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Ukko Kari

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Ukko Kari last won the day on March 26

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About Ukko Kari

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  1. Faital 15PR400, BMS 4594 MTM

    A baffle of infinite size can be considered a 180 degree horn. The acoustic impedance will change rapidly from the mouth of the horn to the baffle. giving rise to diffraction, unless there is absorption, or a very large radius at the mouth where it transitions to a baffle, but this also depends on the frequencies of interest from the horn, the dispersion and the physical sizes of the device in question. In other words, diffraction and re-radiation is still a real problem for horns of finite dimensions.
  2. Real life sounds - instantaneous loudness

    With loud low bass in a vehicle and could discern 15 through 11 hz as distinct different notes, however under 10 hz, it was all just pressure on the ear drum, like you were underwater, having jumped into a pool.
  3. Faital 15PR400, BMS 4594 MTM

    The .PDF from Electovoice is no longer available on their website, but I had a copy on my computer. Xi-Series,%20Merlin%20ISP-100.pdf
  4. Faital 15PR400, BMS 4594 MTM

    What is a good horn in your experience? For a common 90h x 45v horn of 12 inches width and 6 inch height, the vertical polar pattern will widen below 3.7khz, exceeding 90 degrees at just below 2khz, according to this article: https://www.prosoundtraining.com/2010/05/24/understanding-horn-directivity-control/ Even the 18 Sound XT1464 is 'small'. Used with other elements in a vertical 'array' of 3 elements [MTM] leads to increased directivity in the vertical dimension, even when the pattern control is falling from the horn.
  5. Real life sounds - instantaneous loudness

    Harmonic distortion in my experience makes a subwoofer seem louder than it actually is. Picking a frequency that most commercially available ( Best Buy, etc ) subwoofers can reproduce at a decent level, say 25 hz, can result in 25 hz + 50 hz + 75 hz being reproduced. An SPL meter will integrate these tones and show a high level, however that does not mean the device is capable of reproducing cleanly 25 hz at that level.
  6. Faital 15PR400, BMS 4594 MTM

    One way to cure diffraction is to flush mount the cabinets in a baffle wall with a layer of absorption, like 1" thick. Realistically, larger radius corners should have been used on my boxes, but 1 1/4" is getting a bit hairy to handle in a hand held router even with a large add on baseplate, and 1 1/2 is about the limit without going to MDF substrate and using machined corners. http://www.tapeease.com/cabinet1.htm I could have gone the skeletal route with multiple layers of thin plywood instead, ending up with curved sides, large radius on the baffle. Did I mention the dust was *incredible* when routing all of the corners to 1 1/4" radius? Doing this outdoors with a slight wind, it was still problematic, it was like it was snowing wood dust out.
  7. Real life sounds - instantaneous loudness

    Kvalsvoll: very interesting results, it mirrors other information that I have come across in the past, where 2nd order harmonics are relatively benign in comparison to higher orders. From your data, we can see that higher orders of harmonics are deleterious, and the ear can easily distinguish these from the original signal.
  8. Faital 15PR400, BMS 4594 MTM

    At the end of the day, you have to ask yourself is the juice worth the squeeze? Additional amplifier channels, more complexity, an additional surface for diffraction from your main woofer.
  9. Faital 15PR400, BMS 4594 MTM

    Perhaps juggling chainsaws would be easier than picking trade-offs. Baffle width, roundover size, cabinet depth, height, volume, adequate port area, bracing, ability to get cordless drill inside enclosure for installing the pocket screws on the last side... portability, ease of assembly, etc.
  10. Faital 15PR400, BMS 4594 MTM

    Mic 1/4" from top woofer dust cap: Edit: I don't recall if eq and crossover were enabled, it's been a while since this was measured. Might have to disable the DSP and re-measure this.
  11. Faital 15PR400, BMS 4594 MTM

    I had hoped that the tuning would shift up enough by shortening the ports 2 inches, but their proximity to the side walls and floor of the enclosure means that they are acting like they are much longer than they physically are. It is a bit of a pain to finesse the port length, but I would like to get the tuning point up just a wee bit higher. I can live if they aren't 40 hz.
  12. Faital 15PR400, BMS 4594 MTM

    I also checked for excursion minima with sine waves at high levels. With the shorter ports, excursion minima was 34-34.5 hz. We can debate minutia all day long, but that doesn't change much. When the voice coils have some heat in them, the impedance will shift as well.
  13. Faital 15PR400, BMS 4594 MTM

    As an experiment ( per Lilmike ), I hooked up a pair of UCA-202's, output on one, and measure on the second to get rid of the cross talk issues. Apparently, the absolute value for impedance is off, but the <20hz cross talk is gone.
  14. Faital 15PR400, BMS 4594 MTM

    Had a bit of time today to pull the lower woofer, wiggle the ports out of the baffle, shorten to 8" long, installed they are 8 3/8" total. Net interior volume went up by 0.11 cu ft, to a total of 9.63 cu ft. I had not saved the impedance .mdat prior, but looking at the screen shot, the upper impedance peak fell a small amount, as it would when the box volume increased. Removing 2 inches on each port only raised the tuning ~ 1 hz, observed excursion minima was at 34-34.5 hz. I also found a leak around a screw during testing, the foam seal had compressed some since assembly.
  15. Faital 15PR400, BMS 4594 MTM

    The closest I could place the cursor was -0.9 degrees, yes it coincides with the peak on the right, but the others are shifted some. I get 0.5 degrees at 0.7 hz above the left peak, and centered it's already at 20 degrees.