Rock-steady speakers

Imagine:

Sitting in an average sized living room and your ideal choice of speaker drivers are mounted directly into the brick wall opposite you with no chimney breast to interfere with the stereo image.

What would this sound like? Better than floorstanding speakers?

Ta and merry Christmas!

 

A reviewer did this a few years ago, can't remember the chaps name, I seem to remember that he rather liked them. A few thoughts that I remember him commenting on was where to vent the rear sound to. In his case, he had a storage room behind the listening room. A major issue would be trying to get a predictable frequency response, bearing in mind the complexities of the "cabinet" that will be created (or not as the case may be).

 

Paul Messenger. Tannoy 15"ers.

 

Not sure what you mean by "ideal choice of speaker drivers". Are you thinking DIY?

There are several manufacturers who make good in-wall speaker systems. KEF, Tannoy, Linn, Focal JMlab, JBL.

 

You should hear the built-in speaker system PMC installed at the Radio 1 studio in Maida Vale...

 

Actually the plan has changed. The room I'm now thinking of installing the drivers in has a chimney breast. I'm considering setting up two thick shelves about a foot above each other on each side of the chimney breast and filling the space between the shelves with another piece of really thick wood. The drivers would be mounted in this front piece to bring them flush with the chimney breast.

I'm thinking the main issues would be:

-Avoiding creating boxy space below or above the structure which might cause standing waves - would it help to keep the drivers small (increasing the effective size of the enclosure?)

-Keeping the construction free from resonating as much as possible (using wood from reclaimed joists)

I don't know anything about venting considerations. Is it not possible to have a non-ported, non-vented design or would the air pressure behind the drivers interfere with their movement?

I need to look into speaker enclosure design obviously. I would be interested to hear if anyone thinks this idea is a good one fundamentally or is there a flaw?

 

Badger, what do you know about crossover design? I hope you know that you can not just stick some expensive drivers in a box and use some ready made crossover. You need to choose a crossover point that is suitable for the drivers and drivers that will work well with a simple active Xover. (if that’s the route you are thinking of taking).

You may get good results from some commercial speakers that are either front ported or closed and then mounting them in the wall. You can then use a simple filter to account for the bass response change. Some active speakers have this built in. PMC AML1 would be suitable.

 

Good point. I need to look into the right kind of crossover.

Really in a nutshell what I was asking is whether the shape of a design like this would have any downside that defeats the object. Recording studios have soffit mounted speakers in a flush wall but these are large speakers quite a distance from the listener. I've never heard a set of small drivers in a kind of half-soffit design. Has anyone done it before?

 

The main advantage is better control in the bass, and effectively, more bass because all of it is going towards you. You also get better directivity in the lower midrange, so you can get really good imaging.

Most studios have the walls angled inwards to aim the speakers so I'm not sure what you would do about that. I think the best solution is to brick up either side of the chimney completely and just remove bricks where the speakers go, placing a fully built speaker in the gap. i.e. don't just mount drivers in there and try to build the speakers from scratch. Doing it this way you could have a slight gap either side of the speakers to give a bit of toe-in. A few cm either side should have minimal effect on the sound. You would also be able to change speakers if you wanted to at a later time, provided you left some loose bricks to change the size/shape of the gap.

The PMC AML1 probably are a good place to start for an average size room. They have great bass already, and mounted in a wall they would have almost another 6dB headroom.

 

Hmmnnn. Don't think I want to actually reduce the size of the room though. Would a wide shelf be as effective with regard to the imaging do you think? Would the driver size in comparison to the shelf front area be a factor?? Ta

 

Not really, no, its the wavelength of the frequency that is the factor.

Am I pictureing what you mean correctly? Like this?



If so, then yes I expect imaging will be improved, but you may get odd diffraction issues at the top of the shelf for the midrange and treble. The bass would only get partly stronger. You could model the difference between a really wide, but not high baffle against a normal speaker baffle in 'The Edge' or BDS from FRD Consortium.

To be completely honest though, and without being rude, you don't seem to know what you need to know to pull it off properly so I'd suggest getting some good speakers and using them as intended.

 

Nope, you failed, it did sound rude.

If you're concerned that the poster doesn't have the level of knowledge required, why not post some links to sites where he can do further reading?

 

Oh well...

Because there is rather a lot to do and I'm not sure where to start. Also without experience of at least building some more 'normal' speakers and having a good measurement set-up it would still be a big shot in the dark.

By all means read up on all aspects of speaker design, www.diyaudio.com is a good place to start. But I think for actually getting good sound, buying a commercial speaker is a better route. That or building from an existing design to gain some experience. www.zaphaudio.com has some very nice ones.

www.bgcorp.com have some nice in-wall speakers under the ‘Radia Architectural’ name. How well they would work in an alcove I don’t know.

 

No worries. I understand there's more to speaker design than meets the ear. That's why I'm asking questions. If there's an imaging advantage to mounting pre-built speakers with the front face of them extended like the drawing across the wall this is an easy thing to do.

The drawing shows a larger woofer than I was imagining. I'd probably be putting them nearer the chimney breast given the size of the room. I'll take a look at those sites for more info. Ta.