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  • Writer's pictureSteve Elford

Supports and why do they matter?

Updated: Jun 13

I’ve put off tackling this topic for a while now. But it’s incredibly important and a major part of listening optimisation. So here goes.

When we get into hifi, we soon see on every dealers’ website, in the hifi press and at every hifi show, a plethora of racks and stands. Literally hundreds of them. And we’re told “never use granny’s sideboard for your hifi components - you must have a proper rack.”

But why?

It all stems from the fact that a lot of analogue and digital electronic components have electro mechanical transfer functions in their fundamental methods of operation. Oh damn. Let me give you two fairly easy examples.

The inductor (including chokes and transformers)

Anything with a coil of wire relies on a reversing magnetic field forming when an ac signal passes through it, to have a motor effect, an impeding effect or a transferring effect (two coils in a transformer). The current and the magnetic field creates a forward or backward force as part of the process. We can see it’s there in a speaker driver or electric motor, but the forces are there equally in any other coil device even though it’s constrained from moving. 

The capacitor

Two rolled up plates with a very thin insulator between them that can store small amounts of charge but also pass AC signals through. This time it’s an electrostatic process as opposed to an electromagnetic one, but it has a repelling or attracting force as part of it's operation. That’s how an electrostatic speaker works, or in reverse, a condenser microphone. 

The Problem

So both of these devices can make speakers and microphones - they can turn an oscillating signal into an oscillating movement and an oscillating movement into an oscillating signal. The problem is, when we don’t want them to do either of these functions, ie employing a static coil as a choke or static plates as a capacitor, they still do it. They are in essence static motor generators.

So you will then often hear two phrases banded about regarding all this – a component is said to create self-generated acoustic noise, and a component is said to be microphonic. They suffer from both of these problems.

It's the microphonic part of all this that's the real issue. Any vibration that gets into these microphonically sensitive devices is turned into a small unwanted electrical signal that is added to the signal that should be there. So if we take a circuit, say a pre-amp stage and say that circuit is being vibrated by a mains transformer that is mounted on the same circuitboard, then some amount of that vibration energy will be turned into unwanted background signals in the various microphonic devices in the circuit. And don't assume that if a capacitor is there say for local power supply smoothing (and not directly in the signal path), that it doesn't matter – the capacitor's microphony will modulate the power to the gain circuit.

Now you can start to see some of the factors in this debate, that are always the concern of audio engineers and audiophiles. Can better quality capacitors and inductors, that are designed for low microphony help? Yes. Is it better that I don't have power supply transformers on the same circuitboard as sensitive audio circuits? Yes, Can I protect preamp stages from vibration from power stages? Yes (split pre and power stages into separate chassis). Can I place my main components onto supports that help to lower the overall vibration levels in the component chassis. Yes.

So there it is. The purpose of specialised hifi furniture fundamentally is to help in the cause of lowering microphony. It depends on the type and quality of the components of course – some are much more microphonically sensitive than others. And it depends on the quality of the supports. There is a huge price range and varying types of technology out there offering different ways to do the job. But that's what it's all aimed at – reducing microphony.

There you are. Tip of the iceberg so far. I'll go into other aspects, such as coupling and isolation, in my next blog.

Gryphon, Bergmann and Ideon components on low-microphony racks
Gryphon, Bergmann and Ideon components on low-microphony racks

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