Long cables from turntable or phono stage

09-21-13: Dbphd
Last night the local Thorens expert recommended I move my Parasound JC-3 to a shelf just below my TD 124. The arm is an SME 3009 Series III with Ortofon SME 30H cartridge. Should I use a 1 meter cable even though a half meter would be sufficient? I'm thinking of using Linn Silver cable.

It appears that the Ortofon SME 30H moving magnet cartridge has a recommended load capacitance of 400 pf, which is on the high side. And your phono stage does not provide adjustable load capacitance, so its input capacitance is probably smallish, perhaps something like 50 pf or even less. I couldn't find any info on the capacitance per unit length of the Linn Silver cable, but I suspect that it is unlikely to be more than around 50 pf/foot.

So the problem you would probably have with either length is too little total capacitance. With a MM cartridge having too little load capacitance is likely to result in thinness somewhere in the treble region.

You might want to consider using, at least experimentally, this kit, which makes possible adding various amounts of capacitance. It costs $46, and is sold by DB Systems (see the "Accessories" link).

After determining the optimal amount of added load capacitance you could then install a capacitor of that value into the JC3, for each channel. Or, if you would prefer not to make any modifications to the JC3, using a pair of the capacitors that are in the kit in conjunction with good quality y-adapters would probably be a reasonable long-term solution. (IMO, that is. Other opinions about using y-adapters as a long-term solution will certainly differ in some cases).

Regards,
-- Al

Thanks Al. I'll order a kit from DB Systems. The turntable currently has what looks to be a 1.5 meter AQ cable that I understand cost less than $200. I think really good vinyl sounds superb, a bit better than SACD of the same recording played on my Oppo 105 with analog to Cary Cinema 11a inputs set to bypass. The JC-3 also inputs to the Cary.

db

The capacitance issue is very interesting. So as well as the transcriptors, I also have a Technics SL5200 turntable which I find sounds sort of flat and lifeless. It has an Ortofon Bronze MM with a recommended capacitance of 150-300pF. The Moon 110LP has adjustable input capacitance of 0 or 100pF. So I should have set the Moon at 100 I guess, assuming that the cables in the turntable are not so superb (basically 35 year old wires) but are unlikely to add up to more than 300?

BTW - using the advice you all gave me, I ran the turntable to the phono stage using the wires from the table and then ran long RCA from the phono stage into the stereo pre amp. Seems to work fine. Happy.

Ninox, in the case you described just above my guess is that the total load capacitance would probably not be very far outside of the recommended 150-300 pf range for either setting of the Moon's input capacitance. And it's quite possible that you might even be within that range for both settings. So while I would expect the two settings to result in some difference in sonics in the treble region, both settings would have to be tried to determine which is preferable.

A point to be aware of, btw, is that the "0 pf" setting will not really be zero. It will be some small amount of stray capacitance in the connectors and internal wiring, plus some small amount of input capacitance of the circuitry. The "100 pf" setting will presumably be 100 pf greater than that amount.

Regards,
-- Al

Al,

The input capacitance of the JC-3 is about 200 pF. I'll probably use Mogami 2549 cable cut to length for my application, most likely around 3'. I suspect LA Pro Audio can tell me the capacitance per foot. They've been very responsive to making cable lengths to my specification. The advice I'm getting is to keep the cable short without putting the motor of the TD 124 on top of the JC-3.

Thanks for your help.
db