RIAA Curve on LPs same for CDs?

RIAA encoding became an industry standard peculiar to vinyl technology. The grooves are cut with this RIAA'd signal and from there reconstituted or converted by the phono preamp. Why? My guess is to make LP's achieve high fidelity. Preamp makers certainly used to tout the accuracy of their RIAA conversion sections. So, assuming CD's are mastered from something other than LP's, RIAA conversion never enters the picture in CD production.

The RIAA curve was introduced to allow LP's to be recorded with a fairly constant groove width by engraving them with reduced bass signal and increased treble signal. Lower frequency signals have a larger groove width requirement and without this correction there would be less playback time and higher distortion levels due to cartridge tracking problems. At the treble end the increased level during recording results in an improved signal/noise ratio when playback occurs. So on recording the bass signal is reduced and the treble signal increased, on playback the opposite correction is applied. On the other hand, audio CD's are produced to the Philips/Sony "Red Book" standard and this is so that any CD can be "read" by any CD player. The data is written in Constant Linear Velocity format. This has so many blocks per second, each block being divided into so many frames. These frames are encoded using EFM (eight to fourteen modulation) and use CIRC (cross interleaved reed solomon code) for error detection and correction. Hope this helps? Regards, Richard at www.vantageaudio.com

Both of the above are correct and pretty much answer your question. The RIAA equalization is built into a phono stage, which, along with added gain, is why you run your turntable into a phono stage and not a line stage. Since you don't need that equalization for the CDs, they can run through a line stage, or direct into an amplifier.

Well that certainly clears the air. Thanks so much for the information,greatly appreciated. I can always count on audiogon members. To the respondents of this thread my heartfelt thanks.

Some CD player or DAC have de-emphasis filter which is a form of equalization used in both analog FM tuners and CD players to reduce noise and distortion in program material that has received pre-emphasis. If you have a lof of CD collection with pre-emphasis recording, it is highly desireble that your CD or DAC has de-emphasis filter.

Sk- My CAL LC-10 has demphasis but it has never lit. I wonder if it was turned off in the software (bought it used) Can you provide a rock, bluegrass or folk type CD that was recorded (is that the right term?) with pre-emphasis so I can check this out? In addition to intellectual curiosity, some CDs just sound a little "hot" and I've always wondered if this is the reason. And thanks to Richard for his detailed explanation. I always knew it was a kind of equalization to make up for some quirks in the LP medium, but didn't know exactly what. Your frequent and generous sharing of your knowledge helps make this a great site.

Hi Swampwalker, if you get the chance check out the Stereophile Test CD1, track[19] (J.S. Bach: Concerto in d, after Vivaldi, BWV 596, Allegro) as this track was recorded with pre-emphasis. Seasons greeetings to you all, regards, Richard at www.vantageaudio.com

BTW, all cd players should know how to de-emphasise a signal that has been recorded using pre-emphasis and recognize the pre-emphasis flag. Regards, Richard.