frequency resonance

[alanford]

arm: schick 16 gr mass
shell orsonic 16 gr. mass
cartridge ortofon hmc30 10 gr. mass compliance 14 to 10 hz

totally I have a frequency resonance of 6.5hz

do you think it's too low?

[dlaloum]

Yes a resonant frequency of 6.5Hz is generally considered too low.

Peter Pritchard (famous cartridge & arm designer) used to say that he aimed for a resonance of around 6Hz. (statement was in a Boston Audio Society quote)
However that probably assumes a very well isolated table, and records that do not suffer from warp and off centre issues...

Things like footfall vibrations, and other environmental vibrations can be close enough to 6.5Hz to cause trouble. If the Res peak is at 6.5Hz, the resonance will extend out to around 12Hz and 3Hz roughly - any vibrations within that frequency range (that reach the arm and/or platter) will cause a reduction in tracking ability (if it is substantial enough it may cause skipping) - and intermodulation distortion due to the up/down and side/side motion of the resonance.

How sensitive you are to this varies with the individual too.

10Hz is the usual "target" resonance frequency, going up to 12Hz or down to 8Hz is generally considered to be the acceptable limits - 6.5Hz is substantially below 8Hz, and therefore Yes I think its too low.

[Alec124c41]

The Orsonic is a good headshell, but too heavy for use with this cartridge.

Cheers,
Alec

[pogo]

arm: schick 16 gr mass
shell orsonic 16 gr. mass
cartridge ortofon hmc30 10 gr. mass compliance 14 to 10 hz

totally I have a frequency resonance of 6.5hz

do you think it's too low?

No. The issue is whether there will be effects in the audible range. 6.5 Hz doesn't qualify. Those who know otherwise are free to comment.

[dlaloum]

For a rather comprehensive treatment of the Audible effects of resonance, the B&K article is excellent:
viewtopic.php?f=46&t=1281

From which article the following quote (page 5):

The physical meaning of a resonance is increased amplitude of the relative movements between the record surface and cartridge and, in addition, the lower the frequency the greater the amplitude. Therefore all the time the cartridge wil oscillate at the tonearm resonance with large excursions - just the prescription for making intermodulation distortion on tones in the audible band.

I would also refer you to the test plots (page 9) showing the intermodulation sidebands on a 3kHz tone for three setups, undamped 7Hz resonance, undamped 9.5Hz resonance and damped 16Hz resonance.
The best result, with the least additional distortion is the damped 16Hz setup.

From a conclusion paragraph on page 9:

From this it is clear to see that to improve audible quality the main problem is to reduce the relative movements between cartridge and record as much as possible. In other words, one has to damp the arm resonance and move it upwards in frequency.

Note that this only focuses on distortion / IMD sidebands - it is not looking at the impact on the bass of having the resonance too close to the lowest audio frequencies. If the resonance is undamped and get up over 12Hz it will start to impact/boost the lowest frequencies... 18Hz is the frequency of the lowest / biggest pipe organ pipe. - so raising the res f higher may impact of the low end performance (by boosting it)

Lots more good info in that article!

Another good article for information on resonances, stylus scrubbing (the motion that causes the intermodulation discussed above) and other parameters of performance is the Shure Technical Seminar:
http://shure.custhelp.com/app/answers/d ... aWhZbGs%3D

bye for now

David

[Hanuman]

The Orsonic is a good headshell, but too heavy for use with this cartridge.

Cheers,
Alec

The whole combo is mis-matched, I think. I tend to associate the Schick with SPU's, '103s & EMT's. Never-the-less, if the only issue is that the resonance number is not exactly "perfect" then I wouldn't necessarily fix it if there's no actual negative effect.

[alanford]

thank you very much for all the replies
Maybe there could be a misunderstanding
I read in internet the shick tonearm has 16 gr mass
It is not clear if 16 gr includes shick headshell or not
please do you know anything about?

[dlaloum]

Normally the tonearm effective mass specification includes the original OEM headshell.

If using a lighter or heavier headshell, weigh the headshells and adjust by the difference between them.

[Alec124c41]

Jelco/Sumiko HS-12 headshell is about 11.5 grams, well built, with Litz wires.
Standard Technics headshell is about 8 grams.

Cheers,
Alec

[alanford]

thanks again for your reply
I wrote to Thomas Schick asking info on his tonearm mass
hoping reply from him, I'll keep you informed

[vinylsky]

I wrote to Thomas Schick asking info on his tonearm mass
hoping reply from him, I'll keep you informed

any news? thx!!!

[Trackside]

6.5 hz on a suspended subchassis deck may be too low as it may be very near the frequency of the suspension. On a solid plinth design it may not be a problem. My DL-103 runs at 7 hz on my SL-1200 and sounds fantastic.

[dlaloum]

The peak is at 6.5Hz but it normally extends to half and double (roughly) so the bell curve would extend to 3.25Hz and 13Hz (roughly!)

The lower end of this range is within the footfall zone - and on my solid plinth JVC, this was a major problem.

I had to do a lot of work engineering isolation into the TT platform, to absorb footfall before it reaches the TT... and have achieved a 20db+ improvement in footfall coming through - but it is still there (isolation can only go so far...)

And with a setup having a sub 7Hz resonance it can become noticeable (although no longer majorly objectionable)

bye for now

David