My Audio Origami rewired RB303 arm with grounding wire attached to the stud on the Reflex M produces no hum, even at high vol (without the wire, there was a small amount of hum).

The Audiomods V arm without using its grounding wire to the Accession produces no hum, again at high vol (with the wire, there was a small amount of hum).

Graham's statement pretty much reflects my own experience.

I have an issue with a dimmer switch causing hum in my system, but only when light is on. I noticed the hum disappears (when light on) if I touch my equipment - the phono cable interconnects on back TT, or if I touch my ULDE or Accession. Obviously I can’t stand there holding my equipment. Wondering if this grounding method would act similarly to me touching the equipment.  Andrews also talks about improvements to sound from this additional grounding. 

Thoughts?

David, can I start by saying the guy is selling a product. He also sells interconnect cables that do not shield-out RF.

Ever since I was a lad, there have been "problems" with dimmer switches interfering with small signals.

The earliest form of radio was spark transmission - it had no position on the dial - it was so broadband anything picked it up.

Now, inside some monolithic silicon, your lamp's power is being abruptly switched. There isn't any spark; instead, it is a reactance due to inductance and capacitance. Its transmission medium is the mains supply.

When the lamp is fully on, the Triac (or a rectified Thyristor) cannot contribute any noise. However, when dimmed, the Triac gate is "fired" to switch during a mains half-cycle.

Whereas the diodes of a rectifier cause enough problems in switching somewhere close to a volt, the bi-directional controlled silicon diode (Triac) switches power to the load at some point during the much larger potential of a mains half cycle.

The voltage can be anywhere between zero and 350 volts peak. It "spikes" back down the supply cable, transmitting distorted noise at 100 cycles per second, both airborne and mainsborne.

The occasional earthing of class-II equipment through the human body is not related as simply as some marketing suggests.

If each source item were to be mains earthed, loops would exist to inject mains frequency noise into every interconnection. This is most noticeable with turntables and less noticeable with line sources. There are different degrees of signal to ground noise ratios.

Therefore, it is crucial to either have only one mains earth connection so that a loop cannot be formed or even none at all.

There is no connection to mains earth in a fully class-II system, which has to exist in an "accessory only" system. Mains earth is what it says. It is a connection between the mains supply and terra-firma - the ground we walk on.

That fully class-II system can then connect at any point with a class-I item, such as an integrated or power amplifier, without causing an earth noise loop.

What is important is the ground continuity, such that the shield - the common conductor of the interconnect - has no resistance at signal frequencies to speak of—the two class-II items so connected become one. The case/screening of one is the same potential as the case/screening of the other; therefore, no ground noise can exist.

Suppose everything in a system is class-II (some older amplifiers just had live and neutral and no earth in their supply cables). In that case, there is no mains earth, but as explained above, there can be no ground noise (including mains buzz).

But, if we introduce the human body in the form of touching any case/screening, the human body conducts it to terra-firma - or earth. Still, no noise can happen unless the loop is completed somewhere else, and the interconnect shield allows a rise in potential between the units.

That somewhere else is usually because the accessory system connects to an earthed amplifier. However, if it results in buzz, then it is because the human body can conduct to earth more effectively than the interconnect's shield can conduct between the equipment.

That last statement might sound a little odd. Surely wire can conduct more effectively than the human body? It depends on the inductance of the wire!

Suppose the connection between the cases/screenings is inductive. It acts as resistance at some frequency, and resistance allows the cases/screenings to break company.

As I said earlier, buzz (interference) is also airborne. At the frequency where the wire becomes resistive, it becomes an antenna - a receiving aerial!

Therefore, the cases/screenings have a signal potential between them. This forms a differential signal with the music signal (or, indeed, the silence when not playing), and buzz is amplified. The transducer/s reproduce it for you to hear.

Therefore, the shield needs to be effective at all frequencies, right up to the highest radio spectrum frequencies which may be encountered. A velocity of propagation of 85%, multiplied by the frequency of light, will do nicely.

But, and this is the but, the shield must be connected at each end. It must not be subordinated to another piece of wire that completes the run - as do many "hi-fi cables." As you should be now able to see, that wire will have greater inductance and allow that differential signal to form.

Likewise, the knitted or otherwise bell-wire constructed interconnects offer zero signal protection because of the case/screening interconnection's inductance.

Understanding the above shows that if done correctly, there is no requirement for something that treats the symptoms.

My system is plugged into only one wall socket, so I think that takes care of one mains ground. 

I don’t use shielded interconnects. I have some CuSat50 on my wish list. Sounds like once I get those interconnects my problem will be solved.

Or did I totally misunderstand?

I’ll make 2021 the year of the Shield. 

David, you have done high fidelity a massive favour - a much needed reset from the propagandists who have brought so much displeasure - those working the rot from the inside which has done so much harm to our extremely important recreational activity.

The times I have been accused of making noisy products by people using unshielded interconnects is more than enough to test any man's resolve.

Thank you.

And when I unplugged TT but kept ULDE switched to input from the TT (just the Lautus cable) there was not RF noise. 

So I will need to upgrade my TT to get rid of this. 

Question: how do I know which TT brands are properly grounded and/or shielded?

I can tell you that Technics turntables, assuming you're not talking about one that someone butchered, are usually properly grounded. Never had grounding problems with vintage JVC or Yamaha decks either. Of course they all had regular ground wires and metal tonearms. A friend had one of those PJs and it definitely had a grounding issue, among other issues. 

