Rerurn to Romy the Cat's Site

In the Forum: Analog Playback
In the Thread: The last phonocorrector: “End of Life" Phonostage
Post Subject: I love it!Posted by Romy the Cat on: 6/1/2008
I actually woke up today at 6AM, check all settings on my arms (after a few month of not working), demagnetized the needles and was spinning records all mooring. One of the benefits that I got with new phonostage is that the grounding patters for all arms are identical and I might absolutely painlessly to flip between the arms. This morning I play mostly mono records driving from SPU Mono. I just love the result, I truly do. Funny-funny I removed yesterday my reference for this phonostage, selected by years of use, Telefunken –Sylvania-Telefunken tubes combination and put there cheap and no particularly good sounding 12AX7 (for a next 30 days I am not planning to shut this thing down). The corrector still sounds very pleasant and very much listenable and extremely peaceful for my iterated and sick audio mind. Very cool!


 Paul S wrote:
Do I "remember" that you had a stash of exotic adjustable air-core caps? As you can tell from the question, I have not tried to run the math, but would the "trim-able" cap give you enough range to dial in the network?
Paul, it has nothing to do with math. It is one of the unlikeness of the Paravicini’s design. He runs feedback not to cathode but to high impedance of plate. So it is very high impedance and very low capacitance feedback (contrary to usual RIAA feedback with low impedance and high capacitance). Moreover he uses current feedback (cathode resistor) on the fist tube to raise the first stage plate impedance. Then he unites the miniature capacitance of the feedback with Miller capacitance of the first stage and et then let the combined capacitance to be amplifier by the second stage. Very slick, pay attention that the first stage Miller capacitance, the minute values of the feedback caps and the capacitance of the entire assembly are no consider in this design as parasitic but actually used for a purpose. In a classic RC design you would need relatively large caps to write the RIAA cure and you will be way beyond the range of no dialectic caps (air or vacuum). In the 834P design the feedback caps are very small values: 110pF and 330pF that allow using “nothing” as dialectic in the caps. The only thing that I would consider from here is to use doted symmetric air caps where the signal does not go over the movable contacts or the body of the cap. The only place where I see such air capacitors was inside my Rohde & Schwarz Tuner


but I clearly understand that I will never found such caps…

The Cat

Rerurn to Romy the Cat's Site