phono stage with different replay equalization?

[hesener]

Hi,
there is a new japanese phono stage (Zanden Model 1200 Mk2, check out www.zandenaudio.com) that features three different settings for the replay equalization: RIAA, DECCA, COLUMBIA.

I was thinking to build a phono stage along the lines of attached schematic found here (passive RIAA equalization), and was wondering who could help me with finding out the time constants for these different settings, and modify the schematic to accomodate them.......

thanks a lot

[Robert McLean]

Try this link for a start. It is not tube based, but it does have a chart of various curves and the frequencies of the poles and zeros.

http://www.rfwilmut.clara.net/repro78/repro.html#eq

Convert frequency to time constant as follows

T = 1/(2 * pi * F )
and
RC = T.

How to pick R and C and what to do next depends on the circuit.

I know I have a link here somewhere to a tube based phono amp that has 3 or 4 curves selected by a switch, which will be of a lot more practical help than what I have given here, but I just havent found it yet.

[hesener]

thanks a lot! that is very helpful.

this danish guy actually has a preamp with quite a number of settings, and explains all the time constants used by various companies on his website.

appreciate your help....
alfred