Shielding adds capacitance. Cable geometry also affects capacitance. The 12AX7 tube, often used as the input voltage amplifier in tube MM stages has a high Miller capacitance that adds to cable capacitance. Transistors also add capacitance at the input.
SUT Interconnects
What cables have you tried between an MC SUT box and 47K MM phono stage? What was your favorite?
I’ve tried the AudioQuest upper-line "normal" ineterconnect cables (Sky, Fire) - great cables in other slots - but very colored coming out of a SUT. Not great performance. I assume that at 1.0m+ lengths, their capactitance is far too high for this application. I’ve tried 0.5m runs of Wind & Niagara (a bit lower in their "normal" IC line, slightly smaller guage wire and less shielding to boot) and got better results. However, my best results by far are with a 0.5m AQ WEL Signature LP phono cable (optimized for low capacitance phono applications). I’ve also tried the Bob’s Devices custom cables, 0.7m, both copper and solid silver versions - these have good performance (particularly the silver), but are more on the level of the 0.5m Niagara, still short of the WEL LP.
The problem I have is that the WEL LP is quite spendy, and I want a 2nd good SUT cable for a 2nd arm & SUT setup. Looking for more reasonably priced options. I’ve had excellent results with a Synergistic Research Foundation phono cable on a tonearm (DIN plug), and wonder how a short all-RCA run of it might do off a SUT (also interested in the Atmosphere X series). Any experience with SR or other cables off a SUT would be appreciated!
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I use a very short 0.4m Van Damme XKE cable terminated with ETI connectors, made by Aurealis Audio, between my EAR MC4 SUT and Nagra VPS phono stage: www.aurealisaudio.com.au/phono-cables/ This is very low capacitance at less than 50pf per metre, is inexpensive and sounds very good. It is also the same as the captive cable of my Audio Origami PU7 arm. |
WBC (Worlds Best Cables) offers a line of low capacitance cables called PRO LO-CAP in a variety of lengths from .5 foot up to 100 foot. Capacitance is rated at 14pf per foot, 46.5pF per meter; 99.99% OFC 22 gauge center conductor; 99.99% OFC 97% shield. Amphenol gold plated brass RCAs. Not so heavy to pull your SUT off the shelf 😆. $41 for a 4 foot pair. |
MC to SUT connection is a “low impedance: high current, low voltage” one, while SUT to Phono-amp is a “high impedance: low current, high voltage” variant of it. SUT to Phono-amp connection is very sensitive to RFI and other outside noise, thus shorter connection is better (ideally SUT is integrated into phono-amp). To optimize performance of MC to SUT line, need to check resistance between each of head-shell wires and phono cable SUT input ends. Resistance of each line should not exceed 0.5Ohm (in my setup ~ 0.1Ohm). Aged tone arm wiring, oxidized contacts could cause significant resistance increase, which will negatively affect SQ. Capacitance of MC-SUT cables is less important, than SUT-Phonoamp ones, because resonant frequencies are much higher than audible range there. good overview online: https://myemia.com/Loading.html |
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