Cartridge incompatibility, Soundsmith and Luxman


I have a Soundsmith Zephyr MIMC Star cartridge that sound really amazing, but I just changed to a Luxman L-590AXII and the gain and loading is fixed.

Output/loading for cartridge: 0.4mV, recommended load resistance 470 ohm

Input sensitivity/impedence for the amp: 0.3mV, 100 ohm

 

The gain should be ok, but the load is way off and you can clearly hear it. The highs are rolled off and I need to crank up the volume to be acceptable level.

 

So here's the question... what cartridge would work in this setup? Would love to keep the Soundsmith, but I'm not going to add SUT with additional cables and all that complexity.

128x128audiojan

Dear @audiojan : " need to go down the route of an SUT. "

Well, due to what you have in the Luxman that’s the bad move ( is up to you. ) that degrades the higher the cartridge signal against a " simple " internal modification below Luxman advise. Maybe I have to say SUT is the wrong way to go for the quality level of the cartridge you own, can’t benefit you in anyway but the other way around but as I said: is up to you.

 

" there is no problem to replace the 100 ohm load resistor with a 470 ohm load resistor. Any skilled technician can do that. I would do that way before throwing either baby out with the bathwater.  "

 

R.

Purchasing I rather inexpensive dedicated capacitance meter 

with zeroing lead capability can be quite handy for confirming

cable suitability.

@audiojan You might want to take a look at this website

http://hagtech.com/loading

Since your cartridge is a low output, scroll down to where the low output calculator is.

I dropped the values of your cartridge (2.75mH) and input load (0.1KOhms or 100 Ohms) and it spits out a rolloff value of only about 5KHz. That might sound rolled off 🙂

So you either need a different cartridge or modify the input load to be something higher. I put in the the 470 Ohm value as recommended and the rolloff changes to 27KHz!

So I think we found the problem.

@atmasphere Greatly appreciate it! So at least I'm not going mad (although my wife would disagree with that statement...).

It seems that every other solution but to replace the cartridge has quite a bit of drawback... going to an SUT adds complexity and additional cost; modifying the Luxman limits my ability to use something different in the future; standalone phono preamp adds more cost, more cables, more complexity.

 

Easiest solution seems to be a different cartridge.

The fact that the sound seems rolled off in the treble to you suggested that the relatively high inductance of the cartridge, compared to that of a typical LOMC, is causing a loading issue, as Atma-sphere just showed us. This was mentioned in my previous analysis as a possibility. SS do recommend a higher than minimum load resistance, and now we have confirmatory evidence that this is to compensate for the inductance. But I repeat, all you have to do is open the chassis and change the phono load resistors to any value equal to or above 470 ohms. I believe it would be a mistake (or at least an unnecessary expense) to go to a SUT, but if you do, be sure to consult Peter Ledermann who made the cartridge and probably has a deep understanding of how to match a SUT to it. Of course, then you use the MM inputs. I don’t understand why changing the phono load resistors, the simplest solution imaginable, incurs any more of a limitation in the future than the 100-ohm resistors constitute in the here and now. Worst case scenario: you switch back to 100 ohms for some future hypothetical cartridge. There really is NO cartridge that requires a 100-ohm load, actually. A cartridge that works well with a 100 ohm load will also work well with a 470 ohm load, but the reverse is not the case, as you now know. Good luck.