Koestu original Onyx Sig pre-platinum cart vs. later/current platinum Sig comparisons

Hi @statman71
I own a Koetsu-rebuilt Onyx Signature (original Alnico magnets), Koetsu-rebuilt Onyx Platinum, and Coralstone. All 3 styli are still in early life (but well broken in); good for comparison. I had the Sig - an original Sugano Sr. build - rebuilt because its original stylus was very worn (inner groove distortion, marginal tracking), even though it still sounded great. I instructed Koetsu to keep the original magnets. These magnets have the added benefit of fully DOUBLE the output signal vs. Platinums. That really helps keep down the noise floor.

The Signature has become my all-time favorite cartridge. It’s more musical and somehow also more neutral than the Platinums. It renders a better 3D soundfield with greater depth. And dynamics are a little more explosive. The magic Koetsu midrange/vocals are there in full force.

I also love the Platinums; they have a creamier, smoother spin on the sound that seems more refined at first. But at least for now, I love the Signature even more.

At first the Signature was a little bit disappointing after rebuild; it was just a touch dry and soulless for a Koetsu (still a Koetsu though), but it broke in beautifully and now sounds like it did before the rebuild, but without the worn stylus issues.

It’s of course possible my preference is due to the peculiarities of my setup & gear. I also listen to quite a bit of hard/alternative rock and heavy metal, which may affect preference as well (the Signature is brilliant for this genre). In a few weeks I should be trying out a Fidelity Research FR64S against my current Graham Phantom Supreme. I also have a Shelter Harmony on a Clearaudio Universal, that I really enjoy in the rotation to take some hours off the Koetsus.

If you do plan to source an Onyx Signature, please only have it rebuilt by Koetsu Japan! I cringe every time I see a beautiful Koetsu thoughtlessly affixed with that ridiculous SoundSmith ruby cantilever. You frequently see these for sale here with "under 20 hours" and the ubiquitous claim "it sounds better than stock"...yeah, right! There is also rumor that Koetsu Japan will reject any Koetsu modded by a 3rd party, though I cannot confirm this myself.

-- Mike

@edgewear

By now I’ve seen pics of several slightly different pre-Platinum Onyx short bodies; it’s almost impossible to say exactly what you have, unless you get in direct contact with Koetsu. Still so much mystery with Koetsu!

I don’t personally know of any Platinum Koetsu that doesn’t have a leading "P" in its serial number, but that doesn’t mean it can’t exist. There could be pre-Platinum Koetsus that were later rebuilt with Platinum magnets (with original top plate retained).

You might join the "Koetsu Users" Facebook group, which has some interesting vintage Koetsus posted & discussed by members. These groups have the advantage of easy image inlining.

In a revision of my previous comment on this thread, I would now estimate my non-platinum Onyx at between 0.4 and 0.5mV output. Not fully double the Platinum model’s 0.3mV, but still quite noticeably higher. I would guess its magnet is most likely samarium-cobalt or permendur (i.e. like the Black, Rosewood, and Urushi models). The fabled long-bodies should use alnico - very large alnico magnets were necessitated by the (relatively) weak magnetic material, which required the long bodies to house it!

As to sonic matching - I absolutely prefer all my Koetsus with EAR SUT (or Koetsu SUT, or Quadratic MC-1 SUT) over any active MC stage, including that of my ARC Reference 3SE. FR64S and 64fx arms here. But then, every system is different! 

I experiment with swapping a lot of gear - depending on partnering gear, the non-Platinum magnets (Onyx in my case) work better in some cases, and Platinum works better in others. The non-Platinum magnets have more output to work with. They're also a bit more brash and dynamic / punchy sounding. The Platinum magnets are smoother and more refined sounding. But OP need not stress over which magnet his Onyx has - just listen and enjoy! The Platinums cost more but are not necessarily better. 

Blue Lace Platinum combines the smooth lushness of Platinum magnets with better dynamics and detail compared to other stones or RSP. It's the best. I also like Onyx Platinum, but it lags a little behind the Blue Lace. The warmer / softer sounding stones like Jade and Coralstone can be just too over-smoothed for many systems.