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It’s that time audio enthusiasts! Registration for the 2019 Speaker Design Competition is now open! Visit midwestaudiofest.com for details and to list your speaker project. We are excited to see all returning participants, and look forward to meeting some new designers this year, as well! Be sure your plans include a visit to the Parts Express Tent Sale for the lowest prices of the year, and the Audio Swap Meet where you can buy and trade with other audio fans. We hope to see you this summer! Vivian and Jill
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Tectonic BMR SPL limits

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  • Tectonic BMR SPL limits

    I'm looking to use the Tectonic Elements TEBM46C20N-4B and wondering how I should determine it's usable SPL limit. I haven't settled on a crossover but I may use it as low as 300hz and fullrange above that. Applying a BW2 @ 310hz results in an acoustic response of roughly LR4 @ 300hz. Applying the max rated power of 20w gives an SPL of 98dB. Excursion is 1.1mm, which is close to the 1mm I guessed would be about the limit one would want to push this driver. Does that seem reasonable? Going down to 10 watts only drops that to about 0.8mm. Anyway, if someone who has used this driver can share their experience I would appreciate it.
    ~Brandon

    Soma Sonus
    DriverVault

  • #2
    No one is familiar with this driver yet?
    ~Brandon

    Soma Sonus
    DriverVault

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    • #3
      I have one here for a center channel build which I intend to use in a similar range as you but I haven't done anything yet other than listen to it open. I'm probably gonna wind up doing first order though since the AC130 woofers I intend to use are so smooth so high up.

      Here's a link for some extensive testing on the 35 which is pretty impressive as well. I've considered using this instead simply because the off axis response is on par with that of 1" domes which might be needed for a horizontal CC.

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      • #4
        I like that small one too but it is SO inefficient. Last weekend I listened to the new Cambridge audio using this BMR with no tweeter. Sounded promising! But I didn't get a chance to explore the offaxis behavior. Still given the price of these and the Dayton DSA90s I thought it would be a cheap and fun experiment.
        ~Brandon

        Soma Sonus
        DriverVault

        Comment


        • #5
          Originally posted by augerpro View Post
          I'm looking to use the Tectonic Elements TEBM46C20N-4B and wondering how I should determine it's usable SPL limit. I haven't settled on a crossover but I may use it as low as 300hz and fullrange above that. Applying a BW2 @ 310hz results in an acoustic response of roughly LR4 @ 300hz. Applying the max rated power of 20w gives an SPL of 98dB. Excursion is 1.1mm, which is close to the 1mm I guessed would be about the limit one would want to push this driver. Does that seem reasonable? Going down to 10 watts only drops that to about 0.8mm. Anyway, if someone who has used this driver can share their experience I would appreciate it.
          I am using this midrange in my new NanoTech project for the upcoming InDIYana 2017 competition (see pic). My crossovers are 320Hz and 2.4kHz at 12dB/octave electrical. (Other drivers in my 3-way are the Tang Band W5-2053 subwoofer and the Morel MDT-39 tweeter).

          I measured the harmonic distortion at various SPL levels with OmniMic at 1 meter on design axis. I put together a chart showing the 2nd-5th harmonic distortion by SPL and Frequency (see pic attached). As you can see, the HD rises into the 4 to 5% range when you approach the lower crossover frequency when driven at the 95-97dB SPL level. But this is extremely loud, much higher than I would ever play them in my listening room.

          When the speakers were played at IowaDIY and the Meniscus GTG, the 1 meter SPL levels were more in line with my 86-89dB SPL test level, which is a moderately loud level and only shows a distortion of about 2.6% near the lower crossover. Many listeners commented that my NanoTech speakers seemed to sound well balanced from top to bottom and did not seem to sound overdriven or strained.

          In answer to your question as to whether or not this driver can do 98dB with 20 watts when crossed very low (300Hz at 12db/octave electrical), I would say the answer is no. If you are testing this SPL at 1 meter, the distortion would probably go up into the 5 to 6% range near the crossover. Even the 95-97dB SPL level is too high for this driver, IMO. I have cranked these drivers up to the 97-98dB levels briefly and the sound becomes somewhat strained and the dynamics seem to flatten out (a compression effect). I think the 93-95dB SPL level, at 1 meter for one speaker, is the highest I would play them.


          Hope this helps,

          Bill


          SideTowers: http://techtalk.parts-express.com/fo...corundum-build
          Totally Flat: http://techtalk.parts-express.com/fo...5-totally-flat
          Plumber's Delight: http://techtalk.parts-express.com/fo...notech-winners
          Linehopper: http://techtalk.parts-express.com/sh...Esoteric-build

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