Post by Owen Y on Jun 10, 2017 11:17:38 GMT 12
Another basic question that arises, relates to the combined natural Resonant Frequency of tonearm Effective Mass together with cartridge Compliance & Mass. There are plenty of calculators available & I have used quite a few. However, like a lot of things in audio, this is not a precise, right-&-wrong answer thing. This Ortofon visual graph is helpful I think & probably all you will need:  Notes: Total Mass - is tonearm Effective Mass + cartridge mass + mounting hardware (1.5 - 2gm for a set of stainless screws/nuts, depending on length). Compliance - cartridge compliance, um/mN is the same as cm/dyne x 10−6 or cu (compliance unit). Compliance specification at 10Hz is more useful here than compliance at 100Hz. However, traditionally, Japanese cartridges have specified at 100Hz. Conversion is according to a sliding scale I believe: 6.5cu (100Hz) = 15cu (10Hz) - ie 2.3 times. 10cu (100Hz) = 18cu (10Hz) - ie 1.8 times. Ortofon recommend here a range between 7 - 12Hz. However, I hear that sometimes cartridges preform well outside this general range. I think that lower range is possibly better (record warps/eccentricities are usually below 5Hz) than higher range (you don't want to approach low bass freqs, say 15hz). The danger of the cartrdige stylus suspension going into resonance is (i)losing LF output (ii)risk of suspension damage.
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Post by Owen Y on Jun 10, 2017 11:31:12 GMT 12
Note also that tonearm Effective Mass is not a precise specification either, because: When the tonearm counterweight is moved, 'moment of inertia' changes & Effective Mass varies, a bit. eg. Typically a counterweight could move in & out by say +/-10mm - Effective Mass could thus vary by +/-10% or more. I assume that tonearm manufacturer's specify Effective Mass with c/weight somewhere in the middle(?).
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Post by Owen Y on Oct 8, 2019 14:26:21 GMT 12
From the Ortofon website: To maintain a cartridge/tonearm system resonance frequency within the acceptable range of 7 to 12 Hz, whereas 10 Hz recommended, it is necessary to choose a cartridge with the mass and compliance matching the tonearm : Low mass arms* mate well with both moderately high and very high compliance phono cartridges.
*A tonearm whose effective mass is rated at 10 grams or below is considered low mass (e.g. early SME’s, Grace 747, Ortofon AS-309S, RS-309D, TA-110 and TA-210).Moderate mass tonearms** are good companions for moderate to low compliance cartridges.
**A tonearm whose effective mass is rated between 11 and 25 grams is considered moderate mass (e.g. SME 309, IV, IV-VI, V, Triplanar, Graham). Arms above 25 grams of mass are high mass in nature (Eminent Technology, Dynavector).The Ortofon graph :  
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Post by Owen Y on Oct 8, 2019 14:37:34 GMT 12
In short, if the resonant frequency of the whole tonearm & cartridge assembly is: - Too high (ie above 14 Hz), then this will intrude up into the audible range - compromising LF reproduction. - Too low (ie below 6.5Hz), then this could cause mistracking on record warps.
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Pundit
Post by belbo on Oct 10, 2019 15:41:33 GMT 12
In short, if the resonant frequency of the whole tonearm & cartridge assembly is: - Too high (ie above 14 Hz), then this will intrude up into the audible range - compromising LF reproduction. - Too low (ie below 6.5Hz), then this could cause mistracking on record warps. What happens if you are within that range but not on the “ideal” frequency of 10hz? So if you are let’s say at 8hz does that mean that you’re not getting the most out of your cartridge? Based on experience Owen is it a problem being on the lower or higher end of that spectrum but not exactly at 10hz? (I understand that if you are below 7hz or above 14hz then it will resonate with either wraps or music).
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Post by Owen Y on Oct 10, 2019 20:15:36 GMT 12
Hi belbo - this is as I understand it: The commonly recommended 'target' range is 8 to 12Hz. Ortofon recommend 7 to 12Hz - more or less the same. Ortofon are saying that 6.5 to 14Hz will probably be no problems. However: - Lower than 6.5Hz, then you could encounter problems with warped records (ie vertical resonance coinciding with a short warp 'frequency'). - Higher than 14Hz, then you could compromise LF performance (ie horizontal resonance approaching very low frequency bass lateral (mono) groove cuts). In my experience (this is strictly IMHO  ) : You get MUCH better bass reproduction if you can get the Resonant Freq (of the whole tonearm-cartridge assembly) down in the lower part of that range & as low as possible - my current setup is down at around 5Hz I estimate. (Mainly due to the linear tracker carriage being relatively heavy.) (Fluid or other tonearm damping has a similar effect, lowering Effective Mass, usually laterally.)
