dlaloum wrote:Totally repeatable - cartridge was meticulously set up, and tracking tested using the HFN torture tracks and an oscilloscope - the cartridge tracked all the way up to the +18db track 9 torture test cleanly (!!)
So you didn't actually repeat it then.....eg across cartridges, setups etc. That's not actually 'totally repeatable' then..... C'mon, this is misleading stuff !
dlaloum wrote:In this case, I strongly disagree, the test signal is at a relatively low level (-20db with 0db being the usual 5.6cm/s...)
Well no, because of RIAA, at 8kHz -20dB is about 2.2 cm/s physical velocity, for example. That's not exactly a low level.
dlaloum wrote:There really should be no mistracking with that type of signal at that level, on a cartridge the easily passes the torture test.
'Torture test' stresses completely different aspects of trackability, at radically different frequencies, with different limiting mechanisms. And, in any event, 2.2cm/s@8kHz is not a low level physical level.
dlaloum wrote:There is a high midrange "hump" in THD which appears to correlate with the high midrange "trough" in frequency response - this effect is not eliminated by increased VTF - but it is reduced...
IF it's real and repeatable, it could have many candidate mechanisms, including mistracking distortion.
dlaloum wrote:An unexpected effect, and one that appears to indicate that at least part of the midrange trough common to all cartridges (btwn 2k and 10k roughly) is generated by something that is sensitive to VTF.
Like.....mistracking ? Friction and flicker noise ?
dlaloum wrote:THD at frequencies above 10k was completely unaffected by the varying VTF - another reason for doubting mistracking as a cause.
No, trackability at hf is relatively insensitive to VTF. No matter how much vtf is applied it can't be usefully applied to the stylus. At massive risk of confusion, it's because of cantilever impedance. That's an entirely seperate mechanism from what you're suggesting here, DL.
dlaloum wrote:My assumption is that it points to some sort of cantilever behaviour, and that the additional VTF is pre-stressing the cantilever, and therefore making it behave as a more rigid device... of course that is just a guess... but it is based on some interesting measurements!
Indeed, it's entirely a guess. Without a mechanism, and without evidence. C'mon it's unsupported speculation, without a basis, and where preferable explanations aren't contradicted. If it's real and repeatable at all.