What is a good way to measure resonance up to 20Hz

[Quando]

On the Internet, you can read that we should match the cartridge's compliance to the effective mass of the arm so that the peak of the unwanted resonance is in the range of 8Hz-12Hz.

There are many such tables and guides.

Maybe that's what we should do.

However, I noticed that two different cartridges, both with a resonance peak at the same frequency, e.g. 8 Hz, can have, on the same tonearm, a very different amplitude of the unwanted resonance, sometimes the difference reaches up to 10 dB.

So I would like to make a reliable measurement of the amplitude of the unwanted resonance in the range of up to 20 Hz.

 

[Thomas_A]

The Denon technical record XG-7001 low frequency sweep goes from 4 Hz to 100 Hz. It will however test both lateral and vertical resonant point at the same time since it is purely L or R.

 

[Quando]

The Denon technical record XG-7001 low frequency sweep goes from 4 Hz to 100 Hz. It will however test both lateral and vertical resonant point at the same time since it is purely L or R.

Sorry for my questions.

I do not intend to use the turntable to play sounds with frequencies other than 20Hz-20 kHz.

So why should I play test signals with frequencies below 20 Hz to make a measurement?

 

[DVDdoug]

So why should I play test signals with frequencies below 20 Hz to make a measurement?

You asked for a way to measure it! Something has to "stimulate" the resonance... Probably normally record warp or rumble. i.e. An 8Hz resonance has no effect with a pure 1kHz signal.

on the same tonearm, a very different amplitude of the unwanted resonance, sometimes the difference reaches up to 10dB.

Just a guess, but maybe a combination of frequency response and mechanical resonance. If the output is low at 8Hz, the "resonance" shouldn't be as bad.
But with a warped record it might cause tracking or IM distortion even though it doesn't "measure" as strongly... That's just a guess too.

On the Internet, you can read that we should match the cartridge's compliance to the effective mass of the arm so that the peak of the unwanted resonance is in the range of 8Hz-12Hz.

Or, give up on the outdated analog technology!

 

[Nopiano]

Sorry for my questions.

I do not intend to use the turntable to play sounds with frequencies other than 20Hz-20 kHz.

So why should I play test signals with frequencies below 20 Hz to make a measurement?

Because that way you can measure it! You wanted to, after all.

As you say yourself, it is pretty unpredictable. My experience a few decades ago with many cartridges suggests that samples vary, as they are quite inconsistent even if mass produced.

 

[Thomas_A]

Sorry for my questions.

I do not intend to use the turntable to play sounds with frequencies other than 20Hz-20 kHz.

So why should I play test signals with frequencies below 20 Hz to make a measurement?

Well this is just to quantify the resonant peaks in a standardised way. One can do it with other records as well; using 20 Hz- 20 kHz pink noise lateral and vertical as a "basic music content" and then quantify the resonant peak. However, the excitement of the resonance will depend on both the resonant character of the cartridge/tonearm and the distribution and levels of record warps. So to to this in a standardised way, you rely on a fixed record to record quality.

 

[Quando]

See, the same cartridge. Compliance 15/10 Hz
The same tonearm, but the effective mass has been increased by adding a weight.

The peak of the unwanted resonance occurred at 8 Hz (without the additional weight it was at 11 Hz)
The amplitude of the resonance decreased by 7.7 dB, which is a lot.

Please note that both resonance peaks are at a frequency within the recommended range of 8 Hz-12 Hz, but the amplitude of both is far from the same
That is why I want to take measurements to determine what the amplitude is, and choose such an effective mass that the amplitude is as small as possible.

 

[Thomas_A]

Yes you will get different levels due to the damping characteristics of the stylus suspension. You should also get similar results with any record, and you should see the difference on a LF sweep.

Edit: Test also a music record which mostly has frequency content to 40 Hz.

 

[Quando]

It would be interesting to see on a graph, in a legible way, how reducing the resonance amplitude, in the range up to 20 Hz, by increasing the effective mass, affected the entire band, or did not affect it.

Unfortunately, I cannot do this in the form of a legible graph.

It is not clearly visible from the audacity graph.

Both files can be downloaded here.

Concorde_20_przeciwwaga_Ortofon.wav

drive.google.com

Concorde_20_przeciwwaga_Technics.wav

drive.google.com

 

[Thomas_A]

This is what I get from REW, directly imported:

Channel 1:

Channel 2:

 

[Quando]

This is what I get from REW, directly imported:

Channel 1:
View attachment 396773

Channel 2:

View attachment 396774

Thank you

Increasing the effective mass reduces unwanted resonance in the range up to 20 Hz, but does not affect the band from 20Hz to 6.16 kHz
There is a greater discrepancy, a difference between channels in the amplitude level with increased effective mass. Perhaps the reason is purely mechanical.

Interesting........

