Re: My experience with current sensing MC phono pre's

Posted by Jon Risch (B) on December 5, 2002 at 10:26:45

In Reply to: Re: My experience with current sensing MC phono pre's posted by RJM on December 5, 2002 at 00:59:21:

[ You hit the button on the op-amp criteria: DC offset and voltage noise are the major factors. High PSRR a plus. ]

NO!. It is CURRENT! Low bias current, low current offset, and low current noise!

This was my way of trying to say that the 797 will not necessarily be the best choice.

As for worrying about DC offset, as I suggested, think of the current sensing front end as a seperate circuit, and place a DC servo around it. Use about 36 dB of gain. Then go for the RIAA EQ and "normal" phono stage gain at 1 kHz of approx. 40 dB. This should result in a decent signal level with all but the lowest output carts, REMEMBER, the output is NOT the output voltage, but the output CURRENT, and most MC's wioth a medium low out0put Z can put out gobs of current into a virtual ground input.

The virtual ground and feedback R Q's will ahve to wait till tonight.

Jon Risch

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Follow Ups Full Thread

Topic - A current input MC phono preamplifier project - RJM 06:37:01 12/4/02 (16)

Re: A current input MC phono preamplifier project - jcarr 09:18:14 12/11/02 (0)

Induction & voltage/current debate rebuttal - Claude Abraham 12:26:56 12/10/02 (0)

Further thoughts on the opamp - RJM 01:40:48 12/5/02 (1)

Re: Further thoughts on the opamp - Jon Risch 18:00:47 12/5/02 (0)

My experience with current sensing MC phono pre's - Jon Risch 19:46:39 12/4/02 (11)

Re: My experience with current sensing MC phono pre's - RJM 00:59:21 12/5/02 (7)

Contd - Jon Risch 20:05:07 12/5/02 (5)

Re: Contd - RJM 00:46:39 12/6/02 (4)

MC phono cartridge is a Voltage Generator: e=B*l*u - jcox 11:24:52 12/7/02 (0)

Re: Contd - Jon Risch 08:23:52 12/7/02 (2)

Re: Contd - RJM 07:21:01 12/9/02 (1)

I actually went with LT1028 over AD797 in strain gage amplifiers - jcox 08:54:16 12/9/02 (0)

Re: My experience with current sensing MC phono pre's - Jon Risch 12/5/0210:26:45 12/5/02 (0)

Re: My experience with current sensing MC phono pre's - jcarr 23:55:23 12/4/02 (2)

Re: My experience with current sensing MC phono pre's - Jon Risch 10:36:30 12/5/02 (1)

Re: My experience with current sensing MC phono pre's - jcarr 12:16:48 12/5/02 (0)

Follow Ups

Re: My experience with current sensing MC phono pre's - Jon Risch 12/5/0210:26:45 12/5/02 (0)

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