Confused concerning baffle step compensation

[ModMark]

At a high level, I understand the need for baffle step compensation in the crossover.

I want to replace my "evil eyeball" speakers (Klipsch quintet's) with a pair of Nat p's and a MTM center channel. My wife came up with the 'eyeball" comment so she was not impressed with these micro speakers...

The concept I am working on, I want to build an entertainment system with the Nat P's (front port tower design) and sealed center channel built in. The cabinets will be 24" deep and attached or next to the wall.

But internally, the volume for the speaker section of the cabinet will be as the designers recommend. Basically the speakers will be a separate box inside these rather large cabinets.

So the center channel for example will be a 2' deep by ~5' wide box with the speaker box inside . Same for the Nat P's.

Should the cross over which includes baffle step compensation for this design? What is the determine factor, having an open space behind the speaker or how far the baffle is from the wall?

[Bear]

I suspect this might be a valid starting point:

http://sites.google.com/site/undefinition/diy-faqs-provendesigns

After that, a quick perusal of the in-wall/on-wall design is probably in-order.

http://www.htguide.com/forum/showthread.php4?t=22626

For in-wall/on-wall, you want your cabinet to mimic -- a wall. BSC will be basically non-existent in such a design, but the details are there in the second thread.

[kvardas]

For my two-channel audio system, I pull the M8ta speakers about 3 feet away from the wall.

For my HT system, the speakers sit in cabinets within openings of my entertainment center. My A/V receiver provides the ability to cross the speakers at 60 or 80 hz. I find a 60 hz crossover point eliminates the BSC issue with on- or in-wall placement.

[---k---]

This is the exact same type of post as made 4 days ago by 'ctf'.

There are some excellent responses and suggestions to him there. Make sure you check it out.

[ModMark]

Thank you Mr. K

I did go back 4 days and read your post concerning Mr Toole analysis. Pardon the pun but what baffled me is why "on the wall" is the same as "in wall". And sure enough, figure 12.9 show a difference as "on the wall" mounting would not be a true 2 pie space. Darn close.

So to answer my question, we have a Nat P crossover designed to work in 2 pie space and another for ~4 pie space. As the speaker moves closer to the wall ie: 2 pie space, you are on your own and should learn how to design you own cross over.

I solved my "wife issue" by suggesting a true in wall design. Great she said, we can get speaker cloth which matches the curtains.

What speaker cover I relied... Back to the drawing board.

Thanks again....

[---k---]

So to answer my question, we have a Nat P crossover designed to work in 2 pie space and another for ~4 pie space. As the speaker moves closer to the wall ie: 2 pie space, you are on your own and should learn how to design you own cross over.
.

You must remember, there is perfect and there is good enough ... and often the difference between the two isn't as much as many of the internet parrots would have you believe.

[ModMark]

For in-wall/on-wall, you want your cabinet to mimic -- a wall.

My design goal is to build some Nat P towers into some type of entertainment center. An entertainment center which mimics a wall may look like a plain wall. And to be honest, building walls is quite easy and I was looking for something more challenging such as an unit where the Nat P's are away from the walls ie: operating in that ~4 pie space.

But concerning your dig against us newbies..

For my self, the appeal of DIY speaker is building a great sound system integrated into my family room. I gutted the majority of the rooms in my house and remodeled with extensive use of molding. I even made my own crown molding out of MDF, my poor router was hurting after that.

So building a black box with a high gloss 2K poly is easy, designing and building an entertainment center with elaborate molding is a challenge.

[ModMark]

You must remember, there is perfect and there is good enough ...

Understood Mr K, close enough for exploding grenades on my DIY 12" sub woofer which by the way, did get the wife approval. Nice plant stand she said...

Now can I ask for your opinion, if I was build a Nat P tower (front ported) and the front baffle was 26" away from the wall.

which crossover would you use?

[Bear]

My design goal is to build some Nat P towers into some type of entertainment center. An entertainment center which mimics a wall may look like a plain wall. And to be honest, building walls is quite easy and I was looking for something more challenging such as an unit where the Nat P's are away from the walls ie: operating in that ~4 pie space.

But concerning your dig against us newbies..

For my self, the appeal of DIY speaker is building a great sound system integrated into my family room. I gutted the majority of the rooms in my house and remodeled with extensive use of molding. I even made my own crown molding out of MDF, my poor router was hurting after that.

So building a black box with a high gloss 2K poly is easy, designing and building an entertainment center with elaborate molding is a challenge.

It's not a dig. It's an all too common question for people just getting into the hobby, myself included (I may have had more background in the electrical side than most, but I've had to climb a learning curve the same as everyon else, and I still have a LONG way to go).

Beyond the basic electrical control over the drivers, the crossover also often supplies a filtering function for issues like baffle step and edge diffraction. There are multiple posts here and elsewhere talking about why changing the baffle dimensions essentially requires a complete re-work of the design. For high-quality designs, the hard work often is not in the basic crossover implementation, but in controlling for the cabinetry and ambient environment (e.g., floor bounce).

Look up the "Blackbird" project. It was Zaph's SR71 design for use in an entertainment center. That should help with some of the issues about what can and can't be done. The bigger and more elaborate your cabinetry, the more you will deviate from the design intent. Smooth fronts and recessed handles are good. Lots of hardware and detailing will begin to add diffraction and/or resonance.

As --k-- indicates, though, there is perfection and then there is good enough. If you want good enough, then go with what makes you happy. If you need to adjust later, you know some of the assumptions that need to be addressed to remediate any performance issues. I did highlight something in your post, above, that may be more true than you currently appreciate.

[---k---]

Understood Mr K, close enough for exploding grenades on my DIY 12" sub woofer which by the way, did get the wife approval. Nice plant stand she said...

Now can I ask for your opinion, if I was build a Nat P tower (front ported) and the front baffle was 26" away from the wall.

which crossover would you use?

You got yourself a keeper there! :T

I believe that Jon designs for the front to be about 3' from the wall. Here is a great post about boundary effects by Jon. It might give you some insight to his thinking.

http://www.htguide.com/forum/showpost.php4?p=138262

If the front of the speaker is 26" away from the wall than I would definitely use the original crossover. With that much space behind them, I wouldn't worry about a rear port either. I don't think you'll have a problem at that distance, but as Toole points out that if you do, that is exactly what the tone control on your receiver is for.