 

[Thomas_A]

Thank you

Increasing the effective mass reduces unwanted resonance in the range up to 20 Hz, but does not affect the band from 20Hz to 6.16 kHz
There is a greater discrepancy, a difference between channels in the amplitude level with increased effective mass.

Interesting........

If you have some music record you could post the result as well. Music records seldom go below 40 Hz. This is from Suzanne Vega Solitude standing side 2 song 1, two different tonearms.

 

[Quando]

If you have some music record you could post the result as well. Music records seldom go below 40 Hz. This is from Suzanne Vega Solitude standing side 2 song 1, two different tonearms.

View attachment 396776

I have only one music sample Technics 1200GR2 + Ortofon Valencia. (James Last recording from the 1969 album)

T1200GR2_Ortofon_Valencia.wav

drive.google.com

 

[Muddywaters]

If you have some music record you could post the result as well. Music records seldom go below 40 Hz. This is from Suzanne Vega Solitude standing side 2 song 1, two different tonearms.

View attachment 396776

I need to test my DP8 like this sometime. Don’t really want to pull the AT 155LC off it though. ‘Spose I could pull the stylus and pop it on one of my other AT’s and test on a couple other arms. Thanks for the idea!

 

[Thomas_A]

I need to test my DP8 like this sometime. Don’t really want to pull the AT 155LC off it though. ‘Spose I could pull the stylus and pop it on one of my other AT’s and test on a couple other arms. Thanks for the idea!

The good thing is the damped response in the lateral direction. Right now I have the Shure brush so I get both lateral and vertical damping, but I am getting a bit hesitant to use the vertical damping. While it damps the resonant hump, it also cause a more shallow slope below resonance where most of the warp energy is. Perhaps Moerch is correct about this; damping in the vertical direction seldom beneficial and is not recommended. I'll do some more testing regarding this.

 

[Quando]

Operation of the electronic system for suppressing unwanted resonance in the Denon DP-67 turntable - Straight arm tube
Cartridge: Ortofon Valencia,
Needle pressure: 2.5 grams
Electronic anti-skating: 2.5
The manufacturer recommends setting Q-Damping to the same value as the needle pressure.
Test, at Q=0, Q=1, Q=2, Q=2.5, Q=3

HiFi News test Record, Side B, Track 7

Files for downloads:

Q 2.5.wav

drive.google.com

Q_0.wav

drive.google.com

Q_1.wav

drive.google.com

Q_2.wav

drive.google.com

Q_3.wav

drive.google.com

darmowy adres www

 

[morillon]

The good thing is the damped response in the lateral direction. Right now I have the Shure brush so I get both lateral and vertical damping, but I am getting a bit hesitant to use the vertical damping. While it damps the resonant hump, it also cause a more shallow slope below resonance where most of the warp energy is. Perhaps Moerch is correct about this; damping in the vertical direction seldom beneficial and is not recommended. I'll do some more testing regarding this.

the fairly classic damping "from the time before", by "vertical pallet" in silicone worked essentially laterally.... seem to me... ;-)

 

[narud]

so does the 8-12hz recommendation need to be bothered with? if im understanding this correctly, raising the effective mass is lowering the frequency of the peak but also lowering the amplitude and lowering the amplitude of the resonance in beneficial? so, with a high compliance cart like my at33ptg/ii thats mounted on a technics arm, i could see a reduction in resonance amplitude with a heavier headshell? ive got all my carts mounted on stock 7g technics headshells.

 

[Balle Clorin]

https://www.audiosciencereview.com/forum/index.php?attachments/1720193716688-png.379187/

Damping is both good and bad, lowers the peak but a shallower roll off means “more “warps may trigger resonance, according to conventional wisdom.

What the resonance does to the music is to add intermodulation distortion ( seen as sidebands on a single tone) and wow and flutter, a wavery unstable sense to a tone,like light vibrato.

Listen to the music when the record passes a warp… is it affected or not.
A warp is not just at one frequency, a bump contains a series of frequency, so it will most likely trigger a resonance whatever Hz value it has. So I think maybe keeping the resonance peaking low in magnitude is more important than the Hz point it is at?

 

[Quando]

so does the 8-12hz recommendation need to be bothered with? if im understanding this correctly, raising the effective mass is lowering the frequency of the peak but also lowering the amplitude and lowering the amplitude of the resonance in beneficial? so, with a high compliance cart like my at33ptg/ii thats mounted on a technics arm, i could see a reduction in resonance amplitude with a heavier headshell? ive got all my carts mounted on stock 7g technics headshells.

This seems to be true.

Increasing the effective mass will reduce the amplitude of the unwanted resonance, as the measurements show.

It is best to measure your system yourself.

In my experience, increased effective mass reduces the amplitude of resonance, however, sometimes it reduces it a lot, and sometimes it reduces it minimally.

The question is whether increased effective mass will not affect, in the long run, faster wear of the suspension parameters of the bracket?