SUT Interconnects

My Verion - aka Cotter - Type P SUT came with a captive lenght of Verion Tri Axial cable for its outputs. IMO still one of the best SUT’s ever! I paid $375 for mine in 1978! Used with the GAS Sleeping Beauty (Coral 777) mc cartridge. Word to the wise: keep any cable from the SUT output jacks short to avoid capacitive roll-off of highs!

The lenght of the Verion cable off the SUT was about 12 inches. I still have six pairs of the one-meter Verion RCA cable pairs! Alas, they remain buried in storage!

.5 meter atlas element integra tonearm cables, low capacitance. Also, rothwell the river .5 meter interconnects...these sound a bit brighter than the atlas to my ears. They are silver plated copper. A well shielded cable is a must to reduce noise and hum. The same cable should be used from TT to SUT. You can use whatever interconnect you want from the phono preamp to your integrated/preamp. For that, I use an Atlas elements integra conventional interconnect. My goal is to keep the sound Signature consistent from TT to the integrated line input. My preference is the Atlas cables, they seem to be neutral. I use two different SUT’S, the Jensen mc-2rr-l (made in USA, 1:10 ratio, 430 ohm input impedance) and the Rothwell mcx (UK, 1:10 ratio, 100 ohm input impedance). My cartridge of choice is the Hana EL (.5 mv, >400 ohm) and Goldring Eroica LX (.5 mv, 100ohm) They are a good match to both SUT’s, impedance loading wise, as well as step up ratio requirements. Yes, my set up is low budget in relative terms, however, the cables and SUT’s are of high quality. If I were using a cartridge worth thousands, and a turntable like Mike Fremer’s, then maybe I’d spend more...what I got is fine to my ears.

Auditorium23, also used as a tonearm cable. 

I had also used the Bobs silver plated copper but switched to the 

top line Anti-Cable and or top line Morrow silver, 

all .5 M.

What ever Denon used in the AU-320 SUT for the output cables seems to work really well.

BillWojo

My Fidelity Research FRT-4 has a captive cable, with verry common rca connectors and a ground wire.

I sometimes think of changing it, but it sounds great, gives me no trouble, doesn't lose contact or give intermittant balance issues like some flexible jacks like these do.

Entre ET-100 lets you use your own cable.

Captive, low capacitance, short length leads are best, sometimes known as "flying leads", because the leads are directly soldered to the transformer secondaries inside the chassis of the SUT, at that one end. That way you at least eliminate an RCA jack and plug in the signal path and effectively minimize capacitance. But if you must traverse a distance of 3 ft or greater from cartridge to phono inputs, it would be preferable to have shortest possible (flying) leads on the cartridge to SUT side and make up the remaining distance on the SUT to phono inputs side.

@lewm

The "flying leads" makes sense, thanks. But as far as optimizing total run length to a phono 47K input - I always though it was more critical to keep capacitance low AFTER the SUT, rather than BEFORE the SUT, becasue of the after-SUT’s capacitative load supposedly "reflecting back times the sqaure of the turns ratio" (i.e. the opposite of what happens to load resistance)? I don’t pretend to understand the electrical theory behind this. What’s the theory behind prioritizing the tonearm to be as short as possible? My tonearm cables are all the "standard" 1.2m, but I definitely don’t need all of that length.

I try to use a short length of whatever I'm using as a tonearm cable.

@mulveling , The advantage of making your own cables is being able to keep them as short as possible. If you use a high bandwidth balanced cable like Canare Da206, use the two inner connectors for signal wires and connect the shield only at one end ( I usually use the load end), you will have a better cable than you can possibly purchase. You will also save a pile of money which you can spend on music.  

DNM Reson for unique coherency and overall sound and cost effectiveness but these are not shielded. Shielded ICs are safer in general between SUT and phone. I added custom mu metal foil shielding to my SUT section to facilitate using unshielded ICs with the SUT. See my system pics. I use DNM Reson ICs whenever possible. Cheers!

I always though it was more critical to keep capacitance low AFTER the SUT, rather than BEFORE the SUT, becasue of the after-SUT’s capacitative load supposedly "reflecting back times the sqaure of the turns ratio" (i.e. the opposite of what happens to load resistance)?

