Graham's Blog

Zero Negative Feedback

Posted by Graham
July 14th, 2016
Feedback block diagram (Image licensed under Creative Commons)

Right now negative feedback is bad. They're selling amps without it.

As a circuit designer I didn't understand what zero negative feedback meant! Well, I did, and I didn't...

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All About The Phono Preamp

Posted by Graham
July 13th, 2016

This piece on phono preamplifiers, which originally appeared on our previous website, is written from my personal experiences with gramophone (phonograph) records which started in July 1969 (at the age of 14), and my subsequent work with AV equipment during the 1970s . . .

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Analogue Audio Needs Headroom

Posted by Graham
June 17th, 2016
Vacuum tubes

Analogue audio signals (mainly from vinyl these days) are not constrained like digital audio signals, so they need headroom to expand into.

Think of a digital signal as a 14 ft 4 1/2 in double-decker bus. Will it pass under a 14 ft 4 1/2 in bridge? Yes it will. In real life however, it would probably take the paint off the roof.

Now think of the road underneath the bridge being bumpy...

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Not Enough Volume From A Valve Amplifier

Posted by Graham
June 13th, 2016
Vacuum tubes

You know you can't fit a square peg in a round hole - although it might go in it would not be a fit - and so most people are really-sensible. But when it comes to valve amplifiers I often find common sense goes straight out of the window.

When something doesn't work it cannot be the valve amplifier's fault - it simply can't be that - can it?

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Moving Coil Cartridges: Mobile Phone Interference

Posted by Graham
June 12th, 2016
Audio Interference

The hi-fi industry was (and still is) unprepared for cellphone interference when it comes to the high gain circuits essential to phono preamplification for moving coil cartridges. The problem is that . . .

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Graham's older blog posts can be read here . .