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Cimpliance Vs Cartridge loading

Hello allI know I'm a pain, but need help??I have a PS Audio, phono stage, trouble is cartridge, loading starts at 100 ohm, then next adjustment, is 500 ohms, I'm running a Dennon?Zu 103, rated as 300 ohms, into 500 ohm, Yea great bass, but the treble is far to harsh, turning, back to 100"ohms,  I have lost all my bass slam??, an the sound is very boring!!, I'm stuck!!
I'm thinking of buying the "Herron VTPH 2 A phono stage, I don't know how this will sound, or is available in Australia??, at lease I can insert any RCA connectors?? , But am confused the difference between  impedance, and cartridge loading??, can some one help, with all the above, the main object, is to keep the great bass, but shaved the top end, just a bit??, it is a bit hard for me as you have many shops, in the US, we have three, and where I live, I'm four hours drive, from them, but they are not any where good??, cheap stuff!!,
Regards
David SpryAustralia

daveyonthecoast

Showing 2 responses by lewm

lewm
13,690 posts
 
Glenn, Your personal experience is telling, but the OP seems to be saying that 500 ohms is too "harsh" sounding, and 100 ohms is "boring".  Since 500 ohms is not significantly different from your idea of the optimal 470 ohms, it's possible that the harshness he experiences is due to some other element of his system.  On the other hand, I have read elsewhere that some prefer to really load down the DL103, using load Rs that are near equal to the internal resistance.  I don't know why this would be good, but it suggests that something about the hf response from the DL103 is best attenuated.
lewm
13,690 posts
 
For the second time, compliance (of the cartridge) has nothing to do with loading the cartridge.  Every cartridge has an internal resistance or DCR.  The DCR is equal to the resistance you would measure with a meter, if you put one probe on the "hot" pin of the cartridge and the other probe on the "ground" pin of the cartridge, same channel.  (But you shouldn't do this, because the current provided by the meter could fry the coils in the MC cartridge.  Just rely on the manufacturer's number.)  For any MC, the DCR is going to be between around 1 ohm and 40 ohms.  This number affects what will be the load resistance that the cartridge "wants" to see when you hook it up to the phono stage.  For MCs, most phono stages offer values ranging from 100 ohms on up.  In order for the audio signal to travel into the phono section from the cartridge with max efficiency at all audio frequencies, the input impedance (largely determined by that load resistance) ought to be about 10X higher than the internal resistance or DCR of the cartridge.  When you go below this rule of thumb 10X ratio, you begin to lose some of the audio signal to ground; this preferentially affects high frequencies at first.  Thus, when the load R is too low compared to the DCR of the cartridge, you hear that the sound gets "duller".  When the ratio between the two impedances is greater than 10X, e.g., a cartridge with DCR of 10 ohms driving a phono stage with an input load resistance of 100 ohms or higher, you should be ok with regard to flat frequency response within the audio range of 20 to 20KHz.  That's really all you need to know.

When you use a SUT with an MC, that's a different story.
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