What is a regulated power supply for?

Regulated means that there is some kind of semi conductor circuit fixing the voltage to a certain value. An unregulated power supply would just be something simple like a rectifier into some caps. The output voltage would vary depending on load and input voltage - ie AC mains from your wall.

 

The two types of regulated power supplies are switching and linear. Switching supplies use pulse width modulation to achieve a voltage, meaning that they turn the output on and off rapidly to achieve an average desired voltage. These are smaller and cooler but generally noisier than linear supplies. Linear supplies supply a constant output voltage and will require a larger transformer and more heatsinking.

 

The sigma 22 is an all discrete extremely high performance linear regulated power supply. It is dual rail, meaning it has a positive and negative output, and tracking refers to that any fluctuation in one rail will be mirrored in the other so you never have unbalanced voltage between positive and negative. AMB's website under the technical details does a very good describing the features of the sigma 22. Most modern headphone amp power supplies will be linear regulated.

Edited by bcg27 - 11/21/11 at 7:52pm

X2. Regulation guarantees a particular voltage. That is a good thing. Do it if you can.

you forgot shunt regulation, probably the most popular (and inefficient) high performance regulator in audio at the moment. (although i mostly use linear)

 

most regulators work on the principle of a known voltage reference which is fed to an amplifier (with or without gain) and often some form of error amplifier to produce a low noise and steady voltage at the output

 

and actually its not really the particular voltage thats important, within reason most parts (particularly in audio) dont really care if the voltage is a bit low or a bit high and it wont effect performance at all in most cases; whats important is the voltage is steady with low voltage ripple in the desired operational frequency, then its up to the decoupling caps

Edited by qusp - 11/22/11 at 3:01am

A voltage regulator takes some input voltages and tries to ensure that you get a fixed desired voltage out. The regulator needs to be able to deliver the required current to the load, or it may fail to regulate properly.

For headphone audio, we strive to have low noise on the output signal.

Some regulators incorporate the AC to DC conversion and some do not. Some regulators work better with a pre-regulator to reduce noise.

If you want some background, Tangent's article is very good.

A regulated supply has one advantage in the case of headphone amps that hasn't been mentioned.

 

Many headphone amps use opamp drivers. Opamps have quite strict limitations on their power supply voltages. A regulated supply permits an amplifier to be run at the specified maximum supply voltage without the risk that variations in the mains AC supply will either overdrive or underdrive the amp. Neither is good, the first can destroy the amp, the second results in a low volume in adverse conditions.

 

Since most opamps are otherwise insensitive to PS variations, mostly the difference goes unnoticed.

 

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>>What are the benefits of regulated power supply?

 

Try building a headphone amp powered by a wall-wart, 2 diodes, and 2 capacitors. Test it by listening and also with a scope.  Now insert 2 linear regulators in a standard circuit configuration.  Repeat the test.

 

Report back your results.