A question of loading...

I have just replaced my aging tube preamp with a new model. When I was using my older model with tube phono stage, I would run my Lyra Kleos and other MC cartridges with a load of 750 ohms. So, I assumed that with my new tube phono stage, which also utilizes a transformer in the phono stage and is also built into my new preamp, that the same cartridge loading would apply. I listened to the Kleos for about a week with this loading, and frankly, while it was fine, I wasn’t bowled over. Tonight I decided to experiment, so the first thing I did was to run the cartridge straight in, with no loading plugs. WOW, the increase in overall musicality and soundstage width was eye opening! Lesson learned is that not all gear is going to react the same when it comes to cartridge loading, particularly if there is a transformer involved and even if you are using the same cartridge from one phono stage to the next! An eye opener, anyone else experience something like this?
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Showing 2 responses by lewm

fsonic, May I just ask a question without making you angry or making anyone else angry.  As the owner of a Manley Steelhead myself, I am wondering how you achieve a load of 50K ohms or 100K ohms or "25", by which I take it you mean 25 ohms?  As you know, the max load if you use one of the MC inputs on the Steelhead is 400 ohms, and it offers choices going down from there to 25 ohms minimum.  I assume that is what you did in that case.  The Lyra website says the Etna Lambda has 4.2 ohms internal impedance, so 25 ohms would be a bit on the low side for phono input resistance and your description of the aural effect makes a lot of sense in that context.   The Steelhead uses autoformers in its MC section to achieve the various load resistances, which is a bit different electronically from using a SUT. I'm sure you know that.  I sure wish I could get hold of a schematic, because I would like to see how they use the autoformers.

If you connect an MC cartridge to the MM input, there you can have 47K ohms, but 50K and 100K are not offered.  However, if you change the fixed load resistor inside the chassis from 47K to 50K or 100K, by that means only can you achieve either of those two load resistances.  Is that what you have done?  I've actually purchased the resistors to change the max MM load resistance from 47K to 100K, but so far I have not done it.  I found the Steelhead to benefit greatly from a modification to its output stages (both the phono output and the passive linestage output), for what it's worth.

Not that it matters a lot, but I have to agree with Dover. In the conventional parlance, to increase the value of the load resistor is to decrease its load.  Capacitance is also a "load", but that is a different parameter.  In any case, I knew what you meant, when you discussed the effects of various load resistances, and that is what counts.