Perfect TL with MJK mathcad graph?
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 Multi-Way Conventional loudspeakers with crossovers

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 5th January 2004, 10:17 AM #1 christophorus diyAudio Member   Join Date: Dec 2003 Perfect TL with MJK mathcad graph? Hi guys, I have difficulty to understand graphs in MJK mathcad. I quite familiar with graph #6 only! Maybe somebody can help us or at least me, to draw how does a "perfect graph" (= perfect result) look-like for each graph, so we can design our TL speaker close to that "perfect graph". Or maybe with some explanation for each graph what should to reach and what should to avoid. Please guys, I desperate need this help to design "the best TL in the universe"... MJK, would you mind...? Thankyou. Chris.
 5th January 2004, 11:40 AM #2 Bricolo   diyAudio Member     Join Date: Nov 2002 Location: Grenoble, FR I think that #6 is the most important it should be flat, with a 24dB/oct LP roloff like this: _______ / The impulse response (last one) is also important
 6th January 2004, 06:27 AM #4 christophorus diyAudio Member   Join Date: Dec 2003 Hi Bricolo, Thanks for your advice. Hi MJK, Wow, thankyou, now I'm gonna make a perfect speaker, at least for me at specific time until I hear something better, then it becomes no longer perfect. About your graph: 1. fully understand. 2. skip as you said. 3. how if, instead of flat, I raise it +3dB toward TL resonant freq.? 4. OK. 5. There are 2 graphs, what should to achieve and to avoid for each graph result? 6. leave it. 7. how high or low for the voltage is good and how many ringing is bad? Almost..... Chris.
 7th January 2004, 12:14 AM #5 MJK   Account disabled at member's request   Join Date: Feb 2002 Location: Clifton Park, NY Hi Chris, 3. how if, instead of flat, I raise it +3dB toward TL resonant freq.? (MJK) You can do this but my guess is that the impulse resposne will start to ring a little. I have never tried this approach. 5. There are 2 graphs, what should to achieve and to avoid for each graph result? (MJK) Watch the graphs as you move the woofer along the line and add or increase stuffing at different locations. The goal is to have a strong first peak in the terminus to augment the driver's rolling off bass bass, then damp out the other peaks to reduce ripples. Play with the program with an example and see what can be achieved. Other then that I don't have any firm rules. Don't get too fixated on perfection, the worksheet probably over predicts the ripple a little and your room is going to do a lot more damage to the SPL response. 7. how high or low for the voltage is good and how many ringing is bad? (MJK) Don't worry about the absolute magnitude, look at the shape of the time trace and make sure you don't get a lot of oscillations or reflection pulses. Hope that helps,
 7th January 2004, 07:59 AM #6 tda   diyAudio Member   Join Date: Dec 2003 Location: Bucharest ------------------------------------------------------------------------------- 1. Acoustic Impedance plots - if you set the stuffing density to zero you can see the peaks in this plot that are the quarter wavelength resonant frequencies of your design. The first peak is the tuning frequency. I use this plot to tune the enclosure relative to the driver resonance. --------------------------------------------------------------------------------- Hello MJK, I have a question regarding the tuning frequency. I have a driver with fc=60 Hz. Is any problem if my enclosure is tuned at 40Hz? SPL look very linear and I used your latest Ported Box sheet. I'm asking this because I saw in this thread that you recommend tuning the enclosure close to the driver fc (if I understood correctly). Thanks, tda
 7th January 2004, 12:12 PM #7 MJK   Account disabled at member's request   Join Date: Feb 2002 Location: Clifton Park, NY Hi tda, "I have a driver with fc=60 Hz. Is any problem if my enclosure is tuned at 40Hz? SPL look very linear and I used your latest Ported Box sheet. I'm asking this because I saw in this thread that you recommend tuning the enclosure close to the driver fc (if I understood correctly)." In most cases tuning near the driver fs works well. However, nothing says that you cannot tune above or below fs. If the SPL response looks good and nothing looks way off in the other graphs, then I don't see any reason not to use the design you describe.
 7th January 2004, 12:24 PM #8 tda   diyAudio Member   Join Date: Dec 2003 Location: Bucharest ------------------------------------------------------------------------------- If the SPL response looks good and nothing looks way off in the other graphs, then I don't see any reason not to use the design you describe. ------------------------------------------------------------------------------- What do you mean: "nothing looks way off in the other graphs”? Beside SPL graph what else should I check to see if everything is right? Thanks
 7th January 2004, 04:58 PM #10 christophorus diyAudio Member   Join Date: Dec 2003 Hi MJK, I hope you're not tired to answer my questions, 5. (MJK) The goal is to have a strong first peak in the terminus to augment the driver's rolling off bass... There are 2 graphs, which graph did you pointed, phase or impedance? I made a simulation, I made TL resonant freq. 20% below Fs and the SPL response looks good, however TL box total volume= 4,5x Vas! Is it still OK, or too big? Is there any optimum number for TL box total volume agains Vas? Thankyou, Chris.

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