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An Introduction to Compression: Basic Compression - A free download from Audio Masterclass

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The worst item of equipment in your studio is the one you rely on most. Why?

Your studio is full of expensive, hi-tech equipment. It all sounds great. But something is letting you down badly, and really it doesn't have to be that way...

Let me tell you a little story...

I was at a hi-fi exhibition with a friend who was seriously into that topic. After perusing a turntable that cost £50,000 ($100,000) - without arm or cartridge - we turned our attention to loudspeakers.

We went to the demo room of a company whose flagship product cost around £20,000 ($40,000) a pair.

We sat and listened to a program of classical music including orchestral and vocal.

Great loudspeakers, we both agreed. Fantastic loudspeakers. How we wished we could afford a pair of loudspeakers like that.

Anyway, we couldn't even have realistically afforded one each. When the demonstration ended we were, quite frankly, rather shell-shocked with the quality of sound we had just heard.

We sat in silence for a moment.

And then we heard a piano, somewhere outside. "Hey, that will make a change." said my friend "Let's go and listen to the pianist."

I liked the sound of that. We had heard so much hi-fi that it would be good to refresh our ears.

So we wandered outside in search of the piano. It was in a room just opposite.

So we walked in and looked round, it was quite busy with people. We could see a pair of speakers on a small stage, but we couldn't see the piano.

And then we realized - it wasn't a real piano. The sound of a real piano was coming from the loudspeakers!

Honestly, it was uncanny. I could close my eyes and hear a piano in the room, but there was no piano, and the sound actually was coming from a pair of loudspeakers.

This was quite a shocking moment, because I realized that the 'fantastic' sound I had just heard in the other room - $40,000 dollars' worth - wasn't at all realistic. Great hi-fi it might have been, but it wasn't a real sound.

And neither was anything else I had heard at the show. Until now.

The speakers in question were Quad Electrostatics, playing a DSD recording direct from DVD-RAM, recorded by ace engineer Tony Faulkner. And, closing my eyes again, I could swear that piano really was in the room.

Electrostatic loudspeakers are very different to the normal moving coil type, which almost every loudspeaker you will ever come across is.

The big problem with moving coil loudspeakers is that the motive force comes from the center of the diaphragm (the cone). That force must be transmitted outwards to the edge of the cone, traveling through the material of the cone itself.

If the cone bends at all, then some parts will be moving out as others are moving in. Ideally it would operate as a 'rigid piston' - all parts moving in step.

But to do this the cone would have to be very stiff. And to make it stiff it would have to be heavy. But if it were heavy, the speaker would be inefficient and not very loud.

So a compromise is made. The cone is made of a lightweight material, and it is expected to bend a little. And this causes one of the distortions that make loudspeakers sound like more like loudspeakers and less like the instrument they are supposed to be reproducing.

The diaphragm of an electrostatic loudspeaker, on the other hand, is driven over its entire surface area. Therefore it can be as light as the designer chooses. All parts of the diaphragm move in step, with no bending and therefore no distortion.

Quad electrostatic loudspeakers have another feature - they are not mounted into a box. Arguably, the cabinet of a traditional loudspeaker is the main reason why they do not sound realistic. The surface of the cabinet pumps a lot of bad sound into the room.

But electrostatics don't use a cabinet, so they don't suffer from this problem.

This does lead to a drawback however. They put out as much sound from the back as they do from the front.

Without going into long-winded explanations, the best way to deal with this is to position electrostatic loudspeakers well away from reflecting surfaces - i.e. away from the walls of the room.

And in fact Quad had done this in the demonstration room. There was a small stage with a backdrop, but the speakers were either side of the backdrop and free to radiate some distance to the rear. It was a little bit of fakery - to a first glance, it looked as though the speakers were in a smaller room than they really were.

But the question of course does arise, if electrostatic loudspeakers are so great, why don't we all use them?

Well one reason is this rear radiation, as explained above. Another reason is that they are expensive, another reason is that moving coil loudspeakers are entrenched in the market, another reason is that people expect loudspeakers to be enclosed in a box, another reason is that people expect loudspeakers to sound like loudspeakers...

Yes... people expect loudspeakers to sound like loudspeakers, and not like real instruments.

So, to put this into a studio context, if you really want to know what your recording sounds like, then you should monitor on electrostatic loudspeakers, properly positioned in a fairly large room.

The snag is that this won't tell you how your public will hear your recording. So you are virtually compelled to monitor on moving coil loudspeakers.

Still, you can always have electrostatics for pleasure, can't you?

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By David Mellor Thursday November 30, 2006
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