These coaxial cable can transmit up to 18ghz or higher frequency. I think the capacitance should be very low compare to ordinary audio signal cable. And cheap (used) compare to "hi-end" audio cables.
What about SCSI data cable? Any thoughts?
Well if you want Mhz/Ghz noise in a low KHz signal. Also it will be happy to transport noise at those frequences. Lastly what voltage/current is required?
Test it and see with a frequency sweep?
Test it and see with a frequency sweep?
Here is a spec for 26.5ghz cable micable brand. I wonder how an "hi-end" cable does, or even cheap audio cable.
Unless you like untangling and straightening plain insulated wires, you're wasting your time with SCSI cables - it makes reasonable hook-up wire, that's all.
I'd experiment with the more promising coax leads, as you can get lucky with some, since the capacitance is so low but you'll have difficulty using and matching cable to suitable size connectors.
Look into what fits without adaptors and other extra costs before marvelling over the cable qualities.
I'd experiment with the more promising coax leads, as you can get lucky with some, since the capacitance is so low but you'll have difficulty using and matching cable to suitable size connectors.
Look into what fits without adaptors and other extra costs before marvelling over the cable qualities.
On a pure scientific indagation of how the cable performs for audio signals, One should strip first a whole piece (1m?) to get access to the bare conductor.
Then...
Then...
I didn't catch you about the scsi cable part, just use the whole cable. And what adaptors? Cut the wire and weld a new RCA connector.
The SCSI cable ( I assume that's the flat, woven cable in the second pic.) would be a bad idea for audio in its present form as it doesn't provide enough shielding against the broad spectrum of likely EMI in and around a typical home. It may well be fine for its intended use or in one range of frequencies but poor in others, due to multiple reactances in the open weave of cable wires.
I don't doubt that almost anyone here could mess about with making similar cables to commercial products that are completely shielded, low noise and preserve the audio signal in the form it enters the system but we still have to fit connectors that are compatible with existing gear, match with sleeving sizes and do it securely to ensure you wind up with a reliable cable that withstands whatever rough treatment it's likely to get. Usually, commercial audio cables are assembled and sealed with ultrasonic "welding" of the flex to the plug shell etc. It's a great idea for the integrity of the cable but beyond our resources, like many other manufacturing techniques. Up to a point, heat-shrink sleeving can be a good gap filler too.
I don't doubt that almost anyone here could mess about with making similar cables to commercial products that are completely shielded, low noise and preserve the audio signal in the form it enters the system but we still have to fit connectors that are compatible with existing gear, match with sleeving sizes and do it securely to ensure you wind up with a reliable cable that withstands whatever rough treatment it's likely to get. Usually, commercial audio cables are assembled and sealed with ultrasonic "welding" of the flex to the plug shell etc. It's a great idea for the integrity of the cable but beyond our resources, like many other manufacturing techniques. Up to a point, heat-shrink sleeving can be a good gap filler too.
I tried to measure a capacitance of rf cable and regular shielded audio cable , rf had few times lower capacitance, so it have benefit on longer runs and when output resistance of source is higher.
But what is the difference between cables for DC to tens of Mhz and cable for DC to Tens of Ghz? I cannot under stand how to transfer 26.5ghz signal with 100pf/m cable?
Is the 50ohm impedance have a particular frequency?
Higher capacitance per meter for rf frequencies means a more energy is needed to recharge that capacity , so higher power loss .RF impedance 50 ohms have different meaning ,for dc or audio frequencies it means nothing.
Not at all. The cable has a characteristic impedance (normally 50 Ohms) that is sqrt(L/C), so the shunt capacitance between the conductor and the screen is matched to the series inductance of the conductor. The capacitance is an indication of the velocity factor, but in a terminated system there is no power loss due to the capacitance - how else could a GHz signal propagate along a long cable?
I agree that the characteristic impedance is probably irrelevant for audio, but for serial data (e.g. from CD player to DAC) is does.
