Focal In-wall speakers

T

Truett

Enthusiast
The Focal 1000 ICA6 angled height/ceiling speakers are open in the back. If I have plenty of room would it be better to build a box for each of the speaconstructions. Also, is it good enough to just attach these to the sheetrock like the instructions say?

The Focal 1000 IW6 surrounds come with a built-in 4" backbox. If I have plenty of room (10" walls) should I cut away the built-on backbox and build larger ones? I have heard complaints about 4" box constrictions.
 
Last edited:
TLS Guy

TLS Guy

Seriously, I have no life.
The Focal 1000 IA6 angled height/ceiling speakers are open in the back. If I have plenty of room would it be better to build a box for each of the speaconstructions. Also, is it good enough to just attach these to the sheetrock like the instructions say?

The Focal 1000 IW6 surrounds come with a built-in 4" backbox. If I have plenty of room (10" walls) should I cut away the built-on backbox and build larger ones? I have heard complaints about 4" box constrictions.
The problem is that you don't know the Thiele/Small parameters of the drivers, so you can't calculate the correct volume of the back boxes. The box has to enclose the correct volume of air and damping. You can measure the T/S parameters with the right equipment, or Focal may tell you, if you ask them.

Certainly the correct size of back box is the way to go. Personally I think firing drivers right into the wall space is an awful idea. So when I designed and built mine, all drivers were loaded by the optimal sealed box and I designed with drivers with optimal T/S parameters for sealed loading. I personally think mounting in wall speakers to sheet rock is a terrible idea. I have to say I think most in wall systems are half baked, and not well thought out. So the old adage applies, if you want it done right do it yourself.













That is my wife's system, designed and built for this large space at her request, and powered with 1000 watts all channels driven. She loves it. I get to play and watch what I want in our AV room. We were both in the AV room this evening.

In wall systems are a little tricky and present there own unique challenges.
 
T

Truett

Enthusiast
The problem is that you don't know the Thiele/Small parameters of the drivers, so you can't calculate the correct volume of the back boxes. The box has to enclose the correct volume of air and damping. You can measure the T/S parameters with the right equipment, or Focal may tell you, if you ask them.

Certainly the correct size of back box is the way to go. Personally I think firing drivers right into the wall space is an awful idea. So when I designed and built mine, all drivers were loaded by the optimal sealed box and I designed with drivers with optimal T/S parameters for sealed loading. I personally think mounting in wall speakers to sheet rock is a terrible idea. I have to say I think most in wall systems are half baked, and not well thought out. So the old adage applies, if you want it done right do it yourself.













That is my wife's system, designed and built for this large space at her request, and powered with 1000 watts all channels driven. She loves it. I get to play and watch what I want in our AV room. We were both in the AV room this evening.

In wall systems are a little tricky and present there own unique challenges.
Nice! In a couple of places we will be installing these open back speakers where most all of the sheetrock will be removed, leaving just enough sheetrock or board to mount the speaker on. Everything else will be insulation behind and all around and covered with fabric. So the sound from the back of the speaker will be able to come out to the room. Is that okay?
 
TLS Guy

TLS Guy

Seriously, I have no life.
Nice! In a couple of places we will be installing these open back speakers where most all of the sheetrock will be removed, leaving just enough sheetrock or board to mount the speaker on. Everything else will be insulation behind and all around and covered with fabric. So the sound from the back of the speaker will be able to come out to the room. Is that okay?
No, that is not OK! That is totally wrong. The sound from the back of the speaker is 180 degrees out of phase with the front. So the rear wave will cancel the front wave, reduce output and make a really lumpy response.

In a reflex, ported cabinet, the design invers the phase from the rear of the driver, and what come out of the port is in phase with the front of the cone.

So you must adsorb the rear radiation.
 
T

Truett

Enthusiast
No, that is not OK! That is totally wrong. The sound from the back of the speaker is 180 degrees out of phase with the front. So the rear wave will cancel the front wave, reduce output and make a really lumpy response.

In a reflex, ported cabinet, the design invers the phase from the rear of the driver, and what come out of the port is in phase with the front of the cone.

So you must adsorb the rear radiation.
So do I fix that by making a box? Maybe one cubic foot?
 
TLS Guy

TLS Guy

Seriously, I have no life.
So do I fix that by making a box? Maybe one cubic foot?
I can not possibly guess. I have no clue as to the Thiele/Small parameters of those drivers. Much hunch is that 1 cu.ft. is likely far too small. If you can get Focal to give you the parameters of those drivers, I can calculate the optimal box for you. I suspect a box that small will really honk, but that is just a guess.
Making a good in wall system is a difficult challenge.
 
T

Truett

Enthusiast
I can not possibly guess. I have no clue as to the Thiele/Small parameters of those drivers. Much hunch is that 1 cu.ft. is likely far too small. If you can get Focal to give you the parameters of those drivers, I can calculate the optimal box for you. I suspect a box that small will really honk, but that is just a guess.
Making a good in wall system is a difficult challenge.
Without that specific information can I just go big? Make it two or three cubic feet, for instance? Maybe put some insulation in the box?
 
TLS Guy

TLS Guy

Seriously, I have no life.
Without that specific information can I just go big? Make it two or three cubic feet, for instance? Maybe put some insulation in the box?
You will need damping material for sure, like Polyfill. The enclosure has to have the correct volume of air. The drivers are powered weights on a Spring. This combination of weight and compliance of the suspension define that part of the spring. Now when you place it in the sealed box, the enclosed air is also a spring. Now the 'Springiness' of both the driver and enclosed air, define the performance of the speaker, especially the low end response. So the enclosure parameters must match the driver parameters. That is why the Thiele/Small parameters must be known or measured. Then you can design the speaker.

I would bet that Focal can supply the information you require.
 

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