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NEED HELP WITH DAYTON iMM-6 MICROPHONE

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  • Chris Roemer
    replied
    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.

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  • Stash
    commented on 's reply
    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.

  • Stash
    commented on 's reply
    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.

  • Chris Roemer
    replied
    For your 6kHz dip, did to try reversing polarity on (just) the tweeter?

    Leave a comment:


  • DeZZar
    replied
    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.

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  • DeZZar
    commented on 's reply
    Its ok, it was just a harsh critique of a well respected piece of software where the internationally located author has done no wrong by electing to use original English. Often reflective of our own frustrations that a new item of software doesn't come with an instantaneous learning curve and requires a little effort and some patience to become proficient. Such is the iPhone age.

  • Stash
    replied
    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.

    Leave a comment:


  • Stash
    replied
    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.

    Leave a comment:


  • Stash
    commented on 's reply
    Well, I wouldn't go so far. According to Webster's, "Z" is the correct spelling, here. If you were in a foreign country and misspelled, mispronounced or used poor grammar, natives would take notice. It is what it is, and. I'm afraid "equalise" is not correct, here.

  • Stash
    commented on 's reply
    Good to know, regarding the spelling. Maybe I jumped the gun.
    If I do not need a USB adapter, then I'll look into the apps, again. I've read a little on gating. I understand the idea of ruling out reflections.

  • DeZZar
    replied
    Originally posted by Stash View Post
    The directions also show a separate SPL meter. That also turned me off. I assumed such an app has a built-in measuring device of some sort.
    ​​​​​​You don't need to worry about that until you really want to be able to validate the sensitivity of your speakers. Otherwise you just need to know (which by the way applies to any software like this) that 70db on the graph may not actually be 70db specifically until you configure the spl.

    Leave a comment:


  • DeZZar
    commented on 's reply
    Lol. I was about to chime in with the same thing. Oh boy what a golden example of a typically American thing to say...the real atrocity being the genuinely innocent ignorance of who the real butchers are...hahahaha

  • a4eaudio
    replied
    Originally posted by Stash View Post
    Lastly, I cannot stand the butchering of the English language by the author. He spells words, such as equalize, with an "s" (equalise). This spelling atrocity...
    Not to sidetrack too much, but... The English language comes from England. Those of us in America are fine that Americans butchered the English language by arbitrarily replacing s's with z's.

    Leave a comment:


  • wogg
    replied
    Originally posted by Stash View Post
    I will hold off on the apps. I did download the REW app onto my laptop no problem. But, it is a bit much. And I am not certain I can use my mic as-is. According to the app directions, I may need a USB converter/adapter, which does not thrill me.

    The directions also show a separate SPL meter. That also turned me off. I assumed such an app has a built-in measuring device of some sort.

    Lastly, I cannot stand the butchering of the English language by the author. He spells words, such as equalize, with an "s" (equalise). This spelling atrocity repeats so often, to the point I could not read any more. I uninstalled the program. It is a shame. A person who is obviously well educated.
    No USB converter needed - it will read just fine from your laptop headset port. You (and myself) are in a very, very small group of people doing this poor man measurement method with these iMM6's, the general assumption is that you'll have a mic that needs an interface.

    The separate SPL meter would be required to get or verify actual SPL you're measuring at. That is also not required, but the "85dB" in REW may not actually be 85dB. There's no way for the program to know exactly what input level = real world SPL. This is not important for measuring relative frequency response.

    REW is developed out of Europe, they spell some words differently and the engineer may not even be a native English speaker. That's a silly reason to dismiss a well regarded program.

    FFT real time spectrums are OK for spot checks, but a real impulse response with gating capability is what you'll need to get deeper.

    I have a bunch of ARTA instructions with the iMM6 in my speaker build published on my site here.

    Leave a comment:


  • Stash
    commented on 's reply
    FYI...I did not purchase the MOVO knockoff mic. I was simply making others aware of its existance.
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