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Getting to know, Circuits, Parts, and Concepts, that can assist audio reproduction.


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1 hour ago, andyr said:

Talking only about spkr cables - these will have a resistance, inductance and capacitance measurement.

 

My understanding is that high inductance is not good for a spkr cable - as spkr cables can carry a lot of current ... and inductance acts as a brake on current.  So the ideal spkr cable has very low inductance?

 

Unfortunately low inductance carries with it the penalty of high capacitance - and whereas capacitance doesn't affect current ... it does have an affect on the amplifier driving the spkr cables!

 

A speaker cable, in 1st approximation, is a network with resistance and inductance in series, and capacitance in parallel. Both inductance and capacitance matter, depending on their actual values.

 

As an example, let’s assume a cable with an inductance of 1µH (typical zip cord) and a capacitance of 1nF (rather on the large side). Let the resistance of the cable be small enough to not matter.

 

At 20Hz, 2kHz and 20kHz, these values will result in the following series and parallel impedances, respectively:

 

@ 20Hz: 0.13mΩ in series, 8MΩ in parallel

@ 2kHz: 13mΩ in series, 80kΩ in parallel

@ 20kHz:  130mΩ in series, 8kΩ in parallel

 

The series impedance forms a voltage divider with the speaker impedance, and the parallel impedance forms a current divider with the speaker impedance. Both will reduce the power into the speaker terminals. Assuming an 8Ω speaker impedance across the frequency range, and a frequency of 20kHz (worst case), the 1µH inductance of the cable will reduce input into the speaker terminals by about 1.6%, and the 1nF capacitance will reduce it by about 0.1%.

 

So, while both matter equally, the real-world value ranges of inductance and capacitance of speaker cables make the inductance somewhat significant, and the capacitance rather insignificant.

 

 

 

Edited by Steffen
typos and clarity
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You started a thread entitled "Getting to know, Circuits, Parts, and Concepts, that can assist audio reproduction.".   My comment was directed to that.      My advice remains - seek proper i

Very well said. This very thing is very often used in marketing, for product differentiation in the market place. Some new buzz-word is introduced and is backed by a very valid technical arg

The internet is an amazing source of information.  Unfortunately not all of it is true.    There's one hell of a lot of misinformation being thrown around with zero accountability for poten

15 minutes ago, Steffen said:

@ 20Hz: 0.13mΩ in series, 8MΩ in parallel

@ 2kHz: 13mΩ in series, 80kΩ in parallel

@ 20kHz:  130mΩ in series, 8kΩ in parallel

 

you appear to have left out 20GHz …..😜

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14 minutes ago, Steffen said:

the 1µH inductance of the cable will reduce input into the speaker terminals by about 1.6%, and the 1nF capacitance will reduce it by about 0.1%.

 

Imagine these small figures against the typical response curve of a tweeter and typical room responses.  Also, it's a predictable thing that is simple to eq out.

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1 minute ago, sir sanders zingmore said:

 

you appear to have left out 20GHz …..😜

 

Yep. At 20GHz the signal travels much easier outside the cable than through it :)

 

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7 minutes ago, Steffen said:

 

Yep. At 20GHz the signal travels much easier outside the cable than through it :)

 

 

Well there you go, a perfect illustration of the exhortation to think outside the normally accepted boundaries. We should think "outside the wire" - cable-free speaker cables

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2 minutes ago, sir sanders zingmore said:

 

Well there you go, a perfect illustration of the exhortation to think outside the normally accepted boundaries. We should think "outside the wire" - cable-free speaker cables

 

Some audiophiles and manufacturers take it even further – they think outside the physical reality :D 

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Just now, Steffen said:

 

Some audiophiles and manufacturers take it even further – they think outside the physical reality :D 

 

And why not? It's so narrow-minded to be bounded by reality :)

 

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8 minutes ago, sir sanders zingmore said:

 

Well there you go, a perfect illustration of the exhortation to think outside the normally accepted boundaries. We should think "outside the wire" - cable-free speaker cables

 

Sure why not, if you are interested in listening to 20GHz 

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And the elephant - noisy, spike riven, unstable electrical supply is still stomping around the room, ssh be quiet and it will go away.

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35 minutes ago, Steffen said:

 

So, while both matter equally, the real-world value ranges of inductance and capacitance of speaker cables make the inductance somewhat significant, and the capacitance rather insignificant.

