Small High-end Phono (RIAA) Amplifier
This is a high quailty phono amplifier for high-level pick-up's. It is suitable everywhere a phono input is missing. I use it for transfering old vinyl to my PC - together with a high quality soundcard (or a soundcard with digital in + a external ADC) and CoolEdit Pro, You got a perfect setup for making CD's out of Yor old LP's. You could also use it to Your home HIFI in case of it lacks the phono input or You want something better.
This amplifier is built for MM-pickups - it can not be used with MC-pickups because these requires more amplification before the filtering. The output fits any normal line level inputs.

	The amplifier board before it will be placed in the box.
	The symmetrical design can easily be seen here - the channels are identically built and enough space is placed between for a shield.
	The use of high quality OP-amps can be seen here - Burr Brown OPA604. The data shows an excellent performer: * Low distorsion - 0.0003% at 1kHz * Low noise - 10nV/¬Hz * High slew rate - 25V/us * Wide gain bandwidth - 20MHz * Wide supply range - ±4.5 to ±24V
	The power supply - enough for a small power amplifier...
	All together - observer the shielding walls made by copper. These are grounded and should minimize noise between the parts of the amplifier.
	Final design put together - really a minimum of controls, just plug it in and use - nothing to learn. l

Shematics to download:

Amplifier Stage

Only one channel shown - both channels are identical. You could build both on same board or on separate boards - it is a good idea to separate the channels by some shield connected to ground. It is also important to keep the amplifiers shielded from the power supply and transformer to avoid interference. Keep the cables to the panel connectors as short as possible - specially at the input side.

Power Supply

Rather straight-forward. Use a toroid transformer for best quality. The best choise is a 2x12V/15VA. The primary side could be 220V or 110V depending of country You live in. If You like, You could increase the voltage for the amplifier (I'm using ±9V=) to maximum ±24V=. In that case, the transformer must be choosen to fit and the regulators must be of desired type. Also the capacitors must stand the selected voltage (recommended is to use 63V types - they will take any voltage the amplifier works at and higher voltage cap's also have better performance).