Quite likely that the phono stage could not handle the 0.2mv output from the Platinum.
Having owned more than half a dozen Koetsu:
1) Important to load at 100 ohm.
2) Black is the 'classic Koetsu' sound, a bit slow, rich. Bass is big, high-end is not fully extended. A 'Tube' like sound.
3) Rosewood Sig (RS) is the "real Koetsu' cartridge. Even the original late 80's/90's RS properly loaded, in today's electronics, sounds conetemporary, in the same league as VDH, Lyra, etc. But overall, I detected a slight hard-edge which is gone after moving up to:
4) Urushi - one of the most musical and high end Koetsu. I had the original Sugano Sr. version, and 2 years ago, refurbished to current spec. Both spec has the strong musicality, but none of the slowness or comnpromises as in RS or Black. It is very fast, goes down deep and goes up high. If I would say that the Urushi sounds like 'Dom Perignon', then the Helikon sounds like Evian mineral water. This is not to say Helikon is a bad cartridge, but it is very neutral, and pure as water, while Urushi extracts the full flavor of the music.
5) Onyx - Onyx compared to Urushi, it has the same tonal and refinement (having the same coil and stylus structure), but it has different dynamics. This cartridge has extremely linear power, from ppp to FFF, but it however does not have the 'sparkle' effect like the Urushi. A gloriously Hi Fi spectacular, but not as fluid and musical compared to Urushi, in my opinion.
6) Platinum version - different magnet, different coil and can be had with Rosewood, Urushi, or Onyx. The Platinum would retain the same characteristic as the non-Platinum counterparts, what Platinum improves upon is the dynamics and the realism of the playback (but remember, the drop in voltage makes the phono stage setup extremely tough, so the improvement may not be fully realized). It is very difficult to describe the sound of Platinum in words, but basically, you would hear a beautiful violin through the non-Platinum, but with Platinum, you hear more of the shape of the violin box, and the radiation energy of the sub-tonal pressure from the wood beyond the string sound. In a bass drum, Platinum can project the pressure of the drum that makes the music more 'live'.
Hope above helps.
Having owned more than half a dozen Koetsu:
1) Important to load at 100 ohm.
2) Black is the 'classic Koetsu' sound, a bit slow, rich. Bass is big, high-end is not fully extended. A 'Tube' like sound.
3) Rosewood Sig (RS) is the "real Koetsu' cartridge. Even the original late 80's/90's RS properly loaded, in today's electronics, sounds conetemporary, in the same league as VDH, Lyra, etc. But overall, I detected a slight hard-edge which is gone after moving up to:
4) Urushi - one of the most musical and high end Koetsu. I had the original Sugano Sr. version, and 2 years ago, refurbished to current spec. Both spec has the strong musicality, but none of the slowness or comnpromises as in RS or Black. It is very fast, goes down deep and goes up high. If I would say that the Urushi sounds like 'Dom Perignon', then the Helikon sounds like Evian mineral water. This is not to say Helikon is a bad cartridge, but it is very neutral, and pure as water, while Urushi extracts the full flavor of the music.
5) Onyx - Onyx compared to Urushi, it has the same tonal and refinement (having the same coil and stylus structure), but it has different dynamics. This cartridge has extremely linear power, from ppp to FFF, but it however does not have the 'sparkle' effect like the Urushi. A gloriously Hi Fi spectacular, but not as fluid and musical compared to Urushi, in my opinion.
6) Platinum version - different magnet, different coil and can be had with Rosewood, Urushi, or Onyx. The Platinum would retain the same characteristic as the non-Platinum counterparts, what Platinum improves upon is the dynamics and the realism of the playback (but remember, the drop in voltage makes the phono stage setup extremely tough, so the improvement may not be fully realized). It is very difficult to describe the sound of Platinum in words, but basically, you would hear a beautiful violin through the non-Platinum, but with Platinum, you hear more of the shape of the violin box, and the radiation energy of the sub-tonal pressure from the wood beyond the string sound. In a bass drum, Platinum can project the pressure of the drum that makes the music more 'live'.
Hope above helps.