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From the vault... Seas/Focal design revisited.

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  • From the vault... Seas/Focal design revisited.

    Here's a design created by Darren Kuzma around 2002 that I recently pulled from my file cabinet. I know Darren has long moved on, but I held onto these pages because I have both these midbass drivers and tweeters gathering dust in the closet from past projects, years ago. With an itch to build something new from something old, it may be time to put these classics to some use. But I fail miserably when it comes to crossover design. I am much more of a builder than a designer, and welcome a fresh set of eyes to look over this schematic and offer any opinions or suggestions before I start spending money on crossover components. Any and all suggestions are most welcome and appreciated. - Thanks! Matt
    Attached Files

  • #2
    Re: From the vault... Seas/Focal design revisited.

    I remember these from the DIY Iowa event way back in the dark ages. They were very, very good. I'd start with Darren's XO. You may find it is sweet!

    Comment


    • #3
      Re: From the vault... Seas/Focal design revisited.

      That's what I'm hoping for, that Darren's XO will be sweet! I think this is as good of a place to start as any, I have wanted to build this design for almost a decade now!

      That 27uF cap in the high-pass filter threw me off, maybe it's not that unusual. And then he also mentions a "useless .1uF film and foil bypass on the woofer" that's not shown in the schematic. Since it's useless, I guess I shouldn't be concerned about that one, huh. I just thought it might be smart to ask the opinion of the wise-ones before beginning!

      Honestly, I love the way they look. To my eye, those drivers are very handsome together! Let's hope they please the ears as well!

      Comment


      • #4
        Re: From the vault... Seas/Focal design revisited.

        Take everything I say with a grain of salt. It is before the age of computers. Stuff like wolf's calculator can do more in a few minutes than my slide rule could accomplish in weeks.

        that said - is that xover accurate? 27mfd on a 2way really jumps out.
        27mfd into a 26ohm load .... 250Hz ish? The inductor shunted across tweeter will drive up the crossover frequency. but by how much? google search shows focal90 with an Fs 1470Hz.
        Using an xo too close to a tweeters Fs can make harsh sounds even at moderate volume. Maybe somebody who knows how to use these modern tools could identify the xo frequency.

        Better yet, are there any listening reviews on the box? That would be an easy way to check. They would be sure to mention it if tweeter was struggling to go low.

        Comment


        • #5
          Re: From the vault... Seas/Focal design revisited.

          Whatever happened to Darren?

          Dan

          Comment


          • #6
            Re: From the vault... Seas/Focal design revisited.

            I haven't heard anything about Darren in a while now. I believe he landed a pretty nice job with Tymphany as head ScanSpeak distributor... but that was five years or so ago. Not sure where he is now. Anyone?

            Comment


            • #7
              Re: From the vault... Seas/Focal design revisited.

              He works in OH for another industry and is no longer in the speaker biz.
              Later,
              Wolf
              "Wolf, you shall now be known as "King of the Zip ties." -Pete00t
              "Wolf and speakers equivalent to Picasso and 'Blue'" -dantheman
              "He is a true ambassador for this forum and speaker DIY in general." -Ed Froste
              "We're all in this together, so keep your stick on the ice!" - Red Green aka Steve Smith

              *InDIYana event website*

              Photobucket pages:
              https://app.photobucket.com/u/wolf_teeth_speaker

              My blog/writeups/thoughts here at PE:
              http://techtalk.parts-express.com/blog.php?u=4102

              Comment


              • #8
                Re: From the vault... Seas/Focal design revisited.

                Originally posted by moron#99 View Post
                Take everything I say with a grain of salt. It is before the age of computers. Stuff like wolf's calculator can do more in a few minutes than my slide rule could accomplish in weeks.

                that said - is that xover accurate? 27mfd on a 2way really jumps out.
                27mfd into a 26ohm load .... 250Hz ish? The inductor shunted across tweeter will drive up the crossover frequency. but by how much? google search shows focal90 with an Fs 1470Hz.
                Using an xo too close to a tweeters Fs can make harsh sounds even at moderate volume. Maybe somebody who knows how to use these modern tools could identify the xo frequency.