 

 

Thanks for the real-world analysis, Steffen.  :thumb:

 

So foil spkr cables (bcoz they consist of 2 ribbons in close contact along their length) will have very low inductance ... and relatively high capacitance.  For 3m this capacitance shouldn't deliver a problem to any amp ... but for 10m length, maybe!  So - due to their low inductance - foil spkr cables will sound great!  :thumb:

 

Whereas Naim spkr cable - which is 2 wires separated by a ~10mm 'joiner' is high inductance for a reason (the Naim amp circuit needs to 'see' a high inductance load).  For non-Naim amps, these spkr cables are not able to deliver a great sound.

 

My spkr cables are made using strands of 24g teflon-insulated wire - as many strands as are needed to provide a suitable guage for the current which will pass along them ... and their length.  My normal construction is:

  • the full colour wire of each twisted pair goes to the +ve (red) spkr terminal
  • and the striped wire goes to the -ve (black) spkr terminal.

I have found this gives the lowest inductance and highest capacitance - whether 1 pair of wires is used ... or 8.

 

OTOH, the highest inductance - and lowest capacitance - is obtained by using separate 'jackets' (ie. 4 pairs) for red & black spkr terminals ... I use this for long (10m or more) spkr cable runs.

 

In between - in terms of inductance measurements and capacitance measurements - is when you use alternate tps for +ve and -ve.  So this is appropriate for cables which are 3-10m long, when used with amps which are sensitive to cable capacitance.

 

Andy

 

1 minute ago, Southerly said:

And the elephant - noisy, spike riven, unstable electrical supply is still stomping around the room, ssh be quiet and it will go away.

 

Absolootely, mon ami!  :thumb:

 

Andy

 

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21 minutes ago, andyr said:

 

Thanks for the real-world analysis, Steffen.  :thumb:

 

So foil spkr cables (bcoz they consist of 2 ribbons in close contact along their length) will have very low inductance ... and relatively high capacitance.  For 3m this capacitance shouldn't deliver a problem to any amp ... but for 10m length, maybe!:thumb:

 

Andy

 

 

My post above ignores the effects on the amp, and assumes it’s stable and has super-low impedance (as any amp should). I know there are amps that oscillate with capacitative loads, I reckon they should be avoided.

 

23 minutes ago, andyr said:

 

My spkr cables are made using strands of 24g teflon-insulated wire - as many strands as are needed to provide a suitable guage for the current which will pass along them ... and their length.  My normal construction is:

  • the full colour wire of each twisted pair goes to the +ve (red) spkr terminal
  • and the striped wire goes to the -ve (black) spkr terminal.

I have found this gives the lowest inductance and highest capacitance - whether 1 pair of wires is used ... or 8.

 

 

This sounds very much like the speaker cables I made for myself – 20 pairs of Cat6 (23g, solid copper, PVC insulated, 2.5m). They have very low inductance and higher than average capacitance. Do they sound better than, say, Canare 4S11? I don’t think so, but they were fun to make and look great. I think that quality termination is more important, this is where resistance can creep in over time.

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9 hours ago, stereo coffee said:

Were you with him that day ?

 

No, of course not....  🙄

 

A "a group of high quality dome tweeters" from the 80s/90s doesn't have responses within a bulls roar of +/- 1dB of each other... and the differences are often of very low Q to boot.

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23 hours ago, Southerly said:

Should'nt this be the start point - rational replies please.

The power supply in my converter / amplifier takes care of this.

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9 hours ago, bob_m_54 said:

 

Yes, I have always loved the way that high frequency electronics more closely resembles plumbing than electrical circuits :) 

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2 hours ago, aussievintage said:

 

Yes, I have always loved the way that high frequency electronics more closely resembles plumbing than electrical circuits :) 

Takes a bit to get your head around too, when you looking at things like this: Rat Race Coupler with respect to wave propagation. And the fact that when a radar is transmitting full power, you can put your hand on the metal waveguide and don't feel a thing. LOL

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8 minutes ago, bob_m_54 said:

Takes a bit to get your head around too, when you looking at things like this: Rat Race Coupler with respect to wave propagation. And the fact that when a radar is transmitting full power, you can put your hand on the metal waveguide and don't feel a thing. LOL

 

I think we should avoid getting into transmission line theory, waveguides,  Smith's charts, travelling and standing waves, characteristic impedance, stubs, etc etc   We are having enough trouble with simple "complex" impedance  :)   

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7 minutes ago, aussievintage said:

 

I think we should avoid getting into transmission line theory, waveguides,  Smith's charts, travelling and standing waves, characteristic impedance, stubs, etc etc   We are having enough trouble with simple "complex" impedance  :)   

This is where I spend most of my time at work, only the practical side more than the theory.

