Cartridge Loading for Pass Labs XP-15


I took delivery of a Pass Labs XP-15 phono preamp this week. Biggest gains thus far are in noise floor, dynamics, etc. as it should be considering I was using the built-in phonostage on my Cronus Magnum. Rogue intimated their built-in stage rivals externals in the $250-$400 range.

Of course, there are tweaks to complete as well as break-in so I will reserve my critique for another time. There are tons of loading (47Kohm down to 10 ohm) and capacitance options (750pf to 100pf) available.

I am running a Soundsmith Zephyr MKII HOMI (47Kohm, 100pf-200pf) on a JMW 9 tonearms, VPI Scout 1.1, Zu cabling, Rogue Cronus Magnum Integrated (using for linestage pre and power amp) and Zu Soul MKII speakers.

You would think, "oh ok, you’re done. You have your load values so set it and forget it."

Of course I am knee deep in threads reading about how 47Kohm loading for MM or HOMI is vanilla and the conspiracy theories that surround it (companies want to make it as vanilla as possible because those with MM or HOMI do not want to tweak and/or invest in a pre with a lot of loading options such as those who invest in MCs. 47Kohm is an easy value to float as there are many variables in one’s system to consider.)

If you have experience playing with various loading and capacitance values with this preamp and cartridge or at least just the cartridge type (MM, HOMI) I would appreciate your feedback and or insight into how to find the optimal setting. I have adjusted the loads and listened and some of the differences are so minute it’s inconsequential (or maybe my hearing isn’t as finely tuned as it could be.)

The Pass Labs owner’s manual recommends starting at 100ohms, listen for an hour, then move down to 50ohms and repeat. When the sound deteriorates, move back to the last setting and that’s your optimal resistive loading value. Why such a large arbitrage between the recommended greater than/equal to 47Kohms (manufacturers rec.) and 100ohms (Pass Labs rec. starting point?)

Love all the options as you can use about any cartridge and you can really grow into this piece but this non-linear existence lends itself to more tweaking and critical listening.

Thanks.

asp307
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LOL!

Chill out, buddy.
If you're interested in conspiracy theories go to the 6th floor museum.

Otherwise, for your cartridge, load it with at least 47 K ohms. You don't have a moving coil. 47kohm is soundsmith's recommendation. 

How to find optimal setting? Manufacturer recommendation plus your ears. So feel free to experiment. Only costs your time.

Phonostage A with 100Ω hasn't the same sonic result like Phonostage B with 100Ω. It is a endless discussion, best you can do, try your setting and what you like best, that's it. When you buy a new Phonocable, you can roll the dice again. There is no technical Standard, the Signal passes the wire inside Arm, connectors, Phonocable, Input Preamp ... what technical solution is active for signal amplification and how good is it executed.....
So, don-c55 gave the correct answer, you have to try what setting will sound best for you. When you want a area to start, I would go first to 1k ...
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@zavato @syntax thanks for the feedback. @syntax when you recommend starting at 1k is this after experimenting at 47k? What differences other than damped bass exist with ohm values? Should impedance and capacitance be considered collectively or not? Thanks.
Of course you can try 47k first, when it sounds probably too sharp, thin, you can go lower, some Phonostages can handle 47k quite well, some not. Just try. Impedance is also important and should be seen independently.
 Normally you hear with 47k the cartridge the way it is made, no damping, no coloration, as straight as possible, maximum headroom, no compression, purest tone, no coloration of tone...depending on quality of frontend.
Very helpful @syntax; thanks. I can hear what you are describing in your last sentence. This is the type of detailed advice I was seeking. I’ve moved to 1K and the sound is more pleasing. The manual is great (and I have read it several times through) but it does not provide this type of explanation and context.