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About almikel

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  1. Hi from Sunshine Coast !

    welcome John, Your comment made me think of this cheers Mike
  2. Hello from Brisbane

    Hi Brendan, Woofers only start to sound good once they're 18" or bigger, and let your significant other know you'll be filling the lounge room with acoustic batts, otherwise you'll need 21" woofers for good "in room" sound ...enjoy the site...and no you don't need 21" woofers or acoustic batts... ...18" woofers do sound awesome though! Mike
  3. Newbee

    welcome plenty of people here on both sides of the SS vs Valve "which is better?" discussion...enjoy cheers Mike
  4. Catman's Analog Musings

    Interesting - I'd expect hum across all drivers on the same channel (not just tweeter), or all speakers... ...but if you can't hear it at the listening position, IMO it doesn't matter. agreed. IME, tweeters hiss - if you can only hear this with your ear next to the tweeter and not at the listening position then that's fine IMO. If you are able to eradicate it completely as in @andyr's case - well done! My tweeters are around 110dB/w sensitivity - I expect to hear hiss at the horn mouth. I only care that I don't hear it at the listening position. cheers Mike
  5. Catman's Analog Musings

    that's all that matters
  6. Catman's Analog Musings

    Hi Andy, good quality, shielded interconnects of the appropriate length are a good thing, but the proximity of your old interconnects to power cables would not have induced hiss. Coils of cables of course aren't a good idea - many years ago my brother had a CB radio antennae outside my room that induced noise on my stereo - it got way worse when I looped the interconnects (cheap un-shielded). cheers Mike
  7. Catman's Analog Musings

    Just checking - you had a very low SNR (Signal to Noise Ratio), or the noise was very low (which implies a high SNR)? I would expect a valve based phono would have higher noise than a solid state phono, but I don't think that was your point? Hiss and hum/buzz are very different issues, but both are very annoying if audible at the listening position, and both are "noise" that reduces the Signal to Noise ratio (SNR) of the system. Hum/Buzz is an earth loop issue, that can be found and fixed, but sometimes hard to pinpoint (and hard to fix if it's commercial gear with a design issue). Hiss is about managing gain throughout the system, and ensuring the highest possible signal (avoiding clipping) is passed from 1 component to the next in the chain to maintain the highest possible SNR. In the context of this thread, any phono pre-amp generating hiss is a bad thing, as it will be amplified right through the chain. agreed - super quiet rooms exacerbate the issue cheers Mike
  8. Catman's Analog Musings

    Hiss that's audible at the listening position is frustrating and I don't like it. Hiss that's only audible with the ear up next to the tweeter is pretty normal IME, and I'm happy to ignore it. Mike
  9. Bass traps. How tall?

    I agree with all of the above. If using absorption, the traps need to be very large to achieve trapping of "bass" The SpringTraps appear to be a tuned "pressure" trap, which work very differently to absorption (absorption traps work on air velocity, not air pressure). IME most rooms still benefit from some broadband absorption that is large/thick enough, and is appropriately placed to clean up the 150Hz - 500Hz range. Getting absorption to work lower requires them to be too large - especially for shared rooms. To improve the effectiveness of absorption (get them working lower), they should have an air gap behind - this is why you see them straddling corners. But below the modal range of your room (say below 250Hz), it doesn't matter which corners you straddle - you may find "sneaky" locations behind couches for instance, straddling floor wall corners. Keep in mind that "lightly" constructed rooms (stud walls/gyprock) usually don't have major bass issues <100Hz, as the low bass just passes through the boundaries. Some absorption working 150Hz - 500Hz can help a lot IME. Rigid room boundaries are a different challenge, requiring more specialist approaches for managing low bass (like the SpringTraps or other pressure traps such as limp mass, Helmholtz etc). Before venturing down this path I would suggest getting your room measured first, then targeting treatment at specific issues. cheers Mike
  10. Hi Dave, in the context of DEQX, it will automatically time align drivers within a single speaker when doing a speaker correction, but not time alignment of a sub with mains. Given DEQX can provide an Impulse or a Step response, if using the start of the woofer and sub as the reference, would you use the Step or Impulse response for time alignment? Or do they differ so little it makes no difference? cheers Mike
  11. Multi-Sub Optimizer

    Great post @andyc56! It will take me some time to absorb and understand all of it -very interesting that time alignment using Impulse Response applies for FIR linear phase filters and not IIR filters - especially since most processors I know of use IIR filters in the low end due to tap limitations (including DEQX). I'd greatly appreciate your input in the other thread if you have the time/inclination. cheers, Mike
  12. Digging up an old thread due to some confusion on my part/questions I've got based on a different thread that raised the whole time alignment issue. This is the other thread My original thread (this thread you're reading now) was about providing a tutorial on time alignment using DEQX. Originally I had proposed using the "Step" response function in DEQX and aligning peaks between 2 woofers (mid and bass). It was pointed out that the "Step" response was inappropriate for this purpose, but the "Impulse" response could be used - assuming the right "peaks" were chosen - to determine the right delay (accepted that choosing the "right" peak within the "mush" is not trivial). Some pictures of a "perfect" 2 way system grabbed from one of @davewantsmoore's posts in the thread above to assist discussion. Freq response of a perfect 2 way with Xover @300Hz (don't get bogged down on the frequency chosen - this is just the crossover between my mid woofer and bass woofer) Step response Clearly the Step Response is completely useless as a tool to determine appropriate time delays to achieve Time Alignment - possibly the 1st zero crossing of the tweeter could be aligned with the start of the woofer rise if you could find it in a real system? The Impulse Response that Dave posted at the time was this This led to my understanding (perhaps incorrectly) that an Impulse Response measurement was a valid measurement to use to align peaks to achieve time alignment of 2 drivers. Mathematically my understanding is that the impulse response is the derivative of the step response, and based on a (very) casual analysis I thought this was why the peaks on the IR lined up compared to the Step response. I figured the difference between the peaks for each Step Response - Mid vs Bass - were constants, so vanished when calculating the derivative - hence the peaks lined up with the Impulse Response but not the Step Response. Based on @davewantsmoore's comments in the other thread I'm no longer sure of any of this... Is the Impulse Response useful for determining the time alignment between 2 drivers in a crossover scenario (ie tweeter to mid or mid to bass or bass to sub)? Can "peaks" in the Impulse Response be used at all for this purpose as the reference? - especially in the mush, peaks are easier to find than starts...assuming you can find the "right" peak... I need some learning please? cheers Mike
  13. Multi-Sub Optimizer

    me too.... ...and I'm now completely lost on the difference between Step Response vs Impulse Response (in relation to usefulness for time alignment) - neither appears useful for this purpose. I'll post some questions in the other "Time Alignment" thread to stop further pollution of this thread cheers Mike
  14. and @Celts88 a quick google of HAF filters only gave me "High Airflow Filters". What are they and can you provide any links? cheers Mike
  15. agreed - as I mentioned a few pages ago, it's OK to use a splitter connection to split a signal from a single output to multiple inputs, but you can't use a "splitter" connection to join 2 outputs (eg pre-amp out left and right) to form a single "mono" input for the sub. Quoting from the Rane Paper "Why not Why" http://www.rane.com/note109.html "Outputs are low impedance and must only be connected to high impedance inputs -- never, never tie two outputs directly together -- never. If you do, then each output tries to drive the very low impedance of the other, forcing both outputs into current-limit and possible damage. " Nelson's idea suggested to @Ozcall above essentially achieves a similar outcome to that suggested in the Rane paper. In Ozcall's case he was splitting signals, but it could be used also to join signals and avoid a dead short across the low output impedance of a pre-amp. cheers Mike