Critic's Corner

That's completely wrong...

174.115.82.123

Doug Schneider

R

In Reply to: RE: An added complication is the non-linearity of the "Phenomenon of the 'Weak Fundamental' " posted by John Marks on July 21, 2024 at 07:56:50

It's often said that if you can blow out a fundamental premise of an argument, then the rest of the argument falls away: "As far as I know, there is no crossover-design software that can compute BSC."

Transitioning from a 4pi to 2pi environment is well known and is easy to computer model these days.

There is absolute no reason to not remove the baffle step if you want a proper response in a room.

Doug

Follow Ups:

RE: That's completely wrong... - tomservo 13:42:05 07/23/24 (1)
What one can do is take an anechoic measurement or one far enough from reflections for a crossover use, exported as a text file (freq/mag/phase) and use a program like LSPcad.

With a corresponding impedance measurement, one can use the computer to iterate to a target you set (like say flat response). This is the best tool for passive and some active crossovers i have run across and it can make this kind of passive filter's values a breeze.

Really.
- RE: That's completely wrong... - Doug Schneider 19:17:47 07/24/24 (0)
  Hi,
  
  Yes, interesting approach -- and it makes sense. Thanks. Obviously, crossover work takes a lot of work to dial in the sound just right, but the 50 hours to iron out the baffle step that John Marks talks about -- as well as the lack of tools to do so -- just isn't true.
  
  Doug
  SoundStage!
That was NOT the fundamental premise!!! - John Marks 15:27:05 07/21/24 (3)
I said "As far as I know," because I am familiar with only three such programs. "Auto-BSC" was not on any of the lists of features. I was talking about "Auto-BSC" and perhaps I was not emphatic enough on that. (I have no experience with the very expensive modules from Loudsoft.com. I am told that Harbeth uses those.)

I had a phone conversation with the designer of the program I believe to be the most respected package (X-over Pro version 3) and he said that it was not part of his software and that he did not envision it as a possible feature of any "Insert the data, press 'Process' and you get a crossover design" packages, because there are too many cabinet-related variables.

Regardless, my point was that Baffle Step Compensation, as important as JA and I (and apparently you) think it is, is not something that every loudspeaker designer thinks is worth the trouble.

I was surprised as all get-out when JA commented upon the apparent lack of BSC on a very expensive solid-rock-enclosure loudspeaker he was measuring. I thought that with all that money on the table, why no BSC?

"Though the response in the crossover region is flat, there is a broad peak in the upper midrange, which implies a lack of baffle-step compensation in the crossover. The tweeter's output between 5kHz and 20kHz is 3-5dB higher than it is in the presence region, almost matching the level of the midrange peak."

john
- https://www.stereophile.com/content/acora-srb-loudspeaker-me (Open in New Window)
- Not sure where you got this idea... - Doug Schneider 17:12:13 07/21/24 (2)
  "...is not something that every loudspeaker designer thinks is worth the trouble."
  
  I'm not sure how you can make a statement like that. That a designer doesn't think it "is worth the trouble"?
  
  It's about the behavior of the driver when it is attached to a box. Baffle step isn't some magic -- it's an acoustic result as the driver goes from radiating from 4pi (free space) to 2pi (half space), because of the baffle it's now attached to.
  
  On a freestanding loudspeaker, the choice not to compensate indicates not a design compromise, but a fundamental misunderstanding of how drivers work with their enclosures. Compensating is part of designing. And once again, this is an easy thing to model, even with a calculator and a piece of paper.
  
  Doug
  SoundStage!
  - Whoa - John Marks 18:15:47 07/21/24 (1)
    You complained about:
    
    "I'm not sure how you can make a statement like that. That a designer doesn't think it "is worth the trouble"?"
    
    Did you read my reply, in the context of JA's statement about the Acora Rock Box???
    
    Are you privy to some double-secret explanation why the Acora Rock Box had no BSC?
    
    john
    - Nope, Didn't... - Doug Schneider 18:43:04 07/21/24 (0)
      Nope, didn't read your reply in the context of anything but what baffle step compensation is and why it has to be dealt with.
      
      Doug
      SoundStage!

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