Introducing the Phono Cartridge Measurement Library

[Ragnarsson]

I need to edit my previous post, but the Edit command disappeared. Does anyone knows why and how to fix this?

 

[JP]

It’s time-limited unless you’re a forum donor.

 

[Ragnarsson]

So a stupid mistake will last...

 

[JP]

You can ask a mod to change it, or ask them to delete the post so you can post another with the changes you want.

 

[JP]

Ortofon Super OM 40
This was acquired new from thakker.eu around a year ago. For an exact date, ask @Thomas_A

As the recommend load range is 200-400pF, I started right in the middle at 305pF:

Not horrible, but not great. Wish the response deviations at the extremes were less, and the behavior above 15kHz looks like a monster resonance right around 20kHz. Perhaps later I'll add some plots up to 50kHz to see what's going on there.

These are filtered plots (for readability) of various loads, using the right channel as it was the hottest showing both channels as they vary so much:

And at 30K/305pF, as that's what looked the most reasonable:

EDIT: Added 55pF to Cload plot and 43K/155pF to RCload plot.

 

[Balle Clorin]

Many thank, now I do not need to buy that one! .. How well does it track the Ortofon test record?

 

[Thomas_A]

Ortofon Super OM 40
This was acquired new from thakker.eu around a year ago. For an exact date, ask @Thomas_A

As the recommend load range is 200-400pF, I started right in the middle at 305pF:


View attachment 427942

Not horrible, but not great. Wish the response deviations at the extremes were less, and the behavior above 15kHz looks like a monster resonance right around 20kHz. Perhaps later I'll add some plots up to 50kHz to see what's going on there.

These are filtered plots (for readability) of various loads, using the right channel as it was the hottest:


View attachment 427943

View attachment 427944


And at 30K/305pF, as that's what looked the most reasonable:

View attachment 427945

Thanks for this. Just to mention that the Swedish Audio-Technical Society recommended 195 pF/42 kOhm for the Super OM40 to get a linear response. Interested in the OM30 with 150 pF and 40k.

 

[JP]

From the data I have, can’t see that 195pF and 42k would get us anywhere near that goal. Maybe very low Cl like 50pF would get us nearly flat to around 15kHz.

I noticed your 2023 measurements were very different to my example. Do we know why?

 

[Thomas_A]

From the data I have, can’t see that 195pF and 42k would get us anywhere near that goal. Maybe very low Cl like 50pF would get us nearly flat to around 15kHz.

I noticed your 2023 measurements were very different to my example. Do we know why?

I had a rise as welll in the top end at 140 pF/47k. Lowereing R to 35-40 would probably do it. The OM10 is even more hot. Perhaps some slight individual differences exists.

 

[JP]

Looks like the shape of the curve is markedly different - more so than is typically seen from unit variation. Do we know what test record SATS used?

 

[JP]

Many thank, now I do not need to buy that one! .. How well does it track the Ortofon test record?

No idea. I've the OM and Super OM bodies both mounted on 8g arms, and will just swap the four styli between them. At the very end I'll likely mount the second bodies (I've two each) and see what the unit variation is. I'll edit the measurement posts to include LCR values as well.

 

[Thomas_A]

Looks like the shape of the curve is markedly different - more so than is typically seen from unit variation. Do we know what test record SATS used?

I think Ingvar Oehman used the JVC TRS-1007. At the time, paper printers were used. 147 pF and 50 kOhm showed a rising top end, reducing it to 42.8 kOhm gave a more linear response. This was done many years ago though.

 

[JP]

Hmm. Looking like a generator change, perhaps. If anyone has a body that is from that time frame, that could be interesting.

 

[Thomas_A]

Hmm. Looking like a generator change, perhaps. If anyone has a body that is from that time frame, that could be interesting.

Not sure about that when I look at your results. Can you test 100-150 pF/43k? (Noted that I remembered wrong. Not 195 pF but 147 pF as in the article).

 

[JP]

Updated both load plots. 47k/55pF isn't too far from 43k/155pF. If we consider the HF behavior of the left channel, either one of those could be reasonably flat. So nod to @Thomas_A that it's likely unit variation. Color me unimpressed.

EDIT - plotted both channels since they vary so much.

 

[USER]

Updated both load plots. 47k/55pF isn't too far from 43k/155pF. If we consider the HF behavior of the left channel, either one of those could be reasonably flat. So nod to @Thomas_A that it's likely unit variation. Color me unimpressed.

EDIT - plotted both channels since they vary so much.

Any way to get some pictures of the stylus tip? Perhaps we will find bad setting, off cut, or other issues that could be illuminating. But, yeah, Ortofon is one of my least favorite cartridge manufacturers. I don't think I have ever been impressed. They are still living off their emphasis on higher compliance in the 1970s, though the others caught up quick and surpassed them. Audio-Technica every day of the week.

 

[Thomas_A]

Updated both load plots. 47k/55pF isn't too far from 43k/155pF. If we consider the HF behavior of the left channel, either one of those could be reasonably flat. So nod to @Thomas_A that it's likely unit variation. Color me unimpressed.

EDIT - plotted both channels since they vary so much.

The high-Q resonance just below 20 kHz gives a dip and peak in L/R respectively. My OM40 just gave a dip. Phase of crosstalk signal is the most likely reason; in my case both out-of phase, in yours one in phase and the other out of phase.

Edit. Probably not...since this is single channel measurements...

 

[JP]

No idea. Anyway, seems that around 47k/55pF, 43k/155pF, or 30k/305pF could all be reasonable loads depending on the variability of a given example.

 

[Thomas_A]

No idea. Anyway, seems that around 47k/55pF, 43k/155pF, or 30k/305pF could all be reasonable loads depending on the variability of a given example.

Try the OM10-20-30 stylii. The divergent HF response L/R may indicate a stylus/suspension issue.

 

[JP]

Ya -that's almost assuredly a suspension issue.