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  • Iron-core inductors

    Hello,

    In a just-finished system, I decided to crank the resistance of the main woofer inductor down to the very minimum. 0,25 ohms on an 8,2 mH inductor. See the attached Picture.

    Now, this was possible by means of an iron-core and a lot of dineros…..

    Now, what do you think? is this a good idea? I have read of “saturation” of the core, leading to distortion but at what level will this happen? Is this a real issue or a theoretical one?




    Best regards//lasse



    Click image for larger version

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    Perry Mason talking to his dentist:

    "Do you swear to take the tooth, the whole tooth and nothing but the tooth, so help you God?"

  • #2
    Yes Hysteresis and Saturation are real considerations, I heard it at high power levels; at what level depends upon core construction.
    "Not a Speaker Designer - Not even on the Internet"
    “Pride is your greatest enemy, humility is your greatest friend.”
    "If the freedom of speech is taken away, then dumb and silent we may be led, like sheep to the slaughter."

    Comment


    • #3
      "A rule of thumb is not to let DCR get over 5% of Re." - Taken from diyAudio forum.

      Comment


      • #4
        Originally posted by hardcorecap View Post
        "A rule of thumb is not to let DCR get over 5% of Re." - Taken from diyAudio forum.
        Re for Dayton RS270-8 i 6,8 ohms, so 5% should be abt 0,34 ohms.

        Seems like I could have bought one size cheaper inductor….

        Regards//lasse
        Perry Mason talking to his dentist:

        "Do you swear to take the tooth, the whole tooth and nothing but the tooth, so help you God?"

        Comment


        • #5
          Lasse- I implore you to try a 'steel-laminate' coil instead of the P-core you have there. It should sound better.

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

          Comment


          • #6
            That is just a rule of thumb, and like all RoT - it comes with a lot of caveats.

            That being said, the ferrite core such as the Jantzen there, start saturating at much lower power than laminate core. They "soft saturate", though - so you do not get the clipping you experience overloading a laminate core, you just get more and more noise the louder you play.

            You will be amazed at how poorly the P-Core coils perform compared to laminate core. The differences start at just a few watts.

            Personally, I'll take a slight sensitivity hit over P-Core noise. The Dayton 18awg laminate core 8mH is under $10 and less than 0.7ohm DCR. It will not saturate until your ears are bleeding, either.

            Not sure of availability in Europe, though, but I imagine laminate core inductors can be found pretty much anywhere.
            Don't listen to me - I have not sold any $150,000 speakers.

            Comment


            • #7
              Originally posted by johnnyrichards View Post
              That is just a rule of thumb, and like all RoT - it comes with a lot of caveats.

              That being said, the ferrite core such as the Jantzen there, start saturating at much lower power than laminate core. They "soft saturate", though - so you do not get the clipping you experience overloading a laminate core, you just get more and more noise the louder you play.

              You will be amazed at how poorly the P-Core coils perform compared to laminate core. The differences start at just a few watts.

              Personally, I'll take a slight sensitivity hit over P-Core noise. The Dayton 18awg laminate core 8mH is under $10 and less than 0.7ohm DCR. It will not saturate until your ears are bleeding, either.

              Not sure of availability in Europe, though, but I imagine laminate core inductors can be found pretty much anywhere.
              Do you measured results of these tests?
              Guess xmax's age.

              My guess: 15. His grammar is passable. His trolling is good.

              Comment


              • #8
                Hi again,



                Thanks for the feedback and have a cigar.

                (It´s a tough thought to have that my 100 USD investment in woofer coils is a sub-optimum one)



                Anyway, yesterday evening, I went to a concert here in Stockholm with the group ”P-Floyd”. You probably guess, quite correctly, that this is a tribute band to the great Floyd. I then realized that there probably is a very god test-material in the music from the Floyd and so consequently, I have tortured my neighbours with abt one hour of Floyd music on a level well above both my normal listening level and beyond my comfort zone.



                I honestly cannot hear anything in the low region, sounding like anything but ”loud low-fequency-sound”, nice and clear (but LOUD). I think that this test made my Citation12 put out what it has, abt 60 W per channel.



                Referring to the picture below (Found on the net and if it tells the truth…) I can think of a very simple test I can perform on my conductors. Just unsolder one lead and connect it to a series resistor, 8 ohms, 100W. Attach an amp of abt 50-100W and a oscilloscope over the resistor. Run a series of sinus-tones into the amp and see if the voltage differs from the sinusidoal input at any level. At that level you could calculate the power level and current.



                But this probably has already been done by some of you??



                See you all on the dark side of the moon!

                Regards//lasse



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                Perry Mason talking to his dentist:

                "Do you swear to take the tooth, the whole tooth and nothing but the tooth, so help you God?"

                Comment


                • #9
                  That is very revealing indeed. I wonder if you can do the same tests with capacitors and SEE the results?

                  BTW, the value of DCR in the 2.8 mh woofer air-core inductor in the famous AR3a is about 0.8 ohm. Therefore, DCR is just a part of the overall design.

                  Comment


                  • #10
                    Originally posted by xmax View Post
                    Do you measured results of these tests?
                    +1. Just as with caps a more expensive coil is no guaranty of a better coil. It's been a long time since I've seen measured results, but I do recall one extensive test that showed solid core inductors had much lower distortion than air core at high power levels. The best were Sledgehammer, from Madisound. PE sells a similar Erse coil. This was around 20 years ago, I don't recall if any sintered core were tested.
                    www.billfitzmaurice.com
                    www.billfitzmaurice.info/forum

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                    • #11
                      Originally posted by lasse View Post
                      ...But this probably has already been done by some of you??...
                      1st article I saw:
                      "Inductors For Crossover Networks" by Richard and Erin Honeycutt Speaker Builder magazine Issue 7, 1996

                      "Not a Speaker Designer - Not even on the Internet"
                      “Pride is your greatest enemy, humility is your greatest friend.”
                      "If the freedom of speech is taken away, then dumb and silent we may be led, like sheep to the slaughter."

                      Comment


                      • #12
                        Originally posted by Sydney View Post
                        1st article I saw:
                        "Inductors For Crossover Networks" by Richard and Erin Honeycutt Speaker Builder magazine Issue 7, 1996
                        Hi,

                        can this article be made available to us without violating something?

                        Regards//lasse
                        Perry Mason talking to his dentist:

                        "Do you swear to take the tooth, the whole tooth and nothing but the tooth, so help you God?"

                        Comment


                        • #13
                          I don't know about that one; Some articles have been made public by either the author or the publisher
                          "Not a Speaker Designer - Not even on the Internet"
                          “Pride is your greatest enemy, humility is your greatest friend.”
                          "If the freedom of speech is taken away, then dumb and silent we may be led, like sheep to the slaughter."

                          Comment


                          • #14
                            Originally posted by xmax View Post

                            Do you measured results of these tests?
                            He may not have, but many of us either have or at least heard the results of the saturation on the P core inductor. Very audible and measurable.
                            https://www.facebook.com/Mosaic-Audi...7373763888294/

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                            • #15
                              So what does the saturation or noise sound like?

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