Curious Why Benz Micro Slid Into Obscurity

@sierrasoundllc 

I purchased a Zebra L through Osage Audio two years back. I can't recommend it enough. The sound quality is amazing with all the great hyperbole and analogies you could call out. Add to it their trade-in replacement deals, then a Benz becomes a no brainer. Thanks for popping in here to clarify, and keep up the good work.

@sierrasoundllc 

Hello and welcome to the forum!

Thank you for participating in this thread.

I'm the proud owner of the Ruby ZH and absolutely love it.  I'm curious, what is the current policy for trade-in and/or rebuilding this cartridge?

Best wishes,

Don

@mulveling   You had mentioned above "...For Ruby, Gullwing, and LP/S models you have a ruby plate. Magnetically, this is not nearly as efficient. These models do NOT work well with a SUT..."

I was hoping that you could help me better understand why you feel that because the higher end Benz cartridges that use the ruby square plate do NOT work well with an SUT?

Thanks much and best wishes,

Don

@no_regrets

The ruby plate is non-magnetic so it requires more coil windings / turns to effect the same output voltage. With the iron cross armature, the iron core basically makes coils more efficient at generating AC signal. So for example, let’s look at specs. First the ruby plate models:

LPS, Gullwing L, Ruby L: 40 ohms (DC) coils for 0.38mV output
Gullwing H, Ruby H: 80 ohms for 0.7mV

Pay attention to the ratio of ohms to output mV. Now look at the much higher ratio effected with the iron cross models:

Ebony L: 5 ohms for 0.26mV
Glider SL or Zebrawood L; 12 ohms for 0.4mV
Glider SM or Zebrawood M: 24 ohms for 0.8mV
Glider SM or Zebrawood M: 90 ohms for 2.5mV

(note some of the specs on the outdated Benz Micro North America site are clearly miscopied) So the ruby plate "Low" models are using larger coil windings, comparable to somewhere between a "Medium" and "High output" coil configuration in the iron cross line, but with an output strictly in the "Low" category!

This poor ratio is at root of why they don’t match well to a SUT. A SUT basically converts cartridge current into voltage gain. MC carts with a high ohms-to-output ratio have plenty of current to spare for this. But cartridges with a weak ratio run out of current, and then experience voltage divider losses (losing gain) before they achieve the necessary voltage gain. The more you push it, the more the losses start exceeding the intended gains. On paper, an LPS (or Gullwing L or Ruby L) should still be OK with a 10x SUT. This boosts its signal to around 3.8mV into a 47Kohm MM stage. However, that’s still a little on the low side (I shoot for at least 5mV) and there’s about 0.7dB of losses from the net ~470 ohm load (47,000 / 10 / 10) reflected to 40 ohm coils (voltage divider - Ohm’s law). And then we have practice - in practice, I did not like the LPS paired to any 8x or 10x SUT I tried. It was OK, but not great. Just anemic and bland. JFET MC stages were much better (Hagerman, Herron, ARC Reference). Conversely on "normal" MC cartridges, including iron cross Benz, I easily prefer a good SUT to any active MC gain stage.

Note that SUT limitation goes out the window if you have an MM stage which can load much higher than 47K, but so very few do. MM loading at say 100Kohm or higher solves the voltage divider issue. The Rogue Ares allows this! That blew my mind when I realized that.

My Sonic Lab is an interesting manufacturer with cartridges that have insanely high output ratios. Like 1 ohm coils for 0.5mV output. I think they do this by using larger gauge (thicker) coil wire than usual. Which probably makes the coils just as massive as typical High output coil configurations anyways, lol. Still, I want to hear them.

@mulveling 

Thank you for that thoughtful and detailed reply!  It certainly helped be better understand your reasoning.

Best wishes,

Don