Ortofon ST-70 Moving Coil Transformer Review

[mike70]

It practically is. Outside of possible phono stage issues I’ve never seen any data put forward that LOMC carts are load sensitive. Even in pathological scenarios where the load resistance is 5x lower than cartridge DCR the only change was output level.

But ... isn't a real physics effect? I mean, resistive load changes the MC cartridge response ... or all the literature about it is wrong?

 

[sergeauckland]

But ... isn't a real physics effect? I mean, resistive load changes the MC cartridge response ... or all the literature about it is wrong?

View attachment 462739

I'd like to know what cartridge that is. I can't see why a change in resistance would affect HF response to that extent, given the low inductance of LOMC cartridges. I find it significant that it takes 1.5uF of capacitance, a huge amount, to flatten the HF response. It strikes me that what it's flattening is the HF resonance, possibly even the stylus/vinyl compliance resonance rather than the cartridge's own resonance.

In other words, more information needed.

S

 

[JP]

But ... isn't a real physics effect? I mean, resistive load changes the MC cartridge response ... or all the literature about it is wrong?

View attachment 462739

All the literature? What all? You're showing graphs lifted from the marketing material of a boutique manufacturer. No disclosure of what was tested, what the test setup was, etc. The R figures don't make sense for a competent active stage, and the C figures are downright pathological.

Actual measurements of Rl changes are at the bottom of this post.

 

[mike70]

All the literature? What all? You're showing graphs lifted from the marketing material of a boutique manufacturer. No disclosure of what was tested, what the test setup was, etc. The R figures don't make sense for a competent active stage, and the C figures are downright pathological.

Actual measurements of Rl changes are at the bottom of this post.

Well, I had the opposite experience
Maybe there's something more to check in the test (yours or mine), you used active headamp (I think), as an example.

 

[JP]

So you have measurements that can be duplicated?

 

[Newman]

Maybe his sighted knowledge of those graphs he posted led him by the nose to 'experience' those curves in sighted listening 'tests'. Happens all the time!

 

[mike70]

I don't know how to do measurements, I made ABX tests with digitalizations.
And a little respect is something that generally comes with more wisdom and age ... so, I think I already said / saw enough. Continue with your great exposure, I'll listen to some music.

 

[JP]

Share the files, controls, and details of the test setup.

 

[Sokel]

I don't know how to do measurements, I made ABX tests with digitalizations.
And a little respect is something that generally comes with more wisdom and age ... so, I think I already said / saw enough. Continue with your great exposure, I'll listen to some music.

It's easy to compare the digitized files if you're willing to share parts of them.
Deltawave them and see the results.

(I can do it too if you post some (same part) segments )

 

[JP]

DeltaWave doesn’t work well with vinyl due to the speed irregularities.

 

[Sokel]

DeltaWave doesn’t work well with vinyl due to the speed irregularities.

Yes, but here we don't search small details as the effect is audible as claimed.

The spectrum differences alone could show if something is going on.

 

[Sokel]

DeltaWave doesn’t work well with vinyl due to the speed irregularities.

Here's an example.
"True Love Waits" by Radiohead, Blue trace is original flac, Red trace is its LP digitized copy through LOMC at 24-bit/96kHz:


original spectrum



matched spectrum

Not much of a difference.

(strangely this strange spike up high at the original flac got ironed out a little by vinyl playback)

 

[LTig]

Here's an example.
"True Love Waits" by Radiohead, Blue trace is original flac, Red trace is its LP digitized copy through LOMC at 24-bit/96kHz:

View attachment 462962
original spectrum


View attachment 462964
matched spectrum

Not much of a difference.

(strangely this strange spike up high at the original flac got ironed out a little by vinyl playback)

Could you apply aggressive smoothing to both curves so it's easier to see the general tendencies?

 

[Sokel]

Could you apply aggressive smoothing to both curves so it's easier to see the general tendencies?

Can't apply smoothing but what I can do is lower FFT size (from 256k of the above to 16k) to lower accuracy.
Seems like its working.
Same as above, Blue original flac, Red LP digitized at 24-bit/96kHz.



Differences are even smaller with reduced accuracy.

(I have to point out that the sample is minus 20 seconds from start and minus 20 seconds from end, this helps avoiding whatever surface noise may digitization may have caught at the beginning or end)

Edit:

Delta of spectra may be more revealing:

 

[Balle Clorin]

Or just load into REW and take the difference by using trace arithmetic |A|/|B|

 

[Sokel]

Or just load into REW and take the difference by using trace arithmetic |A|/|B|

Like that?
(That's peaks only of course)
Red is flac, Green is LP.

I first aligned SPL at 400Hz which the previous showed small tinny difference and for 5 octaves as the general level difference between the two is big and applied 1/3 smoothing.
Let me know if you want some other view, haven;t closed it yet.

Edit: added magn,

 

[JP]

Here's an example.
"True Love Waits" by Radiohead, Blue trace is original flac, Red trace is its LP digitized copy through LOMC at 24-bit/96kHz:

View attachment 462962
original spectrum


View attachment 462964
matched spectrum

Not much of a difference.

(strangely this strange spike up high at the original flac got ironed out a little by vinyl playback)

Yes, I understand basic spectrum comparisons. In such cases there are a myriad of tools that are more feature rich for spectrum analysis. I love DW for digital sources, and while some of its capability can be utilized for content that simply can't null due to time errors, it's really not the use case for it.

 

[Sokel]

Yes, I understand basic spectrum comparisons. In such cases there are a myriad of tools that are more feature rich for spectrum analysis. I love DW for digital sources, and while some of its capability can be utilized for content that simply can't null due to time errors, it's really not the use case for it.

Sometimes I post charts with the hope others, far more educated and with the proper tools at hand to follow

But, as always...

Regardless, the above Deltawave and REW charts may be far from ideal but do give a picture for differences, @mike70 can take it from here to show us its case.

 

[JP]

I get it, but suggesting a tool for a use case it wasn't intended for without disclosing said limitations or how to navigate them doesn't set someone up for success.

 

[Balle Clorin]

Like that?
(That's peaks only of course)
Red is flac, Green is LP.

View attachment 463001

I first aligned SPL at 400Hz which the previous showed small tinny difference and for 5 octaves as the general level difference between the two is big and applied 1/3 smoothing.
Let me know if you want some other view, haven;t closed it yet.

Edit: added magn,

No, go on the second tab showing all curves and do trace arithmetic as I wrote.
You can adjust the curve level to equal at say 1000hz, and then do subtraction