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  • Originally posted by Wolf View Post
    Don- I don't know that an LC is simpler/better than another LC. Both series and parallel are notch filters.
    Later,
    Wolf
    I agree ..... you don't know.

    Comment


    • I got distracted and didn't finish.... sorry. The two different approaches do present different input impedances to an amplifier at high frequencies and could in some cases affect amplifier stability with the case where the notch filter with two capacitors in series appear between the input and ground connections of the speaker.

      Comment


      • http://www.eetimes.com/document.asp?doc_id=1274906

        Comment


        • Originally posted by fdieck View Post
          I got distracted and didn't finish.... sorry. The two different approaches do present different input impedances to an amplifier at high frequencies and could in some cases affect amplifier stability with the case where the notch filter with two capacitors in series appear between the input and ground connections of the speaker.
          I know that a tank provides amp instability in some cases by providing an ultrasonic short without a resistor tagged along. BUT- that is not what I was getting at, Fred. I was meaning that Jeff's circuit is a notch filter, just like what 'Everyone else used a notch filter' is a still notch filter. I know they work differently, and some work better for certain applications, but that wasn't my point.

          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:
          http://photobucket.com/Wolf-Speakers_and_more

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

          Comment


          • As a general rule of thumb, the series notch is usually better when dealing with out of band issues and the parallel notch is better for in-band issues. If you look at designs by other experienced designers like Bamberg, Kreskovsky, Murphy, etc. you will see that they tend to follow this convention also.
            Click here for Jeff Bagby's Loudspeaker Design Software

            Comment


            • Originally posted by Wolf View Post

              I know that a tank provides amp instability in some cases by providing an ultrasonic short without a resistor tagged along. BUT- that is not what I was getting at, Fred. I was meaning that Jeff's circuit is a notch filter, just like what 'Everyone else used a notch filter' is a still notch filter. I know they work differently, and some work better for certain applications, but that wasn't my point.

              Later,
              Wolf
              It all depends on how the components are laid out. My circuit does not do that because the series inductor controls the high frequency input impedance.
              Click here for Jeff Bagby's Loudspeaker Design Software

              Comment


              • Originally posted by Jeff B. View Post

                It all depends on how the components are laid out. My circuit does not do that because the series inductor controls the high frequency input impedance.
                We are referring to the parallel notch with a small cap across a large baffle step inductor that appears in series with the cap to ground on many second order woofer low pass filters. It makes me a bit wary when this cap becomes close to value of the cap used in series with a 5 to 10 resistor used for a zobel network on the output of typical power amps.

                Comment


                • Originally posted by fdieck View Post

                  We are referring to the parallel notch with a small cap across a large baffle step inductor that appears in series with the cap to ground on many second order woofer low pass filters. It makes me a bit wary when this cap becomes close to value of the cap used in series with a 5 to 10 resistor used for a zobel network on the output of typical power amps.
                  Yes, I agree with you on this layout......
                  Click here for Jeff Bagby's Loudspeaker Design Software

                  Comment


                  • Agreed on all counts, fellas.
                    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:
                    http://photobucket.com/Wolf-Speakers_and_more

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

                    Comment


                    • Hi All,

                      I got my hands in a pair of R28AS-4 so I'll try to implement the original design in a Trans Laminate cabinet, what would you recommend as far as crossover components go?

                      I'm not asking about $150 dollars Caps but more about what's the recommended quality to get the closest to the original design?

                      I wish I was experienced enough to be able to tell from the picture what components Mr. Bagby used .

                      Click image for larger version

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ID:	1337026

                      Thanks,
                      Alex

                      Comment


                      • Panasonic mylar caps, Jantzen air-cores, and an NPE cap. I think that is the tweeter xover only.

                        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:
                        http://photobucket.com/Wolf-Speakers_and_more

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

                        Comment


                        • Originally posted by Wolf View Post
                          Panasonic mylar caps, Jantzen air-cores, and an NPE cap. I think that is the tweeter xover only.
                          Later,
                          Wolf

                          Thanks Wolf!

                          Looks like those don't exist in anything bigger than 10uF, at least I haven't been able to find them, that's why it looks like he may have used 2 X 10uF in parallel to fit the 20uF needed in the woofer.

                          I'm not sure what he meant when he said that Poly Caps can be "Pretty Salty" for the 50uF on the tweeter but I guess that's bad? That's why is safer to stick to the NPE right?

                          Best,
                          Alex
                          Last edited by AlexRivera; 06-29-2017, 10:41 AM.

                          Comment


                          • "pretty salty" means expensive. A 50uF in a poly might be $15, where a NPE would be $1.10. Any decent poly for everything but the 50uF in teh woofer circuit (there use a NPE) and you will be fine. I typically use Dayton poly caps, or Audyn.
                            Paul

                            The "SB's" build page
                            http://techtalk.parts-express.com/sh...-4-(pic-heavy)

                            Comment


                            • Originally posted by bullittstang View Post
                              "pretty salty" means expensive. A 50uF in a poly might be $15, where a NPE would be $1.10. Any decent poly for everything but the 50uF in teh woofer circuit (there use a NPE) and you will be fine. I typically use Dayton poly caps, or Audyn.
                              Hahahah, struggling with slang here, OK, I got it now.

                              Thanks Paul!

                              Comment


                              • Originally posted by AlexRivera View Post
                                Hi All,

                                I got my hands in a pair of R28AS-4 so I'll try to implement the original design in a Trans Laminate cabinet, what would you recommend as far as crossover components go?

                                I'm not asking about $150 dollars Caps but more about what's the recommended quality to get the closest to the original design?

                                I wish I was experienced enough to be able to tell from the picture what components Mr. Bagby used .

                                [ATTACH=CONFIG]n1337026[/ATTACH]

                                Thanks,
                                Alex
                                That picture shows the passive filtering for the amplified version of the speaker. That's not the crossover for the passive version of the speaker.
                                Click here for Jeff Bagby's Loudspeaker Design Software

                                Comment

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