Reverse EQ linear phase response?

[Dan Brown]

Hi Craigue...
I own Millenium and was thinking of ways to do better de-clicking. Do the 78 RPM curves do the processing in linear phase (forward and backward). I would like to play with dubbing a 78 RPM record into the PC with no EQ, just set my Radio Systems RIAA preamp to flat, then do a particular 78RPM curve after de-clicking to see if detection is better(better reproduced transients from the record).
Any thoughts???
Thanks!
Dan Brown

[Craig Maier]

Re: Reverse EQ linear phase response?

The phase and frequency response of a record will be the same whether recorded forward or reverse. The phase angle will shift 180 degrees, but that does not matter, since humans have no sense of absolute phase. As for phase linearity, the curves for turnover, as you will see from the graphs, contain a pole - zero pair just for straight 78 turnover's. If you convolve that with the reversal of an RIAA curve (which the software will allow) when the original was recorded with RIAA equalization, I doubt that the system will exhibit phase linearity. In the case of a "raw" transfer, you get whatever the Turnover curve produces as a result of the frequency domain requirements for the same. I hope this is of some help to you.