Phono 3 Cartridge Loading

[Greg.]

Ok, moving on, I now want to experiment with different cartridge resistor loadings. I have already fitted terminal pins in the loading resistor (R13/14) holes on the Phono II PCB. To make experimenting of different values convenient and quick, is it OK to solder flying leads to the load resistor pins I've fitted and at the other end of the leads crocodile clip in whatever resistors I want to try to vary the load in order to make an aural assessment? If what I suggest is OK, it seems to me to be the best way of making rapid comparisons on load effect considering the need for speed to overcome the shortness of our aural memory. What do you think?

[John Caswell]

Hi Greg et al,
The most elegant way to do this is with either a rotary switch with various resistors or a DIL switch.
The biggest problem you will have is with hum if the cover is off so something needs to be dreamt up to keep the switch inside the cover.

John

[NealG]

Yes, I've made load selection a feature in mine:

[bob orbell]

What a good idea, I must do somthing like that myself, thanks Neal.

[Greg.]

I agree. Very elegant and user friendly. Thanks, Neal and John.

[vinylspinner]

Good idea, and very neat, must get the recipe!

Nigel

[Greg.]

Hi Neal,

Just to clarify, I believe what you have done is fitted a six position stereo selector switch and then chosen six different resistor loadings within the cartridge's specified loading range. I'm I right?

Regards,

Greg

[NealG]

Yes, thats right Greg, AFAIK they are 4K7, 10K, 15K, 22K, 33K, 47K...these where the values I had to hand...TBH I only use 47R and 100R for cartridge loading, Ortofon KB at 47R and DL103R at 100R....also maybe they should be close tolerance metal films as well...

[John Caswell]

Hi all,
Close tolerance Rs are fine but not necessary, as I said in previous note I very much doubt that you will notice any difference between a 10K secondary load and a 9.55K (47K//12K) =95.5R or a 11.3K (47K//15K) load = 113R.

John

[NealG]

True, however, metal films should have less self induced noise than carbon types...