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1st order at 5k, any tweeters that can handle that?

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  • 1st order at 5k, any tweeters that can handle that?

    any thoughts on the Neo3PDR? I may try it since i have them on hand, but I realize they may not be the best choice. I'd probably blow up my Fountek Neo3.0's if I tried those. Any suggestions?

  • #2
    Re: 1st order at 5k, any tweeters that can handle that?

    Originally posted by Zero the Hero View Post
    any thoughts on the Neo3PDR? I may try it since i have them on hand, but I realize they may not be the best choice. I'd probably blow up my Fountek Neo3.0's if I tried those. Any suggestions?
    They should do alright, but I'd still add a large inductor to shunt below 1KHz. Just makes doubly sure you keep the low frequencies off the membrane.
    R = h/(2*pi*m*c) and don't you forget it! || Periodic Table as redrawn by Marshall Freerks and Ignatius Schumacher || King Crimson Radio
    Byzantium Project & Build Thread || MiniByzy Build Thread || 3 x Peerless 850439 HDS 3-way || 8" 2-way - RS28A/B&C8BG51

    95% of Climate Models Agree: The Observations Must be Wrong
    "Gravitational systems are the ashes of prior electrical systems.". - Hannes Alfven, Nobel Laureate, Plasma physicist.

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    • #3
      Re: 1st order at 5k, any tweeters that can handle that?

      Originally posted by Zero the Hero View Post
      any thoughts on the Neo3PDR? I may try it since i have them on hand, but I realize they may not be the best choice. I'd probably blow up my Fountek Neo3.0's if I tried those. Any suggestions?
      Well, I guess it depends on the intended output level, but the the Seas 27TBFC/G is among several that would probably sound OK doing 1st order at 5k. As you can see, a notch filter is still required, though. In the model below the notch is for the baffle diffraction peak. In some cases, first order slopes will require more than one notch filter.

      Click image for larger version

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      "Looks like you may have to design your own speakers. Its not that hard." -DE Focht

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      • #4
        Re: 1st order at 5k, any tweeters that can handle that?

        They should do alright, but I'd still add a large inductor to shunt below 1KHz. Just makes doubly sure you keep the low frequencies off the membrane.
        Thanks Pete, I hadn't thought of that. Might as well try it, whats the worst that could happen?

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        • #5
          Re: 1st order at 5k, any tweeters that can handle that?

          Originally posted by jbruner View Post
          Well, I guess it depends on the intended output level, but the the Seas 27TBFC/G is among several that would probably sound OK doing 1st order at 5k. As you can see, a notch filter is still required, though. In the model below the notch is for the baffle diffraction peak. In some cases, first order slopes will require more than one notch filter.

          [ATTACH]5272[/ATTACH]
          I'm not surprised that tweeter was suggested, although I didn't model it so didn't think about the notch filter - thanks for the thoughts.

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          • #6
            Re: 1st order at 5k, any tweeters that can handle that?

            First off, did you mean that your goal is to achieve a 1st order acoustic slope, or that you simply want to use a 1st order electrical XO on the tweeter (eg: just a cap)?

            At 5K, there are a good variety of tweeters that will work fine with just a cap. Down lower, it's a tough call. I used a single 5.1 uF cap on the 27TDFC when I did the Aethers. When combined with the L-pad, it gave a picture-perfect 2nd order acoustic slope @ 2500 Hz. I believe John Krutke had very similar results in his waveguide TMM using that tweeter.

            I'm all for keeping it simple, however, with ribbons and planars, I don't think I'd use anything less than a 2nd order electrical simply for protection. Dome tweeters are typically more robust.
            Isn't it about time we started answering rhetorical questions?

            Paul Carmody's DIY Audio Projects
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            • #7
              Re: 1st order at 5k, any tweeters that can handle that?

              Gemme audio using the XT19 with a single cap on their Tanto loudspeaker. It's crossed around 5K (on the V1 iirc).

              http://www.stereomojo.com/Tanto%20Re...antoReview.htm

              http://www.gemmeaudio.com/page2/page9/Tanto.html

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              • #8
                Re: 1st order at 5k, any tweeters that can handle that?

                Originally posted by dubbreak View Post
                Gemme audio using the XT19 with a single cap on their Tanto loudspeaker. It's crossed around 5K (on the V1 iirc).

                http://www.stereomojo.com/Tanto%20Re...antoReview.htm

                http://www.gemmeaudio.com/page2/page9/Tanto.html
                That seems very odd to me, especially with the XT19 due to its very high impedance peak at resonance (even Zaph and others have implemented dedicated notch filters to tame it with steeper sloped filters). The problem with using a single series capacitor on any tweeter is that it will result in a response peak at the resonance frequency of the tweeter and the higher the impedance peak at resonance, the less attenuation by the capacitor at that point.
                RJB Audio Projects
                http://www.rjbaudio.com

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                • #9
                  Re: 1st order at 5k, any tweeters that can handle that?

