Introducing the Phono Cartridge Measurement Library

[narud]

Signet TK10ML

this came on a table i just bought. diamond looks like it only has very light use. ridge is still curved and contacts are short. unfortunately too much anti skate was used with the little use it did get. the curve looks the same as the one i measured last year. I sold that one, but am debating keeping this one around to use.

 

[narud]

Nagaoka MP-500

180pf

280pf

just picked up this mp-500 with a claimed 150 or so hours. i dont have a new one to compare it to, but the front view was looking pretty good so i dont think the estimate is too far off.

edit-i just mounted this to a different table connected to another pre so i could test this with another 100pf of capacitance. i think im going to run this at 280pf for a while.

 

[ElectricWarrior]

AT-VM95ML

Just got myself a test record. Looks like I’ll have to take greater care about azimuth. This may be an issue with the headshell. I had tweaked it a little using the play of the headshell in its connector. I guess this might be as good as it gets.
Loads of distortion, too
This is at approx. 200 hours.

 

[Thomas_A]

Something wrong with that measurement. Drop at 20k + high distortion. What's the C of the phono pre?

 

[ElectricWarrior]

180p. + around 70p between the amp and cartridge. I was expecting quite a bit of a roll off.

I guess the distortion may be an amp issue. It's pretty old. Maybe I should get it serviced.

I'm getting similar levels of distortion with a VM95C on a different headshell.

 

[Thomas_A]

Probably cheaper to buy a separate phono pre, unless you can fix it yourself.

 

[JP]

I was expecting quite a bit of a roll off.

Why?

 

[ElectricWarrior]

It's a low pass filter and I'm using more capacitance than recommended
But yeah, I guess it's quite a bit steeper than it should be, even though the resonant peak is not crazy high…

In the meantime, I managed to improve crosstalk quite a bit:

 

[0bs3rv3r]

What are the basic requirements of the test track that needs to be recorded to be used with this script? I am gathering it is a sweep of some kind. 20 to 20Khz? Does it matter how fast the sweep is? Does it need to be stereo, or two mono sweeps, one for each channel separately?

Is there an extended list of test records that work, or is it only the three mentioned in the first post?

 

[JP]

It's a low pass filter and I'm using more capacitance than recommended
But yeah, I guess it's quite a bit steeper than it should be, even though the resonant peak is not crazy high…

In the meantime, I managed to improve crosstalk quite a bit:

View attachment 493635

Well, you've something quite not right. I'd guess your load capacitance is markedly higher than you think it is, but that doesn't explain your distortion measurements.

 

[ElectricWarrior]

Well, you've something quite not right. I'd guess your load capacitance is markedly higher than you think it is, but that doesn't explain your distortion measurements.

View attachment 493638
View attachment 493639

Yeah, -3dB at 20kHz sure is much less dramatic..

I had another look at the preamp's schematic:

I guess I’ll have to add C123 0.001µF = 1000pF to the 180pF.

I'll try to record a sweep without pre-amp later..

 

[ElectricWarrior]

Ok, so the distortion is not caused by the amp. I guess the next suspect is my audio interface.

 

[ElectricWarrior]

Or not. Holy crap.
I tried the C with an E stylus and got much lower distortion. and something funny happening with the right channel's frequency response.

Then I tried the ML again (different cart on a different headshell) and all of a suddeen the distortion is greatly improved. And I have no idea what coud have caused this.

EDIT: I figured it out. I had set the sampling rate to 96kHz for the last sweeps. Exporting the same file at lower sampling rates results in higher distortion readings.

 

[lini]

I guess I’ll have to add C123 0.001µF = 1000pF to the 180pF.

Not really - that would only fully apply to the MC setting.

Greetings from Munich!

Manfred / lini

P.S.: However, it would look like C105 (270 pF) would apply in parallel to C101 (180 pF).


edit: Post scriptum added.

 

[ElectricWarrior]

ah. thanks! That switch is really confusing for me
450pF total sure would be a lot more reasonable. Considering cable and tonearm wiring, I'd end up at 520pF. The simulated electrical response for this is quite close:

 

[JP]

I've toyed with the idea of adding the feature to overlay electrical response on the plots. And ~500pF is more reasonable - your plots definitely didn't look like anything near 1000.

 

[ElectricWarrior]

That could be useful! I recently saw this, which takes the concept one step further: https://www.mvaudiolabs.com/vinyl/cartridge-loading-calculator
apparently this software can calculate frequency responses for different loading setups. The curve their calculator generates looks too dramatic, though..

 

[JP]

That could certainly be simplified rather easily once a good sim model is put together.

 

[Dr.Deadwax]

Shure V15 IV with Jico VN45HE SAS B Stylus

In my experience, it looks fantastic and sounds amazing. The resonant frequency is a bit low at 5-6 Hz, but otherwise I'm very satisfied.

Depending on how cheaply you can get a V15 Type IV, this is probably the best price/performance ratio for linear and distortion-free vinyl playback.

I'd appreciate your opinions on whether there's anything that could be improved.

Cheers

 

[ElectricWarrior]

Interesting, I would have thought the resonant frequency would be higher, as Jico’s suspension is supposed to be less compliant than Shure’s.
Also interesting that the FR is quite flat with that much capacitance. They were spec’d for 200–300pF. With the boron cantilver’s resonance being lower than Shure’s berryllium, I would have expected it to perform at its best at under 200pF. Go figure..