Resonant Frequency

I am really digging this thread, and thank you Stefanl and JanVoorn for your comments. I have found an interesting piece that references the 1977 AES paper of Ladegaard - to wit: Multidimensional Audio, by Henning Moller, Bruel & Kjaer.

It is located here: http://www.zainea.com/multidimensionalaudio.htm

As I understand it, the author is making the case for the higher RF, say 10Hz-14Hz, in part, b/c it will not interfere with record eccentricities and the actual resonance of the turntables suspension. But we should perhaps agree that a decent enough suspended table will have its resonance somewhere between the 3 and 4Hz range, blocking for certain footfall induced and other resonances above 4Hz. It will also then provide very good acoustic isolation.

I will have to do as JanVoorn suggests and test this in practice. Setting the low frequency limit of the turntable to 8Hz versus say 10 or even 12Hz seems like a fairly reasonable place...more after I find and read the entire AES paper, but the point that we NEED to sort of tackle this issue and publish a guide of sorts is not lost on me. I agree - nobody seems to be giving this any attention and of course manufacturer's are doing nothing to recommend particular combinations of arms and cartridges based in part on their own testing with respect to RF and its effects on the optimum performace, at least not to my knowledge.

I did get a Shure engineer to narrow down the effective mass of the arm they recommend for the V15VxMR, and I have measured (as opposed to calculated) a 9Hz horizontal and 10Hz vertical resonance with the V15VxMR on an SME IV arm, stabilizer brush up.

This is a lower medium mass arm (10-11g acc to SME). Certainly not what we are lead to believe as optimum considering the alleged high compliance of the cartridge.

I have NEVER heard the Shure sound as good as it did on my SMEIV....

Here is the piece I referenced above, sans graphs:

"5. Audible Effects of Wow and Flutter, Rumble, Tone Arm Resonances etc.



The Transient Distortion (section 4) was an example of how the high frequency domain influences the music domain by creating products that fall down into the audible range. This section will consider a similar effect from the low frequency domain that creates serious problems in the music domain by modulating the signals. In other words, the effect of subsonic signals folding up into the audible range (dare we call it BIM - Bass Intermodulation Distortion). Also here it is often heard that people say "I cannot hear 10 Hz, so I do not care". Again it is true that 10 Hz cannot be heard directly, but the effect of 10 Hz, however, is certainly audible. Some of these pheno­mena are illustrated in Fig.7.

The curve in the upper left hand corner of the figure shows a straight­forward frequency analysis of the low frequency range 2 Hz - 60 Hz produced by an ordinary turntable with preamplifier. The most severe peak is produced by the mechanical resonance of the tone arm and the stylus, but motor rumble and hum is also clearly visible. Unfortunately, the tone arm resonance has a level typically only 10-20 dB lower than the signal produced simulatenously in the audible range.

This effect is indicated on the right hand side of Fig.7. Although the low frequency signals are not di­rectly audible, they produce some clearly audible sidebands on the music signals. Also in this domain, the effect is typically 10% distortion. The most critical range of this is known from the wow and flutter weighting function which is most sensitive around 4 Hz. So really the closer the tone arm resonance is to 4 Hz, the worse the audible effect. A frequency analysis of the demodulated wow and flutter signal is also an interesting measurement of the phenomena. A typical result of this using the automatic B & K Wow and Flutter Meter 6203 is shown in the lower left hand corner of Fig.7.

The pronounced resonance at 0,61-1z is due to wrong centring of the record. It is a paradox that often we think we measure wow and flutter when in reality we are measuring the influence of the tone arm cartridge combination. It does not help to improve the turntable motor mechanism when it is the tone arm resonance that is creating the problem.

Unfortunately, the mechanical resonances in tone arms are excited all the time by the warps in the records. The effect seen in the time domain is a ringing that sometimes goes on for half a revolution of the record and also affects the tracking force so it changes from near nothing to twice the "steady state' tracking force.

An interesting test of this can be made simply by making a cut in the record and offsetting the two parts. Every time the stylus passes the

"step-function" a transient is produced. A recording on a storage scope or the B & K Narrow Band Analyzer 2031 will show the time function or the time and frequency functions respectively. A typical result of different time responses for different tone arms with the same cartridge is shown in Fig.8.

The phenomena of audible effects of mechanical resonances in turntables are described in further detail in the B & K Application Note 17-233 (Ref.7). The audible effect of the phenomena again is a "frequency smear" or a "confusion effect" of the sound picture."

How does one download these files in the Vinyl Engine - I right click on the HTML file description and get instructions...HELP - I remember having this issue a year or so ago and still the same thing. Using IExplorer

Found the download button.....got it, thanks!

I have tried a little bit of tweaking with Blu-Tac on top of the cartridge on my Ariston arm.Some possible improvement in sound-staging ocurred, but is this the right place to put it.Anyway I was only estimating the arm's effective mass at 23g giving about 9hz resonance.Is this correct? That is the figure Jelco gave me for their "curved" 250 arm and I am using the straight arm which looks very similar.Also I would like to know if you can stay with the recommended tracking-force or play it by ear to start?stefanl