Blog Forums DIY Speakers and Subwoofers Measuring Speakers using xsim – measuring 1W@1m and measuring driver alignment

2 voices
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    • #14536
      lvx
      Member

      Hi ladies and gents,

      I’m currently busy designing my own crossover for fun.
      I’m using the Dayton DS135-8 (paper cone) woofer and the Dayton ND28F-6 tweeter. 
      I wanted to go about this scientifically, so I’m using an umik to measure and then make the crossover in xsim.
      First question is, how do you measure 1W@1M for either speaker, since one is a 8 ohm speaker and the other a 6 ohm speaker?
      Right now I did the following:

      – Measured 2,83V output from the amp outputting a @60Hz sine using a DMM, then on the same volume setting measured the DS-135-8

      – Measured 2,3 V output from the amp outputting a @60Hz sine using a DMM, then on the same volume setting measured the ND28F-6

      After I input this in xsim it looked pretty similar to what Dayton Audio actually had in their specs, but could you possibly confirm I’m not over- or undercomplicating this?

       

      Furthermore, in order to ensure the sound sources are aligned (i.e. woofer is about .4 inches recessed) in the crossover I want to take a measurement in parallel, which should be easy to do. However, seeing that both drivers have different impedances, do I measure them both at 2,83V? You can probably see the source of my conflict, this method conflicts with above method of measuring at 1W@1m, meaning that the tweeter levels will be different.

      Can this still work? What would you recommend I do to measure the drivers in order to input in xsim

       

       

    • #14537
      123toid
      Keymaster

      You did everything correct. Once you have your amplifier set at that 2.83 volts, just measure everything at that setting. Don’t change the volume, don’t move where the speakers are being measured at or anything else. Keep everything set up the way it is

       


    • #14538
      lvx
      Member

      @123toid Thank you for the extremely fast reply 🙂 

      So you would recommend measuring the tweeter as well at 2,83V I understand, or did I misunderstand? 

    • #14539
      123toid
      Keymaster

      @lvx 

      No it’s the amplifier that gets measured at 2.83 volts with nothing connected to it. It doesn’t matter what the voltage that the individual drivers see.


    • #14540
      123toid
      Keymaster

      Now that we’ve said this, I should mention I don’t measure at 2.83 volts. I just pick a volume around 85 decibels on the woofer. And measure everything at that same volume level. You don’t really care about the sensitivity of each individual driver. What you do care about is the final sensitivity of the system. So once the system is complete, if you want to then measure it at 2.83 volts, you’ll get the final system sensitivity.


    • #14541
      lvx
      Member

      @123toid Ah, sorry, my lack of electrical knowledge caught up with me.
      Now I think I understand though, at that point the amp is putting out 1W.

      You’ve also made measuring much easier for me with your last comment. I do have a tendency to overcomplicate things in my head. 

      Thank you for the clarifications!

       

    • #14542
      123toid
      Keymaster

      @lvx 

      You’re welcome. Feel free to share your results at the end. I know that we would love to see the finished project. It sounds like a really cool project actually. And if you need any more help while your designing it, feel free to ask for it.


    • #14543
      lvx
      Member

      @123toid Thank you! I will share them. They’re actually a v2 of an existing speaker with a Dayton Audio rs125-4 instead of the DS-135. I made those based on the specs alone and found out that unfortunately the T/S parameters,when measured, didn’t come close to spec. Couple that with me having over damped them to compensate they ended up sounding a bit thin and had a really nasty spike at around 130-150Hz. Miraculously enough though, I got the crossover right that time. 

      That was my first speaker and I’m now reusing the cabinets, which seem to fit the DS135 relatively well. I’m having a lot of fun with this!

    • #14544
      123toid
      Keymaster

      @lvx 

      Excellent!  That is one of the joys of building and designing speakers.  I love it as well.  Such a blast.  It seems there is always something to learn.  It’s pretty cool to see it all unfold. 


    • #14545
      123toid
      Keymaster

      @lvx P.S I moved this to the DIY Speaker section.


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