@mulveling Its critical to keep the capacitance down on either side of the transformer. Ultimately you'll want to load the transformer correctly for the cartridge you have and the input impedance of the phono section (typically 47KOhms). Some SUTs are designed for a specific cartridge and assume a 47KOhm load so these are less worries. Something like a Jensen which is designed to work with a wide variety of cartridges will need very specific loading to work right. The interconnects are part of that loading and very simply have to be low capacitance.

@atmasphere 

Could you please explain why it is important to have low capacitance cable before the transformer. how does that affect the transformer ?

I understand the need for low capacitance after the transformer, but not before.

I would have assumed you want low capacitance all the way from the cartridge to the phono inputs. Now you’ve got me thinking.

audioguy85, can you say more about your 1:10 SUT that results in the cartridge seeing 100 ohms? Insofar as transformers have no intrinsic impedance (ideally) you would have to place a 10K resistance across the secondaries of a 1:10 SUT to achieve a 100 ohm load. Maybe that’s what you do. Just curious.

@lewm 

The Rothwell MCX uses both primary and secondary internal loading to achieve a 100 ohm load for the cartridge from a 1:10 transformer and minimise ringing etc.

@mulveling I have tried numerous interconnects within my system and have had a very tight focus on the Vinyl Chain from Cart' Tag Wire through to Phon'.

After trying  many Cables and then commencing in a investigation of Wire Types.

I urge you to look into a Cable that has a PC Triple C Wire or a D.U.C.C Wire. 

With your willingness to trial and compare, I think this will be a great addition and very very worthwhile to add to your trials.

At first I thought I was over rating the positive influence I was being met with, but after loaning the Cables in both PC, 5 Pin DIN Phono and RCA Phono, the responses from others has pretty much proven to myself, these cables are adding extra in a very attractive way.

I am now working with a few friends to produce and Internal Tonearm Wire in both Wire Types, as well as the RCA and Later on XLR Cables in PC Triple C to be used upstream of the Phonostage.     

Could you please explain why it is important to have low capacitance cable before the transformer. how does that affect the transformer ?

The inductance of the cartridge and transformer in parallel with the capacitance of the tonearm cable causes an electrical resonance. Best to keep that resonance as high as possible. Depending on the transformer design you may well have to load the transformer in a certain way to deal with this resonance. So its best to minimize variables by minimizing the capacitive aspects since there is little you can do about the inductances involved.

This is one reason why I prefer to run direct if I can.

@atmasphere 

Very interesting! Your vast and deep expertise is always appreciated. 

Considering that SUT box users like me are, for practical reasons, usually limited to a 0.5m minimum cable length on either side (and usually RCA) - what are some good "audiophile" cables with the smallest possible capacitance per foot? Capacitance specs aren't always listed. From the specs I have seen, Cardas interconnects seem to consistently show an impressively low capacitance - much lower even than my AudioQuest phono / LP cables (AQ's normal interconnects are WAY too high). Is there anything likely to be better than Cardas for this role?

I know that besides a spec, there are some clues you can use - like avoid large gauge wires (keep it smaller than 23 AWG) and avoid braided geometries. The Stax headphone cables uses a ribbon layout (with large spacing gaps) to minimize capacitance. 

20pf/foot is a practical value for a cable. Mogami makes a console cable that specs in this area. Since transformers can receive either a single-ended signal or balanced, you could run a balanced connection from your arm to the SUT and thus obviate the sonic attributes (or artifacts, however you want to look at it) of the cable.

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.

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. 
Anyone try these yet?  
I’ve had great luck with their microphone cables.  Durable, noise-free and neutral.  I’m going to try a 4 foot pair on my Ortofon ST-80S to Luxman L-590AxII MM phono and let you all know.  

Audio Sensability out of Canada. Silver interconnects are awesome 

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

This discussion prompted me to experiment a bit.  I use Audiosensibiliy Statement Silver interconnects throughout all of my equipment.  I tried 0.5 meter. 0.7 meter, and 1.0 meter phono cables on both inlet and outlet of both Bob's Devices Sky 10 and Consolidated Silver SUT (10:1), cartridge was SoundSmith Experion, C-J ART Phonostage.  The limitation is undoubtedly this old man's ears, but frankly given the time lapse between each setup, I could not discern any difference between any of the cable lengths.  The Bob's Devices SUT is a shade warm compared to the Consolidated.  The latter has slightly better micro detail, but you have to really strain to capture the difference.  But again and in keeping with the spirit and intent of this discussion, cable length differences in my experiment were not a factor.  Note, I kept inlet and outlet lengths the same in all cases.

Curious how one measures capacitance of an interconnect?

