Compliance examined

the thin end of the wedge
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Alec124c41
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Compliance examined

Post by Alec124c41 » 16 Jun 2018 06:11

An informative examination of compliance:
http://korfaudio.com/blog33

Cheers,
Alec

cafe latte
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Re: Compliance examined

Post by cafe latte » 16 Jun 2018 06:23

Very interesting Alec,
Kind of explains why the Kab damper works so well with all carts as there is a lot more going on than we realise.
Chris

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Re: Compliance examined

Post by goatbreath » 16 Jun 2018 06:38

Would that mean if you could damp the vertical compliance only that 50s Mono groove records would play and sound better..So a tonearm could have a feature to improve mono playback..?

Or have I just over simplified things.. :lol:

PS I've just woke up..

DeepEnd
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Re: Compliance examined

Post by DeepEnd » 16 Jun 2018 07:52

Thanks for the link Alec - I even made sense of it!!

It potentially explains some AT spec queries (e.g. AT OC9/iii vs AT OC9ML/iii and ART 7 vs ART 9) which have the same static compliance but very different dynamic. If the suspension material hardens up more with higher frequencies you would get a lower figure.

I might try to show this by checking resonance with pure sine wave, pink noise, white noise and a few “typical” tracks. If I get different res freq then case proven.

Byron4
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Re: Compliance examined

Post by Byron4 » 16 Jun 2018 15:46

great article thanks Alec.

This article cleared up some confusion I had about the way the Japanese measure cartridge compliance. The manufacturer list the Hana EH with a dynamic compliance 10*10-6cm/dyne@100hz. People are estimating the dynamic compliance by using 1.7 to 2 times the dynamic compliance of 10hz to 17-20hz which is totally different from all of the test reports which shows it to be a low compliance cartridge. Turntable guru George Merrill measurements show the resonance frequency to be 11hz with a heavy headshell and tonearm. This translates to a dynamic compliance between 8hz to 9hz @10hz which is even lower than the the dynamic compliance @100hz. According to the article dynamic compliance, when quoted by Japanese manufacturers, means something else entirely. It's a product of a different test, designed to highlight tracking ability of a cartridge and its relationship with downforce. Nothing to do with LF resonance. This would make estimating other Japanese cartridge compliance such as Denon and Audio Technica difficult.

chiz
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Re: Compliance examined

Post by chiz » 16 Jun 2018 18:24

Very interesting Alec, thanks for sharing this.
Byron4 wrote:This article cleared up some confusion I had about the way the Japanese measure cartridge compliance. The manufacturer list the Hana EH with a dynamic compliance 10*10-6cm/dyne@100hz. People are estimating the dynamic compliance by using 1.7 to 2 times the dynamic compliance of 10hz to 17-20hz which is totally different from all of the test reports which shows it to be a low compliance cartridge. Turntable guru George Merrill measurements show the resonance frequency to be 11hz with a heavy headshell and tonearm. This translates to a dynamic compliance between 8hz to 9hz @10hz which is even lower than the the dynamic compliance @100hz. According to the article dynamic compliance, when quoted by Japanese manufacturers, means something else entirely. It's a product of a different test, designed to highlight tracking ability of a cartridge and its relationship with downforce. Nothing to do with LF resonance. This would make estimating other Japanese cartridge compliance such as Denon and Audio Technica difficult.
The common rule of thumb for multiplying compliance at 100Hz by 1.5 to 2 or dividing static compliance by 2 to get an estimate of the compliance at 10Hz did not seem sufficiently reliable to me so I recently did some testing of this theory.

I used cartridges from four different manufacturers who all quote their compliance specs differently.

Here are my results.


Ortofon OM5E
Spec: 20 cu @ 10Hz (lateral)
Measured: 20.6 cu @ 10Hz (lateral)

The first cartridge measures encouragingly close to spec and this seems reasonable to use as a baseline for measuring some examples from other manufacturers.


Denon DL-110
Spec: 8 cu @100Hz
Rule of thumb estimate: 12 to 16 cu @ 10Hz
Measured: 16.7 cu @ 10Hz

Close to the estimate. So far so good.


Audio Technica AT150MLX
Spec: 10 cu @ 100Hz / 40 cu static
Rule of thumb estimate: 15 to 20 cu @ 10Hz
Measured: 24.3 cu @ 10Hz

Not so close to the estimate.


Shure M35X
Spec: 20 cu static
Rule of thumb estimate: 10 cu @ 10Hz
Measured: 13.9 cu @ 10Hz

Even further from the estimate.


Some notes.

All my figures are for lateral compliance. If I find a suitable test record for my method I’ll do some tests for vertical compliance too. I would expect VTF to make a difference to vertical measurements but a brief test did not indicate it made a significant difference to lateral measurements.

My tonearm has no damping mechanism. I would be very interested to examine the effects of variable damping if I had access to suitable hardware.

I realise that mass and effective mass are not the exact same thing but based on some testing with varying the mass of the cartridge / headshell assembly I’m hoping my effective mass figures used for the calculations are accurate to within perhaps 0.5g at worst.

Having now read the article Alec linked to I would have to question my own testing method as the test signal I used to measure resonance is not a pure sine wave as it has a (1kHz?) pilot tone mixed with it. I’ll have to check other test records but don’t think I have any with pure subsonic tones.

Alec124c41
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Re: Compliance examined

Post by Alec124c41 » 16 Jun 2018 18:33

I think the spec on the DL-110 is 15 , not 8.
My take is that published specs can get one in the ballpark, but some tweaking can help fine-tune the sound.

Cheers,
Alec

chiz
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Re: Compliance examined

Post by chiz » 16 Jun 2018 18:57

Alec124c41 wrote:I think the spec on the DL-110 is 15 , not 8.
The manuals here all say 8 @ 100Hz
https://www.vinylengine.com/library/denon/dl-110.shtml
Alec124c41 wrote:My take is that published specs can get one in the ballpark, but some tweaking can help fine-tune the sound.
Agreed but perhaps published specs (if accurate) are most useful before purchase to avoid potential mismatches of equipment.

From discussions here and elsewhere I think many people try to choose arm / cartridge combinations using these published compliance specs.

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Re: Compliance examined

Post by billshurv » 16 Jun 2018 22:49

Whilst they post a lot of interesting stuff on their blogs I think they seriously missed the point in a number of areas on this one. Clearly they didn't read Walton's papers in that AES anthology.

What I agree with
1. There are 3 compliance figures quoted that are separately measured and cannot be converted between however much wishful thinking of rules of thumb there are.
2. horizontal and vertical compliance are different (they knew that in the 50s).

What I have an issue with is:
Compliance in vertical or horizontal planes are not the ones you are really interested in. It's the +/-45 planes as this is where the cartridge is not supported and mistracking* occurs. OK I know this snippet has been forgotten by everyone since the late 50s, but it's still true.

They go into a big song and dance about elastomer non-linearities without looking at how much the suspension actually moves in normal operation. It's only an issue on warps.

They completely ignore the reason for elastomer suspension is to provide damping otherwise all manner of bad things happen. The spring side is just a happy byproduct.

They don't address the audibility of LF resonance. With a PC you can measure resonance using a silent track.

Otherwise a good start and lets see where they go with it.

*If you think about it, mistracking is where the stylus heads up one groove wall and then 'catches air' before coming crashing down again. There are ways to address this. I rather like the way ortofon went with their S-120 cartridge which uses a shaped elastomer to give low compliance in the vertical plane and ended up with a bonded spherical that can track 120um at 315Hz. Not sure what their new concorde line have for that.
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