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    Posted: 15 Jul 2020 at 11:29am
Originally posted by capetownwatches capetownwatches wrote:

This thread certainly has veered off course somewhat...did we not begin by discussing Audio Science Review..? Wink

That said, interesting stuff although much of it goes over my head...Embarrassed

Like the science and logic goes over the heads of those at Audio Science Review. Geek
Just listen, if it sounds good to you, enjoy it.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote capetownwatches Quote  Post ReplyReply Direct Link To This Post Posted: 15 Jul 2020 at 10:53am
This thread certainly has veered off course somewhat...did we not begin by discussing Audio Science Review..? Wink

That said, interesting stuff although much of it goes over my head...Embarrassed
Solo UL=Kingrex HQ1=NFB11.32=Little Dot Mkll=SRM252S=Benchmark DAC1 USB=RL Concero
LCD2F=HD600=SR207=DT990 600Ω=TH-X00=K612Pro=K240S=K171Mkll=M4U2=Y50
RCF Ayra 5=Mogami/Sommer->Neutrik/Amphenol
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Ash Quote  Post ReplyReply Direct Link To This Post Posted: 15 Jul 2020 at 7:19am
Yeah, otherwise with digital, you may find yourself attenuating the signal rather than the interference.
Lautus USB or S/PDIF>Majestic>Lautus-R3 TRS-XLR>2xProprius>MySphere 3.1
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Graham Slee Quote  Post ReplyReply Direct Link To This Post Posted: 14 Jul 2020 at 10:58pm
@ Jon: I wouldn't even try to measure frequency vs amplitude, because the cable reflections will swamp any theoretical attenuation. It is theory after all.

@ Ash: Where a second ferrite is used, the first ferrite is for the upper frequency. The origin for the lower frequency is still at the cable start.

The 2nd harmonic will peak in the middle of the filter frequency's first quadrant, and so, theoretically also be attenuated to a lesser degree.

Hint: wavelength is in inverse proportion to frequency. Higher frequency - shorter wavelength.

For the USB, I decided not to try 100MHz due to the possibility of "rounding-off" the properties of (what should be) the squarewaves. The FFT of a squarewave being the fundamental and all its whole number odd harmonics.

But all this is theory anyway, although I would like to be able to measure it one day.


Edited by Graham Slee - 14 Jul 2020 at 10:59pm
Not simple enough for Google-Bot to understand...
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Ash Quote  Post ReplyReply Direct Link To This Post Posted: 14 Jul 2020 at 7:13pm
Thanks very much Jon. Thumbs Up

So Graham, if the ferrite position is essentially the end of one circuit and the beginning of another, would it not be wiser to place the next ferrite at the same distance again, to attenuate the fundamental frequency rather than its second harmonic?? The amplitude of the fundamental is also higher than that of subsequent harmonics so more to attenuate?

With all the expense of setting up speakers for optimum performance and reference sound, perhaps £3.5k MySphere is a more sensible choice? An expensive investment but backed up with plenty of R+D and extensive sound measurement techniques.


Edited by Ash - 14 Jul 2020 at 7:27pm
Lautus USB or S/PDIF>Majestic>Lautus-R3 TRS-XLR>2xProprius>MySphere 3.1
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Fatmangolf Quote  Post ReplyReply Direct Link To This Post Posted: 14 Jul 2020 at 6:16pm
Originally posted by Ash Ash wrote:

Finally getting my head around Jon's mental arithmetic there. Calculating the distances for ferrite placement is one thing; what about the qualities of the ferrite itself? Does it have to be a certain size or have a particular inductance or "crystal" resonance?

> I bought some ferrite blocks from Maplin that werea about 30mm long and centred them on the cable at the calculated distance.

Why a 200MHz calculation? For the second harmonic of the fundamental wave?? If you had a 10m cable and the signal amplitude were not significantly attenuated by that length, you could have a series of ferrites along the cable that gradually get closer together by a factor of VF%, as long as they fit on the cable?

> Yes, in theory a longer cable needs more ferrites as you create a node and the wave starts there. In practice one or two was enough but I didn't have an oscilloscope to look at the waveforms so very subjective on my part.

The physical contact that the sheath/insulation makes with the EM shield is also important. I assume that is why users were encouraged to gently and carefully bend the cable slightly along different parts of its length to ensure that the sheath is as separated from the shield as possible. If not, could the filter be bypassed to some extent? I understand that I may be asking too many questions...

> Not sure whether if it would make a difference. Your chance to explore...

One more thing, is velocity factor a similar principle to refractive index? A constant between 0 and 1 that considers the speed of light in the medium compared to the speed of light in free space
(vacuum).

> Yes but different frequency range.

Jon

Open mind and ears, whilst owning GSP Genera, Accession, Elevator EXP, Solo ULDE, Proprius amps, Cusat50 cables, Lautus digital cable, Spatia cables and links, and a Majestic DAC.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Graham Slee Quote  Post ReplyReply Direct Link To This Post Posted: 14 Jul 2020 at 6:10pm
Originally posted by jupiterboy jupiterboy wrote:

Honestly, my room imposes such dreadful nodes and antinodes on the bass that I'd have a hard time telling if I had the ferrite core right. lol


That's why we go through the pain for you Wink

Room ratios, BBC acoustical engineering guide, rebuilds, laser cut absorbers, lots of wasted effort and materials (an abandoned new building!), and eventually we arrived at the equivalent of a control room regarding how it sounds... or we can use headphones!
Not simple enough for Google-Bot to understand...
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