almikel

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About almikel

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  • Location
    Brisbane
  • Country
    Australia
  • First Name
    Mike

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  1. from Wikipedia "In at least some parts of Sydney, the ripple frequency is 1042 Hz. The signal usually consists of several bursts of a few seconds on and off, followed by a period of up to 50 seconds on. This is coded to affect only selected equipment. Occurrences are very frequent, sometimes several times an hour throughout the day, not just at evening and morning off-peak times." https://en.wikipedia.org/wiki/Zellweger_off-peak Mike
  2. in Brisbane there are 2 "controlled" tariffs - 31 which is super economy, usually only on 10pm - 7am, and 33 which is economy, and guaranteed 18 hrs a day, but can turn on/off anytime, so the control tones can come down the power lines at variable times
  3. that's a great result - well done! Mike
  4. I got a sixty-nine Chevy with a 396Fuelie heads and a Hurst on the floorShe’s waiting tonight down in the parking lotOutside the Seven-Eleven storeMe and my partner Sonny built her straight out of scratchAnd he rides with me from town to townWe only run for the money got no strings attachedWe shut `em up and then we shut `em down
  5. I feel your frustration agreed And my personal experience doesn't help a lot in your case - since I've been measuring my speakers and room, I've always done speaker measurements outdoors, then corrected the speaker response to flat based on the outdoor measurement, then moved the speakers into the room and worked on room correction (knowing that the baseline speaker response outdoors was flat). I've also never dealt with large floorstanders like yours with multiple woofers - I run a "simpler" system with one driver covering 40 - 300Hz. In your case we have an additional "degree of freedom" where we don't know the "anechoic" response of the speakers, so being able to tell what is room related and what is speaker related is much harder - but even outdoor measurements will have reflections in the measurement down low. Keep posting and I'll keep trying to assist - but if it get's too tiresome you could consider contacting someone like @Paul Spencer who does this stuff (room measurement and consulting) commercially, and he will possibly be able (with your assistance) to do some remote measurements - a (likely long) phone call, internet and tools like Team Viewer make remote measurement possible - just a thought and I have no idea if Paul has tried remote measurement... Reviewing your graphs I don't think you've done a series of on-axis measurements on 1 speaker at different distances. Unfortunately large tower speakers like yours with multiple woofers in a D'Appolito config is trickier. I think the Xoxer between mid and woofer is 125Hz on your speakers. We're trying to find an issue <300Hz so let's ignore the tweeter response Do a series of on axis measurements in line with the midrange from close miked (nearly touching the driver) to as far back as possible (still on axis). We "should" see a smoother result close miked, with more peaks and dips that shift in frequency as you move the mike further away. cheers Mike
  6. As Dave said, non-zero negative phase (phase lag) is delay - let's leave "phase lead" alone for a second. Take the graph above and look at 1kHz - the brown phase line is approx -90 degrees. To convert this to time delay the formula is time delay = phase / (360 x F) So in this case time delay = 90/(360 x 1000) = 0.25 ms Now look at 10kHz - the brown line is approx (30 - 360) = -330 degrees (remember we're looking at a wrapped phase plot so subtract 360 degrees as it's after 1 vertical line) time delay = 330/(360 x 10000) = .092 ms @andyr - does that make it easier to understand that the delay varies with frequency? All IIR filters have variable delay with frequency. A linear phase FIR filter has constant delay for all frequencies. The nice thing about an LR4 Xover is that High Pass and Low Pass responses are always in phase - as Dave said the brown line is the phase response of both HP and LP - so although the delay varies with frequency, the delay is the same for each. The same can't be said for a 2nd order Butterworth Xover for example (hence the bump or dip in FR at Xover). It's because the drivers of an LR4 are in phase that you get a perfectly flat FR after summing. The benefits of the LR4 Xover requires you've achieved an "Acoustic LR4" and not just an "Electrical LR4" within the Xover - Linkwitz discusses the need for time alignment of non-coincident drivers etc etc, and unless the drivers (or in your case panels) are flat several octaves away from the Xover point, you'll never achieve close to an Acoustic LR4 response. These are some of the complexities Dave was alluding to in designing Xovers. cheers Mike
  7. When I joined SNA way back when, I didn't understand phase much at all. A lot of what I've learned has been from SNA directly or inspired by SNA to make me look further. To coin a new SNA term - this is a daveism (@davewantsmoore) - reading similar in a dave post a long time ago had a profound impact on my understanding of the relationship between FR and phase - if my recollection is correct Dave even used the technical term "wiggle". I greatly enjoy my membership in the SNA community - adding something is what SNA is all about. cheers Mike
  8. fortunately the "insert more expensive device here" didn't fail to protect the fuses. decoupling caps and transformers become part of component design when you don't know the DC status of the previous component. If you don't know, then safest to design in some de-coupling - you need to balance that with the FR impacts of caps and transformers. Mike
  9. Mutliple subs and overlapping frequencies is a bit off topic...but This is where integration comes in, especially time alignment. Having the mains overlap with the subs is a valid and common approach to smoothing the bass response in the room (assuming your mains and amps are up to it). I'd never attempt it without a measurement rig and DSP, but in my case (mains overlapping with a single sub) it means 3 bass sources working 25-70Hz or so, and the room bass response is smoother. My sub runs 15Hz - 60Hz, my mains run down to 25Hz. The sub is not close to either main speaker. To get it right requires independent delay and EQ control on each bass channel - IMO this is a requirement for appropriate bass management in a room when managing multiple subs (or in my case 1 sub but 3 bass sources). You can get cancellations with having your mains overlap your sub, but with placement, measurement and time alignment you can achieve smoother bass across a larger portion of the listening position than mains on their own, or the mains Xing to the sub at a particular frequency. You could possibly dispense with the overlap with multiple subs - it comes down to integration. unfortunately not - depending on the filters, the sub needs to be much closer to the listener than the mains to achieve "time alignment". Filters cause delay, and the low pass on the sub will mean the mains need delay to let the sub "catch up". IMO, EQ and DSP are just as essential as treatment and placement in creating the best sound possible in room. cheers Mike
  10. my experience using subs is that evil way beyond EQ is required - you may need the diabolical assistance of DSP. In my case I chose to use a tapped horn sub which has a nasty resonance at 90Hz. I low pass at 50Hz with a 48dB DSP LR Xover, so nearly 48dB down by 90Hz. An 8th order low pass IIR filter has quite a lot of delay, hence DSP is handy to manage time alignment. The sub mouth is about the same distance from the listening position as the mains, but needed the mains delayed approx 20 msec to achieve time alignment. Mike
  11. Pink, pink, pink, pink, pink moon
  12. that's not sub territory - that's mid bass - something your speakers should be up to and then some Agree with above comments about getting the room tuned by a pro. Can you get away with room treatment? That mid bass/high bass area between 100-250Hz is greatly helped by some absorption. I've measured enough rooms now to know most rooms benefit from some broadband absorption - especially if "feel it in your chest" is a requirement. Without even measuring i'd recommend floor to ceiling 600mm wide polymax XHD straddling the 4 room corners. Tricky to get approval from SWMBO though Those 4 traps would clean up 100-250Hz considerably, and you never know, the boss may like the sound. My wife has gotten so used to my room she can't listen to a stereo up loud in an untreated room anymore - bless her. I love the mid bass kick in the chest - once you have a room with a dry sound in that range with your Focal's, you can't go back. cheers Mike
  13. which by all accounts on this forum also sound superb - although I've never heard a pair