Still use coax cables for 20+GHz albeit mostly semi rigid.

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Just now, Batty said:

albeit mostly semi rigid.

Gotta be a joke there somewhere :)

 

However, lucky you to work in such an interesting area of electronics.  I only dabbled.  I know I enjoyed watching a girlfriend's father build some cavity resonator/filters out of large copper pipes for a local radio repeater in the 70s.

 

Back to the subject of the thread, which is audio.  We got on this sidetrack because people keep introducing ideas like skin effect,   and audibility of frequencies higher than 20kHz and cable effects on them, building strange cable structures that supposedly sound better etc etc.   This stuff just doesn't apply significantly down at low frequencies. The lack of understanding, is what allows people to theorise that it is having possible effects on audio,  and borrowing from the science lends some plausibility to those theories, until you actually examine it closely.

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3 minutes ago, aussievintage said:

 

oh and btw, coax cables are transmission lines :) 

So is my sub woofer :)

 

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The restriction of 20-20khz began largely self imposed by the digital era.  This was the price we paid for the sampling at 44.1khz and compliance with the Nyquist -Shannon theorem. Moreover it was the size of disc chosen, and time limitation of disc length before that,  which chose the 44.1khz sampling rate.  What we awkwardly also got,  was steep filtering at the Nyquist point, of just below half the sampling frequency.

 

One just has to read the on going dedication and interest to analog ( tape /phono ) to know something is missing in digital, never the less, I would be the first to agree it is very good at what it does. I think the most incredible moment in digital history was missed ( but could return )  in the form of moving away from PCM ,  instead to companded predictive delta modulation. We might then hear what digital was capable of, the DBX700 though was tied to VHS tape, and was its downfall, but the specifications were amazing.  http://www.technofileonline.com/texts/dbx700recorder86.html

 

Embracing that many pieces of source equipment other than digital has frequency response much higher, we can see trend to perhaps impose the 1983 digital era sound, by not thinking any higher.

 

A Denon 103 cartridge as example has specification here to 45Khz

 

Screenshot from 2021-03-01 13-52-12.png

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22 minutes ago, stereo coffee said:

The restriction of 20-20khz began largely self imposed by the digital era.  This was the price we paid for the sampling at 44.1khz and compliance with the Nyquist -Shannon theorem. Moreover it was the size of disc chosen, and time limitation of disc length before that,  which chose the 44.1khz sampling rate. 

 

 

Let’s put the horse before the cart, shall we? The restriction of 20Hz-20kHz began much earlier, in the deep, dark past of human evolution. The sampling rate of 44.1kHz was chosen to cover our hearing range (+10% for good measure). The sampling theorem is a discovered fact about the natural world, it’s not something to be complied with. Nature doesn’t care what we find out about it, or how we make use of the knowledge.

 

A higher value could have been chosen for the sampling rate, requiring a shorter play time (even down to LP length), but this was considered unnecessary and wasteful.

 

BTW, the enhanced RIAA curve forcibly rolls off frequencies above 20kHz (with the original RIAA curve those would have been raised boundless during recording), not sure how useful 45kHz phono cartridges would be.

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18 hours ago, andyr said:

So the ideal spkr cable has very low inductance?

In theory... but in practice amplifier outputs and speakers can be lot more inductive.

 

Like with many many things.... as long as it's not "too much", then it's benign.

 

 

18 hours ago, andyr said:

Unfortunately low inductance carries with it the penalty of high capacitance - and whereas capacitance doesn't affect current ... it does have an affect on the amplifier driving the spkr cables!

 

It can do.... it depends on the amplifier as to "how much is too much".

 

Again.... as long as the capacitance is not too much, then it is basically benign.

 

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1 hour ago, stereo coffee said:

The restriction of 20-20khz began largely self imposed by the digital era.

