Phono Cartridge Response Measurement Script

[ariendj]

Well look at that... Seems to work

 

[ariendj]

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.

Well not straigt out of the box. We might be able to get it there, though.

We'd need to first build a test setup with very low crosstalk, preferably with active crosstalk cancelling so that we get more than 40dB of separation, as high a value as possible. We could verify that with the QR2010. Then we'd need to sample the other test discs (starting with STR 100) to find the phase relation of the crosstalk inherent in the test disc. Knowing this we might be able to compensate for the inherent crosstalk in the test disc so that we're left with the actual cartridge crosstalk value.

I'd get right on it but all I can offer is a CBS STR 130, the prices they charge for an STR 100 shipped to europe are outrageous. For that kind of money I'd rather buy the Clearaudio TRS 1007.

 

[ariendj]

Just grabbed 10 minutes of audio from a record and made a CSV file of a spectrogram, then compared it to a spectrogram from the same track off of spotify (didn't have a FLAC handy). Came from the same setup as the two graphs I posted earlier.

Ignore the data beyond 18k, the audio from spotify will not have any content at those frequencies. This graph was made with both channels feeding the RTA instead of L and R being seperate, as above.

I'm fascinated by how well it all matches up though, despite my quick and dirty approach.

 

[AaronJ]

Would it be possible to take some measurements comparing dust cover open vs closed? I expect there will be no noticeable difference but so many people swear by open dust cover and I’d be curious if there is anything to it.

 

[JP]

Would it be possible to take some measurements comparing dust cover open vs closed? I expect there will be no noticeable difference but so many people swear by open dust cover and I’d be curious if there is anything to it.

I’ve done open, closed, and off. Each manifested small differences in different areas of the spectrum. Will vary depending on situation, but I don’t see a “right” answer, rather pick your poison.

 

[dlaloum]

Would it be possible to take some measurements comparing dust cover open vs closed? I expect there will be no noticeable difference but so many people swear by open dust cover and I’d be curious if there is anything to it.

I did measure it on my JVC QL-Y5f above 15 years ago - and it was better with cover open.... sadly I did not save the measurements.

No difference if you are not playing back at the time in the same room (eg: if you are recording, or listening on headphones...)

The impact has to do with resonances either coming up through the mounting/platform/rack, or airborne...

 

[narud]

6 150MLX bodies including yours:

352/364
354/358
352/350
360/363
304/333
346/354

just picked up another 150mlx and im getting 420 for inductance just like the other body i have. theres got to be a couple runs of these with different specs. my 150sa body measures 480mh and 150ea at 369 so pretty close to published spec for those carts. these mlx's i have seem way out. never measured the two previous ones i had. maybe you got all the neutral ones because everyone ive had has been bright as hell!

 

[Thomas_A]

Would it be possible to take some measurements comparing dust cover open vs closed? I expect there will be no noticeable difference but so many people swear by open dust cover and I’d be curious if there is anything to it.

There are some measurements in the "fun with vinyl measurements" thread.

What I found out was playing a sweep at *very high SPL * from another source causes acoustical vibration peaks of the record that matches with the standing waves created between the platter/record and the roof, which it also should according to physics. When the lid is on, these are damped and switched somewhat in frequency due to the altered distance (standing waves on the lid that is transferred, rather than the record surface). Others have found other results, but due to that there is no standard test procedure, it cannot be compared. I would expect all tests to get the peaks corresponding to the standing waves between record and roof, given sufficient SPL. If not, it is not enough SPL.

For frequency response alterations, I would say none. At least during normal listening levels (which the above example is not!).

 

[restorer-john]

I’ve done open, closed, and off. Each manifested small differences in different areas of the spectrum. Will vary depending on situation, but I don’t see a “right” answer, rather pick your poison.

What is also interesting regarding dust cover open vs closed is the shift in the levelling of the turntable. Depending on the design and compliance of the feet (and the weight of the lid), it can be quite significant.

