In wall speakers

I am helping my neighbor, Dana, an experienced woodworker, design and build a home theater. It is going to consist of five in wall speakers and a sub. The in wall speakers have a seas tweeter and an audax 5 1/4" woofer. The woofers will go in a ported box of a little less that .2 ft3 and have a f3 of around 80 Hz (very well damped speakers, total Q is .25). The sub will be a blueprint 1201 powered by a dayton 250W sub amp. The amp has a variable lowpass xo that I can match to the speakers' mechanical roll off.

Now I have never done an in wall speaker before. What do I need to know? Vibrations?
I also need some help with the mid/tweet crossover. The 6 ohm tweeter is about 2db louder than the 8ohm woofer. I also want to cross over as low as possible to keep dispersion at a max.
I would flatten the woofer's impedence, adjust tweeter level, and make a 2nd order LR filter centered at 2.5 kHz. That's about all I know how to do. No baffle-step, because it doesn't really have a baffle.

What would you guys do? I don't have much in the way of measuring equipment(SPL meter, frequency generator/counter, and a multi-meter), and I'm not buying anything unless it's really really cheap:D .
Thanks in advance,
andy
 

pinkmouse

diyAudio Moderator Emeritus
2002-04-03 7:15 pm
Rotherham, England
Hi Andy,

Sounds like an interesting project...

I don't know much about crossovers, but this sounds to me like an ideal use for actives, that way you should be able to set your levels easily with gain pots, and just using tones and your level meter around the crossover point get a fairly good balance, as any variations in sensitivity of your spl meter are liable to be at the frequency extremes, and therefore you shouldn't need to work out a correction curve for any measurements taken.

As regards boxes, the main influence will be the depth of the wall, as having the rear panel of the enclosure too near to the front could result in reflections interfering with the drivers and causing cancellations, etc.

If you have a shallow stud wall, I would mount an angled baffle behind the driver to defelct the rear radiation from the driver down (or up!) away from the driver.

Fixing the enclosures into the wall would be a matter of trial and error, as it all depends on how rigid each wall is, and they all likely to be different.

If you have masonry walls, you should mount each one directly to the wall, as this will maximise damping of the enclosure.

With stud walls, screwing directly to the framing may prove effective, or it may be worth using a surrounding box lined with stiff foam, such as flightcase foam, in which your main enclosure is a very tight fit.

hope this gives you some food for thought...

Cheers

Al
 

pinkmouse

diyAudio Moderator Emeritus
2002-04-03 7:15 pm
Rotherham, England
Ah, but speakers in walls could be ideal, just think no edge diffraction problems, and the achievability of rigid mounting, not to mention all the cables, stands and speakers cluttering up the floor,( increased wife/partner approval factor!!!).

However you do lose all the tweakability of changing cables, stands, toe in etc..

Al
 
Pinkmouse:

Theater, as I have spelled it, is correct. Consult a dictionary if you don't believe me.

In-wall speakers are for the masses, it make the requirements of multi-speakers more digestible. For almost two decades now, audio reproduction perfectionists have known that speakers against a wall are a no-no if a believable sound stage is to be established.

I had heard a rumor that one person still has their speakers in the corners of the room. Are you that person?
 

pinkmouse

diyAudio Moderator Emeritus
2002-04-03 7:15 pm
Rotherham, England
Bill,

Yes, if you use Websters rather than the Oxford English Dictionary, ( grins and ducks!)

Seriously though, I have speakers set well into the room with loads of toe in to get a good stereo soundstage in my room, and I know what you're saying, but I am open minded enough to wonder if in wall speakers may have some of their own advantages.

I don't know, I have never tried it- have you?

Cheers,

Al
 
I didn't notice until now that you are in the UK. We'll call it a draw.

Sure, in-wall speakers have their advantages as you well pointed out; no stands, no wires to trip over, etc. And, there is no reflection from the rear wall to provide a delayed signal which, when combined with the direct sound from the speakers, can add to or subtract from the already existing irregular frequency response due to the reflections from the floor, side walls, ceiling and rear walls. In addition, in-wall speakers, particularly if they are in the corners and even more so if they are in a tri-corner do sound quite a bit louder, perhaps an important point considering some of the wimpy home theatre electronics available.

So, back to Bostarob. You ask what we would do, home theatre wise.

Here's what I do. I don't have in wall speakers. I bi-amp. I don't have ported speakers. I have 2 12" woofers per channel. I avoid 5.1, 6.1 or 7.1 and I guess next week they'll have 8.1. I don't want anyone but myself to manage my bass. My home theatre system kicks *** and does so because I have avoided all the ********. My VHS driven system beats the **** out of every DVD HT system I've every heard and I saved a ton of money. It is my opinion that current home theatre technology sucks. Remember when CDs first arrived? Just awful sounding. Now we get to do it all over again; lots of fluff and bells and whistles but no meat. Gentlemen, we are being taken for a ride . . . again. Promises, promises, promises and the check is in the mail.
 
Bill Fitzpatrick said:
I didn't notice until now that you are in the UK. We'll call it a draw.

In Canada we say that "theatre" is the Brit spelling, and "theater" the Yank spelling, and then go ahead and use either.

In wall speakers have some big advantages. I have built a few hang-on-the-wall-like -a-picture speakers, and own a semi-commercial pr designed by a friend. Because they are at a room boundary they cause maximum excitement of the standing wave that they sit at the end of. This can make them tricky to sound right -- if you are designing the room you could make sure the far end of that axis is severely non-parallel.

They can be made to image -- it's just not as easy as when you can pull the speaker out into the room. You should build the speakers into an appropriately thin/wide enclosure that is independent of the walls, and placing them in front of the wall listen and tweak their placement before you commit to installing them. If the box is of any volume it will get tall and you may want to take advantage of the 1/4 wave resonance.

dave

PS: Bill, your signature is almost the same as mine -- i know where mine came from, where did yours :^)
 

pinkmouse

diyAudio Moderator Emeritus
2002-04-03 7:15 pm
Rotherham, England
Thanks Dave for your profound comments...

Sorry Bill, I sometimes forget that you folks over the pond are too pleasant and good natured, and so have no need for satirical humour.

I wasn't trying to get into an argument with you, but just trying to help Andy out with what struck me as some reasonable advice on the topic he asked about, rather than holding a debate on the pros and cons of such a system.

Personally, unless I could build a specific room from scratch, bearing in mind Dave's comments and some other ideas of my own, I would never use in wall speakers, but I am fascinated with the idea, and wish Andy and Dana the best of luck, and I hope they will achieve their objectives, whatever they are.

Cheers

Al
 
Bill-Your home theater sounds great. Sounds like something I would like.
lots of fluff and bells and whistles
but no meat
Simpler the better!
-Bi-amping is great, just ask Dave. However, Dana already has one of those dvd player/integrated amps that he picked up for [guess] $3-400. This is a budget system, so no bi amping. He is trying to keep this project around $1000.


Dave-the room is a small study. Standing waves, from what I gather, will be nasty. I will, of course, listen before mounting. What else can I do about standing waves that will not disgust Dana's wife? (In spanish, the word for wife is the same as for handcuffs)

pinkmouse, thanks for all of your kind words. We will have to mount into the studs.

Good sound is not on the top of the list in this project. This we must remember. Time, money, and wife are the most important. Dana's wife does not want her walls ripped apart and our project 95% complete.

I never got any feedback on the filter...
Thanks again, all
andy