Question on loading and interconnects

Maybe this link might help you understand how resistance (measured in ohms) and capacitance play together...

http://www.play-hookey.com/dc_theory/rc_circuits.html

You didn't mention your cartridge. Basically MM cartridges are all loaded at 47Kohm so no problem there --- one size fits all. But they are sensitive to capacitance, which is additive. The manufacturer of MM cartridges lists the proper capacitance loading in the specs. So you have to know the capacitance of your tonearm cable (the one between the tonearm and the phono preamp) in pico-farads/foot (times its length in feet) plus the default capacitance in the phono preamp section. Usually, unless your cables are very long (not recommended over 3 feet anyway) you'll need to add a little capacitance to the phono preamp in the form of small capacitors soldered across the inputs -- usually there's a place for loading resistors and/or capacitors provided on the circuit boards or elsewhere in the preamp.

MC cartridges are the reverse. They're not affected much by capacitance, but are critical to loading resistance. 47Kohm will never do for the (comparitavely) lower output MCs. It's way too much. A good rule of thumb (i.e. place to start) is 25 times the coil resistance of the cartridge. That generally winds up somewhere between 100 - 1000 ohms. Then you can vary it up or down 50% (from the 25 times number) until you get the best results.

MC cartridge loading is covered quite extensively elsewhere in these forums.

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Dear Wrtickle: +++++" Is there a way I can experiment with cables (higher or lower capacitance maybe?) that will create a percieved load closer to 1k or 1.5k ohm? " +++++

First the capacitance comes in measure Farads and impedance comes in measure Ohms. What you want is a higher impedance than the 400 Ohms that you are using at the moment. No, you can do it through cables. What you can do is to change the resistors value on your phono-pre to the desired value.

Btw, what problem do you have with your Cardas/Benz Micro cartridge?, the 400 Ohms seems ok. Do you already try it at 47K?

Regards and enjoy the music.
Raul.

Your Cardas/Benz cart is a moving-coil, which means it isn't critical as to load capacitance. 400 ohms resistive loading could be in the higher range for proper response with a low-output MC anyway, but regardless, choice of interconnects won't have any appreciable impact on resistive loading since they've got neglible resistance. If you want to experiment with higher values, you'll have to accomplish it through substitution of loading resistors in the phono preamp, a subject you might want to contact Rowland about, and maybe also Cardas to see what their experience and recommendation is on the loading topic with your cart.

Thank you all for your responses, very much appreciated...especially the circuits-for-dummys type site.

Raul - I have no "problem" with the cart, just a desire to try more loading values. Of the four available on the phono boards the 400ohm is certainly the best for me, and things are sounding the best they ever have, although a touch (and I do mean just a touch) on the dull side at times. I thought bumping up the load might put me in absolute nirvana.

Dear Wrtickle: I know very well the Cardas sound and I like it. I think that the " dull " perceived sound at the frequency extremes is not really a dull sound per se: I think it is a little polite and relaxed one against other more alive cartridges sound.

Maybe, and I say only maybe, if you change the phono cable you could have or be nearest for what you are looking for.

Regards and enjoy the music.
Raul.

circuits-for-dummys was a fun read.

If you want a convenient way to experiment with loadings, make or have made for you a phono cable that has a box in the middle that has two sets of binding posts. I had John Chapman of Bent Audio make one up for me that had male RCA connectors at both ends so that it could connect to the terminal box on my VPI turntable. For my other turntable, that has male RCAs coming out of the tonearms, I had a knowledgeable friend build a similar cable using Cardas' finest wire and connectors - a cable with male RCAs at one end and female RCAs at the other. You can buy from Bent Audio a set of resistor pairs in 20 different values. This should be enough to get you started.

With the binding posts, swapping resistors in and out is a 30 second task, so comparisons between resistor values is very easy. Plus, the cost of buying additional loadings is very cheap, just the cost of two resistors.