Quote:
Originally Posted by Electronpusher0
There is a theory that another (Neumann) pole was used when recording:
"It was suggested by Wright in The Tube Preamp Cookbook (1995) that Neumann cutting lathes incorporated this bandwidth defining filter by means of an extra, high-frequency pole at 3.18µS (50 kHz) in the cutting equaliser."
http://www.pspatialaudio.com/neumann_pole.htm
It is debateable however whether such a pole exists. |
That would be against the spirit of the Recording Indusries Association of America, though. The aim of the standardisation was that it's the record manufacturer's job to compensate for studio equipment, amplifiers, tape recorders, and cutting lathe heads to produce a record with the overall RIAA recording curve, and the record player manufacturer's job to produce amplifiers with the overall RIAA reproducing curve (the inverse of the recording curve) so that the overall characteristic is flat.
For a record cutter to allow a pole to exist, whether electronic or mechanical, because he thinks that the replay equipment may not be quite right, is wrong. It would mean that an amplifier designer who DOES get it 100% right, the overall chain would be compromised!
As for how accurate does the RIAA replay curve have to be respected, well, it depends on your overall aims and the resulting error budget. If you want it all to be correct to +/- 0.5db over the entire AF range and your pickup cartridge has a level response within 0.1db (stylus velocity to output voltage), your speaker/crossover is level to within 0.22db, then you can allow your amplifier to have a maximum error of 0.18db (so using R's and C's of 2% tolerance virtually assures this). If you have speakers which show a 1db variation, then you might be dead before you start. However, if you know what the speaker variation is, you can compensate for it in your amplifier's equalisation just as the record manufacturer compensates for their cutting equipment in the recording equalisation.