Convert your LPs into CDs

RIAA Equalization

Now that you have already connected your turntable to your PC, it’s time for us to explain some more technical details of the conversion procedure.

In the recording process of vinyl records the sound is equalized according to a curve called RIAA (Record Industry Association of America) or CCIR (ComitéConsultatif International des Radiocommunications, which was the European institution equivalent to the RIAA; nowadays the CCIR is called ITU, International Telecommunications Union). This equalization attenuates the sounds below 500 Hz and increases the ones above 2.120 Hz. In other words, in the recording process of vinyl records the low sounds are cut and the high sounds are increased. This process started to be used in order to standardize and make easier the LP recording on a large scale, allowing all manufacturers to use the same equalization pattern for the recording of vinyl records.

When a record player is connected to the Phono input of a receiver, the existing pre-amplifier circuit makes the reverse of the RIAA curve: it amplifies the low sounds and attenuates the high sounds, in order to cancel the “wrong” equalization made when the record was recorded, in order to achieve a perfect sound reproduction, that is, with the lows and highs at their correct levels and not exaggeratedly attenuated or amplified.

You will find a big problem converting records made before 1955. It was in that year that the RIAA process started to be adopted by the recording industry. Before that year, the RIAA curve was not used. This means that when you play LPs recorded before 1955, the low sounds will be amplified and the high sounds will be cut by the receiver pre-amplifier circuit. As the sound has not been recorded with attenuated lows nor amplified highs, the sound will not be equalized. The solution is to apply, in the program used to record the sounds, an inverse RIAA equalization, canceling the equalization made by the pre-amplifier circuit, making the lows and highs to be set at their correct equalization levels. This can be done by means of the program DC Art (https://www.diamondcut.com), by using the function “Reverse RIAA” in its parametric equalizer.