- Joined
- Mar 22, 2019
- Messages
- 129
- Likes
- 30
I have a little article on transmission line effects in speaker cables on WBF and/or here if Amir brought it over. See e.g. https://www.whatsbestforum.com/threads/rf-speaker-cables.3759/#post-59881 (did not see it here). Since the rise time of a 20 kHz signal is about 17.5 us, reflections would have to be severe and sustained to be audible. In most systems the reflection at the speaker is absorbed, or mostly so, by the low source impedance of the power amplifier so triple-transit issues are inaudible. Assuming there is enough energy to generate a significant reflection to begin with, something I have not attempted to analyze. For audio circuits, reflections are usually buried in the rise time of the signal o do not appear as isolated events; the limited bandwidth of the system kills the stairsteps (bounce diagrams, anyone?)
It's not even a matter of masking. With a 10-metre cable, the round-trip delay is typically 100 ns. At 20 kHz, this is a phase shift of merely 0.72 degrees. This is utterly insignificant.To be audible a reflection would need to be extremely high in level and sufficiently moved in time from the stimulus. Otherwise it will be masked.
Indeed its buried within the original signal. Also 10 m is probably on the long side in domestic situations. IME less than 5m is more typical.It's not even a matter of masking. With a 10-metre cable, the round-trip delay is typically 100 ns. At 20 kHz, this is a phase shift of merely 0.72 degrees. This is utterly insignificant.
But he had a video!!!!It's not even a matter of masking. With a 10-metre cable, the round-trip delay is typically 100 ns. At 20 kHz, this is a phase shift of merely 0.72 degrees. This is utterly insignificant.
He even has several videos but expect him to feel vindicated by now.
Even though he is correct about the impedance matching thing he is wrong about the audibility of it.
Audiophiles hear all sorts of things that simply aren't there. When put under controlled conditions they fail.The terrible sound IS NOT a roll-off. It is an increase brash sound that is clearly audible. In the last 30 years we have sold thousands of sets of cables to many fussy audiophiles who can hear this distortion and choose to stick with these cables. I can see that you are not prepared to believe there can be such an audible difference.
There are many audiophiles who have good sound as their passion and are easily prepared to pay for the hard work necessary to produce first class cables and their systems are good enough to resolve this. It is no accident that we get awards see http://www.townshendaudio.com/the-ear-the-best-of-2013-townshend-isolda-speaker-cable/ http://www.the-ear.net/review-hardware/townshend-f1-fractal-loudspeaker-cable https://www.hifiplus.com/articles/townshend-f1-fractal-loudspeaker-cable/
Professor Cyril Murray, Sydney university electrical engineering and many other graduate engineers. They all agree.
Professor Malcom Hawksford, who also loved to muddle up basic EM theory for fun and profit.
I am askingSo Dr Murray is still alive is he? How old is he now, surely he must be 100+ years old?
I recently (a few years ago) restored and tested one his creations (a Murray integrated amplifier K106) for my (85yo) audiophile father, as he likes to buy odd and rare pieces from the 1970s to play with (and get me to 'look at' i.e. fix if they need it...) This amp is a classic 1970s design. All Philips semis, classic BC549C (ooh, low noise) TO92s, motorola T03s, a beautiful flux strapped Aussie made transformer, heaps of tantalums and a PA amplifier type construction. That said, the chassis is aluminium, countersunk flush screws and clearly utilized considerable thought in design. All the PCBs are fibreglass and stacked, edge connected and nicely hand routed.
Issues are numerous and the frequency response plot has to be seen to be believed. It is the worst I have ever seen in any commercial product.
I kid you not. (if you want to see it, just ask)
View attachment 24180 (internet pic)
Of course there is, the frequency dependence only drops out for the simplifying assumption of lossless lines, which doesn't remotely apply here. https://en.wikipedia.org/wiki/Telegrapher's_equationsNote, there is no frequency component in characteristic impedance and it applies for DC attached.
Me too.I am asking
I am asking
Me too.