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3-Way Active - High WAF - Hi-Vi-Fas

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  • kid_twist
    replied
    Re: 3-Way Active - High WAF - Hi-Vi-Fas

    holy heck your project is awesome.... makes me embarrassed of my projects... but... active 3 ways all the way

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  • dtruck
    replied
    Re: 3-Way Active - High WAF - Hi-Vi-Fas

    Just put your mic right up 1cm from a woofer cone. You should see a deep notch in response at Fb.

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  • devinkato
    replied
    Re: 3-Way Active - High WAF - Hi-Vi-Fas

    Originally posted by dtruck View Post
    A few tips:
    - did you take a nearfield measurement of a woofer to verify Fb? (or verify with impedance measurement, etc.)
    How do you go about verifying Fb? I did some searching, and know how to calculate it, but how do you measure in the real world? Play a tone and look for a peak?

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  • dtruck
    replied
    Re: 3-Way Active - High WAF - Hi-Vi-Fas

    A few tips:

    - did you take a nearfield measurement of a woofer to verify Fb? (or verify with impedance measurement, etc.)

    - Try to set yourself up to take some nice clean gated measurements with the speaker way out in the room and on the floor pointed up (and propped up enough to leave to port clear). Measure up and down the vertical axis. That will give you an idea of how your phase tracking between drivers is.

    - Remember to turn it up. Speakers that have flat on-axis response in-room tend to sound pretty dull at low volumes.

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  • ReissM
    replied
    Re: 3-Way Active - High WAF - Hi-Vi-Fas

    Originally posted by devinkato View Post
    I've been struggling with tuning - crossover points, levels etc - using a RTA and a calibrated mic. ...... I'm able to get the response very flat with no issue (one of the easy parts of using a 3-way with good drivers), but it doesn't sound "right". The sound feels rather dead and the low frequency extension is very one-note.
    Hmmmm... I could just be clutching at straws here, but two things come to mind:

    1. What about the room dimensions? Have you done any calculations on Axial, Tangential and Oblique Modes? There are several internet sites that have this available for your use. (I could send you a quick and dirty version I have for MS Excel.) Certain ratios of Length to Width to Height will produce fabulous results while others can make the sound quite bad (regardless of ANY speakers used in that room.) Once you understand those modes (Axial contribute the most) you can attempt to make adjustments so that you will not stimulate the problematic (coincident) modes. Or even create a Helmholtz resonator to help with certain problem frequencies. Ask the TT forum for help after you run through the calculations.

    2. The other important thing that people sometimes forget about is the ratio of Reflection to Absorption to Diffusion. A "normal" sounding room will have a good balance of all three. Too much of one, or not enough of another will cause some of the problems that you are describing.


    Hopefully this helps.

    Your speakers look friggin awesome. Nice job.

    Leave a comment:


  • devinkato
    replied
    Re: 3-Way Active - High WAF - Hi-Vi-Fas

    Thanks for all the kind feedback. Here's some pics of the guts of the entertainment center.

    This is the HTPC side - Running a i5-2550k @ 4.2ghz with 18TB of storage. Audio comes from an Asus Xonar D2X locked in @ a native bitrate of 16bit-44khz since the critical listening I do to is @ that rate/resolution. I've since added 2 intake fans to the holes on the right. Air is designed to travel from the right side to the left side, and exhaust there. It is a very positive pressure design, and since it is so big, I rely on localized directed air on components that need it, such as the hard drives, CPU, etc. The intake/exhaust flow is mainly to keep the ambient temperature in the case acceptable, not to actually cool anything specifically.



    This is the audio side. Running a JL XD 600/6 amplifier with a 60amp 13v power supply. Processing is done by a pair of MiniDSP units. I have a delay/power regulation unit in the chain as well. At power up, it will immediately send regulated power to the DSP units, then power the amp on after a few second delay. Shutdown is done in reverse.



    I've been struggling with tuning - crossover points, levels etc - using a RTA and a calibrated mic. I've had good success doing this in many cars with active crossovers, but I'm having a bit of trouble with this. I'm able to get the response very flat with no issue (one of the easy parts of using a 3-way with good drivers), but it doesn't sound "right". The sound feels rather dead and the low frequency extension is very one-note. I used the same ported alignment as the OS MTMs (also using 2 of the same woofer), so I'm not sure what the issue is. I'll keep at it (can't wait for the Active Crossover Design tutorial session at the upcoming get together).

