Introducing the Phono Cartridge Measurement Library

[Jimi Floyd]

So if I understand it:
Using 3 records to raise the tonearm angle causing cantilever change ≈26° to ≈24.8° -> within a dB change of x-talk
Using a shim between head shell and cartridge, cantilever change ≈26° to ≈24.5° -> 8 dB change in x-talk

The only other thing that I know of will change is the arm pivot point vs the record surface and COG. I have no idea how much it will affect tracking force during friction but I suspect it is very small.

You right, this strange.

 

[sqrl]

So if I understand it:
Using 3 records to raise the tonearm angle causing cantilever change ≈26° to ≈24.8° -> within a dB change of x-talk
Using a shim between head shell and cartridge, cantilever change ≈26° to ≈24.5° -> 8 dB change in x-talk

The only other thing that I know of will change is the arm pivot point vs the record surface and COG. I have no idea how much it will affect tracking force during friction but I suspect it is very small.

Not quite. Using 3 records to raise the tonearm angle, causing cantilever change from an unknown angle to a 1.2° lower unknown cantilever angle.

However, it's true, I can't exclude alignment vs VTA as the explanation, as you have to unmount and remount the cartridge to shim it.

It's also not an easy cartridge to align due to the soft damper. If anything is slightly off, the cantilever deviates to one side as it lands.

I aligned it using a single point protractor (Smartractor) and USB microscope. 1. Check the cantilever is straight on the cartridge (so it aligns with the arrow at the front). 2. Align the protractor in the viewfinder with an extended depth of field image (left image). 3. Draw a line (blue) in the viewfinder along the alignment. 4. Align the cartridge so the arrow, cantilever and stylus align along the drawn line (right image). 5. Rotate the platter slightly so the stylus lands on a flat area (Smartractor has a dimple), doesn't deviate as it lands and still aligns with the drawn line.

To test a hypothesis that VTA affects channel separation, you'd need to randomize mounting it with or without the shim several times and record sweeps for each. It would be hard to eliminate bias though. You'd want an independent assessment of alignment, to show it doesn't differ between conditions, but you can't blind the assessor, because the cantilever is more visible with the shim than without. I'm lucky it isn't my job to design and run this experiment!

 

[Erogen]

Some Nagaoka MP-700 measurements, around 25 hours use.

Cartridge DC Resistance: 820 Ω
Inductance: 738 mH

View attachment 514685


The angle of the cantilever to the microridge is ~115°, averaged across several measurements.

View attachment 514688

With the headshell level, the angle of the cantilever to a record was 26° at a VTF of 1.4g and VTA at somewhere around 31-33°, not knowing exactly where the pivot point lies (the specified VTA is 30°). Shimming the headshell by 2° would give a VTA of ~30° and static SRA of ~91°. However, only 1.5° is doable without the rear of the cartridge bottoming out. As a result :-

Frequency sweeps done at cantilever angles of 26° and 24.5°.
Measured capacitance: TT leads/connections, 20 pF; phono cable 20pF (1 ft Blue Jeans Cable LC1); phono stage 110 pF. 12g effective mass tonearm and 0.2g nylon fasteners.

Results at 26°
View attachment 514695
View attachment 514697


View attachment 514698

Results at 24.5°

View attachment 514699
View attachment 514700
View attachment 514701
View attachment 514704
Limitations are (1) not at the specified loading capacitance for the cartridge, (2) Clearaudio TRS-1007 is slightly off centre and mildy warped, STR-130 is slightly warped, QR 2010 is mildly warped (and cut at 20°); (3) although demonstrated by Nagaoka with a Technics tonearm and a heavy headshell, the high compliance is better suited to a low mass or damped tonearm.

The main finding was that channel separation improves from a below spec 29 dB with the cartridge set level, to 37 dB with the rear shimmed down by 1.5°, to a cantilever angle of 24.5°.

The resonance for this example is at 9,100 Hz and was unaltered at ±1.5 dB by any set-up changes. However, it is fairly narrow, harmonic distortion not obviously affected and the frequency response was otherwise flat in my audible range (to 14-15 kHz).

My assumption is that the resonance is a transitional phase in a dual control system (soft damper and suspension wire), and is an intrinsic feature of the design.

Set-up would be simplified with a stylus with a cantilever angle of 23-24°. For music, I'm using a rumble filter and low pass HF filter.

Here's the cartridge directly into the ADI 2/4 RIAA stage, 190 pF total capacitance.

View attachment 514715

I'm very sorry, but this copy seems to be faulty.

 

[Thomas_A]

I'm very sorry, but this copy seems to be faulty.

Why? All of the measured ones so far look the same.

 

[Erogen]

Why? All of the measured ones so far look the same.

A collapse in frequency response indicates either a defective unit or a faulty design. I would return this unit to the seller.

 

[Thomas_A]

A collapse in frequency response indicates either a defective unit or a faulty design. I would return this unit to the seller.

View attachment 514847

I would like Nagaoka to answer this issue, but so far there are three different units showing the same glitch. Design issue or just a coincidence that three different units are faulty?

 

[Erogen]

I would like Nagaoka to answer this issue, but so far there are three different units showing the same glitch. Design issue or just a coincidence that three different units are faulty?

