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-   -   MM Cartridge loading question (http://www.diyaudio.com/forums/analogue-source/24304-mm-cartridge-loading-question.html)

gurevise 16th December 2003 01:54 AM

MM Cartridge loading question
 
Guys,
I'm working on phono corrector preamp and at this time I don't have any high quality 47k resistors. They used at the input to load cartridge.
I have precision DALE 62k resistor.
So, here is my question:
What would happen if I load my cartridge (MM Sure V15) with 62k instead of 47k?

Thanks
Sergey
Dayton, OH
USA

sreten 16th December 2003 02:04 AM

Quote:

phono corrector preamp
The capacitance loading (lead and amplifier input),of a MM
cartridge has much more influence than the resistive loading.
Varying 47k to 62k shouldn't make that much difference,
i.e. easily adjusted for by a change of capacitance.

:) sreten.

ashok 16th December 2003 02:15 AM

using higher input impedance.
 
I remember seeing graphs of the effect of different input impedances and capacitances long ago. IIRC a larger resistor value will increase the hf response .
Capacitances will cause peaking in the hf response at a frequency determined by it and the cartridge inductance. The resistance will control the level of the peak. Right ?

Like the previous post says 62k will probably not affect it too much. 100k on the other hand may cause an audible increase in HF.
Cheers.

Brett 16th December 2003 10:07 AM

http://www.hagtech.com/loading.html

peranders 16th December 2003 11:21 AM

I have a preamp (Denon PRA-1500) with variable capacitance by a capacitance diode. The value goes from 50-100(?) to 600 pF(?) and the difference is very very small when it comes to sound. I'm amazed in fact that the difference is so small.

Fred is that so, or is the difference HUGE?

sreten 16th December 2003 11:50 AM

Hi Peranders,

it probably doesn't appear to make much difference due
to the capacitive loading of your tone arm cable.
If you want low capacitance you need a short tone-arm
cable, and low capacitance type cable, a lot are not.
(Often 200pF to 300pF per metre)

Some cartridges are more sensitive to loading than others.

I can assure you that I have shortened long tone-arm leads
in the past or replaced them with low capacitance cable,
and it does make an appreciable difference.
(The lowest capacitance cable I could use was 100pF/m)

In one case in turned a horribly 'spitty' and 'sibilant' cartridge
(Audio Technica) into a smooth but slightly dull performer.

Cartridges that work best with low capacitance loading are
in a sense poor designs, as its difficult to arrange in practise.

:) sreten.

fdegrove 16th December 2003 11:51 AM

Hi,

Quote:

and the difference is very very small when it comes to sound. I'm amazed in fact that the difference is so small.
You think so?
I always found it to be easily audible and in not such a subtle way either.

Cheers,;)

peranders 16th December 2003 12:30 PM

Quote:

Originally posted by fdegrove
Hi,
You think so?
I always found it to be easily audible and in not such a subtle way either.

Yes, with my "normal" stuff. Original length of the cable and a Ortofon FF15, the cheapest model from Ortofon long time ago.

I refer only to when I turn my capacitance knob of my preamp.


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