Utter Confusion - SUT Settings

[Boyse6748]

Thanks for that Alan,

Can I ask a further question regarding the Ratio Setting +20dB (1:10)

There are also resistance settings as detailed below. Is there a preferred setting to use based on the information already supplied for the Benz, or does it really make no difference.

Resistance. Ratio Setting.
10k. 82 ohms
20k. 140 ohms
30k. 183 ohms
50k. 242 ohms
75k. 289 ohms
OC. 470 ohms

Many thanks in advance

Peter


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[RothwellAudio]

Can I ask a further question regarding the Ratio Setting +20dB (1:10)

There are also resistance settings as detailed below. Is there a preferred setting to use based on the information already supplied for the Benz, or does it really make no difference.

Resistance. Ratio Setting.
10k. 82 ohms
20k. 140 ohms
30k. 183 ohms
50k. 242 ohms
75k. 289 ohms
OC. 470 ohms

First off, I think one of the specs you have is incorrect. I doubt very much that the coil resistance of your cartidge is 0.12 ohms. It's more likely 12 ohms.

Secondly, I agree that a turns ratio of 1:10 is best for your cartridge.

Thirdly, regarding those figures in the table above (resistance/ratio setting) it looks to me like the "resistance" is the value of a resistive load in parallel with the secondary winding. That resistance will be in parallel with the phonostage's input impedance and will appear to the cartridge as a load with the figure in the second column (bizarrely labelled "ratio setting"). So, given a 1:10 turns ratio, a 47k phonostage and no additional load resistor (ie open circuit, or OC) you get the figures in the last line. If you have a 10k resistor in parallel with the secondary it will also be in parallel with the 47k phonostage and become 8.2k, but will appear as 82 ohms to the cartridge. Those are the figures in the first line.
However, those additional resistors are mostly a waste of time, or at best a hit-and-miss approach to getting anything right (in my opinion). Yes, they may flatten the frequency response by eliminating ringing or compensating for any deficiency in primary inductance but you have no way of knowing that from the figures given.
My advice is to use the 1:10 turns ratio and keep the secondary load at OC (open circuit) to start with. Then try some additional resistance and just listen for any beneficial effect.

BTW, this illustrates how confusing SUTs can be. Say for example you find the 30k resistance setting to sound best, you see that equates to a 183 ohm load on the cartridge and conclude that your cartridge works best into a load of about 180 ohms. No, not necessarily so - the 30k resistance is not acting on the cartridge alone, it's acting on the cartridge and the SUT. It could well be having more effect on the SUT than the cartridge.