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In the Forum: Analog Playback
In the Thread: The Expressive Technologies SU-1

Post Subject: Loading details secondary vs. primary on XF-1Posted by Axel on: 7/24/2009

First of all, thanks for additional detail.
As mentioned I can speak only for my Fidelity Research XF-1 (30dB).
Loading it on secondary as you mentioned, it ALSO damps the trannie - result in my case: less resolution.
Primary loading is MUCH more sensitive to start with, but only cart damping takes place, the SUT is not 'directly' involved.
As for the secondary's cable going to the phono-pre --- sure! Capacitance is reflected back to primary, and in the case of 30dB, 1000 times for any capacitance of what is the case on secondary, cable and all.
XF-1 has no connectors only one short (~18cm) low capacitance cable to the phono-stage.
I have the phono-pre INSIDE the pre-amp and when I did secondary loading it was done DIRECTLY on the phono-modules (SS)

Now, in case of a 0.3mV cart and 30dB trannie with secondary loading, best result was to load with 18k resistor parallel with 47k (phono-pre) = 13ohm reflected to primary. Loading on primary 18ohm resistor to achieve the same 13ohm was not as good as a 13ohm resistor = 10.18ohm for the cart to see (i.e. parallel with 'natural impedance' of 47ohm reflected from 47k input impedance of phono-modules).
In my case I got more resolution with primary loading, BUT it gets very quickly too bright with even small changes, sounding all wrong. The 18k on *secondary* sounded fine, but was missing some more detail that I know from connecting the cart straight with no SUT and using full 78dB gain of phono (60dB + 18dB raised input gain of pre-amp).

Why I used SUT? More tight really powerful bass, better upper-mid-bass (German for once shorter: "Grundton"), more "hall information" better "live feel" (there-ness) compared to all MC in general. When in my rig most of the time MC without SUT sound a bit skeletal. NO SUCH PROBLEM WITH MM RIGHT NOW! The Windfeld will have a hard time to replace Shure V15 III xMR.
Axel

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