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davewantsmoore

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About davewantsmoore

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    Log! It's big, it's heavy, it's wood.
  • Birthday October 16

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    Hobart
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  1. Damping Factor

    There are numerous effects ... To keep it concise for now, it all stems from the fact that the speaker does not care what the voltage at it's voice coil is.... it is driven by the current flow. When then do our "voltage drive" amplifiers force the voltage at their output terminals to represent the signal? When this happens .... the amplifier sets the voltage at its output .... and what current actually flows in the voice coil, depends on a whole host of other factors. I agree with all of your post, except these two. Speaker drivers tend to have a lot of mechanical 'damping'.... and they just don't require the amplifier to be adding any (dirty IMO) electrical damping. Sure, if you take away the electrical damping, you will immediately have a different response form the speaker - and that should almost certainly be corrected by some other way (if the speaker is an 'already finished product', the designer has likely designed it expecting amplifier damping).
  2. I think the former is a much better choice. I have also found the Liittle Dot IV to be quite nice
  3. Audio myths and misconceptions

    Yes... it's a complicated one though. Rate/depth is not in itself a proxy for quality ..... BUT, well recorded and un-damaged audio, likely these days comes at a high sampling rate. Unfortunately you can't really tell much by the label on the tin. Which is a shame for consumers.
  4. Audio myths and misconceptions

    </understatement>
  5. Audio myths and misconceptions

    Does it really matter?!
  6. Damping Factor

    That seems to assume there is no advantage to using an amplifier with a high output Z. One could also apply EQ to increase the bass on the ME150+Isobarik. Granted this is not something a regular consumer would do.
  7. Damping Factor

    Yeah, sure. I understand.... I was just making the point that the change in frequency response/ringing that you'd get (on a typical speaker) would be very small with a few ohm of amplifier Zo ..... but it would be a larger ('pour' / poor) distortion of the response with hundreds of ohm Zo. .... but sure, speaker can be be made which "work" great form any amplifier Zo.... but just like we've said quite a number of times in this thread, most expect a low amplifier output impedance. As you know, I think a high amplifier output impedance is the way to go .... but you can't just go doing that with any old speaker as you will get varying results.
  8. Damping Factor

    Naah, surely it has only a few ohms of outputZ ..... that's heaps 'low enough' (for any 'normal' speaker, of moderately reactive impedance) Now, some 'current source' amp, with hundreds of ohm outputZ ..... that's 'pour'
  9. Audio myths and misconceptions

    99 times out of 100, or more ... when these things are compared, it isn't an apples to apples comparison ... and so of course, they can sound different. If you drop an opamp into a circuit, designed for a different one.... even if those opamps are quite similar, there will still be differences, and you'd need to redesign the circuit around it. It's all about how you use them. Clearly most opamps have the ability to be completely transparent, as their specs show ... but how they are used, and how the circuit around them is design, is the big factor in what the overall outcome will be. This is one of my favourites .... and at the core absolutely true. There are aspects of it where, there ARE reasons why larger rate/depth could sound better. It does just depend on what was done with the audio in the production chain (you can butcher the audio) .... and what is going on in your playback device (some devices may enjoy high input sampling rates)
  10. Low pass required?

    Like Newman said.... You need to shape the low pass response of the mid, so it matches the high pass response of the tweeter.... matches, mean in-phase and producing a flat response through their overlap. You may see different things, depending on where/how you measure the drivers.... and so it's easy to take a measurement, which says X ... and then design a correction for X ..... but if X was "wrong", then it's all stuffed. What filter do BMS suggest? I would like use exactly those ones.
  11. Ceiling panel speaker array build

    what are the drivers?
  12. Damping Factor

    It would always be helpful to have a proper box. The mechanical system parameters are a lot more significant than the electrical ones, and often not symmetrical for the driver (ie. on both sides of the cone) -------- If you have a speaker that has a flat response .... and then you EQ a bump into it's response (1) .... then it now also has ringing. If you have a speaker which has a bump in its response (same as 1) due to a incorrectly designed enclosure then it has ringing (the same ringing as 1) If you have a speaker which has a bump in its response (same as 1) due to lower electrical damping, causing the response to rise where the speaker impedance rises .... then it has ringing (the same ringing as 1) ... and vice vera. (ie. we could make any of these three examples be "1") The ringing, inherent to "damping factor" .... is just the ringing you get from a non-flat frequency response.
  13. Damping Factor

