Phono Cartridge Response Measurement Script

[mattking52]

Famous last words. Thanks @mattking52 for the assist.

Happy to help! Hopefully we can add some more functionality as well.

 

[Balle Clorin]

What is the hardware setup for this? Any old turntable/alignment of the cartridge will do???

An ideal partner if you have MC cart (puffin has only one MM loading , MC has no loading issues) is Parks Audio Puffin with optical out and an optical-USB converter into PC. By using the Puffin selectable eq 500R-0 it makes the constant velocity tracks( no treble emphasis -but bass turnover -as on TRS-1007 and many other test records ) linear. The script seems to work well on my full range sweeps of TRS-1007 , BK QR2010 using EQ «500R-0». I still use the script from the original thread….and modified the frequency range myself….

I should get the newest 1hz version I guess

 

[JP]

By using the Puffin selectable eq 500R-0 it makes the constant velocity tracks( no treble emphasis -but bass turnover -as on TRS-1007 and many other test records ) linear. The script seems to work well on my full range sweeps of TRS-1007 , BK QR2010 using EQ «500R-0».

Next version can do compensation for the popular test record characteristics. One of the primary objectives of this batch of work is to make it independent of electronics and reduce pre-processing work.

 

[JP]

Here's a test version of the improvements:

• Full range plots
• STR 100 compensation
• RIAA roll-off and shelf, 10kHz attenuation, or both, along with the ability to invert all three

I've not done any rigorous validation of the plot amplitudes though they seem to check out. The distortion axes in the LF are a bit suspicious at times, though it may just be because I've not seen much of that data before.

This is for test only - I wouldn't be taking it for gospel just yet. More work to do but it'll be awhile before I can get back to it.

EDIT: Post #3 contains the latest alpha/beta code.

Sample:

 

[USER]

I tested a working version of the script and CBS test record with a wide variety of cartridges, MC, MM, $11 special, one with a bent cantilever, one supposedly incompatible with my tonearm, V15VMR. Basically, I tried to throw the book at them. I figured I would share some early results for the sake of curiosity.

NOTE: THESE ARE ONLY FOR TESTING PURPOSES.

I think that they can show why the initial script--rightfully--started at 1000Hz. Simply, as was reasoned, cartridges behave similarly below 1000Hz. The differences here are less than 0.5 dB in most cases. The hump from around 200-800Hz is due to the CBS test record (and, as in my previous measurements, the switch at 5kHz and messiness around 17kHz is also the test record). Differences below 50Hz may have to do with tonearm influence. (I will be testing Denon's classic Dynamic Servo tonearm to see if it helps with resonances if I can. This record may not go low enough to show anything conclusive.) The one that stands out belongs to a beloved line of cartridges. I want to confirm that result by testing a second cartridge but it seems to make sense to me. (Their headphones are also weird.)

 

[Balle Clorin]

Weird cartridges and headogones? Must be Grado
Beloved? Maybe not Grado then , AT? But mine look good.. Iwill be watching this space

 

[USER]

Weird cartridges and headogones? Must be Grado
Beloved? Maybe not Grado then , AT? But mine look good.. Iwill be watching this space

You are wrong...is what I would say if you were wrong, but you're not.

People do still love those cartridges. You know old vinyl audiophiles, they love outlier frequency responses because they get to make things up to say about them.


Added one more for fun. Another well-liked cartridge. I'll post details when we start a proper cartridge measurement thread once the new script is ready. I'll have close to 50 to share.

 

[JP]

Needed to clear the brain a bit today so started working on another feature. @al2002

 

[USER]

Needed to clear the brain a bit today so starting working on another feature. @al2002

View attachment 259415

I was hoping you'd go there. Didn't want to add more to your pile, however.

This one is tricky as it really depends on proper set-up. (And even perhaps a separate test record to confirm results.) It could muddy things up. I find frequency response to be extremely forgiving of imperfect set-up. I am not sure how much I would trust other people's crosstalk measurements (or my own early ones of cartridges I no longer have around). It's relatively easy to exaggerate or degrade channel performance if a cartridge is not set-up perfectly. Some folks may not have the tools or tonearm for that. That said, I would trust JP's results, his TRS-1007 seems like a solid test record for it, and the spirit of this endeavor is to do it right.

Would love to hear thoughts on this matter.

 

[Balle Clorin]

Yes a good crosstalk test record is hard to find, I have seen the recent Ortofon test record perform well on Youtube (Parks audio Puffin crosstalk demo +30db) while my copy is much worse than others like Ultimate Audio. I found it hard to deceid which one to trust for my azimuth adjustment.

Same cartridge and setup measured the same day... EDIT: green line added

EQ 500R-0 is to linearize the TRS-1007 constant velocity chacacterisic above 1000Hz

 

[JP]

Yes, crosstalk can be all over the place. I don't typically pay much attention to it unless it's off enough to be audibly detrimental, and that means it's a bad stylus 99/100 times.

 

[Balle Clorin]

I the plot above L to R only?, would be nice to have crosstalk both ways L>R and R>L

 

[JP]

L/R to show difference between test records.

 

[levimax]

L/R to show difference between test records.

So which one is right? How can you tell?

 

[JP]

So which one is right? How can you tell?

The record that shows the biggest difference. A record can only limit this measurement but can't make it better than it is.

 

[Balle Clorin]

That is why I like to see the crosstalk both ways Left to Righ and Right to Left
My staring point before Azimuth adjustment

END of sidetrack

 

[USER]

Yes, crosstalk can be all over the place. I don't typically pay much attention to it unless it's off enough to be audibly detrimental, and that means it's a bad stylus 99/100 times.

If I am reading this correctly, and the same cartridge is being used, then it appears that CBS test record is no good for crosstalk measurements.

Would the best course be to have crosstalk as an selectable option?

And is the difference between the test records really what is <80Hz and 0.5dB-1dB from around 5k and 9k? If so, that's remarkable! Do you have a zoomed in view that you can share?

As far as left and right channel comparisons go, how does the JVC-1007 fare? The CBS record seems to have a modest discrepancy.

 

[JP]

BUT... if you look at the plot I messaged you where the only difference is the stylus....

It crosses the line from being as fool-proof a measurement method as possible. Handy info in the right hands, or rather useless if not.

 

[USER]

BUT... if you look at the plot I messaged you where the only difference is the stylus....

It crosses the line from being as fool-proof a measurement method as possible. Handy info in the right hands, or rather useless if not.

View attachment 259684

This is why I try to provide as much context as possible. How do the cartridges compare in inductance, for example. I rarely even get L & R channels to match in a single cartridge. I have seen wild variations, and certainly from spec.

From what I have seen, spec is supposed to be 450mH. Mine measured L: 347mH, R: 354mH, 98%. Granted, I don't know how they measured it.

Here are different comparable bodies with that same stylus you used. The second body is closer to that 450mH and looks more like what you got.

Edit: I see that you said only difference is stylus. That complicates my argument. But even I had different results with the same MLX body and old and NOS stylus. I also tried about 10 different VN5MR styli and a few stood out. Link to comparison. That's part of the game it seems. Par for the course with this medium.

 

[USER]

Also, congrats on that comparison tool you just introduced.