                  As a follow up to my previous post, I think that the fact that the Neo3PDR has a flat impedance should make filtering much easier without having to worry about the issue that I mentioned above. However, as others may have hinted, if the raw frequency response of the planar tweeter starts to roll off too early at the bottom end you'll end up with an acoustic slope that is only first order until that point (where it will become steeper). This means that if you are trying for a true first order design in terms of integration with the midrange/midbass driver, you may have phase issues due to this phenomenon.
                  RJB Audio Projects
                  http://www.rjbaudio.com

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                  • #10
                    Re: 1st order at 5k, any tweeters that can handle that?

                    Originally posted by Paul Carmody View Post
                    First off, did you mean that your goal is to achieve a 1st order acoustic slope, or that you simply want to use a 1st order electrical XO on the tweeter (eg: just a cap)?

                    At 5K, there are a good variety of tweeters that will work fine with just a cap. Down lower, it's a tough call. I used a single 5.1 uF cap on the 27TDFC when I did the Aethers. When combined with the L-pad, it gave a picture-perfect 2nd order acoustic slope @ 2500 Hz. I believe John Krutke had very similar results in his waveguide TMM using that tweeter.

                    I'm all for keeping it simple, however, with ribbons and planars, I don't think I'd use anything less than a 2nd order electrical simply for protection. Dome tweeters are typically more robust.
                    I was thinking 1st order acoustic... at least for a couple of octaves, but if the frequency was relatively flat at the xo point whats the difference?

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                    • #11
                      Re: 1st order at 5k, any tweeters that can handle that?

                      It seems to me intuitively that crossing 1st order poses the great risk at the resonant frequency. Since a planar doesn't have the characteristic resonant frequency, the excursion issue plays out differently.

                      +1 on needing to know the desired output level... My guess is this would work unless you are going to for rock concert volumes.

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                      • #12
                        Re: 1st order at 5k, any tweeters that can handle that?

                        the B&G does start to roll off by 2k so will that be bad with a 5k 1st order?


                        listening levels for music rarely exceeds 85db in stereo at about 3 meters. Movies may get a little louder with dynamics, but most SPL would likely e coming from bass region in that case...

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                        • #13
                          Re: 1st order at 5k, any tweeters that can handle that?

                          You will be able to use a single cap filter at 5 kHz (-3 dB) with any tweeter that can be crossed at 2 kHz with acoustic LR4 (though it depends on impedance curve whether you will need a conjugate notch or not). But as Paul pointed out, if your goal is strict acoustic 1st order, you need a tweeter whose response is flat down to 1k - 1.5kHz and preferabley with a low Q shallow rolloff below it. Otherwise, you will have a problem in phase tracking (BW1 90 degree shifted tracking) even if you have a BW1 curve near the xover point.

                          Also, crossed at 5 kHz, the system will be very sensitive to drivers' CTC spacing for which a small flange neo tweeter has an advantange. If I were you, I'd consider the new SB dimple dome neo version:

                          http://www.madisound.com/catalog/pro...oducts_id=8664

                          A great choice for low-order crossover application IMO. The ferrite version should be okay if you don't listen much vertically off-axis. If you're willing to spend more, a perfect choice seems to be the Scan Speak Illuminator neo 1" tweeter:

                          http://www.madisound.com/catalog/pro...oducts_id=8498

                          jAy

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                          • #14
                            Re: 1st order at 5k, any tweeters that can handle that?

                            thanks Jay - that SB is really nice!
                            I think I may try the Neo3 first since I already have all the drivers on hand that I'd like to use. I've gotten pretty good with speaker workshop sims and I have a mic, but I don't know how to measure with SW yet. I may just try LSPCAD since it looks more user friendly. Or I'll try tuning by ear off a sim first and measure later. Who knows!

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                            • #15
                              Re: 1st order at 5k, any tweeters that can handle that?

                              Originally posted by Zero the Hero View Post
                              thanks Jay - that SB is really nice!
                              I think I may try the Neo3 first since I already have all the drivers on hand that I'd like to use. I've gotten pretty good with speaker workshop sims and I have a mic, but I don't know how to measure with SW yet. I may just try LSPCAD since it looks more user friendly. Or I'll try tuning by ear off a sim first and measure later. Who knows!
                              The RS28 is also a nice choice for tweeters with extended low end response. makes implementing shallow slope tweeter XOs much easier.
                              R = h/(2*pi*m*c) and don't you forget it! || Periodic Table as redrawn by Marshall Freerks and Ignatius Schumacher || King Crimson Radio
                              Byzantium Project & Build Thread || MiniByzy Build Thread || 3 x Peerless 850439 HDS 3-way || 8" 2-way - RS28A/B&C8BG51

                              95% of Climate Models Agree: The Observations Must be Wrong
                              "Gravitational systems are the ashes of prior electrical systems.". - Hannes Alfven, Nobel Laureate, Plasma physicist.

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