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

I’ve recently acquired a previously owned Koetsu Onyx, but would like to find out more about its vintage. It has black blocks with unthreaded mounting holes and a black upper side with ‘made in Japan’ and ‘18333’. No P before the serial number. Is it correct to assume this is a pre Platinum version, or are there platinum versions without that P? The box only has the three letters ‘PLO’ handwritten in pencil. With some fantasy this might indicate PLatinum Onyx, but obviously anyone could have scribbled this on the box. Does anyone here know what version this might be?

I have more than 30 cartridges but this is my first Koetsu, believe it or not. I was not impressed by hearing a Rosewood in my own system a few years ago. So I lost interest in the brand, for a while anyway. While this Onyx sounds much better than my memory of the Rosewood, I’m still not overwhelmed. Any tips on getting the most out of it?

PS: I followed the general consensus and started with an FR64S with SUT (Ortofon T-3000). When I moved it to a Micro MAX-237 with solid state mc phono amp it opened up and sounded more powerful and dynamic. Anyone tried it with current gain phono amp?

I have had good success with a Rosewood Signature Platinum on a FR-64S.  The pre I use is a Pass XP-27 which I preferred to a SUT/MM input combo.  Not sure about how one dates a stone body Koetsu.  Did you have a chance to examine the stylus with a microscope?

@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!