M20FL Super Compliance?

I recently purchased one of the NOS M20FL Super carts from William Thakker on Ebay to use with a VPI Classic. The compliance he states is 20mm/µN. I used Vinyl Engine Resonance Calculator to estimate the resonant frequency in my tone arm (JWM 10.5i SE):


Arm Effective Mass: 12.3g
Cartridge Mass: 5g
Fastener Mass: 1g
Cartridge Compliance: 20mm/µN

This gave me an estimated Resonant Frequency of: 8.31Hz A little low, but workable.

When I received the cart, I mounted it and aligned it with a MINT Protractor. The VTF was set to 1.5g. And the VTA was up a little in back. (I read that this cart likes a positive VTA setting.)

I tested the M20FL with the Hi Fi News Test Record on the resonant frequency sweep test on side 2, the cartridge would wobble somewhere between the 7 and 5 voice announcements, showing a resonant frequency of around 6HZ! This is too low and the cart was susceptible to footfalls and woofer pumping.

Using the Resonant Frequency Calculator I would need to put in a compliance figure somewhere closer to 35 to get this low of a resonant frequency with this tone arm.

Is the figure quoted by Thakker wrong, or can these NOS cart vary wildly in compliance?

Has anyone else tested their M20fl compliance?

I wanted to make sure I'm not missing something in my calculation before I contact William.

Thanks for any insight.
Keep in mind that the cartridge is "NOS", which literally means new OLD stock. So for one thing the compliance may no longer be what Ortofon said it was 20 or 30 years ago (or however long ago the thing was built). Moreover, that equation is flawed in many ways in terms of its ability to predict reality. In sum, your results do not surprise me. But at 6 Hz resonance, I am a little bit surprised that it is so sensitive to footfalls. You might try isolating your table a bit better. (I bet you hoped no one would say that.) I have one of these, also purchased from Thakker. I am using it in a Dynavector DV505 with its 11.2 gm headshell, which darn near must approximate the effective mass, since the rest of the vertical pivoting arm is so vestigial. So, not too different from your setup in terms of the parameters. I am having no problems with footfalls, on a Lenco in a heavy but totally unsuspended slate plinth. I have no idea what this means, but maybe it helps you.

I just thought of one more thing. Over on the VA, some experts have noted just in the last day or two that the HFN test LP is very inaccurate in that the actual frequencies recorded are not as labeled, another source of error. The Cardas LP is recommended as being more accurate.
Dear Lewm: I read in the tonearm VE data base that the Dyna 501 ( similar to the 505 ) has a effective mass: 25grs.

Regards and enjoy the music,
Dear vDarekmur: What kind of quality perfromance do you have/hear with that cartridge? do you have real problems with? which kind?

regards and enjoy the muysic,
Derek....you also must remember that there are 2 iterations of the 10.5 VPI arm. There is an arm wand made of aluminum and therefore light as compared to the stainless steel one that you probably have which is heavier. Higher compliance in a cartridge "likes" a lighter arm. The Stainless arm is new and I would guess that the resonance calculator you used is for the aluminum not s/s arm. Your resonance therefore is worse than you post.
Guys, Bottom line is that the HFNRR test LP is not good for determining tonearm/cartridge resonance because the actual recorded frequencies do not necessarily match what the label says, at least as claimed by several knowledgeable contributors on VA. Stringreen, might not the expected extra stiffness of the suspension, due to age, just about counteract the error you note above regarding tonearm mass?

Raul, Thanks for the poop on the DV501. If the information is correct, and if it does apply to the DV505 as well, it would seem that I would be advised to find a very lightweight headshell for auditioning high compliance cartridges. Something that is not much more than 5-6 gm. Do you have any candidates? The DV505 stock does work well with the Ortofon M20FL Super, however, possibly because it is not so high in compliance compared to other MM/MI types.
Dear Derekmur: You don't say if already has or heard something wrong running the 20FL on your set up ( that's why I ask you. ).

I would like to go a little more in deep of what my experiences were/are with several cartridges and tonearms on the resonance subject and if I finded or had problems about:

for years and when I have only 2-3 cartridges I always made everything on hand to meet the theoretical " safe " resonance frequency range with our aware if between that resonance range was better than out of it: I just followed the " rules " as part of my audio learning curve.

