Class G amplifier?

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RayL
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Joined: Mar 31 1999

At the PLASA (Professional Lighting & Sound) show (Earls Court, last day today) was a stand featuring innovative pieces of gear. This included a biamped loudspeaker. The LF speaker was driven by a class D amplifier and the HF speaker by a 'class G' amplifier. Class D I know of - if I remember rightly, the audio frequency modulates a square wave and it's the square wave that is amplified. Since the ampifier is simply switching on and off, very little heat is produced so small semiconductors can be used. Clive Sinclair produced a not-altogether-successful Class D audio amp in the mid-1960s.

So what is a Class G amplifier? Presumably also non-analogue but is it part of a progression of amplifier types - E, F, G, H, etc? I did try to talk to the Italian gent whose firm produced it, but he was a salesman rather than a technical guy - hence this appeal to the fount of all knowledge.

Ray Liffen

Alan Roberts
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Joined: May 3 1999

You're right about Class D, but I've no idea what Class G is about. I'll have a poke around and see what comes up. Google threw this up quickly, but it doesn't help much. However, this one is better.

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RayL
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Joined: Mar 31 1999

Alan, thanks for those links. It would seem, then, that Class G is in fact a type of analogue amplification.

Ray

Alan Roberts
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Joined: May 3 1999

Yep, it's all about increasing the overall efficiency by modulating the power supply. Otherwise, we'd not have all those really nice multi-kilowatt car installations that brighten up our days so much :(

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Camera settings documents are held by Daniel Browning and at the EBU
My book, 'Circles of Confusion' is available here.
Also EBU Tech.3335 tells how to test cameras, and R.118 tells how to use the results.