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The Arm/Cartridge Matching Myth

When I began my journey in high-end audio 36 years ago….no-one ever wrote about arm and cartridge matching nor tonearm resonant frequency…?
Over the last 10 years or so…this topic has become not only ubiquitous, but has mutated beyond its definition, to THE guiding principle of matching cartridge to tonearm….❓❗️😵
The Resonant Frequency can be calculated using a complex formula relating Tonearm Effective Mass to the cartridge’s Compliance….or it can be simply measured using a Test record of various frequency sweeps.
The RECOMMENDED Resonant Frequency of any tonearm/cartridge combination is between 8-12Hz.
But WHY is this the recommended frequency and WHAT does it really mean…?

The raison d’etre of this Resonant Frequency…is to avoid WARPED records inducing ‘resonance’ into the tonearm…..
Say what…❓😵
WARPED records….❓❗️
Yes…..ONLY warped records❗️😎
But doesn’t it have any meaning for NORMAL records…❓
None whatsoever…..😊👍
Let me explain….🎼

A badly warped record induces the tonearm to rise and fall rapidly on the ‘sprung’ cantilever of the cartridge.
Depending on the severity and frequency of this warping…..a subsonic frequency between 2-5Hz is induced so if your tonearm/cartridge Resonant Frequency dips into this frequency range….it will begin resonating and thus miss-track and/or induce hum through your system.🎤
Keeping the lower limits of your tonearm/cartridge Resonant Frequency to 8Hz simply insures against this possibility.🎶

So what about the 12Hz upper limit…❓
This simply insures against the possibility of any ultra low-level frequency information which MAY be on the record, also inducing this same miss-tracking or hum. For instance if your tonearm/cartridge Resonant Frequency was 18Hz and you had an organ record or one containing synthesised bass going down to 16Hz…..your tonearm may miss-track or you MAY develop a hum❓😢

So how many badly WARPED record do you possess…❓
I have three out of a thousand or so……and have NEVER experienced miss-tracking or hum even on these three…❗️😍

Yet these days….everyone (without exception it seems)…even tonearm and cartridge designers….happily follow the dictum of this Arm/Cartridge MATCH as if it affected sound quality…..❓
This Resonant Frequency has ZERO affect on the sound quality of a particular tonearm/cartridge combination and I have proved it hundreds of times with a dozen different arms and over 40 cartridges.

The best match for ANY cartridge ever made….is simply the very best tonearm you can afford…whatever its Effective Mass…😘
128x128halcro
pryso
1,933 posts
 
So Zavato, with clarification from Rodman and Timeltel it was the Disctracker, sold by Discwasher Inc.

Now in addition to the info in links offered by Timeltel we have cartridges with "damping" brushes such as Shure, Stanton, Pickering, etc. (although they may have had other intents as well). And the Townshend Rock attempted something similar with a silicone filled trough and a paddle extending from the headshell.

A number of arm manufacturers address damping with some fluid around the bearing, or immersed in it such as Well Tempered. Then SME and KAB offered external damping troughs at the bearing end of the arm rather than the cartridge end.

So over the years many attempts to attack the resonance issue. But if anyone of these had proved successful wouldn't nearly all arms offer that today?
almarg's avatar
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almarg
9,670 posts
 
10-14-14: Halcro
As anyone with ‘feedback’ problems knows…..with the stylus stationary on the record, as you turn up the volume you will suddenly hear a deep and progressively louder continuous ‘drone’ emanating from your speakers…🔊
This (I suspect) is the Resonant Frequency of your tonearm/cartridge combination being excited by the harmonics of the structure-borne floor....

One thing puzzles me and perhaps Kirkus or Al can help here……😃
The ‘feedback’ on the stationary stylus increases when the volume is turned up….but I thought this is amplified AFTER the cartridge in the preamp stage….❓
The continuous drone you are referring to results from a feedback loop breaking into oscillation, at a low frequency. A feedback loop by definition involves a closed loop, which is to say a continuous path from input to output and back to input.

In the situation to which you are referring, some fraction of the acoustic output of the speaker is ultimately finding its way back to the cartridge. That acoustical/mechanical path from speaker to cartridge forms part of the loop, which is completed by the electrical pathway through the audio system. The volume control setting affects the gain of that electrical pathway, of course.

The gain that is necessary to set the loop into oscillation at a susceptible frequency can exist anywhere in that loop. Susceptibility depends, in addition to the gains that exist within the loop, on the phase shift and frequency response characteristics of what is in the loop, including any resonances which may exist.

Best regards,
-- Al
in_shore's avatar
in_shore
596 posts
 
Syntax sez's, even more audible internal turntable vibrations ( bearings ,
belts , motor (s) platter, suspension ,
They degrade the possible maximum performance more then anything
else.

Profound effect
zavato's avatar
zavato
1,403 posts
 
I wanted the DiskTracker so badly- never got one. Now, don't need one but somehow, I still want one.

It's as though everything I wanted to get in 1977 or 1978 but could because I just didn't have the dough, I want to own now, even if for a little while. What's been on that list that I've actually bought so many years later? Thorens turntable, Philips GA312 turntable, AR turntable, a Marantz receiver, ohm F speakers (still in my garage). Never yearned for Mac gear.

This is how threads get off track
kirkus
502 posts
 
Thank you all for the kind words, and thank you Al for correcting my sloppy math . . .

On the issue of acoustic feedback, I'd just like to add that it rarely occurs at the tonearm/cartridge main resonance point, simply because it takes a speaker with extremely powerful subsonic response to produce enough energy to "close the loop" at these frequencies. But with a big subwoofer, it can definitely happen. Usually it seems to occur at a frequency that's modally related to room dimensions, or in the mid-bass region where the loudspeakers are efficient, but the turntable's suspension isn't.
I have (and had) combinations which have been between 9.7 -10.0- 10.4
Nearly super (from that Theory) but I was amazed that some carts performed MUCH better in Arms where the "calculation" showed different datas.
If you're not actually measuring the resonance point, there's no way to know whether or not you're getting the best results within a given range. Keep in mind that manufacturer compliance and effective-mass data varies wildly in its accuracy - and poor data isn't an indicator that the theory of operation is incorrect. Similarly, many speaker drivers have inaccurate specifications for their Thiele-Small parameters . . . but this doesn't mean that the matching of the driver and the cabinet is any less important.

Of course, the tonearm/cartridge resonance envelope is just one of myriad factors that determine sound quality in LP playback, but it is one of the fundamentals. It's also something that is particular to playback . . . that is, it's one of the ways in which a turntable is fundamentally different from a cutting lathe.
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