Phono Cartridge Response Measurement Script

[GuidoK]

So you've seen this statement directly from Jico? Where?

Sorry, no. I believe soundsmith (Peter Ledermann) said that somewhere on his site.
But again also not with info how to measure etc, so not really useful info.

But the point I tried to make is that when trying to research distortion in relation to stylus wear, one has to make a good assesment on how much distortion is expected at the intervals that are going to be measured for choosing which method to measure that is to be used.

 

[JP]

Sorry I was searching for the "hours" recommendation as in the past I know I saw the hours and method on the same web page. In the past JICO had another page that spelled out the "hours of life" for the different tip configurations and on that page they mentioned 3% distortion at what I remember to be 10 Khz .... could have been 15 Khz but not what I remember. It appears this page is not longer available but the "hours" recommendations still remain. I guess I could try "go back" to find the old page but not right now.

I can't find any evidence that anything outside of hours ever existed. Not that it's fool proof, but I've searched their sites (at least three, maybe four) on Internet Archive back to the beginning of time. They've listed hours since their early days, but not a single mention of a test frequency or distortion metric. Ditto for the typical audio forums - not shortage of people parroting the "criteria" but also nothing outside of anecdote.

IIRC it was this thread: https://www.vinylengine.com/turntable_forum/viewtopic.php?f=19&t=34521&hilit=jico+15khz+3%+thd but there may be another as well. LD's posts were on point, if you can decipher which were his.

I've not read through recently as my brain isn't compatible with mostly content free walls of text.

Sorry, no. I believe soundsmith (Peter Ledermann) said that somewhere on his site.

Yes, he does, and it's a wonder why.

 

[Thomas_A]

That’s what I was thinking - he didn’t use the RIAA network module for half-speed.

Coming back to this, do you know what the differences are at half-speed? It looks as if the usual corrections needs to be applied twice for the Ortofon but I have not tested it.

 

[JP]

Not off the top of my head. He did comment on what the error was later in the thread - it wasn’t exactly that but it was an EQ error related to half-speed cut.

 

[Thomas_A]

Not off the top of my head. He did comment on what the error was later in the thread - it wasn’t exactly that but it was an EQ error related to half-speed cut.

I recall there were time-constants for RIAA at 96 kHz for Audacity discussed in one thread. I wanted to try something. Will do a search and see if I come up with something.

 

[JP]

Phono Cartridge Response Measurement Script

This thread is intended to consolidate the technical discussion and further development of Scott Wurcer's frequency response measurement script to a central area. I'd like to keep this discussion about the tool rather than specific cartridges. Measurement Library thread is here. Usage info is...

www.audiosciencereview.com

 

[JP]

Baller. One whole session yesterday - no issues.

 

[JP]

Beta advanced config option added that allows most of the functionality of the standalone script aside from saving extracted sweeps and output data. STR 100 and XG-7001 correction settings omitted as the script derives those from the test record selection. Everything there works except 1kHz start and end f. I want to amend those to a frequency range for greater flexibility.

Bit rough on the UI.

@Balle Clorin

 

[JP]

I *think* advanced mode is done... unless someone finds bugs. I haven't tested very thoroughly.

• I changed everything to drop-downs or text fields and removed the checkboxes for a cleaner look.
• onekfstart functionality has been replaced with Start Frequency, so you can now just choose a start and end frequency range to plot. Depending what you choose there may be plot scaling issues.
• file0norm is now called Normalization Mode, and the choices are Relative (default) or Absolute. Hopefully this nomenclature makes a bit more sense to folks.
• The File 1 area has a "clear file" button. This is so a single file can be processed without having to reload the page to clear the input.

For both standard and advanced, the plot download button has been moved to the top right of the plot, and I've added a copy button as well.

The only item on my to-do at the moment is to add the ability to download the plot data as a CSV.

 

[Thomas_A]

Phono Cartridge Response Measurement Script

This thread is intended to consolidate the technical discussion and further development of Scott Wurcer's frequency response measurement script to a central area. I'd like to keep this discussion about the tool rather than specific cartridges. Measurement Library thread is here. Usage info is...

www.audiosciencereview.com

Hm, what is the function for the TRS1007 slope to get it linear (the low fr part) ? Admit I am bit novice with these biquad functions.

 

[Thomas_A]

Perhaps.

Original, not corrected.

 

[JP]

If recorded flat its bass only. If recorded with RIAA its treble only with inverse true.

 

[Thomas_A]

If recorded flat its bass only. If recorded with RIAA its treble only with inverse true.

Yes,. I don't really understand what I just did, but just used the below at the Nyquist prompt twice for the Ortofon sweep and ran the script. It affected the lows only, odd?

(biquad-m *track* 9.08612614639649000E-01 -5.22931473883012000E-01 -3.44913691685509000E-01 1.00000000000000000E+00 -6.04500910000000000E-01 -3.90945930000000000E-01)

 

[JP]

That's right: roll-off and Shelf (50.05Hz and 500.5Hz). Running it twice - that's to straighten out the cutting mistake? I can't remember specifically what Flo said the error was.

 

[Thomas_A]

That's right: roll-off and Shelf (50.05Hz and 500.5Hz). Running it twice - that's to straighten out the cutting mistake? I can't remember specifically what Flo said the error was.

He did not say specifically what was wrong, other that RIAA was not correctly set for half-speed, as far as I recall. I just made a guess.

 

[JP]

Hello,
it turned out a bit more complex than expected. I used the half-speed switch on my RIAA encoder cards (which doubles all time constants) when cutting that test record, but then also applied RIAA-off. (That means the upper part of the RIAA curve is flat — the lower part can never be disabled, otherwise the excursion would be far too large.) That combination produced the strange effect: the bass was off. that was out of focus at the time , purpose was more to check the higher frequencies as up to 10k all is easy and flat.

But no worries — I’ll make a proper version for this purpose. If you have other suggestions for what might be useful, I can probably implement them. For me, at least one side will definitely be cut with a true mono head. It would be nice to have reference levels in true mono, and also sweeps — though I can’t yet say what the upper limit will be, since these mono heads are much more fragile compared to my contemporary stereo heads.

 

[JP]

Not trying to wrap my head around it at the moment, but my gut is you're on the right track. Looking back at old plots, if bass EQ was applied to a flat layback what remained to 5kHz follows what one would see from plotting a flat layback of a record that was cut with bass EQ.

 

[Thomas_A]

Unfortunately, I can't translate Flo's error and if it is an error and what it means in correction terms. Using the half-speed switch should give correct values if it is recorded in half-speed, should it not? I just made a guess that it needs 2x RIAA correction in bass.

 

[JP]

I believe so, but he also applied RIAA-off - not sure if that disables half the EQ, or applies a treble cut correction, or if that is supported for half speed where the time constants are doubled. As he says it was part of the issue I'd imagine it doesn't simply disable the treble boost.

 

[Thomas_A]

At least there is something that looks very reasonable, and can be done with Nyquist prompt in Audacity. Whether it is possible to include as a "Ortofon/Flokason test record" option in the script is another question though. This is a test LP still in production and is useful to check the HF resonance and loading with more extension. .