And what an improvement it was... Along with the development of speakers that can reproduce those signals. Back in the pre digital era we were lucky to reproduce anything above 14 or 15k. Happy days 👍

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1 hour ago, stereo coffee said:

A Denon 103 cartridge as example has specification here to 45Khz

Not bad for the time, but why limit ourselves? Pretty much any modern DAC will go higher with more accuracy

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1 hour ago, stereo coffee said:

A Denon 103 cartridge as example has specification here to 45Khz

Have you seen the performance?! ;)

 

 

Digital systems which store and replay above 20khz are trivial.....    but curiously, they don't "solve the problem".

 

The only relevance that frequencies above 20khz have on sound quality .... is as far as they relate to damaging (or not damaging) during the storage and playback processes, frequencies which are below 20khz.

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1 hour ago, stereo coffee said:

The restriction of 20-20khz began largely self imposed by the digital era.  This was the price we paid for the sampling at 44.1khz and compliance with the Nyquist -Shannon theorem. Moreover it was the size of disc chosen, and time limitation of disc length before that,  which chose the 44.1khz sampling rate.  What we awkwardly also got,  was steep filtering at the Nyquist point, of just below half the sampling frequency.

 

One just has to read the on going dedication and interest to analog ( tape /phono ) to know something is missing in digital, never the less, I would be the first to agree it is very good at what it does. I think the most incredible moment in digital history was missed ( but could return )  in the form of moving away from PCM ,  instead to companded predictive delta modulation. We might then hear what digital was capable of, the DBX700 though was tied to VHS tape, and was its downfall, but the specifications were amazing.  http://www.technofileonline.com/texts/dbx700recorder86.html

 

Embracing that many pieces of source equipment other than digital has frequency response much higher, we can see trend to perhaps impose the 1983 digital era sound, by not thinking any higher.

 

A Denon 103 cartridge as example has specification here to 45Khz

 

Screenshot from 2021-03-01 13-52-12.png

 

This cartridge and some other models came about primarily due to the JVC CD-4 / RCA Quadradisc discrete 4 channel records which requires the cartridge to be able to reproduce frequencies to 45kHz and beyond.  The extended frequency response was normally only achieved by the use of stylii with special profiles like the Shibata and other makers using similar profiles.  Conical stylii are simply incapable of accurately reproducing the 45kHz signals as were many elliptical profiles in the mid 1970s, hence the development of the Shibata and compatible profiles.

 

I still have my Shure V15 type III cartridge fitted with genuine Shure VN35MR (Microridge profile) stylus and a NIB spare specifically for playing my CD-4 records in conjunction with one of my many CD-4 demodulators.  Before Shure released the Microridge profile I used their Hyper Elliptical stylii with very good results, but IMHO the VN35MR is significantly better with CD-4 pressings. 

 

Whilst analysis of the range of frequencies on some stereo vinyl recordings can reveal content above 20kHz it isn't as common as one would think.  

 

Cheers,

Alan R.

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4 hours ago, aussievintage said:

 and audibility of frequencies higher than 20kHz and cable effects on them, building strange cable structures that supposedly sound better etc etc.   This stuff just doesn't apply significantly down at low frequencies. The lack of understanding, is what allows people to theorise that it is having possible effects on audio,  and borrowing from the science lends some plausibility to those theories, until you actually examine it closely.

Very well said.

This very thing is very often used in marketing, for product differentiation in the market place.

Some new buzz-word is introduced and is backed by a very valid technical argument. Sadly this argument (circuit/feature/solution) very often has negligible - if any - impact on the actual sound reproduction.

I would risk saying that in analogue electronics, very little is done now what was not known 50+ years ago.

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22 minutes ago, rockeater said:

I would risk saying that in analogue electronics, very little is done now what was not known 50+ years ago.

It's quite accurate.

 

We can achieve some things now which weren't practical 50 years ago ..... but it was all mostly "known" a long time back.

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On 01/03/2021 at 6:24 PM, davewantsmoore said:

It's quite accurate.

 

We can achieve some things now which weren't practical 50 years ago ..... but it was all mostly "known" a long time back.

Following on from this comment, there is always opportunity to explore parts connection that has been sometimes totally ignored. As example a LM336.   The 336 can also  be used as a series diode with unique properties. Can anyone having studied the data sheet see the possibilities. some will just see the manufacturers data supporting as a shunt device, but others may also see a totally unique alternative.  

https://www.ti.com/lit/ds/symlink/lm336-2.5-n.pdf

 

 

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