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Post by ironinthepath on Mar 4, 2024 20:26:43 GMT -6
I think for the x-axis the 2k could actually be 2.5k truncated and 1k would similarly be 1.25k; of course I can't be sure. Taking a second look, I agree that the axis and or labels are strange. I don't think there is anything stopping the cable from just passing DC, so anything strange down at those frequencies likely just a measurement or plotting artifact.
Also, I was thinking that if we can just lump the long route's distributed capacitance as a single value (call it C) and maybe just ignore the wire's resistance we can estimate the bandwidth by considering the output resistance of the driving circuit (call it Rout) and the input impedance of the following circuit block (call it Rin). The capacitor sits in the middle in this simplified model; it would "see" the parallel combination of Rout||Rin.
So the 3dB roll-off would be estimated as f3db = 1/{2*pi*(Rout||Rin)*C}.
Back of the envelope check, if we can assume C = 20000pF (previous post estimate, equivalent to 20nF or 20E-9 F) and Rout =150 Ohm (standard microphone) and Rin = 1.2kOhm (1073 style mic pre input resistance), then Rout||Rin = 133.3 Ohm --> f3db = 1/{2*pi*(133.3)*20E-9) ~= 60kHz
For a 1st-order roll-off with -3dB at around 60kHz, that amounts to about a roll-off of 0.5dB at 20kHz (checked with calculator, since I was curious)
EDIT: thinking about it more, since balanced circuit the 150 Ohm and 1.2k Ohm may need to halved ( search for "differential-mode half-circuit analysis" if interested), meaning the numbers might be less pessimistic by a factor of two...but depending on the interpretation of the capacitance to ground C, it may double bringing us back to same number --> I'm out of bandwidth to think about this further at the moment :-)
-Chris
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Post by EmRR on Mar 4, 2024 21:38:06 GMT -6
^ ....100 meter / 328 feet estimate. translates to -3dB points of: 164' = 120kHz 82' = 240kHz 41' = 480kHz 20.5' = 960kHz This is the 100 meter response of Canare L-4E6S. 328 feet. Oooh - I don't like the look of that peak at 10Hz  that would be the low cutoff of the test equipment used......wire passes DC....as in phantom power.... |
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Post by Ward on Mar 5, 2024 7:16:28 GMT -6
Just remember, "Trust the Science". I know right? - First I was ignorant. Then I trusted the science. Then, quickly, "trust" became an obvious ruse. Then I became a conspiracist. Then I was deemed "right" by alternative science. Then the original science changed to fit a different narrative. Then all science became non-important in real life. And now, I'm left staring at my left foot.....wondering if 96k is going to infect the audio world as we know it, and make storage costs double....  . Things I think about in my spare time while files bounce down.... That's fecking brilliant!! |
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Post by svart on Mar 5, 2024 7:28:31 GMT -6
This is the 100 meter response of Canare L-4E6S. 328 feet. ![]() Oooh - I don't like the look of that peak at 10Hz The graph doesn't look legit to me, but I've seen some kinds of little peaks like that at DC when you interface offset impedances together. The graph is probably normalized to 0dB, which is why you see gain at 10Hz. |
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Post by Shadowk on Mar 5, 2024 20:00:57 GMT -6
But how high should I be HPFing the 808 or that ultra-sub-bass synth along with it? 🫨 OK. OK. How about just a Drop-D 5-string bass? 🥴 on the ATC 150s and the 18” subs on, I miss all those sub-frequencies I can’t hear but can feel. 😣 I guess it's a quick way to stir your coffee, did you know we spend two weeks of our life stirring? Get the Stirmaster now (Any Red Dwarf fans?).. |
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. Things I think about in my spare time while files bounce down....
