Dedicated phono cables, besides having a separate chassis ground, are usually much lower capacitance than line level cables. The XLO site shows a distinctly different cable for their phono. My guess is that there is less wire (higher gauge) to keep the capacitance down. None the less, it does not hurt to try it. You may have to change the capacitance setting though. |
I would add to the previous comments that I'm not sure if the Signature 2's are shielded. Judging by the photos and description provided at the XLO site for the Signature 3's I don't think the Signature 3's are shielded, which prompts me to raise that point. Lack of shielding could result in noise issues in a phono cable application that would not occur in a line-level application. There's no harm in giving them a try, though. Optimizing capacitance is particularly important if the cartridge is a moving magnet type, for which manufacturers usually specify a recommended range of total load capacitance ("total" being the total of the capacitances of the cable, the wiring in the turntable and tonearm, and the input capacitance of the phono stage). For low output moving coil cartridges it is less of an issue, but preferably should be kept as low as possible. Ordinary copper should be fine for the grounding wire. Regards, -- Al |
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You can use any cable at all for starters. Then work backward. If you have noise with an unshielded cable, then you need a shield. If you have hum, you need to play with grounding. If you have high frequency loss or gain, you need to play with capacitance. Etc. Your XLO cables are a perfectly good place to start, if your tt has RCA output jacks, as someone else noted. If the phono cable goes direct into the base of the tonearm, then you probably need a cable with a female DIN plug at that end; one DIN plug carries signal for both channels and grounds. By the way, shielding adds capacitance. |
By the way, shielding adds capacitance.Although, as is usually the case in audio, there are a multitude of variables that affect the bottom line of a given parameter. Blue Jeans LC-1, for example, even though it is NOT specifically intended for phono applications, and even though it is heavily shielded, and even though its cost is very low, has an extremely low capacitance of 12.2 pf/ft. Best regards, -- Al |
Al, But I would guess that the capacitance would be even lower if there were no shield. Which was my point, altho I probably should have been more explicit. Geometry is the major determinant of the IC capacitance, but shielding adds to it. I think that is accurate, but I am open to enlightenment if not. |
Hi Lew, We're both right, as I see it. But the basic underlying point I wanted to convey in my response is that if low capacitance is required for a particular application, focus should not be placed exclusively or even primarily on unshielded designs. Blue Jeans LC-1, btw, is a coaxial cable, with the shield (actually a double shield) serving as the return conductor. So comparison with an unshielded cable that is otherwise similar would not be meaningful or possible, as such a cable would not work. On the other hand, I agree that a cable design having both the signal and the return conductors within a shield, when compared with an otherwise identical cable having no shield, would have higher capacitance. Best regards, -- Al |
If you use a separate ground wire for your phono interconnect, be sure to try different types of wire for the ground. I recently discovered by accident that the type of ground wire made a significant difference sonically. In my case, the ground wire runs from my SUT box to the phono preamp. All it does at the SUT box end is ground the aluminum chassis in which the transformers are mounted. It is not electrically connected to the transformers or any other part of the audio signal path, yet it makes a major difference. Go figure. |
Salectric, It doesn't "figure". The gauge of the wire might make a difference, since any resistance in the ground wire would potentially allow the component to "float" at some tiny voltage above ground, which could potentiate hum, but otherwise, I cannot fathom why the character of the wire would make a difference, assuming copper or silver in the first place. Was there any difference in gauge (thickness) of the conductor? Or is it possible that when you were changing the ground wire, you did a better job making contacts between the two chassis? (That could also have an effect.) |
I agree it doesn't make logical sense (at least anything that makes sense to me). That's why I mentioned it. I didn't notice any correlation between wire gauge and sound qualities. I tried about a half-dozen wires including solid silver, solid copper, and stranded copper before settling on some DH Labs 12 gauge silver-plated stranded copper. Of the ones I tried, this had the most neutral tonal balance with good dynamics and detail. |
Salectric, my guess is that the different grounding wires probably made a difference in the amount and/or frequency characteristics of ultrasonic or RF energy entering the phono stage. Either by making a difference in the effectiveness of the shielding provided by the enclosure, or by differences in antenna effects. With many and perhaps most phono stages audible differences can be expected to result from significant differences in ultrasonic or RF energy that may be sent into them, as a consequence of intermodulation, demodulation, and similar effects. One evidence of that is the number of threads we've seen here over the years in which people have reported problems hearing radio stations when listening to phono sources. Were all of the wires you tried approximately the same length, and were they routed and positioned similarly, relative to other cables, power cords, and components (especially those containing digital circuitry) that may have been nearby? Length differences would affect inductance, which would affect grounding effectiveness at ultrasonic and RF frequencies. Significant length differences might also result in differing antenna effects. Differences in positioning might affect pickup of ultrasonic or RF energy radiating from nearby power cords, cables, or components. Regards, -- Al |
The wires were all about the same length---3 feet or so---and were all positioned about the same. The preamps are all on wood shelves and tables, not near any metal surfaces other than the equipment itself. The ground wires didn't go near any power cords because I use an outboard power supply located on another shelf. You could be right about picking up RFI but I don't hear any noise problems. In fact, my phono setup with SUT feeding a tube phono preamp is the quietest I've ever had. |