Through the years and due that I had more and more cartridges and tonearms too ( I can't remember when. ) things goes more complex to me trying to be in that precise resonance range in the cartridge/tonearm set up so I quit about and just mounted my cartridges testing it on different tonearms/headshells with out worry if each cartridge set up was on target with the resonance frequency range. My target was and is to hear top quality performance from any cartridge.
Well, IMHO I almost always achieve that target and I know that sometimes ( random because I don't check any more. ) the set up is on that resonance range and many times is way off it.

I run my 20FL and 20E where the resonance frequency are ( I check it with your link. ): 6.84 and 4.86 respectively and you know what? I have no single trouble and have great performances with both cartridges.

IMHO the resonance cartridge/tonearm frequency range is almost a " curiosity " but can't tell you how that cartridge/tonearm set up will perform. Of course there are " cases " in extreme set up conditions where the problem is on a extreme resonance frequency range but are not very usual today.

Btw, the compliance spec by the cartridge seller is right.

Lewm, don't worry about but you always can use lower weight headshells and see what happen, Denon and Audio technica made headshells on that weight range you ask but you have make a " fishing " work on the net to find out.

Regards and enjoy the music,
Dear Derekmur: I find these statements in other forum that I think comes from you:

++++++++" I guess I don't mean footfalls. I'm trying to describe what a low resonant frequency sounds like. I guess I mean the arm cart combination is accentuating low frequencies that don't necessarily coincide with musical information. Also the lower frequency spectrum sounds muddy with these artifacts. Is this what you hear with this kind of a mismatch? " +++++

IMHO I think ( like I posted ) that in extreme conditions ( TT set up, LP heavy waves/off center, tonearm poor bearing or faulty bearings, cartridge suspension out of manufacturer design, etc, etc, speaker heavy feedback, , , . ) it could happen what you posted even a deep msitmatch could make that the cartridge skip/wobble over the recording.

Are you on some " extreme " conditions?

Regards and enjoy the music,
So you have muddy bass performance, right?. Other that that " mistmatch " I think that you have to check that the TT and tonearm are perfect level, you have to give 20 hours that cartridge to settle down, after these 20 hours make a check on set up on overhang, VTF, load impedance, capacitance, cleaning the cartridge pin connectors, checking the tonearm wire connection with the cartridge pin connectors, make changes in cartridge/tonearm VTA/SRA set up, azymuth set up ( this cartridge is very sensitive to this parameter and with an unipivot tonearm this is a critical factor. ), antiskating, I don't know which kind of damping " mechanism " ( oil or whatever. ) has that tonearm but you have to play with too, try to find if exist a recording where the cartridge performs great to analize differences, etc, etc.

Regards and enjoy the music,
Thanks Raul,

I'm having a hard time describing the sound I heard from the m20fl. It seemed to be picking up lower frequency unwanted resonances from things like a small warp in the record. It sounded odd to me so I tested it on the Hi Fi News record. When i got such a low resonant frequency it made me wonder if something was wrong with the cart.

I realize that the Hi Fi News record isn't accurate, but it seems to me that this cart would need to be much more compliant than 20mm/µN to get this reading.

My current cart is a Nagaoka MP-50 and it's resonant frequency is close to what the Vinyl Engine calculator predicts.

I guess my question with all of this is:

How can a cart with a 20mm/µN compliance spec give a 6hz resonant frequency in a 12.3g effective mass tone arm?

Stringreen, I have the stainless armtube. Mike @ VPI told me that the effective mass of this armwand is 12.3g (the aluminum armtube is 10.9g)

Dear Derek, I think up above you wrote that the predicted result was 8 to 9 Hz, using the equation and the parameters you note above. So if ALL of your input data are off by a little bit (due to age of cartridge, the variability of dynamic compliance, etc, etc), the interaction of these errors in solving the equation could easily give you any number +/-50% of predicted value. Plus, we know that your test instrument (the HFN LP) is inaccurate. What is the mystery? Garbage in/garbage out.
Dear Derekmur: I want to assume that all what I posted you already checked and is fine.

Two things: check through a microcospe/loupe if the stylus is in pristine condition and second from what you are go up at least 10mm-12mm up at the tonearm pivot ( don't be affraid to do it, can't do harm to anything. ) and listen and see what happen and follow testing from that high VTA/SRA down till you find the cartridge sweet spot.

This time just forget about tonearm/cartridge resonance frequency because the important subject is that you achieve the best performance from the 20FL.

Btw, the MP-50 is very nice cartridge.

Regards and enjoy thye mmusic,