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  • #16
    Agreed. Actual true SPL is not a concern of mine. I rarely play music loud. I am interested in results due to alterations to my speaker systems, movement of speaker systems and room modulations. I use the dB only as a reference by which to compare other speaker systems, individual drivers, etc.


    • #17
      For instance, using the mic and friture app, I discovered a very distinct dip in my custom built Realistic MACH ONE speaker systems. The dip occurs around 5-6kHz and it is sharp, perhaps a 6-8dB drop. Even after several measurements, this dip goes unchanged.

      I built 12dB/oct crossovers at 800Hz and 8kHz, to mimic the original speakers. After several repeated measurements, I see a very smooth transition from woofer to mid-horn. But the steep dip around the crossover point from mid-horn to super tweeter-horn baffles me.

      The speaker systems sound fine, to me. I prefer a dip in response over an excessive peak. However, I'd still like to know why the dip is there, and why so prominent.


      • #18
        Originally posted by Stash View Post
        However, I'd still like to know why the dip is there, and why so prominent.
        Only one way to find out - take some individual raw measurements of each driver in place without the crossover and feed those results into a crossover simulator. Its either a natural dip in the driver response or possibly introduced by diffraction or by the crossover - i.e. drivers not meeting up correctly or cancellation due to phase issues.

        Constructions: Dayton+SB 2-Way v1 | Dayton+SB 2-Way v2 | Fabios (SB Monitors)
        Refurbs: KLH 2 | Rega Ela Mk1


        • Stash
          Stash commented
          Editing a comment
          Yeah, I know. Idk if I'll ever do so, tho.
          When I built these speakers, I promised my nephews I would not begin taking them apart and t tinkering with them. They know me too well. It becomes an obsession and the speakers may end up being ruined. They sound good. My nephews are impressed. I'll probably leave them as-is, and keep my word lol.

          If ever I am able, I'd like to add an old fashioned 31-band/ch equalizer component to my main system. With such an EQ and my mic and friture app, I could probably put a noticeable dent in the peaks and dips. That would be interesting project and also be non-invasive.

      • #19
        For your 6kHz dip, did to try reversing polarity on (just) the tweeter?


        • Stash
          Stash commented
          Editing a comment
          No. I don't believe its the tweeter. I think it is the midrange horn.
          Even when I turned down my tweeter L-pad, the steep dip remained unchanged. All I accomplished was reducing the treble above 10kHz and causing my speakers to sound dull and without detail.
          As I told Dezzar, I'd rather try to reduce the dips/peaks via an external component equalizer, someday.

          I've reversed tweeters in the past. Not really fond of the outcome. The suck-out is usually too much for me. In the old days, we'd sometimes reverse tweeter polarity to create a simulated 'wide sound' effect. It never really worked too well. Sometimes the treble would become too shrill, or, imaging and stereo suffered.

          I have to look up my crossover schematic. I cannot remember if my mids are connected in or out of phase.

          If I had the mic and thought about it, I would have tested the drivers before designing the crossover. What I did was actually ***-backwards. Live and learn.

      • #20
        Well, everything is relative ...

        Your "dip" freq. is close enough to your targeted Fc that it MAY very well BE @ 6k (esp. if you just made up some "textbook" 8k filters w/out using any actual (measured) freq. (.frd) and impedance (.zma) data). It would be silly to not just try it for grins.

        The phase of a driver (once filters get involved) is not determined by some "+" & "-" marks on its terminals. Every additional filter "stage" (component) rotates the driver's phase forward or backward (caps one way, coils the other). It you build a standard 2-way w/2nd order filters (and leave the drivers hooked up "normal" polarity - per the terminal markings) odds are that they will be nearly exactly out of phase (at the Fc point). This would show up as a dip around the Fc. You'll never know until you try.

        (If you mid is "flipped" (and shouldn't be), you'd also have a dip around your 800Hz Fc. Since you don't, your woof & mid could be "in phase" (no matter HOW they're actually wired) with just the tweeter being OOP (no matter how it's wired)). Phase is also affected by "time of flight", meaning the difference in distance that the diff. drivers' voice coils are behind the baffle (plane). Woofers are deeper - so the sound has farther to travel to meet up w/a dome tweeter's output. OTOH, if you've got a horn on your mid (or tweet), then THAT also screws w/the phase.