Phono preamplifier using OPAMPS.

[Joachim Gerhard]

Well add to that 35dB of backround noise in a super quiet rural environment like mine and the vinyl has enough dynamic range to be very enyoable. By the way i got a great CD sound recently. I say only so much that many of my input stages could be used benficial in I/U or U/I converters.

[Joachim Gerhard]

I made a subsonic filter i also described in part in my MPP thread that does the oposite then the arm-cart combo. I called it TDF, time domain filter and it works very well. John Curl heard it without knowing on the last Las Vegas CES. It had even NE5534 in it and most people liked the sound better with the filter in the system. Cleaner and better resolved in the bass. I think a good subsonic filter is beneficial but it has to be tuned for the real world situation. I work with Doc Feikert on a modification of his software to include in situ subsonic filter design. We just did not find the time to finish it. Nevertheless a subsonic filter can not improve the mechanical situation. I will get an Immedia Centroid and the new Schröder arm very soon to try other mecanical solutions.
I think my Triplanar is just a bit to heavy.

[Salas]

Yes, the subsonic cuts the energy to the amp and speakers helping the rest of the system but if the main arm-cart resonance is easily excited is picking up modulation for all signals on the LP. Remember that seminal paper? Was recommending utmost care for how the main resonance can pick up, showing that its much better to control arm resonance than what its there to ride on it coming from the rest of the TT quality and isolation.

[Joachim Gerhard]

Yes i have that paper. I worked closly with B&K in the old times. I still have a lot of that super expensive off green stuff and also the measurement mics. Even a 1/4 " capsule that was especially selected for me. That was in the time where good microphones came without a calibration text file.

[Salas]

Another glass for the vinyl and anechoic room heroic days then! Its too hot for wine in Athens now, I will hit a lager! See ya Joachim, cheers for contributing your thoughts & info to the mini survey.

[Joachim Gerhard]

OK, i hope the case got a little bit more transparent. Wish you a great rest of the weekend. Must be strange in Athens without much cars ?

[Salas]

Busy enough still, at mid August it will be like a village for a week.

[Joachim Gerhard]

Whould be the perfect time to visit you. Anyway, good night, i will listen a bit to soft music. Tomorrow i am busy.

[Salas]

Good night!

[studeb]

Now that everyone is well rested, i had two beginner philosophical questions about the circuit in the AN-1651 app note in post #6 and post #12

If you use a dual op-amp (49720 instead of 2 x 49710,) are there sonic penalites to doing so?
And then does one use one dual for each channel, or one dual for each stage?