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  • Baffle step for Pro Audio gear?

    This is probably a dumb question, but is there any need for baffle step compensation when designing a crossover for PA speakers? I would assume the answer is 'usually, no..' but I might be wrong. Adding BSC would drop the overall sensitivity of the system, so I would think it advantageous to not add any in the first place and keep the system as efficient as possible, then EQ on the spot.

    I'm building two satellites with a subwoofer using Dayton PA 10" woofers crossed to Selenium tweeters for the mains and a PRV 18" for the sub. I'll be running them with an iNuke 3000DSP, so I assume that I can adjust the equalizer in the iNuke to compensate for any bass lost between 200-300 hz. Right now, baffle width will be ~14" for the mains and the sub will handle (hopefully) up to around 200 hz. So I'm thinking that a small boost of around 2db in the 200-300 hz range will take care of any baffle step that would have otherwise been needed.

    Of course, I understand that EQ will be needed to setup properly for each venue that these will be used at, but I'd like to get them close to a flat frequency response to begin with. Right now, modeling for the Dayton 10" woofers shows a 1 - 1.5db boost between 90 and 200 hz in a .7 cu.ft. sealed box. Or 1 db in the same range in a .8 cu.ft. box.

    This arena of music is new to me and this is just a fun project. But it's easier to do something right (or close to it) the first time than redo it... Kinda like the first two sets of bookshelf speakers that I designed that had almost zero baffle step built in. They sounded great and could play decently low, but they sounded really thin down low since there was no BSC. Since one set was an MTM, they were adequate but with a few tweaks could have sounded much better.

  • #2
    Re: Baffle step for Pro Audio gear?

    BSC isn't used in pro audio as the necessary EQ for correction isn't optional equipment, it's mandatory.
    www.billfitzmaurice.com
    www.billfitzmaurice.info/forum

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    • #3
      Re: Baffle step for Pro Audio gear?

      No baffle step is not used in Pro audio outside of maybe with a passive studio monitor design. With PA speakers systems you will find the acoustic response of the whole system often has a significant bass boost.. meaning subs are often run upwards of 10db hotter than mains and the resulting overlap will fill in most of not all of any baffle step loss from the mains. And as Bill has already noted it is senseless to throw away 3db or 6db of sensitivity across the whole spectrum when you could easily compensate for BSC with the EQ or PA processor you're going to have anyway.
      Paul O

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      • #4
        Re: Baffle step for Pro Audio gear?

        Originally posted by Blenton View Post
        ... is there any need for baffle step compensation when designing a crossover for PA speakers? I would assume the answer is 'usually, no..' but I might be wrong. Adding BSC would drop the overall sensitivity of the system, so I would think it advantageous to not add any in the first place and keep the system as efficient as possible, then EQ on the spot....
        Of course, I understand that EQ will be needed to setup properly for each venue that these will be used at, but I'd like to get them close to a flat frequency response to begin with. ...
        As you surmised: BSC is not designed in. Consider that ( unlike home speakers ) PA speakers are frequently moved and placed at varying distances from the surrounding boundaries.
        Because PA speakers placement could vary from outdoors ( without room and boundary effects ) to indoors ( with room effects ), a flat speaker response is desirable. Room effects make prudent placement and signal EQ necessary.
        "Not a Speaker Designer - Not even on the Internet"
        "If the freedom of speech is taken away, then dumb and silent we may be led, like sheep to the slaughter."

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        • #5
          (yes, I know I'm resurrecting a 2-year old thread, LOL).

          ​My previous Blastorama x-overs were designed with no BSC, for the reasons previously given. I recently tried a quick DIY x-over with BSC included with them and I actually like the results. Yes, a little efficiency is lost (~2 to 3dB above 350 Hz), but overall they do sound a lot better in their "usual" use, mounted on stands out in the open. Now I'm trying to decide if I should just use x-overs with BSC, or include some sort of "BSC switch" in the upgraded design...
          Brian Steele
          www.diysubwoofers.org

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          • #6
            Hey Brian,

            Any BSC which I include in my designs comes only after measuring the driver in the cabinet. I find this is more consistently good than attempting to compensate for something which may not exist. If you need BSC, not having it will really make your speakers sound limp.

            So, I would say, measure first and see what you need.

            But also, one of the side benefits of the BSC is possibly making it a little easier to get a bass bump. I think this is what you found so nice. Exactly as you mention, you will loose a little sensitivity, but you'll end up with a rise before falling kind of response in the low end.

            I strongly encourage you to measure and try to correlate what you hear to measurements, that way you'll find what you like, and then be able to go straight to simulation and manufacture.

            You will need to play with the BSC values a little, so measurement and simulation is required.

            Once I found my own target curve I never looked back, and everything was fast.

            Best,


            Erik

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            • #7
              I'm still looking for "Instant Baffle" ( no compensation needed ) 😈.
              "Not a Speaker Designer - Not even on the Internet"
              "If the freedom of speech is taken away, then dumb and silent we may be led, like sheep to the slaughter."

              Comment


              • #8
                Originally posted by ErikSquires View Post
                Hey Brian,

                Any BSC which I include in my designs comes only after measuring the driver in the cabinet. I find this is more consistently good than attempting to compensate for something which may not exist. If you need BSC, not having it will really make your speakers sound limp.
                ​All my testing involves listening to the speakers with the x-overs. The BSC'd version does sound a little better. I think the bass is helped a bit too because the additional series impedance introduced by the larger inductor (0.8 ohms) changes the Q around the speaker's Fb. I engineered for a 3dB BSC

                Brian Steele
                www.diysubwoofers.org

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                • #9
                  Originally posted by Brian Steele View Post
                  .. include some sort of "BSC switch" in the upgraded design...
                  Will you incorporate this? ( to bypass 3db attenuation )
                  "Not a Speaker Designer - Not even on the Internet"
                  "If the freedom of speech is taken away, then dumb and silent we may be led, like sheep to the slaughter."

                  Comment


                  • #10
                    Originally posted by Sydney View Post
                    Will you incorporate this? ( to bypass 3db attenuation )
                    ​It's something I'm considering, yes. As to *how* to implement such a switch, I haven't worked out that part yet
                    Brian Steele
                    www.diysubwoofers.org

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                    • #11
                      If you could see into the "black box" DSP settings for good modern sound reinforcement speakers you'd probably find EQ on the midrange that accomplishes the same thing that we call "Baffle Step". My guess is this would apply to both systems using external processors, as well as powered speakers with built-in processors. No one reputable is still using box-stock Sallen-Key type filter shapes anymore.

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                      • #12
                        As a philosophy of implementation - I'd rather deal with such issues at the signal level rather than post amplification.
                        Brian liked the results, so it can be labeled "voicing".
                        For me, operating conditions are likely too variable to make post amplification compensation.
                        Can't speak for Brian's circumstances however.
                        TI published a pdf detailing an active crossover implementation that includes Baffle Step Compensation.
                        "Not a Speaker Designer - Not even on the Internet"
                        "If the freedom of speech is taken away, then dumb and silent we may be led, like sheep to the slaughter."

                        Comment

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