Curious how one measures capacitance of an interconnect?

@rsf507 By using a meter which measures capacitance. You treat one connection as one lead of a capacitor and the other connection (perhaps the shield) as the other lead of a capacitor.

What Atmasphere said, but be sure to disconnect the cable at both ends before taking a measurement.  For a balanced cable, the measurement between pins 2 and 3 (positive to negative phase) will be equal to about 0.5X the capacitance between pin 2 and pin 1 (pos phase to ground) and between pin 3 and pin 1 (neg phase to ground), because capacitors in series add like resistors in parallel.

"By using a meter which measures capacitance” yeah.. capacitance changes vs frequency, that’s why I measure capacitance / inductance / loss / resistance at 50/1000/10000/20000Hz points. 

You've already tried Bob's cables, so I can't add much value here but that's what I'm using. When I purchased Bob's SUT I got his cables because it's what I demoed and I mentally just considered it part of the system. 

No, westcoast, capacitance does not change with frequency.  What you are thinking about is that because of capacitance, impedance changes with frequency.  (Impedance of a capacitor is infinite at DC and goes down as frequency goes up, by an amount dependent upon the value of C.) But that does not matter when you are simply concerned with the capacitance of a cable, or rather impedance is inherent to the question of whether a certain level of capacitance will cause a resonant peak because of interaction with inductance, the other major player in determining the resonant frequency.  Capacitance and inductance are properties of reactance. You only need an accurate and sensitive C meter to measure C. That value does not change with frequency, at least at any audio frequency. (It will change at RF frequencies in the megaherz band.)

Lewm, here is some cable manufacturer material to read about cables. There is also amplifier circuit input capacitance, which could be quite hard to measure. http://www.mogami.com/e/notes/capacitance.html

"For cable using material having good high-frequency characteristics in non-polar molecule, such as polyethylene, these vales are not varies with freauency and temperature. But for the cable using PVC compound and other polar molecule material, capacitance is largely depends on frequency and temperature."

I think that bit of double talk refers to the dielectric effect. Different dielectrics ( insulation) will affect the capacitance of the cable which in turn affects frequency response. Same goes for the spacing between the conductors and the geometry of the cable. All of those factors plus length determine the cable C, which is a constant at all audio frequencies.

I think that bit of double talk refers to the dielectric effect. Different dielectrics ( insulation) will affect the capacitance of the cable which in turn affects frequency response. Same goes for the spacing between the conductors and the geometry of the cable. All of those factors plus length determine the cable C, which is a constant at all audio frequencies.

Not correct.

• The dielectric constant can change with temperature, and this change can be significant, especially for certain materials. For example, some ceramic materials used as dielectrics in capacitors can have a temperature coefficient, meaning their capacitance changes with temperature. 

• Frequency Dependence:

  At higher frequencies, the dielectric constant may not be able to "keep up" with the rapidly changing electric field, leading to a frequency-dependent behavior. This means that the effective capacitance can vary with frequency. 

Yeah, sure. If it makes you happy. The first thing I said is that the dielectric can affect capacitance. As to your other point, what temperatures do you have in mind,given that most of us maintain our listening rooms at between 66 and 72 degrees F? And if T is stable, no matter what the value, there would be no change in C due to T for a given IC at a stable T. Your point about the dielectric vs frequency is interesting. Does it apply at audio frequencies? In any case, do you want to agree with west coast and say that “capacitance varies with frequency “? That’s just wrong was my point. At frequencies much higher than audio, all capacitors begin to have problems; they resonate and can become inductive. I took that aberrant behavior as irrelevant to the question. Ceramic caps retain their properties to much higher frequencies than do other types used in audio; that’s why they’re often used to filter RF.

@lewm

What I did not elaborate on is that with polar molecule material such as teflon, the dialetric constant can change with temperature changes in and around room temperature - we are not talking extreme temperatures here.

The changes in dielectric constant can affect both capacitance and frequency response, along with phase changes due to skin effect and the change in dielectric constant.

The ceramic caps are a red herring here - we are talking about cables - but the science remains the same.

Shindo and Kondo are known designers of SUTs. In particular Ken Shindo has done wonderful work in this area. The reason I recommended Auditorium23 is that Keith Aschenbrenner is a close associate of Ken Shindo and has substantially adapted and emulated his designs. Obviously original silver cables from Shindo and Kondo equally make the list. all i am is a very happy customer, no further association