                Better yet, are there any listening reviews on the box? That would be an easy way to check. They would be sure to mention it if tweeter was struggling to go low.
                First, what is Wolf's calculator? You have mentioned it in a couple of threads now.

                Second, this circuit simply results in a low Q second order filter with a corner at 2000 Hz and 11 dB of padding. (Though doing all of it with a huge series resistor is not the best way to go about it.)

                Jeff B.
                Click here for Jeff Bagby's Loudspeaker Design Software

                Comment


                • #9
                  Re: From the vault... Seas/Focal design revisited.

                  Originally posted by Jeff B. View Post
                  First, what is Wolf's calculator?
                  Jeff B.
                  I just use what is provided in Microsoft products. That isn't mine, and neither is the old Casio-grapher I have either.
                  Clueless,
                  Wolf
                  "Wolf, you shall now be known as "King of the Zip ties." -Pete00t
                  "Wolf and speakers equivalent to Picasso and 'Blue'" -dantheman
                  "He is a true ambassador for this forum and speaker DIY in general." -Ed Froste
                  "We're all in this together, so keep your stick on the ice!" - Red Green aka Steve Smith

                  *InDIYana event website*

                  Photobucket pages:
                  https://app.photobucket.com/u/wolf_teeth_speaker

                  My blog/writeups/thoughts here at PE:
                  http://techtalk.parts-express.com/blog.php?u=4102

                  Comment


                  • #10
                    Re: From the vault... Seas/Focal design revisited.

                    I think I'll start with Darren's original posted design and just see how it sounds! Can't find a .03mH inductor though, there doesn't seem to be much of a selection for those small values... closest I've come is here at PE - a Jantzen 0.025mH 18 AWG Air Core Inductor. Close enough?

                    Comment


                    • #11
                      Re: From the vault... Seas/Focal design revisited.

                      Originally posted by Jeff B. View Post
                      First, what is Wolf's calculator? You have mentioned it in a couple of threads now.

                      Second, this circuit simply results in a low Q second order filter with a corner at 2000 Hz and 11 dB of padding. (Though doing all of it with a huge series resistor is not the best way to go about it.)

                      Jeff B.
                      I apologize for any msguided credits or accolade.
                      If that is your program then you deserve full credit.
                      It was a massive effort and a very impressive design tour de force

                      I downloaded something from this forum.
                      It wanted microsoft excel with macros and external data files. Huh? what?
                      I fell ill and never learned to use it.
                      Was that yours?

                      I do have project now. maybe your program is the answer?
                      I have a pair of impulse optimized mains. They may be modeled as third order butterworth at 94.5Hz. No additional HP filter allowed since it will disturb TD response.
                      I have sealed box active woofer with linkwitz transform and 25hz 3rd order butterworth HP. I need to design the 95Hz junction.
                      Will your program do this? easily?

                      Comment


                      • #12
                        Re: From the vault... Seas/Focal design revisited.

                        Originally posted by mattfaske View Post
                        I think I'll start with Darren's original posted design and just see how it sounds! Can't find a .03mH inductor though, there doesn't seem to be much of a selection for those small values... closest I've come is here at PE - a Jantzen 0.025mH 18 AWG Air Core Inductor. Close enough?
                        buy a slightly larger value and unwind coils to desired product. your pc can generate a pure tone. Just wire in series with a resistor and use a calculator + VOM to get the value you want.

                        Comment


                        • #13
                          Re: From the vault... Seas/Focal design revisited.

                          Great advice... why didn't I think of that - unwinding a coil to get the desired value. Thanks! Now, how to get that 12.8 uF capacticance... hmmm.

                          Comment


                          • #14
                            Re: From the vault... Seas/Focal design revisited.

                            Originally posted by mattfaske View Post
                            Great advice... why didn't I think of that - unwinding a coil to get the desired value. Thanks! Now, how to get that 12.8 uF capacticance... hmmm.
                            caps in parrallel add
                            10mfd + 2.7mfd = close enough for government work.

                            Comment

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