When is it time to consider adding a SUT?


I have an ARC reference phono 2 and am about to take possession of a Benz LPS with a low output. I have heard that installing a SUT such as one from Bobs devices can help the phono pre and provide better end to end performance. Would this help a quality phono pre like the ref 2?
thanks 

gtaphile

Showing 1 response by wrm57

The LPS is not really a great candidate for an SUT because of its 38-ohm internal resistance (DCR). At .36 mV, you’d likely want to use a 1:15 SUT, which would present an impedance of 209 ohms to the cartridge. That’s pretty low, when you think rule of thumb is 10-25 x DCR (I prefer 25x usually). 1:10 would create a better impedance match at 470 ohms but the gain might be sub-optimal.

I have an older Ebony L at .26 mV and DCR of 3.5 and I use an SUT of 1:20. It sounds good but the loading is a touch high at 118 to the cartridge, accentuating the top a bit. The newer Ebony L has a DCR of 5, which is better for 1:20.

The only Benz that is a truly great match for an SUT is the Ebony TR, which is designed for use with one. With a DCR of 1 ohm and output of 0.1 mV, it should be pretty ideal for an SUT of 1:40.