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Showing content with the highest reputation since 09/22/2020 in Posts

  1. 1 point
    So I've been lusting after a Parts express UM18-22 18" with sealed flat pack. They were out of stock when I looked but I found a CraigsList add for two ultimax's in a crazy looking Dipole box. Very close to this build here https://www.linkwitzlab.com/woofer.htm I've been telling people that the bass is directional and no one wants to believe me. So I finally measure both on-axis and 45 degrees off-axis The build is incredibly inefficiant as I'm currently bridging a crown K1 at 1100wats 8ohm and have to boost sub output from the Denon receiver quite a bit. Not so much nearfield but anywhere else I put in the house. I have a sealed flat packs on the way so I can separate these beasts and pressurize the room better but the fact that I can rattle my brain while watching a movie and have my wife, literally next to me on the couch and she doesn't have to endure the bass that I love is kind of magical. Not sure I want to take this thing apart now. Just thought I would share.
  2. 1 point
    In the end though, you have to build & test to be 100% sure. There are (also empirical, not theoretical) studies / papers on the topic, from the AES for example, that are freely available; the issue has been figured out for decades. The conclusion overall is that you should always use the maximum port size that you can possibly accomodate in a speaker box, because there will always be some compression. There are other concerns like port resonances (only relevant for full range boxes, not subwoofers), or cooling (only relevant for PA subs).. but generally, the larger the port, the better. Flared ports reduce air turbulence at the port ends, which results in noise. So flared ports reduce noise. They do however hardly or not at all reduce compression, which is a result of an inadequate inner port cross-section area. Port noise and compression are / can be two different things.
  3. 1 point
    Good guessing can save a lot of time and money that would be spent building physical things that don't work.
  4. 1 point
    I'd echo SME here. The Othorn is still a very good sounding design but I'd consider the Skram instead. It's smaller, lighter, has flexible tuning options and is simpler to build. Output and SQ should be the same if not a bit better due to the more extended top end. Issues don't start till higher in frequency that the Othorn.
  5. 1 point
    I have been reading these papers by Kipple: http://www.klippel.de/fileadmin/klippel/Files/Know_How/Literature/Papers/Green Speaker Design Part 1.pdf http://www.klippel.de/fileadmin/klippel/Files/Know_How/Literature/Papers/Green Speaker Design Part 2.pdf In the second paper they improve the efficiency of an overhung driver by reducing the coil height to the top plate thickness and then compensate for the resulting non linear behavior. The benefit of this in their example is a 39% in voice coil temperature for a given output compared to an overhung driver (~3dB output gain in the non excursion limited region for the same driver). Considering the IPAL driver already is designed to be a transducer with dedicated amplifier and it has a huge coil overhang it would seem that with just shortening the coil a bit and a new version of the IPAL mod that implements the kipple DSP work they could increase the efficiency/output substantially (IPAL2?). There would also seem to be benefits form changing reducing kms but I understand that this is required to have small clearances in the voice coil gap due to rocking modes.
  6. 1 point
    Hello also from Denver here! You started in on one of the Othorns already? I'm not sure how far along you are, but you may want to consider the Skhorn or Skram instead. They have much cleaner response to well above 100 Hz, and I think most people here regard those two designs to largely obsolete the Othorn. If you have a choice, I very strongly suggest you go with one of these newer BP6 designs. If you already have Othorns you want to use, then I'd say the situation is a bit of a mixed bag. The 80-100 Hz region is pretty narrow---essentially 4 semitones (or a major 3rd) apart. However, crossovers are not an all-or-nothing thing but involve blending over a pretty wide range, even with e.g. 4th order slopes. IMO, the Othorns will probably sound even better crossed even lower at like 60 Hz, at which point, a dedicated mid-bass section (for say 60-150 Hz) starts to make more sense. Looking at Ricci's compression sweeps for the Othorn, I don't expect EQ applied above 100 Hz will be very help helpful because the response above 100 Hz actually changes a lot with the signal level at medium-to-high levels. EQ which sounds good at low signal levels might actually make things worse at high signal levels.
  7. 1 point
    Na, they are in our studio with the big Danleys. Had about a dozen friends over last night for a listening party with the new Tool Album. Holy shit! I am continually blown away with these Skram subs. Danny Carey's drums sounded so immense! kick drums right in the soul haha! In all seriousness we collectively agreed that none of us have ever heard kick drums sound this good out of a soundsystem. Made for a super memorable night, fuck going to concerts lol!
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