No, doesn't work like that, the losses are due to resistance in the copper and dielectric losses in the insulation (and sometimes leakage through the braid if its not compact and tight), the capacitace per se is lossless. RF cables are used as "transmission lines" - good search term. Usually the major losses in an RF cable are resistive due to the skin-effect which increases the cable's effective series resistance with increasing frequency (the currents have to flow close to the metal's surface due to magnetic effects).
Transmission lines can work from DC to "daylight" in theory.
Ok , at RF frequencies RF cable works as transmission line ,matched resistance on both ends ,and so . But if you use such cable not as transmission line ,not in RF , whats then ? You think a "transmission line" term should apply even for DC or audio frequencies ,passing such cable ?
Yes ,i agree that those cables are designed for much more than passing DC or 20 KHz . And inside they are not much different from normal audio shielded cable , just use different material of center conductor insulator, which can work at RF ,distance and diameters etc ,additional foil for screen .
In role of just shielded cable it still have parameters like dc resistance and capacity .Signal source like sound card have some resistance at output , to protect from capacitive load ,or simply shorting output. That output resistance may vary with device .The longer cable is , the higher capacity it has ,more attenuation of high frequencies possible .Some may hear that ,some not . Sharp edges of pulse signal like sqarewave after such filtering may no longer look like square wave .Ofcourse , sqarewave of 1KHz is not a typical audio signal ,and frequency rolloff may start at much more KHz than we can hear .
In my understanding ,less capacity is better , if shielding is not worse than if we use normal audio cable . Many things can be tested and measured and compared to be clear whats better or worse .
Yes ,i agree that those cables are designed for much more than passing DC or 20 KHz . And inside they are not much different from normal audio shielded cable , just use different material of center conductor insulator, which can work at RF ,distance and diameters etc ,additional foil for screen .
In role of just shielded cable it still have parameters like dc resistance and capacity .Signal source like sound card have some resistance at output , to protect from capacitive load ,or simply shorting output. That output resistance may vary with device .The longer cable is , the higher capacity it has ,more attenuation of high frequencies possible .Some may hear that ,some not . Sharp edges of pulse signal like sqarewave after such filtering may no longer look like square wave .Ofcourse , sqarewave of 1KHz is not a typical audio signal ,and frequency rolloff may start at much more KHz than we can hear .
In my understanding ,less capacity is better , if shielding is not worse than if we use normal audio cable . Many things can be tested and measured and compared to be clear whats better or worse .
Most commercial audio cables are about 1.2m in length and should be a lot shorter than that, if we used common sense instead of just plugging in a general purpose cable that hangs down the back of your gear. Long leads are more susceptible to EMI that could largely be avoided with a tidy, short length. We only use them as shielded wire though, transmission lines and specific amounts of capacitance are about RF which is something you really don't want in any audio circuit.
Coverage is the issue with audio cables - sometimes with cheap examples, its very little and near useless - just a ground wire. Good audio cable has more than 90% coverage and where copper or aluminium foil shielding is used, it can be virtually 100%.
Here's a simplified article detailing relevant shielded cable features with the usual disclaimer that I have no "connection" with the author or sponsors: https://blog.epectec.com/overview-of-the-shielded-cable-process samhears
Coverage is the issue with audio cables - sometimes with cheap examples, its very little and near useless - just a ground wire. Good audio cable has more than 90% coverage and where copper or aluminium foil shielding is used, it can be virtually 100%.
Here's a simplified article detailing relevant shielded cable features with the usual disclaimer that I have no "connection" with the author or sponsors: https://blog.epectec.com/overview-of-the-shielded-cable-process samhears
Last edited:
I tested two shortest jump wire as interconnect cable, guess what? put all other cable I have into shame. Sounds bright and transparent.
That's great but now bring some device that radiates a significant amount of EMI into the room and listen again. I have an old fluorescent type maggylamp that sounds like a buzz-saw through my audio system unless the interconnecting cables are shielded and grounded. Otherwise, there is no problem, the system is also silent.
Last edited: