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In Reply to: RE: Watching the thread, however... posted by jupiterboy on May 08, 2022 at 14:15:32
Interesting! The Sorane effective mass is a bit on the heavy side for the cartridges I use, but it sounds like it would be good for those using the DL103 and SPUs. Ammonite Audio make really nice finished arm plates including blank plates so pretty much any arm can be fitted.
Regards Anthony
"Beauty is Truth, Truth Beauty.." Keats
Follow Ups:
As I have been saying for years, it is the secondary arm resonances, not the primary resonance that is coloring the sound. Link below:
but on the iPad it's OK. My seat of the pants is that I agree. That said, I've been living with the same arm so long I've realized I do have a preference for a res. freq. around 10 Hz or 9.5 Hz rather than 7. I'm fully convinced it is the harmonic situation combined with the arm that informs my preference. Can't say if this would carry over to a different arm, though.
My preference mirrors yours - my best sounding cartridge matches give around 9Hz to 10Hz (by measurement) in an SL1200 arm with Jelco HS20/25 (12g mass). The oft quoted 8 to 12 Hz range is just a recommendation that clears the warp frequency range and gives a sufficient margin below 20Hz. Getting too close to the audible range gives a "flutter" effect on low frequency test tones around 20Hz. I had some very low compliance Stanton styli that gave a resonance around 17Hz (likely duds!!) for which I was able to verify these effects for myself.
The LF resonance modulates the VTA and SRA. If you do spectral analysis you see sidebands on either side of the groove signal frequency components - the higher the Q the higher amplitude of the sidebands. Not only does this contribute to signal colouration, but the instability of the cantilever increases the IMD and can degrade tracking ability very significantly.
Knowing the actual effective mass of the arm requires specific knowledge of all masses (i.e cartridge/headshell/fixings/counterweight) plus the VTF set. This is almost never given so the published specification can be a little misleading when comparing calculations and objective measurement with a test disc.
For example with the TA-110 arm, Ortofon quote the effective mass of the arm as 3.5g (without headshell)....then tell you the headshell mass is 15.5g. The missing information is the fixing mass and the cartridge mass and the final counterweight position for the VTF you require.
One has to make some really big changes to headshell and counterweight masses to make any difference, hence why most people find they don't have a problem when they try and mate their cartridge despite the calculations telling them otherwise. To compensate for the higher mass of the Jelco HS20/25, I added a suitable auxiliary counter weight which shifts the main counterweight closer to the arm bearing which improves things with higher compliance cartridges.
You could experiment with that.
Regards Anthony
"Beauty is Truth, Truth Beauty.." Keats
I've got a stock of mounting hardware ranging from .2g to 2g and that's where I'm at. I'm always listening to horns, and those very hot moments and trying to not add anything to the recording under that stress. If that is sweet, everything seems to work. Also, gain matching—it makes a big difference.
Hi Marty
Korf has chosen an example of a cartridge that is already quite nicely matched to the 750D which suits his narrative. What he should be doing is putting on a "fresh" (not aged with a hardened suspension) Shure V15TypeV (or any of the original high compliance Stantons like the CS100 or 881IIS) on to prove his point and I think you will find that his argument breaks down.
These days, most cartridges for sale are already an ideal match for most arms on the market so the need to worry about LF resonance and Q is not there for most people and there is a broad range of effective mass that these cartridges are going to work satisfactorily with.
For me, the SL1200 arm was already too high in effective mass for some of my high compliance cartridges to perform at their best.
The consequence of putting a very high compliance cartridge on an arm that has a higher effective mass than ideal such that the LF resonance is < <8Hz is that the VTA and SRA become very inconstant - the modulation of the groove signal gives rise to an audible warbling if the LF resonance drops too far below 8Hz
On an SL1200 arm, my original AT440ML and Pickering XSV4000 had a LF resonance <7Hz (between 6 and 7). I discovered that some British pressings cut at The Exchange exhibited sub sonic rumble that excited the LF resonance even on a flat pressing and the stylus was bouncing up and down and sideways with an alarming amplitude which degraded the tracking ability massively and there was a coarseness to the sound. I speculated that the building in which the cutting lathe was sited may have been shaking when the underground trains were passing underneath or perhaps they were monitoring live while cutting - either way the result was an unstable cantilever.
Secondary arm resonances are the least of my concerns if the basics like a stable VTA/SRA and good tracking can't be achieved!
Regards Anthony
"Beauty is Truth, Truth Beauty.." Keats
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