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Technical help selecting phono interconnect

I am currently in the process of selecting a phono interconnect for a tonearm rewire project. I intend to solder the tone arm wires directly to the interconnect and will be soldering the RCAs myself.

Up to this point i have been looking at Canare L-2T2S or Mogami 2549, both are 2 wire microphone cable with shield. This morning I stumbled on a tech paper on the Canare website that test and compares results of various cables.

Oddly Canare does not test the l-2T2S but it they include other 4wire variants. They do include Mogami 2549 and 2534 the 4 wire version.

So as a result of reading this paper I have concluded the following in terms of shield aluminum pet tape is best, then spiral wound followed by braided.

My question is regarding the interpretation of the results of the frequency response test, see page 10. The write up appears to me to contradict the charts. Point 2 of results states that 2 wire is superior to 4 wire, but the figures seem to contradict this. EG: figure 44, shows that Mogami 2534 curve remains flat at 0dbV further to the right the the curve of the 2 wire 2549. This is the same for all the graphs. You will note that there is typo in point 2, a key word is missing. What is the correct interpretation of the results?

http://www.canare.com/UploadedDocuments/A%20Technical%20Paper%20-%20Evaluating%20Microphone%20Cable%20Perfrmance%20and%20Specifications.pdf

One side note, despite using a balanced wire, my connection will be unbalanced, I intend on using one wire as the signal the other as the ground and floating the shield at the RCA and grounding to the TT ground wire. If I were to choose a 4 wire cable how would I wire it in an unbalanced configuration, do I simply double up on the signal and ground?
nick_sr
nick_sr OP
263 posts
 
Actually I am being very attentive about the capacitance , as I understand the Impact that this can have on higher output cartridges. So I have been selecting cables for low capacitance.

At first review of the specs it looked to me like the 2534(4 wire) had lower capacitance than the 2549 (2 wire) cable. But going back to the spec after reading your post I noticed that the spec lists a capacitance for "balanced quad connection" and that figure is more than double.

So this to me this is clear.

Where I am not clear is the frequency response graphs shown in the Canare paper linked in my OP. The graphs show the four wire variants having better frequency response their two wire equivalents. See figure
42 & 44 on page 10. Am I misinterpreting the graph or is there an error?
mesch
3,529 posts
 
Willie, what do you consider to be a low capacitance regarding either phono or IC cable? Thanks.
williewonka
3,082 posts
 
Nick - true - the frequncy response is "better" for the 4-conductor cable.

But those response curves are for 100 meter cables - the response curve for a 1-2 meter cable would be completely different.
williewonka
3,082 posts
 
Mesch - I have the Cardas one-piece tonearm wire that I find very good for phono but I don't know the Capacitance

For Interconnects I use the Van den Hul D-102 mkIII as a becnhmark which is rated at 37pF/meter

For speaker wire anything below 30pF suites MY AMP

NAIM actually states on their web site...
- 1.3 - 1.5microHenries per metre (Loop)
- MAX 20picoFarads per metre
- About 25 milliOhms per meter (loop)
- MIN Length 3.5 metres

I use "low capactance" as a guideline, in that too much capacitance in cables may effect the sound

I don't think I would state that all cables should be low capacitance across the board for everyone :-)

For phono it seems to be the case, BUT it REALLY DOES DEPEND on the components you are connecting
nick_sr OP
263 posts
 
Willie,

In general I agree with your statements regarding low capacitance, however the numbers you quote appear to me as very low, are you sure that they are not pF/ft and not meters? I checked the Van den Hul site and they list the d102 as having a capacitance of 61.5 pF/m core to core, which to me seems more inline.

With a combination of Cardas 33awg litz inside the tonearm and the Mogami w2549 Interconnect I am estimating between 100 to 125 pF total. This is arrived at by adding the core to core and core to shield capacitances. Note that VdH only lists the core to core figure.

125pF should be more than sufficient for my current HOMC cartridge and for almost any other cartridge I decide to use in the future.
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