    Leave a comment:


  • bolland83
    replied
    Re: 3-Way Active - High WAF - Hi-Vi-Fas

    Those bases look great, they almost disappear against the dark wood floor. Nice looking setup.

    Leave a comment:


  • dtruck
    replied
    Re: 3-Way Active - High WAF - Hi-Vi-Fas

    I just meant that virtual sources from baffle diffraction, reflections off grills, and that sort of thing would tend to be higher magnitude. I didn't really mean you should worry about that. It's all mostly settled once you choose drivers anyway. I think a decent "rule of thumb" strategy is to measure or estimate the two frequency ranges where the mid matches the woofer and the tweeter in dispersion and try to cross there, adjusting as needed to meet the bandwidths the drivers can handle. I haven't really looked at your project that carefully to be honest, just wanted to comment on the graphs because I thought they were kinda misleading.

    Leave a comment:


  • devinkato
    replied
    Re: 3-Way Active - High WAF - Hi-Vi-Fas

    Thanks for the feedback - When you say "makes baffle influence strong", in dumb ppl terms - what does that mean? That the width/height of the baffle will play a larger role on the frequency response and will have to be addressed via crossover design?

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  • dtruck
    replied

    Leave a comment:


  • Adam_G
    replied
    Re: 3-Way Active - High WAF - Hi-Vi-Fas

    Wow, that's a clean setup. Very nice so far!

    Leave a comment:


  • devinkato
    replied
    Re: 3-Way Active - High WAF - Hi-Vi-Fas

    Been a while since my last update. Here's what's gone down!

    Realized I wasn't going to have time to teach myself the fine arts of pouring decorative concrete, so I decided to go with a wood base.

    I wasted a day fabricating my first idea - a double thick .75" mid "sleeve" stand. I then test fit the speaker to the stand, and realized that it looked terrible. The stand was too chunky and broke up the thin "flow" of the speaker.



    After that, I went back to basics, and used .5" MDF to make a sleek and thin stand that has a base of 10 inches. This kept the overall aesthetics I was looking for, and I painted it in gloss black to match the terminal plate.





    All done - the build at least. Now is the hard part - tuning.



    Last edited by devinkato; 02-27-2013, 08:39 PM.

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  • ReissM
    replied
    Re: 3-Way Active - High WAF - Hi-Vi-Fas

    My previous phase graph showed the acoustic phase of your woofer. Here's the electrical phase of the raw driver (usually displayed along with the impedance curve). Notice that the electrical phase doesn't do anything drastic as we approach 7,000 Hz like the acoustic phase did.

    Click image for larger version

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  • devinkato
    replied
    Re: 3-Way Active - High WAF - Hi-Vi-Fas

    Originally posted by ReissM View Post
    ... but let's take a look at the acoustic phase of your woofer. I took the CLIO data that PE posted and plotted the phase. The "180 degree wrapping" typically seen on phase plots can be misleading, so I unwrapped the phase plot and a trend emerges that seems to follow your intuition. Take a look at how little the phase changes until we approach approximately 7,000 Hz. At 7,000 Hz the rate-of-change of the acoustic phase increases dramatically. This appears to corroborate what you suspected.
    [ATTACH=CONFIG]31493[/ATTACH]
    I suspect this is one of the reasons that I've had more success with 3-way systems (other than polar response). I'm simply not pushing the drivers to their limits as much as in a 2-way, therefore I'm avoiding funky driver induced phase summing issues combined with crossover point phase issues.

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  • Sydney
    replied
    Re: 3-Way Active - High WAF - Hi-Vi-Fas

    Originally posted by devinkato View Post
    As far as drivers - am I correct in understanding that the closer you push a driver towards its frequency limits, that is where you start seeing more unpredictable phase issues? Like the "not exactly in phase, nor exactly out of phase" phenomenon you describe?
    I not sure what you mean either...

    Leave a comment:

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