Will Mcacc and/or Audyssey make baffle step compensation unnecssary? - AVS Forum
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post #1 of 13 Old 02-20-2013, 10:34 PM - Thread Starter
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I'm in the process of designing and construction of a 2-way speaker system.
I'm using a Beyma 10BR60V2 woofer and a Tang Band 28-537SH tweeter.
The box will be sealed 2.7 cu. ft. The front baffle will have minimal surface area beyond
the outer circumference of each driver.
If the sealed box is made smaller than optimal (purposely) using WinISD to create a 3 db upslope as the Hz goes down,
Is that a sufficient way to overcome the baffle-step phenomenon?
Or can I use Mcacc to compensate for the Baffle-step phenomenon?
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post #2 of 13 Old 02-21-2013, 05:42 AM
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Baffle step should be measured and not estimated. The theories used to calculate baffle step don't accurately reflect what occurs in a real placement.

Baffle step is function of boundaries with the baffle only one of them. If the woofer is near the floor or ceiling or if the speaker is near a wall you will likely need far less. The only way to get it right is to measure. Where will the speakers be placed relative to boundaries?

As far as whether the room correction in an AVR will adequately compensate for this, I can't say for sure. In theory, it should compensate but my experience with Audyssey says the results can vary greatly. Are you designing a passive crossover or active DSP?
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post #3 of 13 Old 02-21-2013, 05:46 AM
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Quote:
Originally Posted by LINEARX View Post

Is that a sufficient way to overcome the baffle-step phenomenon?
If you want to push the baffle step to a lower frequency make the baffle larger. If you want to eliminate it flush mount the cab into the wall. Otherwise you must use BSC in the crossover to reduce the sensitivity of the speaker above the baffle step frequency, or EQ it to arrive at flat response. But BSC has an inherent flaw, as it doesn't consider Allison Effect losses when the baffle to rear wall distance is 1/4 wavelength, and rear wall reflection augmentation where it's closer than 1/4 wavelength, so I don't use it at all. So long as you have an EQ you might as well use it, but be aware that no EQ can compensate for Allison Effect, so you need to consider that from the beginning of the design process.

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post #4 of 13 Old 02-21-2013, 06:02 AM
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Quote:
Originally Posted by LINEARX View Post

Is that a sufficient way to overcome the baffle-step phenomenon?
You didn't mention the baffle size or proximity to the surrounding boundaries.
Before it became common place to make such compensation a permanent function of passive crossovers - it was addressed ( when needed ) with an adjustment of bass.
My mains are in-wall and I wouldn't switch - but it's not practical for everyone.

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post #5 of 13 Old 02-21-2013, 06:12 AM
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I would definitely not use an undersized box...bad band-aid. As said before, design the crossover for the environment and/or use EQ.

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post #6 of 13 Old 02-21-2013, 07:39 AM
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Quote:
Originally Posted by LINEARX View Post

Or can I use Mcacc to compensate for the Baffle-step phenomenon?
In my experience, it doesn't do a good job compensating for a lack of BSC. It may just regard the speakers as small or LF limited and recommend a crossover frequency higher than desired.

Mike
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post #7 of 13 Old 03-29-2013, 10:13 PM - Thread Starter
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Thanks for the reply s.
I have the space to place the speakers at the wall or in front.
I'm still in construction stage and only have the first cab built.
It sounds like the MCACC can adjust for BSC after experimenting with the first cab.
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post #8 of 13 Old 03-30-2013, 05:34 AM
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What exactly is baffle-step compensation and how is it implemented in a crossover, both passive and/or active?
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post #9 of 13 Old 03-30-2013, 05:54 AM
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Quote:
Originally Posted by Martycool007 View Post

What exactly is baffle-step compensation and how is it implemented in a crossover, both passive and/or active?

Marty - Here is a rather simplistic explanation of BSC:

http://www.salksound.com/wp/?p=42
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post #10 of 13 Old 03-30-2013, 05:58 AM
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Quote:
Originally Posted by Martycool007 View Post

What exactly is baffle-step compensation and how is it implemented in a crossover, both passive and/or active?
Above the baffle step radiation is half-space; that frequency is where the baffle is one wavelength wide. Below that frequency there's a transition to full space radiation, which is 6dB lower on-axis than half-space. The crossover may be configured to attenuate axial response above the baffle step to realize flat axial response throughout the speaker bandwidth. But there's a major fly in that ointment, that being room modes, especially the reflection off the wall in back of the speaker. If the baffle is less than 1/4 wavelength from the wall that reflection in and of itself compensates for the baffle step. To get perfectly flat response in-room requires that baffle step compensation be performed with the speaker in place. We used to do that by externally mounting the crossover, allowing relatively easy component swapping. Inveterate tinkerers were known to do so for weeks, if not months or years. With DSP it's a lot easier to ignore BSC entirely and use the DSP to get flat in-room response.

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post #11 of 13 Old 03-30-2013, 06:29 AM - Thread Starter
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Quote:
Originally Posted by Bill Fitzmaurice View Post

We used to do that by externally mounting the crossover, allowing relatively easy component swapping. Inveterate tinkerers were known to do so for weeks, if not months or years. .

`
What did you mean, "used to do?". I'm there NOW!
I've spent more time on this "project" than any before trying to capture that perfect combination of Capacitors, Resistors, and Inductors while reaching for that magic audio nirvanna!
It seems the more capable and more numerous my test equipment, the more DIFFICULT it is to find simple answers.
Then you end up using your (own ears) and possibly younger ones to make the final judgement.
What I might add for other "inveterate tinkerers" would be to:
buy CHEAP, yes I said cheap, components for the needed x-overs until yer absolutely convinced you've got it right. THEN go out and buy the 14 gauge perfect lay inductors, the non-inductive resistors
and the special boutique capacitors .
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post #12 of 13 Old 03-30-2013, 08:37 AM
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Quote:
Originally Posted by LINEARX View Post

`
What did you mean, "used to do?". I'm there NOW!
I too used to diddle with crossovers incessantly before DSP. That was then, this is now. What could take months of fiddling to do with a crossover I now do in thirty seconds with an RTA and DSP.

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post #13 of 13 Old 03-30-2013, 08:40 AM - Thread Starter
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I got RTA and DSP and STILL diddle.
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