"Air gap" interfaces and cable

The new PS Audio transport having an air-gap galvanic isolation without the drawbacks of an isolation transformer, what if there was an air-gap interface at all sensible interfaces in the chain?
I assume the air-gap interface is very lossless if lossless in terms of preserving the signal?

Now, imagine extending the practically impedance-free technique of a precise air gap for use throughout a whole cable?
A self-interference resistance, and a good one at that?
Using magnetics as waveguides for conducting without conductors?

Of course this requires very precise conditions, so I’d suggest having rails rather than flexible cables from amps to speakers? Easier to control the uniformity of transmission with a straight rail.


(This isn’t a practical but an expensive and terribly antipractical ideal concept)

I would guess it is an optical link, but over such a short distance that no fibre cable is required, or practicable.

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Exactly, a cable isn’t needed, they are, after all a necessary evil. : )

This is why I prefer a futuristic approach to active speakers whose internals match top of the line discrete amps… Less cable

Especially as signal interconnects are easier to handle via cable than power… I’m considering solding my speaker cables onto my amp’s terminals, should help with connectivity loss.

A potential voltage can be moved wireless, but POWER can’t, and why we still have a power system in place today. Yes, we up the VOLTAGE (potential) to better act like we are moving a pure potential signal, and mitigate current squared resistance losses but the system still needs wires even at 30 KV.

A pure potential can’t do WORK by definition. It has the potential to do work but only if we supply a push from the top of the hill. Electrically this is to supply a load current. No current, no work. The galvanic isolation moves a POTENTIAL signal across a gap, but it isn’t doing work until it reaches the LOAD interface.

All wires use EM fields, to stop using wire we need to cross-over to the RF transmission model, and we do that with Blue tooth and the like but to transfer power we need current and that can’t be done wireless.



Can’t be done wireless unless at very precise small gaps?

That is the only thing that makes sense to me, an optical isolator. No other electrical air gap would prevent the intrusion of interference and noise.

I do wonder whether “air gap” is more of a marketing hook. Galen @rower30 seems to cast doubt on whether a true air gap is viable unless you’re talking wireless/Bluetooth.

I’m down to two boxes and they are connected by an Ethernet data cable that is by design galvanically isolated. The only other wire, inside or out, are speaker cables, and plenty of people avoid those. I have zero hum and it just seems completely avoidable. People use special grounding devices, mains with drain wires, my power system has “Ground Plane Noise Reduction”, and who knows what else.

Plenty of devices have extensive built-in galvanic isolation, such as the Marantz SACD players. .

Paul explained the airgap here.

It does seem to be some sort of fibre connection. I’ve connected my server and streamer alternatively by copper Ethernet and fibre optic and have not noticed any difference. Maybe others have. Paul explains the need for it being to mitigate noisy powerful processors, shared power supplies and grounding issues. The server I and plenty of others use has a very quiet processor and separate linear power supplies for the processor and digital outputs. I have no grounding issues.

It seems that optical is being used to solve issues known about for many years that others have dealt with other ways, or the same way, or not at all. Once the Octave server is in use, people will form their opinions about how effective it is.

I’ll measure my DAC’s noise floor with coaxial and optical, let’s see about this simple comparison, sharing ground…

My Tascam recorder takes line-in and I connect my DAC’s RCAs to it, without signal, then amplify the noise floor with Audacity. Very simple…

Fiber will work fine for transfer of POTENTIAL signal levels, like RF signal transfer or even high impedance IC cable into “infinity” loads (near zero current). When we need to distribute that potential across a load to do work, not move it around, then we need current. Even just a tiny bit. Work is amps times volts. Sorry to make you think I meant only wireless is a proper galvanic isolation. Fiber and other means can work. The oldest way is isolation transformers as the name suggest, we remove a direct electrical “wire” into the system.

The concept behind galvanic isolation, is that noise can’t be sneaking around your circuit blocks in the potential analog signal paths. It can still get in through other means, just not the analog signal pathways.

