The level of the signal from the cartridge is very low, using this length of cable will have undesirable consequences if you are looking for the best possible sound.
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Would the capacitance be too great in phono cables this long?It depends on the cartridge type, the parameters of the particular cartridge, the capacitance per unit length of the particular cable, and ability of the phono stage to gracefully handle ultrasonic resonant peaks.
If the cartridge is a low output moving coil, the response of the cartridge itself within the audible spectrum will be pretty much insensitive to load capacitance. However, greater load capacitance will increase the amplitude and lower the frequency of an ultrasonic resonant peak, which may result in phono stage distortion products that fall within the audible spectrum. See the excellent post by Jonathan Carr (JCarr) dated 8/14/10 in this thread:
If it is a moving magnet cartridge, load capacitance that deviates significantly from the manufacturer's recommendation will cause frequency response in the upper treble to be non-flat. It is possible to have too little capacitance as well as too much.
Assuming you are referring to an lomc, if you choose a very low capacitance cable (e.g., 10 to 20 pf per foot), that also has quality shielding (to minimize noise pickup), fwiw my suspicion is that you'll be ok.
7 ft may not be a problem but any longer than that if you do A/B comparision you will find decresed resolution.
I experimented 1.2m, 1,5m, 2m, 4m and 6m on my both high out put and low output cartridge ( two diff turntables, diff phonos) using same cable make and found 1.5 m was optimumm with 2m being okay (hair lower resolution) and detrioting significantly as you go longer. At 4m it became pretty obvious.
Thanks for all the responses.
I initially plan on using MM/MI cartridges but this may change in the future and I certainly would want to hear a few LOMC just for comparison purposes.
Almarg, could you please list some phono cables with those very low capacitance values?
Paladin, I agree with you about the DM10 and would prefer cables with XLR terminations but my understanding is that the cartridge signals are 'balanced' by nature and RCA or XLR do not change this?
Could you please list some phono cables with those very low capacitance values?Several of the Cardas phono cables shown on this page. Click on the corresponding photos:
Neutral Reference Phono: 20 pf/ft
Golden Presence Phono: 12 pf/ft (rca); 7 pf/ft (xlr)
Golden Reference Phono: 11 pf/ft
Several of the Kimber phono cables linked to on this page:
TAK CU: 47.1 pf for a 1 meter cable, apparently even including connector capacitance
TAK H: 46.9 pf for a 1 meter cable, apparently even including connector capacitance
TAK Ag: 47.1 pf for a 1 meter cable, apparently even including connector capacitance
My understanding is that the cartridge signals are 'balanced' by nature and RCA or XLR do not change this?Connecting the cartridge to an rca phono stage input will convert it to an unbalanced source, because the impedances between each of the two cartridge output polarities and circuit ground in the phono stage will no longer be the same. That will negate the common mode noise rejection advantages that a balanced input stage would provide, but on the other hand it may not matter.
Hi I am a DIY guy I don't know that I can joint to this subject or not, a tonearm cable can make a big change to your system, I mean not only the phono cable the wire inside of the arm too, because of low level signal less contacts always better, my cable is home made 4 ft long direct from cart to amp, no hum problem even without shielded, 10 friends follow my action, I know there are products (tonearm cable)in the market too but need to install by your own, worth to have a try, I am sure you will never go back to the original one again