Perhaps a faulty batch? We don't know what caused this defect. It shouldn't be like this.

 

[Thomas_A]

Perhaps a faulty batch? We don't know what caused this defect. It shouldn't be like this.

Maybe. Only Nagaoka would know.

 

[sqrl]

A collapse in frequency response indicates either a defective unit or a faulty design. I would return this unit to the seller.

View attachment 514847

The aim of the design was :-

"This cart also incorporates the softest damper .. while this can often lead to questions about instability, Nagaoka points out that the MP-700 addresses those concerns with a newly integrated suspension wire in the pivot system as a countermeasure. That suspension wire effectively controls the movement of both the cantilever and stylus, providing stability while preserving enhanced clarity, particularly in the treble range. As a result, Nagaoka adds, this feature “improves separation, increases clarity across all frequencies, and ensures accurate representation of bass tones and timbre.”

This one has ±0.5 dB channel balance, channel separation >30 dB from 200 Hz to ~8,000 Hz, good distortion figures and is flat ±1 dB from 20 - 14,000 Hz with the exception of a ±1.5 dB blip at ~9 kHz (~12 kHz in other examples), with channel separation still 20 dB.

The blip has an adjacent rise and drop in SPL. The Phono Cartridge Response Script is smoothed. Here is the 9 kHz blip in REW at 1/48th smoothing.

And here it is with Psychoacoustic smoothing.

While it stands out as an unusual feature in a zoomed plot and I had the same "what the hell" reaction when I saw it, on reflection I decided for myself that it is just an unexpected feature and the cartridge still performs well. Subjectively it sounds excellent.

I don't think it amounts to a "collapse in frequency response" faulty cartridge or faulty design and I don't plan to return it.

 

[JP]

The Phono Cartridge Response Script is smoothed.

Not really, at least in the common meaning. There's a very minor data smoothing filter to deal with true artifacts, however disabling it doesn't change the output in any meaningful way.

 

[sqrl]

Quite an impressive crosstalk figure. I wonder if you have tested its sibilance performance?

Thanks Thomas_A. Did you have some specific tests in mind? From the point of view of test records, I ordered a Flatten-It in October and it may arrive in late March (as a comfort to people who ordered Ascilab speakers). Even "minty" test records seem to accumulate warps over the decades.

Subjectively, I have played some JJ Cale, who sang quietly and close to the mic, and it sounds like he sang naturally in terms of sibilance compared with the CDs, which are a bit harsh. Whether that is subjective bias or different mastering, who knows?

 

[sqrl]

Not really, at least in the common meaning. There's a very minor data smoothing filter to deal with true artifacts, however disabling it doesn't change the output in any meaningful way.

My bad, I misinterpreted the meaning of #1,539. I should just have said that smoothing the adjacent rise and fall may mitigate them.

 

[JP]

mdB impact. There’s obviously no visible smoothing of sharp changes.

 

[sqrl]

mdB impact. There’s obviously no visible smoothing of sharp changes.

Sorry if I sidetracked this into a discussion of the script, which is fantastic. I brought up psychoacoustic smoothing to make the point that what looks dramatic visually won't sound dramatic listening to music. My fault for making it poorly. For example, the shift is less marked than sharp changes measured in well-liked and -reviewed headphones, e.g. here and here.

 

[Thomas_A]

Thanks Thomas_A. Did you have some specific tests in mind? From the point of view of test records, I ordered a Flatten-It in October and it may arrive in late March (as a comfort to people who ordered Ascilab speakers). Even "minty" test records seem to accumulate warps over the decades.

Subjectively, I have played some JJ Cale, who sang quietly and close to the mic, and it sounds like he sang naturally in terms of sibilance compared with the CDs, which are a bit harsh. Whether that is subjective bias or different mastering, who knows?

I was thinking of this kind of test

Introducing the Phono Cartridge Measurement Library

Nagaoka MP-700 This is certainly a strange one: Here is a measurement of the MP-500 stylus on the MP-700 body: Very similar to the MP-500 body, so the issue seems to be with the MP-700 cantilever assembly. It is interesting that they were able to bring down 2nd harmonic distortion so much...

www.audiosciencereview.com

 

[Erogen]

I don't think it amounts to a "collapse in frequency response" faulty cartridge or faulty design and I don't plan to return it.

Nagaoka customers have a high tolerance for product defects.

 

[Balle Clorin]

@sqrl But please send the test data of this Nagaoka to Nagaoka so they know we know,, maybe they will correct it so other customers will not get more cartridges of this “quality “. Some of the high end Nags here do not show this behaviour . This indicates faulty samples

 

[mackat]

This is what was relayed to me by a distributor who asked Nagaoka about the mesurements:

"I have to say, the dip at 10kHz is the character of MP-700.

It comes from the damper, we use the softest one ( even softer than MP-500) on MP-700 to get the sound performance, but also brings the dip around 10kHz.

This is the only reason."

 

[Balle Clorin]

Hmm, so this means no Nagaoka for me then, this thread just saved me 1500usd

 

[Erogen]

Hmm, so this means no Nagaoka for me then, this thread just saved me 1500usd

Well, that makes two of us who won't buy it