# the speaker placement baffle step compensation question



## kadijk (Jan 23, 2011)

Hello all. I am very new to this world of forums and online discussion, so bear with me please.
I am building a new home theater, the room is 20x20, and am planning to build the Zaph ZA5 speakers for the audio component. Here is my question...how significant is baffle step compensation an issue? My initial thought was to have the screen on a wall, speakers beside on a shelf across the whole front of the room. Rear ported speakers need to be approx. 6" from the wall, and so a 12" deep box is now 18" out from the wall. The solution is to make a screen wall around 18" forward, and have the speakers appear flush to the screen. So now do I build the speakers with an infinite baffle crossover? Or am I splitting hairs? Does a screen count as a boundary( I think it does) and the screen wall with hidden speakers, say behind cloth looks way better than looking at speaker drivers.

Can anyone give me some advice? Zaph, are you out there? Thanks
Kadijk


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## kadijk (Jan 23, 2011)

I need to add to my question. 

I think the right way to go with flush mounted speakers is the infinite baffle crossover. I wonder if anyone has experience with the ZA5 mtm design, and if the one particular to center channel could really be applied to front channels as well, having been optimized for dialogue and mid range sounds. I guess I don't want to end up with front channel speakers that have center channel crossover design...


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## 1Michael (Nov 2, 2006)

There is no Infinite Baffle Compensation Xover...You need the Reduced Baffle Compensation Xover.


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## kadijk (Jan 23, 2011)

Thanks for your response. 
My mistake, but I think you know what I mean. Zaph called it zero baffle step compensation, IE same as in wall. The more I think about it I am going to stick with my original idea, mount the screen on the wall, have the speakers on a shelf or stage, baffles around 18" out from the wall, and around 3' from the side corners. Then I can use the medium baffle step compensation crossover in the front channel speakers(mtm). Looking at pictures of other theatres on this site and around the web I think I am fortunate to have so much room to play with....I just want to do it right.

Kadijk


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## GranteedEV (Aug 8, 2010)

BSC is imo extremely important. 

If you have too much (IE even 3db BSC in an in-wall speaker or full BSC on a wall-mount) you will get a lot of bloatedness in not only bass but also the lower midrange. Male voices won't sound very good.

If you have too little, you will not only lack fullness and bass, but also have a lot of midrange "shoutyness".


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## kadijk (Jan 23, 2011)

I plan to build the ZA5 mtm and mtm center designed by john krutke. I think my situation will be suitable for those speakers with what he calls medium bsc. His research seems very reliable and I know someone who has built another of his designs and it's amazing( the budget mini).


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## GranteedEV (Aug 8, 2010)

kadijk said:


> I plan to build the ZA5 mtm and mtm center designed by john krutke. I think my situation will be suitable for those speakers with what he calls medium bsc. His research seems very reliable and I know someone who has built another of his designs and it's amazing( the budget mini).


Zaph is an excellent designer. I want to make the SB12.3 myself. 

My preference for BSC circuits is the way Kevin Voecks and Vance Dickason make them... with 'toggle' switches to let you change it on the fly depending on desired placement.a


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## fusseli (May 1, 2007)

From my personal experience: 

Full 6dB of BSC is probably too much for a speaker that's a foot or so out from the wall in a small room, sounds heavy in the midbass but is acceptable I'd say, especially with EQ to compensate. In a huge room, full BSC is probably a good idea for speaker out fromt he wall and corners.
No BSC for a speaker a few inches from the wall with a deep cabinet (putting the baffle 1'+ from the wall) will sound empty and hollow.
There are several ways to do BSC. Easiest and most accurate is integrated as part of the Xover, can also be done as a seperate series leg before the entire speaker (less accurate depending on how flat your impedance is), and lastly can be done as an L-pad but that depends strongly on the drivers and cabinet size.

From what I've read:

General BSC range for a speaker "in room" is generally 2-4dB.
Yes, your screen will be a boundary that will reduce the level of BSC you need if your speakers are flush with it.
Some level of BSC, even full BSC, is better than no BSC 99% of the time unless you're wall mounting or in-wall mounting.

Logically, depending on your AVR's room-correction ability, it's also possible an auto setup could flatten any speaker enough so that it takes care of BSC for you.




GranteedEV said:


> My preference for BSC circuits is the way Kevin Voecks and Vance Dickason make them... with 'toggle' switches to let you change it on the fly depending on desired placement.a


Making that accurate can be tricky and I think is best suited for a speaker who's step frequency falls right on an Xover point, so an adjustable L-Pad can be used for varied BSC.


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## 707kevin (Nov 5, 2010)

I ordered Reduced BSC ZA5.2s. Byt te time I built them, the furniture situation changed. Now I have them 10" from back wall, 14" from TV, and at least 4 feet to side walls.

The sound is a bit on the 'shouting' side, good way to describe it, in the mids.

Would it be worth the time/slight effort to change the xover? I tihnk only 2 or 3 components change. It would be cool to leave both setups in the xover selectable with a switch... hmmmm...


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## GranteedEV (Aug 8, 2010)

> Full 6dB of BSC is probably too much for a speaker that's a foot or so out from the wall in a small room, sounds heavy in the midbass but is acceptable I'd say, especially with EQ to compensate. In a huge room, full BSC is probably a good idea for speaker out fromt he wall and corners.


In my opinion speakers sound their best a good 3 feet away from any boundaries, so I would stick to full 6db BSC anyways. But everyone has their limitations and they're not always dictated by the audio aspect.



fusseli said:


> [*]There are several ways to do BSC. Easiest and most accurate is integrated as part of the Xover, can also be done as a seperate series leg before the entire speaker (less accurate depending on how flat your impedance is), and lastly can be done as an L-pad but that depends strongly on the drivers and cabinet size.


I would do it as an active 2.5 or 3.5 way...

Although I alluded to some passive versions of what I prefer, I think active is the way to go. Of course with kits you don't quite have that option.


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