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Pundit
Post by belbo on Oct 11, 2019 0:15:41 GMT 12
Hi belbo - this is as I understand it: The commonly recommended 'target' range is 8 to 12Hz. Ortofon recommend 7 to 12Hz - more or less the same. Ortofon are saying that 6.5 to 14Hz will probably be no problems. However: - Lower than 6.5Hz, then you could encounter problems with warped records (ie vertical resonance coinciding with a short warp 'frequency'). - Higher than 14Hz, then you could compromise LF performance (ie horizontal resonance approaching very low frequency bass lateral (mono) groove cuts). In my experience (this is strictly IMHO ) : You get MUCH better bass reproduction if you can get the Resonant Freq (of the whole tonearm-cartridge assembly) down in the lower part of that range & as low as possible - my current setup is down at around 5Hz I estimate. (Mainly due to the linear tracker carriage being relatively heavy.) (Fluid or other tonearm damping has a similar effect, lowering Effective Mass, usually laterally.) Thanks Owen, clear, so it’s actually ok experimenting a bit with the range. I have a new cartridge coming in but expect resonance to be around 8 due to heavish arm+headshell combination, let’s see.
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Post by Owen Y on Oct 11, 2019 9:05:51 GMT 12
If you (anyone) has a tonearm that is a on the lightweight side (Effective Mass-wise), eg SME 3009 or if you have a low compliance cartridge - a favourite strategy is the old coin-on-headshell trick. This increases the Effective Mass of the tonearm, by not only adding mass to the tonearm, but requiring the counterweight to be moved further to the rear, away from the tonearm pivot to balance. (Because Effective Mass is partially proportional to the square of distance of the mass from the pivot.) In the past, I followed the popular thinking that the counterweight should be located as close as possible to the tonearm pivot for best sound & always used say, the lightest possible c'wt in order to achieve this. But I've found that I usually get better bass (weight, power) if the counterweight is further out. This is due to increasing the Effective Mass of the tonearm - particularly if the Resonance Freq of your particular arm-cartridge combo is near the high end of that 8 to 12 Hz range. (An aside - low bass freqs are mostly monophonic & thus are lateral groove cuts (ie L-R stylus movement only), so horiz Eff Mass is the key factor. However, added mass in this way increases both Horiz & Vertical Eff Mass.) Try it!  (This example is testing with a linear tracker, but pivotted arms respond similarly in this respect.)
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Post by colinf on Oct 11, 2019 20:00:02 GMT 12
The Dynavector DV-505 and 507 have different resonance frequencies for lateral and vertical planes. For vertical (stereo or out of phase) information the resonance is higher. For horizontal mono information including bass the resonance is far lower. 
AMR-iFi R&D
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Post by Owen Y on Oct 12, 2019 10:13:06 GMT 12
The 'bi-axis' Dynavector arms are v cool - I have listened to these a lot in the past at a pal's. The concept is to provide high Eff Mass horizontally (for strong LF stability) & lower (1/3-1/4) Eff Mass vertically (to track any record warps). The Dynas also have a magnet damper acting horizontally. I'm guessing, however, that these tonearms suffer the same drawback of some linear trackers, in that the ultra-short sub-arm wand makes the cartridge v much more sensitive to VTA variation due to record thickness variation, slight warps.
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Post by sub on Oct 12, 2019 13:15:06 GMT 12
So it seems the Linn Ittok LV11 (moderate mass) is not a good match for an Ortofon 2M Black which is said to be a high compliance cart at 22um/mN?
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Pundit
Post by Gryffles on Oct 12, 2019 14:33:19 GMT 12
So it seems the Linn Ittok LV11 (moderate mass) is not a good match for an Ortofon 2M Black which is said to be a high compliance cart at 22um/mN? Looks to work out to be around 7.5Hz which should be fine. My arm/cart comes in under 7Hz and is fine. In fact as Owen mentioned a lower Res Freq has benefits. A calmness and solidity to the sound in my case.
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Post by Owen Y on Oct 12, 2019 14:35:51 GMT 12
Let's do the sums... Ortofon 2M Black: - compliance (lateral) 22 um/mN (cu) - mass 7.2g - add say 1g for fixing screws Ittok LVII: - Eff Mass 11.5g Total mass of cartr + tonearm = 19.7g (aprox) According to the above Ortofon graph, Resonance Freq = around 7.5Hz (- perfect IMO ) (Some might say that this Res Freq is on the low side, but I'd expect that LF reproduction should be v good...?)
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Post by Owen Y on Oct 12, 2019 15:02:38 GMT 12
NOTE: Japanese cartridges traditionally specify Compliance at 100 Hz, whereas for the resonance purposes, we're more interested in compliance down at 10Hz - which is what I believe European manufactuers specify. It varies a bit, but Compliance at 10Hz = Compliance at 100Hz x (1.75 to 2.25x), I understand. eg 10 cu compliance (100Hz) = 18-22 cu compliance (10Hz)
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Post by Citroen on Nov 21, 2021 13:51:05 GMT 12
Rather than just calculating one resonant frequency, this Korf Compliance Calculator will be my new go to measurement tool korfaudio.com/calculator 
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