The benefit to RF isolation if a circuit is swamped with RF noise that it can’t process well this can add distortion into the audio band. Remember the HK amps that had RF range BW limits? Those would often time clip amplifying RF and kill tweeters. Nothing was heard but your tweeters went bye-bye,

There is a lot of RF stuff all over today, so some safe guards isn’t completely illogical at all. Circuits can remove RF with filters or galvanically prevent it’s movement into a circuit block, so there are alternative methods that are also used. The end result is to use just the signal you want, and get rid of the rest. With analog, once noise gets into the actual signal path, it is really hard to remove it and not take some of the signal at the same time.



My all-in-one does A/D conversion that can be recorded from the usb socket via Audacity, which I’ve done on occasion with vinyl. I’m not sure what would be gained by recording any noise from that socket.

I prefer mains conditioning with Class D and digital, I used regeneration with Class A and A/B amplifiers. I upgraded the conditioner last week and spoke to the dealer a few days later. I understood that if you reduce the noise floor you hear more information that was previously being masked. So if the noise floor is already so low that you really can’t hear any noise from your audio system, there would be no more audible information to hear. That theory did not last long, because the new device, which has some serious noise reduction and grounding features, is more revealing, quite significantly so it would seem.

However you can reduce noise in a digital system, from the mains, ethernet switches, RFI, power supplies, cross-contamination, it all seems to help incrementally. What I don’t believe is that there is a magic cure that fixes everything.

Is that not a good argument to convert analogue to digital as soon as possible and after digital to analogue conversion keep the analogue signal path as short as possible? There seem to be an increasingly long list of manufacturers doing this over the last 10+ years. Is the all-analogue signal path preference an audiophile myth?

There is a saying that if it’s too good to be true it probably isn’t, but sometimes I think that some apparently very small and modestly priced digital audio components really are almost too good to be true.

Our total channels are pretty short…so usually are OK. Analog does get worse the farther we go, so yes, a digital conversion early is best between a DAC and analog stage (move the DAC so the DA stage analog cables are reasonably short).

In total the digital cure is not always less progressive than the disease. Look at the DS DAC, the firmware changes and so does the sound. Digital can’t escape that “distortion” even if it simultaneously mitigates RF noise that may not even be there most of the time. RF isn’t guaranteed, but a possibility. If the galvanic fix to cure a seldom seen problem is priced in OK (tech drops in price with volume), I see it as a meaningful option but not always a sign it cures a problem you may not have. Once the superimposed RF “problem” is removed, what does the filter tech leave you with?

Sure, there is more RF now than in 1950, but the certainty of that RF is a worse distortion than DA and AD distortion is not a slam dunk at all. Digital isn’t a solution to every problem and it brings it’s own distortions.

In my case, I have little RF issues, but PLENTY of DA and AD digititus that is every bit as bad as the difference between my two phono cartridges, so don’t seal out the options to weight what sound best, or worse, to you.

Variation in linearity is also why I do use digital as it CAN be good with the right “distortion” AD and DA filters in place. Face the music (ha!) digital is how most music is moved today so your DAC is the sound based on the filters RF or not. Distortions, although made in different places, are an even trade to my ear with DAC’s at least as good as the DS DAC’s latest firmware.

It just isn’t right to say digital is the way it all has to go. I still buy records and my LP’s are very good and…no RF. But, digital is certainly the EASIEST method to experience music right now.

I do understand your though process as to what can be “best” for the value we spend and mitigate noise (long digital links, short analog links). But my digital cost collectively MORE than my LP (DAC, PC, iPAD, Ethernet, streaming service). I think digital can get closer to it’s best at a cheaper price! I agree with that.

Good point on the placement of equipment to keep the DA channel shorter, though. This seems like an overlooked “upgrade” for noise mitigation.


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Thank you!
Okay so let’s keep this part hypothetical, again…

If we had a setup of sorts with helium-cooled hollow tube vacuum electromagnets with the anode and cathode as plates on each end. So cables if you can call em that. As short as possible as a given.
The “anodes” are connected straight to the amplifier’s terminals by ultrasonic welding, same goes for the connections to the speaker side. With thermally isolated connections, what with the helium…

Could such “magnetic waveguide rails” work to transfer power? Especially if we have enough power at hand.

