No, a good quality, correctly set up vinyl playback system should be almost silent and exhibit no noticeable hum.
This is one of the great revelations about vinyl that you get to appreciate in the typical journey from basic gear to more aspirational equipment.
What is Hum?
The term ‘hum’ describes continuous low-frequency tones of a constant frequency or pitch, usually centred around 50/60Hz or 100/120Hz. Hum can be mechanical or electrical in origin and usually indicates a problem in the playback system. Whatever the origin, wherever possible, hum should be tracked down to the source and eliminated.
Electrical Hum
Bad earths or grounds are a common cause of electrical hum, especially in vinyl playback systems. The high sensitivity and gain of a vinyl playback chain takes tiny signals like hum and amplifies them to the point where it can become an audible problem. The trick to ensure a quiet system is to ensure the turntable/pre-amp/amplifier combination is effectively grounded together and that at least one piece is ground-referenced.
Ground loops occur where two elements in the playback chain reference different grounds and therefore sit at slightly different potentials. This causes small currents to flow between them which are heard as hum. Bad cables can play a part here, as some do not have an effective ground linking both ends of the cable structure.
Mechanical Hum
Mechanical hum can originate from turntable motors and mains transformers. The hum from both sources can often be resolved with the right attention and some new parts, with specific attention paid to damping and isolation.
Cheap phono preamps, cartridges and cables will always be noisier than good ones and active preamps will always be noisier than transformers. An English brand of turntables that shall remain nameless opts not to use a separate headshell/arm ground. These decks are generally always noisier than turntables with better, separated ground arrangements. Equipment type, set-up and installation can all contribute to hum.
Feedback
Mechanical vibration from the turntable itself or other equipment can be coupled through a turntable, back into speakers, creating what’s called a positive feedback loop. These loops can occur through shelving for example shared by speakers and turntables, wooden floors and other resonant structures.
In these cases, the hum makes its way to the speakers, which energises the turntable, arm, and record and it is then fed back into the signal chain and further amplified. Positive feedback loops can very quickly go out of control and destroy speakers and even amplifiers, so if you have a hum that appears to be coupled through your turntable, resolve it or seek expert help immediately!
Rumble
Rumble is another source of low-frequency noise generated by a turntable’s spindle and/or motor bearings. This is a broader-spectrum LF noise than hum and may have several fundamentals. Rumble is generally inversely correlated with turntable price. In other words, the cheaper the turntable, the greater the rumble. This is because cheaper decks have poorer mechanical quality, looser bearing tolerances and greater bearing surface roughness. Consequently, cheap turntables are often rumbly and irritating to listen to.
Quiet
In good, well-set-up vinyl playback systems like the Liquid Audio reference system, for example, there is no audible hum. The predominant noise in systems like this is groove noise, a residual component of the cutting lathe, and the friction between the stylus and the groove itself, and some phono preamplifier white noise. Some white noise is present in all systems, but hum is absent in good ones.
Mike, by no hum, do you mean just a little hum..?
No, I mean no hum. If you are curious about how quiet a serious vinyl playback system can be, let me know and if I’m not too busy, you may be able to hear my set-up so that you have a sonic reference point.
