The Arm/Cartridge Matching Myth

Thanks Al,
I knew that you would be able to explain this so that even a dummy (me) would get it....😬❓
And I got it.....😜❗️

Regards
Henry

I would just like to emphasise Kirkus' point about 'calculated' Resonant Frequency...and 'measured' Resonant Frequency because they are rarely (if ever) the same...⁉️😫
Many arm manufacturers provide a dubious figure for their arm's Effective Mass whilst a large number provide no figures whatsoever....😷
The cartridge manufacturers simply provide a 'design target' for their compliance figures which can vary significantly from unit to unit....and also possibly changes over time...❓😱
The Fidelity Research FR-66s tonearm is renowned as one of the highest mass arms at 38 Gm Effective Mass...😲
I have measured the Resonant Frequency with a dozen high-compliance MM cartridges using the Shure V15 Type 5 Audio Obstacle Course test disc and have not recorded a figure lower than 8Hz or higher than 13Hz...👍
So either the Test Record is wrong❓.....or the recommended range is easily achieved in 'practice' as opposed to in 'theory'....❓👀

Just taking a shot in the (very) dark here, but isn't it likely that in practice it is the amplitude of the resulting resonances in the tone arm/cartridge/room/speaker system that are at least as critical as the resonant frequency itself? Such that the frequency range for various cartridge/arm combinations does not vary by that much, but the intensity of the response at the primary and harmonic frequencies can vary by a lot between various arm/cartridge combinations? The result being that theoretical and measured resonant frequencies look roughly the same for many combinations and nearly all within the "accepted" range. But in practice these resonant frequencies are actually excited by and interact with record grooves, room construction and sound fields from speakers such that the AMPLITUDE of the resonances of different cartridge and arm combinations in different listening environments can vary over a wide range, sometimes becoming problematic.

I don't even know enough about physics to get into real trouble, but the above is my very dumb way to try to summarize some elements of the discussion so far so that I can understand it. And it demonstrates to me why a better designed tone arm is highly desirable and can command a higher price, and perhaps why Halcro sees the whole problem as a myth. This coming from a bottom feeder who has only owned 7 turntables in five decades of listening, all cheap, used and/or free, and probably fewer cartidges over my listening life than Halcro has in his current collection, but I have run into this problem in a serious way at least twice.

kn

I hope that I can clarify a few things for everyone. Resonance is a phenomena where a small amount of energy in results in near infinite energy out. It can occur in either mechanical or electrical systems. Static forces and dynamic frequency response are independent of each other. ie. Tracking force does not affect the natural frequency of the cartridge/tonearm system- unless you have so much tracking force that the cartridge suspension is bottomed out. You'll know that is the case if you see a thin ribbon of vinyl curling up behind the needle while playing a record.
Effective Mass is a shortcut for calculating the tonearm/cartridge system natural frequency. Effective mass is really the inertia of the tonearm expressed in grams. That's because the tonearm is resting on a fulcrum (pivot). The tonearm and counterweight weigh much more than just a few grams. Additionally, the effective mass can vary depending on the position of the counterweight. So a lower mass cartridge will lower the effective mass of the tonearm since the counter weight will be closer to the pivot. I guess the tonearm manufactures provide us with a nominal value. Don't forget to add the mass of the cartridge, not just the spring rate to the natural frequency calculation.
The only magic about 10Hz +/-2 Hz is that this is the "quiet" area. Below 8 Hz is the range of record warps and footfalls. Above 16 Hz is getting into the range of the music. The tonearm/cartridge system is still responding at 10Hz. Any energy input will make it respond at that frequency. The key is not to have input at 10Hz. This is so the inherent damping of the stylus suspension and any tonearm pivot bearing friction can be effective at keeping the tonearm/cartridge calm. That small amount of damping keeps things under control. If the tonearm system has a response at say 3-5Hz then the resonance- infinite energy out will overwhelm the damping properties and the tonearm will be greatly excited when rising over a record warp. You could certainly not have a problem with a tonearm system response of 5Hz as long as the records are perfectly flat, hole dead center and the turntable well isolated from footfalls.
I had a cartridge/tonearm system at 16 Hz once. It sounded ok but when I looked closely, the stylus was constanltly moving up and down. I rectified the problem by adding a 4 gram mass to the headshell. That dropped the natural frequency to about 10Hz. Everything was steady then.
The danger is that being outside the quiet zone (10Hz +/-) can result in excessive wear or even damage to your cartridge and records- even if it sounds fine.

Many arm manufacturers provide a dubious figure for their arm's Effective Mass whilst a large number provide no figures whatsoever....😷
The cartridge manufacturers simply provide a 'design target' for their compliance figures which can vary significantly from unit to unit....and also possibly changes over time...

'Effective mass' is the combination of the cartridge and arm, as seen in the post from Tonywinsc. As a result an arm manufacturer can't really publish an actual figure, unless they know the mass, compliance and tracking force of the cartridge (since the position of the counterweight will have an effect).

Harry, I don't think you need any more numbers. Take the grills off of your loudspeakers and see how much woofer excursion you are getting. If its a problem- for example if that is how the amplifier power is being gobbled up, you have a problem. If not- maybe you're in the right window.

If the cartridge can track through anything without breakup then you're fine. If not this is something to look at. Some torture tracks:

'Paranoid' by Black Sabbath - Vertigo white label LP (bass energy brings many systems to their knees in a heartbeat)

Village Music of Bulgaria - Nonesuch LP (massed females voices should sound clear)

Verdi Requiem side 1 track 2 - RCA Soria series LP (wide daynamic range with big bass drum whacks)

'Garden of Worm', side two of 'In the Wake of Poseidon' by King Crimson, pink Island LP (heavy Mellotron tracks tend to break up)

All of these recordings should sound really clean and undistorted in any way.

If you can track these without breakup you are in the window.