I wonder if someone at CERN has tried something like this… I’ve been to the LHC, it’s quite a resort! They sure do have power circling inside the beryllium tube. Lots of.

Strangely, I do know someone who was a nuclear physicist at CERN and a music lover, especially vinyl, and I don’t think he worries about things like that. His core system is the same as mine, Devialet Expert doing A/D conversion from an external MC phono stage (his is rather more expensive than mine). Our streaming systems are also different.

In response to Galen @rower30, I get where he’s coming from, my analogue is more expensive than my digital, but I happily to A/D conversion and the friend referred to above does the same with a very high quality phono stage.

Both dCS and Devialet use technology designed by engineers who were both designing A/D converters for the military/aviation and telecoms respectively long before they got involved in consumer audio, and the founder of Chord Electronics (hello @pmotz!) was a power supply specialist at Marconi Avionics who was a director of Astec, Raytheon and AT&T.

We are lucky that some very serious engineers get involved in audio, as much out of personal interest. You can spot the ones from military/avionics as their products seem to start very expensive and steadily get cheaper! I’m happy to rely on the assumption that they know what they’re doing when it comes to A/D conversion.

One reason why the UK may be good at audio is that it has always been big on military and aviation techonology. BAe Systems was, last time I looked, the largest industrial private sector employer in the UK, close to 200,000 souls.

What I know is limited to magnetic INDUCTION, like your iPHONE wireless charger. Those systems are inefficient and get HOT pretty quick (hysteresis losses most likely) so not much power at a time. OK to charge a small device but supply a variable power demand like music requires?

We have magnetic tracks being trialed in ROADS to boost electric car range but so far, the tech still has a high $$$/mile efficiency. If working is also reducing Co2, induction road strips don’t do that yet over a gasoline engine…too much electricity used and made from…(fill in the blank). That electric waste is like driving two or three cars at the same time, electric or not it kills efficiency. Better still to charge at the “pump”.

Not sure the concern for welding terminals, a thermal inspection won’t show a problem there.

What problem is the mitigating with a better process? Time based issues look likely (hysteresis) and inefficiency. Noise isn’t understood yet, by me anyway. But we need to know what we are improving;

  • Time based distortion.
  • Noise.
  • Efficiency.
  • Simpliciity.
  • Cost.
    What exactly?

Using digital for long haul gets rid of L and C time based distortions as well as invasive ingress noise into the analog signal. Attenuation is even mitigated with perfect BER retransmissions. All good.

A SHORT analog system with no digital filters, external noise and a small L and C time based distortion can still be better (less overall distortion) than digital. It is what we hear after all. We have to place the tech where it exceeds the alternatives. Digital is doing this when we went to digital TV signals. We can see and hear the improvement. TV exceeded VHS movie quality over the air. After digital arrived I had to throw my $$$ Sony VHS unit away. No one wanted that thing anymore.


CAN this work or is it actually impossible even as an experiment? Does the field move like described in such a tunnel?
Oh, oh, I’m getting the vibes of the concept of a “very high-current” “tube” that in a cable’s role acts as a focused beam of both electrons and their power? (hey, let’s also isolate the tubes with vacuum!)

Why this hypothetical setup reminds of vacuum tubes is the sought concept of a magnetically concentrated and guided beam of signal being transferred… Here the beam’s just pushing through at least hundreds of watts.

Then again… Skip this.
Ultrasonically welding the monoblocks’ terminals to the backs of the speakers by using short silver jumpers?
No cable! Even the jumpers can be removed if you re-locate the amplifiers’ terminals to fit the width found between the speakers’ terminals.

Maybe when doing this you should also just switch to lowest-mass least metal volume terminals that are highest grade cryo-OCC silver plated with rhodium. Geometrically, you want a contact surface here that is very precisely making contact even at surface lattice level, right? With this you don’t need even the welding?

Link some patents on this if you find any, please.

Good, concise and cogent “stuff” here.

Thanks for sharing.