than I was seriously contemplating doing this in the near future. I'm just hoping that the Fosgate's I bought recently will work out and I will like the way they sound.

[gidrah]

Russ- Thanks. If that guy EVER gets me the final cost and and address for payment, you can have some 8"ers, or I've got some 6"ers you can have.

Burdette- Those RS speakers are highly regarded if my mind serves me correctly. Unfortunately I've lost mine too. Cheap 4" Pioneers would make for a splendid array. Thanks!

All- I jammed to these Tannoy babes @ Midwest AudioFest.
http://img.audioasylum.com/cgi/view....e=&w=800&h=491 These with a diy sub, gainclone amp, and diy (twisted magnet wire and cheap RS plugs)ICs stole the show for sound/$. He (Kurt Chang) was using thicker magnet wire for speaker wire. I picked up a pair of these RS tweets for my IBs when I get them going.

Let me make it official. I hereby suggest that everybody try to listen to some full (actually wide) range speakers. These can be had pretty cheap at RS close-out prices or E-bay. I'd even suggest some 2-ways that use a quality compression driver for the middle/top end. It removes the x-over from the vocal range. Unless of course you have some rare Barry White & Cyndi Lauper duet.

Ceruleance- Sorry about the derail, but I think most questions have been answered anyways. I just thought of this one though. You might be able to put these on a triangular board and mount in the corners which have plenty of unused volume.
I knew that Fosgate made home electronics, but haven't heard any of their speakers, good luck.
Ski

[Ceruleance]

yup, all my questions answered, besides now i have a new project, RABOS calibrating my powered towers and sub, another infinity thing.. parametric equalizer in fancy clothes. Just got done with the test run, bass is definitely flatter with no peaks, but no impact, cause RABOS CD made me turn down all the amplifiers (I had them on like 2 out of 10, now they are on point 5) I think RABOS is trying to tell me something about the quantity of bass in my modest room. If you have never heard of RABOS, this probably doesnt make any sense, but whatever