2. analog
  3. 1144080343

Helikon LOADING

Hi, I am really confused as to what is the right loading for this cartridge. The info that came with cartridge recommends 100 ohms to 47 K ohms. The inernal resistance is 5.5 ohms. This is quite a big range to decipher the 'correct' loading or 'equalization'(my analogy)and also tough to find the right phono that matches with unknown loading. I am auditioning few phonos at present and want to slect the right combination.

Also I want to have phono that is future proof, that is if I explore in multiple different cartridges, the phono amp is/will be compatible with these Carts. I read form past threads that general guideline is 25 times its internal impedance. How hard and fast this rule is?

So what is YOUR HELIKON LOADING? and how did you decide this value?

thx,

Nil
nilthepill
perose
40 posts
 
47K was too bright and 470 ohms a little too flat. I settled on 5K just as an intermediate order of magnitude which seems to suite my taste. I suspect that 1K would have worked equally well. It will depend on your preferences.
jeff_jones
418 posts
 
Nsgarch - why do you care about impedance matching?
nilthepill OP
842 posts
 
Thanks for lot of inputs and data points for me to work on. 47K for set up I am trying is definitely way too thin sounding. 40 ohm is a tad fat. 400 ohms leans towards lower side of lean, closer to flater, very tight bass but little hot on high freq still. Which means 100, 150, 200 ohm might work for the set up. Although I will try out 1000 ohm just for another data point.

Thanks.
nsgarch's avatar
nsgarch
2,524 posts
 
Hi Jeff, re: impedance matching of cartridges:

A device which is generating a voltage into a load (could be a source like a tuner or CDP into a preamp, or a preamp into an amp, or a cartridge into a phono preamp) has to "see", or work into, enough of a load (resistance or "impedance") so there will be voltage registered at the other end. Or to flip it over, if the other end were just a short circuit (no load) no voltage would register and there would be nothing to amplify.

Depending on the difference between the ouput device's inherent impedance and the input (load) impedance of the driven device, there is an optimum combination that will deliver the best signal transfer, i.e. the most voltage and the most faithful (to the source) frequency response.

You hear more about "impedance matching" between preamps and amps, when someone experiences problems like not enough gain out of their amp, or poor frequency response (usually loss of highs) when their impedances are not optimally matched. Another instance where you often run into this issue is amp-to-speaker impedance matching, which is the reason for the use of auto-formers like the ones Paul Speltz markets.

The cartridge-to-phono preamp interface is no exception. Although to be absolutely fair, I should point out that cartridges are really current producing devices, but there are very few current amplifying phono preamps, so we always speak of a cartridge's output in terms of (micro) volts.

If one takes the time (and it is a bit tedious I admit) to experiment with a variety of load values, it's actually quite easy after awhile to hear when you're getting the flattest response and strongest output from a given cartridge.

The "25-times cartridge impedance (or coil resistance)" convention is a bit like setting an initial 1.5 degree Stylus Rake Angle. It's just a quick way of getting yourself firmly "in the ballpark" so that you don't have to go too far one way or the other in order to find just the right spot.
jeff_jones
418 posts
 
Nsgarch - Thanks. If I understand your approach,the 25x rule of thumb is a loading starting point. You are not really trying to match impedance between cartridge & phono pre but trying to find a sweet spot for cartridge loading that is within acceptable gain parameters for your phono pre.
More to discover