Here is what I wrote to a few of the friends/augiogon inmates asked me regarding Lyra Helikon/Shelter 901/Koetsu Rosewood Sig. cartridges which I have owned.(I had all three until a few months ago). All the comments are based on extended listening in my system with my flavor of music(mostly Jazz/Classical).
> Koetsu has the most romantic sound, work very well for
> vocal and small scale music like jazz. It probably
> has the best midrange sound compared to any cartridge.
> But it's weakness is high's are little rolled off and
> not too good of bass control(little muddy compared to
> the other two). Also big dynamic swings are not a
> strong aspect of this cartridge. Koetsu definitely
> has its own sonic signature one can easily distingush.
> Koetsu may not work on already warm system(too
> much of warmth)
>
> Lyra Helikon is more detailed than Koetsu. It almost
> sound like you are closer to music compared to the
> other two cartridges(it may not be a good thing if you
> have a bright system). It has better highs(more
> detailed) and bass control than Koetsu. Does not have
> as much warmth as Koetsu. It's warmth in midrange is
> not as good as Koetsu nor Shelter. Dynamic swings in
> music is controlled pretty well, very close to Shelter
> which sounds the best on big dynamic swings. Very
> good 3D imaging.
>
> Shelter 901 is probably the most well rounded
> cartridge, it has somewhat of mixture of the Koetsu's
> midrange and highs/bass of Helikon. Midrange is not
> as warm as Koetsu but you get a hint of Koetsu warmth
> which is not a bad thing. Highs are as good or
> equal(maybe better in some music) than Helikon in
> details. Bass control is probably the best compared
> to the other two. Also it handles the big dynamic
> swings in classical music with ease, I would say it is
> the best of the group. Very good imaging and the sound
> stage.
>
> Between Shelter and Helikon, they share more similar
> characteristics than different in bass and highs.
> Shelter and Koetsu have similar midrange
> characteristics(Koetsu being much more warm). Helikon
> gives feeling of that you are in 1st or 2nd row in the
> concert hall(somewhat of in your face presentation)
> where Shelter gives you are in the middle of the hall
> kind of feeling(wider sound stage). Koetsu sometimes
> gives the feeling of that you are actually in the
> music(very laid back, warm, romantic).
>
> Another interesting thing is that Helikon has
> ~0.5mv,
> Shelter in 0.5mv, and Koetsu in 0.6mv output rating
> but Shelter has loudest volume in same volume setting
> in my preamp(I don't know whether it is coming from
> difference of the output measuring methods or due to
> overall presentation in sound).
>
> All three are excellent cartridges and all three have
> different sounds which I can't say one is better than
> the other.
I would definitely say if you have system which is toward bright side(especially solid state system), Koetsu would be a good choice. If you have system which is warm/laid back side(SET tube), Helikon would be a good choice. In a bright system, Helikon may sound little harsh. Where as on a warm/laid back system, Koetsu will sound little dull.
> Koetsu has the most romantic sound, work very well for
> vocal and small scale music like jazz. It probably
> has the best midrange sound compared to any cartridge.
> But it's weakness is high's are little rolled off and
> not too good of bass control(little muddy compared to
> the other two). Also big dynamic swings are not a
> strong aspect of this cartridge. Koetsu definitely
> has its own sonic signature one can easily distingush.
> Koetsu may not work on already warm system(too
> much of warmth)
>
> Lyra Helikon is more detailed than Koetsu. It almost
> sound like you are closer to music compared to the
> other two cartridges(it may not be a good thing if you
> have a bright system). It has better highs(more
> detailed) and bass control than Koetsu. Does not have
> as much warmth as Koetsu. It's warmth in midrange is
> not as good as Koetsu nor Shelter. Dynamic swings in
> music is controlled pretty well, very close to Shelter
> which sounds the best on big dynamic swings. Very
> good 3D imaging.
>
> Shelter 901 is probably the most well rounded
> cartridge, it has somewhat of mixture of the Koetsu's
> midrange and highs/bass of Helikon. Midrange is not
> as warm as Koetsu but you get a hint of Koetsu warmth
> which is not a bad thing. Highs are as good or
> equal(maybe better in some music) than Helikon in
> details. Bass control is probably the best compared
> to the other two. Also it handles the big dynamic
> swings in classical music with ease, I would say it is
> the best of the group. Very good imaging and the sound
> stage.
>
> Between Shelter and Helikon, they share more similar
> characteristics than different in bass and highs.
> Shelter and Koetsu have similar midrange
> characteristics(Koetsu being much more warm). Helikon
> gives feeling of that you are in 1st or 2nd row in the
> concert hall(somewhat of in your face presentation)
> where Shelter gives you are in the middle of the hall
> kind of feeling(wider sound stage). Koetsu sometimes
> gives the feeling of that you are actually in the
> music(very laid back, warm, romantic).
>
> Another interesting thing is that Helikon has
> ~0.5mv,
> Shelter in 0.5mv, and Koetsu in 0.6mv output rating
> but Shelter has loudest volume in same volume setting
> in my preamp(I don't know whether it is coming from
> difference of the output measuring methods or due to
> overall presentation in sound).
>
> All three are excellent cartridges and all three have
> different sounds which I can't say one is better than
> the other.
I would definitely say if you have system which is toward bright side(especially solid state system), Koetsu would be a good choice. If you have system which is warm/laid back side(SET tube), Helikon would be a good choice. In a bright system, Helikon may sound little harsh. Where as on a warm/laid back system, Koetsu will sound little dull.