Lyra and OMA

Hi ​​​@michaellent:

I agree with @tomic601 and @solypsa that a tonearm with only 8.5g effective mass may not bring out the best sound that a Kleos is capable of. No doubt that the combination will track well, but possibly with reduced energy in the lower octaves and lessened dynamic impact.

The Lyras will work OK in tonearms of 10~12g eff. mass (for example SME Type V, Technics SL-1200G), but will sound progressively better as the effective mass increases. Normally I'd suggest 16~18g as the sweet spot, but they also sound exceptionally good in super-rigid, heavyweight arms like the SATs and Kuzma 4-Points (including the SAFIR-9).

As suggested by @tomic601 , you could add weight to the headshell, but that is an added complication which you may prefer to avoid (given that this will be your first foray into MC cartridges).

Regarding an SUT, the 5.4Ω coil impedance of the Kleos should not give any difficulties to most SUTs.

However (and this applies to low-medium output MC cartridges in general, not only the Lyras), most MM-gain phono stages incorporate capacitance at their inputs, which is necessary for equalizing the signal from high-inductance cartridges (MM / MI / IM), but is neither needed nor particularly desirable for an SUT. An SUT performs better with very little capacitance between its output and the input of the phono stage, whether due to a interconnect cable which is excessively long and/or has more capacitance than it needs to, or capacitance which is part of the loading scheme for MM / MI cartridges.

In closing I recommend first searching for an MC cartridge that is known to sound good in the Pro-ject RPM tonearm, next work out how much gain needs to be added by a stepup device to make your Aric Audio Special phono preamp happy, and then decide if you would like to use a transformer or headamp for said step-up device.

hope this helps, jonathan carr (Kleos designer)

PS. Can more manufacturers of MM-gain phono stages offer defeatable input capacitance, for use with SUTs??? 😉

@o_holter 

Experimenting with adding mass to a tonearm (presumably to the headshell) may help dynamics and low-frequency weight and extension, but doing so will also push the counterweight farther away from the tonearm pivot, which may trigger adverse side-effects such as reduced maximum tracking ability.

Pragmatically this may not be such a great concern, as on most LPs you may not notice any difference in tracking performance.

Nonetheless, the overall results will likely be better if it is also possible to add mass to the counterweight, so that the distance between the counterweight and vertical bearing can remain the same as with the unmodified tonearm, or be reduced.

hth, jonathan

A key role of a tonearm is to function as a mechanical high-pass filter for the cartridge.

Roughly speaking, above the resonance frequency the tonearm stays still and allows the cartridge to follow the LP groove, below the resonance frequency the tonearm moves to alleviate the cartridge cantilever and suspension from having to reproduce non-music inputs. These include off-center LPs (horizontal perturbations at 0.55Hz), warped LPs (largely vertical perturbations, generally considered to occur around 5~6Hz, although the affected frequencies may be higher if the warps are steep), plus the act of cuing a cartridge onto an LP (mainly vertical perturbations, with affected frequencies depending on whether an elevator mechanism is used or not, how much damping is applied to the elevator, and how quickly / slowly the cartridge is lowered if the cuing is done by hand).

Therefore, choosing a cartridge / tonearm resonance frequency that is on the high side may be good for tracking performance, but not so great for sound, as the tonearm will move to cushion the cartridge from LP groove signals that it should be tracking.

If there are no issues with the turntable suspension, including the stand structure and floorboards, and the motor(s) are quiet, like @mijostyn I tend to prefer the sound of a cartridge / tonearm resonance frequency in the lower 8Hz ~ upper 7Hz range.

However tracking performance (as well as pop / click noise levels) are also impacted by bearing design, counterweight design, and bending / twisting resonances of the headshell and armtube (a completely separate issue from the cartridge / tonearm resonance), with less rigid / more resonant tonearms more likely to benefit from setting the cartridge / tonearm resonance to a higher frequency.

Conversely, super-rigid tonearms like the SATs or Kuzma SAFIR-9 are likely to sound better with cartridge / tonearm resonance frequencies that are lower than would be prudent with most other tonearms.

hope this will be useful to someone, jonathan