Cartridge Loading- Benz LO.4


Looking to see if anyone has experience with proper phono pre-amp impedence for this cart. Specs say 200-47K. Quite a range and I'd like to narrow it down a bit. Any guidance would be appreciated. Thanks!

Regards
Jim
jimbo3
I think you are right on Jimbo. I would expect that you would end up in that range (100-1K).
Thanks, Swamp. I'm going to try to "bracket" 100 and 20K to start. I'm guessing that the next step is probably going to be 10K, then 5K, 2K and 1K, if necessary. From what you all have been saying, I should probably ultimately end up somewhere between 100 and 1000. Thanks for everyone's input.
I found that my Glider L2 sounded much more three dimensional when loaded down in the 100 ohm range. At 47K, the std in my CAT or using the 22k (if that's what it is which a Benz PP-1, it sounded flat and relatively lifeless. I have not yet started playing around with the 4 loading steps on my new Supratek, but there was a dramatic difference going low. Give it a try.
Oops! It's definitely a log scale when running through trannies. Now that you mention it, I'm not 100% sure when going directly to a phono stage. Do a search for "loading" posts by John Ellison on Vinyl Asylum, or just ask him. He knows the math of this stuff backwards.

You could get cheap resistors for testing, then one pair of good ones once you find the spot you like. Or check with John Chapman at BentAudio. www.bentaudio.com

He sold me 12 pairs of decent quality resistors for $15 with my trannies. He provides bits and pieces to DIY folks all the time, so I suppose he'd put a batch together for you.
Doug- Thanks for the insight. I'm guessing that loading is kinda on a log scale in that going from 200 to 400 is a bigger jump that going from 22K to 22.5K? Sounds like I'll need a buch of resistors- do I need anyting fancy or do I just go down to Rat Shack and get the ones off their shelf?

Thanks
Jim
Okay, here's what I'd do, FWIW of course.

Choose several LPs you're familiar with. This is not a time for unfamiliar music, just concentrate on sonics. Solo piano is excellent. Pick something dynamic that involves the whole keyboard, Beethoven not Debussy or Keith Jarrett. A big orchestral piece with good imaging is useful and natural vocals are too. Don't know if you're into opera or choral but soprano voices are very particular about proper loading. Nobody's as picky as a diva!

I think Benz suggested 47K as the upper limit simply to avoid alienating people with non-adjustable MM phono stages. The optimal load is probably much lower, as others with Benz experience have stated. I'd start right at the bottom of their suggested range, 200 ohms.

Play a selection or two from each LP to get a handle on the sound. At this very low load bass should be fuller, richer, etc. Treble will be less weighty than you're used to. Bass piano strings will sound growly and rich but high notes may lack punch. When I did this I could actually visualize the spot on the keyboard where the rolloff in treble weight began.

Now make a big move up. Don't try to hit the sweet spot by going to 225, go to 400 or even 800. The idea is to bracket the target with your first two tries. Once you establish that 200 is too low and 400 is too high (for example) honing in on the sweet spot is easy. Diddling your way toward it 5 ohms at a time would take forever.

When you get close, tonal differences between loads will become very subtle. The thing to listen for now is imaging. The right load will lend a three dimensional presence and heft to instruments that other loads can't quite match.
Doug- The resistors simply plug in on the circuit internally. It's relatively easy, but a little time consuming.
Jimbo3,

I don't know your cartridge at all, but based on the specs you quoted from Benz I'd be surprised if 47K sounded best. Do you have an easy way to change loading or would you have to strap resistors across the phono inputs?
I use the Benz phono pre with my L2. The Benz pre has a fixed 22K loading. It's a good-sounding unit, but I'm not at all sure that 22K is ideal.
Thanks, Swamp and Oz. The phono pre is the "Gold Card" version in the Audible Illusions M3A, if that makes a difference. AI says that MCs typically sound best at the 47K they put in the stock unit. Seems odd to me, but what I know on this subject is VERY limited!

Regards
Jim
I have the L2, which is the newer version of your cartridge with the same output. A lot will depend on your phono stage, but I have mine loaded @ 300 ohms. I have found that it sounds good most anywhere below 1k ohms, but 100 was way too much. It is very flat and rolled off sounding at that loading.

Oz
Not sure about the L0.4, but my Glider L0.2 sounds best with very low impedence load, 10-100 Ohms.