Asheville, North Carolina ‘s Home Theater and Audio specialists present Cane Creek AV and Paul McGowan – PS Audio, Intl.

It can’t get bigger!

Now there’s an opening line that if this were not a public blog I would just have to add my own punchline to. But…

My friend Larry Borden, editor at the audio website Dagogo, sent me a note just in the nick of time. I was sitting at my desk trying to figure out how I could help people get a really clear view of what we’re discussing in this series; the importance of power supplies in amplifiers. And yesterday I posted a picture that was pure simplicity. Here it is again.

I repost this picture for a good reason. It helps explain something rather profound about amplifiers.

We all think that amplifiers take the small and enlarge it (amplify it) to something larger. And they do. Except… and this is where Larry’s brilliant insight comes into play.

Let me quote Larry:
“Over the years I came to the realization that the biggest misconception is that an amplifier actually makes the electrical signal “bigger.” Once I explained that this is not possible per se, they could then follow the metaphor of a water valve. One that concept was grasped, they would have an “aha moment” regarding the importance of the power supply.”

Okay, I know that’s confusing so let’s step back a moment. Imagine our amplifier valve as that of a water faucet. The power supply is the reservoir of water. We know from that image the faucet cannot make more water than what is available from the reservoir. In fact, the valve can only let what’s in the reservoir out or stop it from flowing. It cannot make more. So yes, an amplifier takes a small signal and makes it bigger – but not bigger than what’s available in the power supply. The valve can only make something smaller than the power supply is capable of providing. It is, after all, a valve.

So now let’s move to the example of an amplifier powering a loudspeaker. We all know that amplifiers have power ratings: anywhere from 1 watt to 1000 watts. What is the gating item that determines the output power of an amplifier? Is it the valve or the power supply? If you guessed power supply, congratulations, you win the prize. Ignoring some of the practical limitations we engineers face when designing equipment for a moment, the difference between a 100 watt power amplifier and a 500 watt power amplifier is not the valve (amplifier) but the power supply. Take a 100 watt amplifier, replace its power supply with one 5 times more powerful and you have a 500 watt amplifier. Plain and simple.

Yes, yes, let us not pollute our understanding of these basic ideas with details such as: bigger heatsinks, stronger valves, etc. I am not trying to help you design a new amplifier.
Amplifiers can only make what their power supplies offer smaller, never bigger.

So why do we call them ‘amplifiers’ when, in fact, they are only valves? For the same reason a small turn of the faucet can release a huge and powerful stream of water. It amplifies the small force into the bigger force but – and here’s the key – never bigger than the power supply.

And never better than the power supply. Let that be your food for thought and our starting point for tomorrow’s discussion.

Asheville, North Carolina ‘s Home Theater and Audio specialists present Cane Creek AV and Paul McGowan – PS Audio, Intl.

Try this on for size

The best chef in the world would have trouble turning out a great meal with poor ingredients. So it is with amplifiers.
The ingredient of an amplifier is power. The chef is the amplification ‘valve’. If either the ingredients or the chef are subpar the music suffers.

Ever notice what happens when you try and spiff up something that started out poorly? For example, if I have a lousy source like a cheap turntable, the best phono preamplifier I have cannot help it sound as good as if I had started with a better source. And so it is with the dance between power supply and amplifier.
Look at the diagram I have included. Note how the power supply feeds the box labeled ‘amp valve’. The amp valve is the amplifier circuitry itself. But note something important. The valve (whether solid state or vacuum tube) has no ability to do anything other than act as its name implies: as a valve. It cannot generate anything and it is completely dependent on what the power supply sends its way.

This is the essence of what we’ll be going over in the next few days. Simple as it may seem, you’d be surprised how many people do not understand the interaction between the source and the modifier. In this case the supply and the valve. It’s my goal to help walk us through this very important subject.