My 2 cents. 

But my modufied HiFi(?) arm containing carbon fibre is grounded, as the Technics methodology has been kept.

Pushpaw wrote: Maybe the ground hum itself would become like a symphony...

You never tried that?

They say that chewed-up cassette tapes sounded out of this world!

And you think I'm taking the piss?

(perhaps we ought to have a confessions corner?)

And there’s no longer any static buildup on the TT either which is great. 

When the cartridge was lowered onto the record, the magnetic attraction was so strong that the cantilever was squashed into the cartridge body. The cartridge remained in intimate contact with the record.

It was a long time ago - the only type of magnetic cartridge in town was moving coil - which might have been around the time of Blumlein (1930s). Those were nothing like the MC's of today, by the way.

The magnets in a MM cartridge are tiny. The stylus causes them to move (some call it "vibrate") in proximity with two coils (two for stereo) and create a minuscule electrical signal. The magnetic attraction to a steel platter might be so weak that it doesn't add much to the playing weight.

Even though the signal is minuscule, it takes hundreds of turns of wire for each coil to produce it. It doesn't take much of an imagination to picture how fragile the wire is. Each coil is an inductor, and the varying distance due to stylus movement causes the variable magnetic field to be induced in the inductors, turning it into electricity.

In the same way as a dynamo gives out an increasing voltage, the faster the bicycle wheel turns, the cartridge output increases with frequency. The 1042's 6.5mV output at 1kHz becomes 1.47mV at 100Hz and 1mV at 50Hz. The phono stage applies more gain at those frequencies as part of its equalisation to bring the output at all frequencies, level.

In the upper mid and treble range, the output increases, and at 10kHz, the output is 31.5mV. A little above 10kHz, the arm cable capacitance and the phono stage input capacitance acts with the cartridge inductance and produces a peak (in the presence of a signal of such frequency). The 47k load impedance damps the peak within about +1dB of what it should be.

Beyond the peak, the signal starts to decay in the opposite direction and at the same rate as it rose. The stylus cantilever has some tuning-fork resonance which "carries" the signal upwards the partial octave required to reach 20kHz.

The cartridge body offers little shielding to the inductive coils against other magnetic fields because any metal shield will influence the velocity of the magnets. Steel has a strong attraction to magnetism, so it would be no use. Aluminium is effective as a shield but has some magnetic attraction (read up about mechanical speedometers).

Although the coil outputs fall after the >10kHz peak, their output reduces and is still slightly viable into the low radio broadcast spectrum (long wave). The cartridge wires, if left unshielded, have a length somewhat longer than the arm, so given an earth plane might readily accept radio wavelengths 1 metre and above.

Radio frequencies having wavelengths between 1 metre and 1000 metres might have a lesser effect, but that depends on their signal strength. For example, Mr H******n, a hi-fi reviewer, lives within a mile of London's Crystal Palace transmitter, but it seems he will not venture into discussing any of the above.

A plastic arm has no shielding, so the cartridge wires are exposed to UHF transmission frequencies, which just about covers every frequency above 200MHz.

The cartridge has no shielding, so might admit long-wave to mediumwave AM transmissions. The input capacitance of a phono stage offers some resistance but is not a short circuit to RF.

The phono stage designer has to make the music listenable, which requires it to perform up to the low MHz as any real amplifier designer knows! At the same time, it has to mitigate radio frequency interference. There are phono stages that might be "slugged down" significantly to block stronger RF, but as a result, slew so slowly as to be fatiguing to listen with.

A ferrous platter is challenging to ground to such a low impedance that the amplification ground "moves with it," not just because of the lubrication but the obvious resistance between the metals; otherwise, they'd not move!

Mutual inductance will ensure a ferrous platter vibrates by the magnetic fields all around it and next to it (e.g. motor).

Dimmers are rectifiers (SCR's - silicon control rectifiers), and all rectifiers fire-off wide-spectrum radio frequency interference due to their abrupt switch off characteristics. The strength of the interference is mitigated in some but cannot be entirely eradicated. They might be made compatible within acceptable limits, but record players are omitted (considered a relic of the past by legislators).

Turntable manufacturers are under no obligation to comply with EMC legislation as there is none. The only legislation is about electrical safety and energy efficiency (EuP legislation).

Whether preamp or power amp, every solid-state amplifier has some crystalline junction because that's how transistors and FETs work. They are the equivalent of a crystal radio with mitigation. There is a limit to as far as this mitigation can go, but turntable/arm manufacturers are not listening.

The earth is a ball spinning in space. There is no such thing as flat earth. I have given this written lecture in several forms over many years. Perhaps one day, somebody will understand it.

Tonight I almost went crazy because I was hearing some hum on the Technics 1210 + Reflex M, which I had never hear even at full volume. Panic! Has the Reflex broken? Has the ground cable got loose? Has the Ortofon cartridge got some issues?

Oh, well, nothing so dramatic: I had forgotten the Sony LCD TV (which is near the turntable) on. I switched the TV off, and the hum disappeared.

I never thought that an LCD TV could cause so much hum (while I knew of the strong EM fields of old cathode ray TVs). I guess it's caused by the LED illumination of the panel, which switches on and off at 50/60 Hz (ideal frequency for hum!). Lesson learned!