    That's exactly what I mean... Yes. The first discussion (Qtc) is boring. Different Qtc will sounds wildly different from each other. (Qtc .... ie. a different frequency response - with it's different inherent ringing of transients) Once we set the SAME response from system A and B ..... but that response is made of up more/less of different components, THEN we can see the pros and cons. While a low amplifier Zo is often essential (eg. a violently non-resistive speaker impedance ... very high current .... or simply for convenience in predictable amp-speaker coupling) ..... I see the effect of the amplifier "back-EMF" as being a signal which is non-linear distortion to the current flow in a voice coil driven from a low amplifier Zo ...... driving a speaker from a "current source" dispenses with that entirely. Is non-linear distortion a big problem? I am sure it is not as big of a audible problem as linear distortion is (hence the fanaticism about ensuring that every system compared has a normalised frequency response)
  14. Damping Factor

    (Sorry?) I didn't (intend to) remove a sentence. Yes, I do. It's exactly the point, you've transformed the system from Q=x to Q=y No issue. As I've deferred to a few times in this thread.... keystrokes are a particularly poor way to do this type of thing. A whiteboard, and 15 minutes of squiggling and talking between a few people works much much better. Pictures, and questions ..... as opposed to letters, and retorts. Indeed ! "EQ" (ie. bending the input signal) is very very powerful .... but also very very limited. I would not (for example) advocate for having a very large Q in the electro-mechanical system .... only to "EQ it away" by bending the input signal ... for just this reason. I only mention it to highlight the tie between the frequency and time views of the response. (Like the page you posted from JohnK points out). ie. that if you have a high-Q (ringing) response caused by lack of electrical damping (or from any cause at all) ...... that as you flatten the frequency response, you arrive at a low Q response (with no ringing). .... People have been led to strongly believe that the "ringing" at the system resonance frequency(ies) is something that happens purely due to a "defective" amplifier (no control). ie. that no matter what the frequency response curve would look like ... that the ringing will still happen, due to lack of "breaking" provided by the amplifier. This is incorrect. NB - As discussed - and I must always mentioned this for completeness (but I fear it may mislead some) .... when the signal STOPS instantly and the cone would be just falling back to rest.... then, the electro-mechanical parameters are the dominant effects. Damping factor proponents would say "Ahaha! it is here where the cone will waffle on for longer than it's supposed to". Perversely - what we find, is almost the opposite. Typical amounts of electrical damping make the cone step back to rest in a sharp distorted kind of way ..... where as hardly any electrical damping is required to prevent it from "bouncing". Although this is dependant on the specifics of the mechanical system (ie. how much technical damping, and excursion, etc.)
  15. Damping Factor

    The most important part is the end result .... and two system (like in your picture) with significantly different response will sound clearly different. In your picture, assuming the input signal is flat from DC to 200Hz+, then above 30Hz curve B rings significantly less in time, than curve A. If OTOH, you posted a picture of two systems with the SAME response ..... where one had a significantly different amount of electrical damping to the other, then we could look at differences in performance which relate directly to that electrical damping. THAT is what I would hope a thread like this would be able to get to. But alas. We've only got one solid comment about that (from Tranquility Bass) ..... which interests me, as it is the opposite to what many people say (he says non-linearities are increased) ..... although I do wonder if the different overall responses (like in your pic A vs B ) were taken into account. 'cos curve A (being 2dB higher) would display more no-linearities than curve B (due to the increased excursion).
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