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In the Forum: Analog Playback
In the Thread: The Expressive Technologies SU-1
Post Subject: “too bright” or “resolution” or “details” with SUT primary loadingPosted by Axel on: 7/25/2009
yes I understand your take with regard to those phrase, now what a about "too dull" or "not resolved" or "lack of detail"?
Those would then be equally 'incorrect' for initial sound determination. If I use a different cart to my current V15 xMR, say Empire S1000 ZE/X with elliptical stylus (i.e. not micro ridge as the V15) I have to resort, at least initially to the same 'avoidable' expressions of the different sound?
I use the word 'initial' on purpose, because there is of course a lot more to it, like e.g. timing, phase?, etc.

With the second cart mentioned, sounding more like secondary loading, I do get a lot of positive results but always something seems to be not there, e.g. like when a coil is over damped --- what would you call this other then "dull" or "unresolved" or "loss of detail"?

I am aware that we have all some form of our own 'ear equalisation' too, and when used to the 'over-resolved' fake bright sounds we often can hear it MAY become something we expect to hear. I do not think I'm talking about this, as primary loading is still somewhat subdued when compared to not going with any SUT.

In fact the case with a good transformer can be made, that it does NOT need any damping of its own, because it would only start to resonate far, far, above the audio frequency band say 200kHz --- so why bother to damp the trannie coils?

Next issue the cart coil. If a cart has, as my initial example, 0.3mV and 4ohm DCR AND has a quoted >=10ohm minimum damping, then these 10ohm would/should? be very close to the 'true' cart impedance for the audio band. Recall that DCR 4ohm is a 0Hz only.

Assuming we are not to way off, next thing is to follow the idea of electrical 'impedance matching' going back to MY original post. Impedance matching occurs when current is doubled at the expense of voltage dropped. So, using 10ohm primary loading to impedance match ~ 10ohm cart impedance would create the best possible 'power transfer' from the cart to the primary. And IF the transformer has no need for any audio band (or beyond) damping then we have a case for primary loading.

The sensitivity, when primary loading, is of course exactly due to this 'impedance matching' as it ONLY occurs in a VERY narrow impedance band/window, in the example at ~ 10ohm. Going to 9ohm or 11ohm will already be outside the window. This with a 30dB SUT and the square of the 1:31.6 winding ration means 1000 times bigger R on the secondary and makes it thereby 1000 times less sensitive.

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