If you level the turntable via the feet, with the lid closed it won't be level (front to back) when the entire weight of the lid is on the rear in the hinged open position. I've got some vintage mass decoupled DDs with heavy lids and compliant isolation feet where you have to make a decision on playback- is the lid going to be closed or open? Due to the entire turntable visibly 'leaning back from level' when the lid is open at around 60 degrees or so.

It actually makes sense to have a complete lift-off lid with four contact points so it doesn't matter whether the lid is on or off, but no pivoted option.

 

[AaronJ]

What is also interesting regarding dust cover open vs closed is the shift in the levelling of the turntable. Depending on the design and compliance of the feet (and the weight of the lid), it can be quite significant.

If you level the turntable via the feet, with the lid closed it won't be level (front to back) when the entire weight of the lid is on the rear in the hinged open position. I've got some vintage mass decoupled DDs with heavy lids and compliant isolation feet where you have to make a decision on playback- is the lid going to be closed or open? Due to the entire turntable visibly 'leaning back from level' when the lid is open at around 60 degrees or so.

It actually makes sense to have a complete lift-off lid with four contact points so it doesn't matter whether the lid is on or off, but no pivoted option.

Oy. Looks like I need to recheck the leveling of my TT’s today.

Thanks for the responses. I play with lid closed because I’ve not been able to tell a difference between the two but it’s good to know that there are actual measurable differences. My main turntable rig is actually on the other side of the wall from the speakers so it sounds like it’s probably not going to pick up on those resonances. In my office I play at low SPL anyway so also probably not picking anything up.

 

[JP]

just picked up another 150mlx and im getting 420 for inductance just like the other body i have. theres got to be a couple runs of these with different specs. my 150sa body measures 480mh and 150ea at 369 so pretty close to published spec for those carts. these mlx's i have seem way out. never measured the two previous ones i had. maybe you got all the neutral ones because everyone ive had has been bright as hell!

Not sure. My bodies were picked up over many years though half were after EOL.

 

[ariendj]

How do you guys feel about making a catalog of the all the commonly used test records with all of their specs, strenghts and weaknesses? There's a lot of info on all of them, spread across lots of threads on all the different audio forums. What there is not is a conclusive list of all of them.

I wouldn't mind capturing sweeps of the test records I have so we can compare how the same system measures up on the various available test discs.

Of course wear is a factor here, but given enough data from different people comparing the same system playing different test discs, I imagine we could even that out to some degree.

I'd be interested in seeing

• frequency response
• distortion graphs
• crosstalk/channel separation figures
• wow and flutter
• EQ requirements, possibly with biquads

... compared across the usual suspects:

• JVC TRS 1007
• Clearaudio CA-TRS 1007
• HiFi News
• Elipson
• B&K QR 2010
• Ultimate Analogue Test LP
• Tacet Vinyl Check
• CBS STR 100
• CBS STR 130
• Ortofon Test Record

I've put the ones I can provide data for in italics. I'd really like to be able to easily compare these records as I often wonder how much distortion, crosstalk or wow&flutter is actually caused by the record/pressing/wear instead of the cartridge being tested.

 

[dlaloum]

How do you guys feel about making a catalog of the all the commonly used test records with all of their specs, strenghts and weaknesses? There's a lot of info on all of them, spread across lots of threads on all the different audio forums. What there is not is a conclusive list of all of them.

I wouldn't mind capturing sweeps of the test records I have so we can compare how the same system measures up on the various available test discs.

Of course wear is a factor here, but given enough data from different people comparing the same system playing different test discs, I imagine we could even that out to some degree.

I'd be interested in seeing

• frequency response
• distortion graphs
• crosstalk/channel separation figures
• wow and flutter
• EQ requirements, possibly with biquads

... compared across the usual suspects:

• JVC TRS 1007
• Clearaudio CA-TRS 1007
• HiFi News
• Elipson
• B&K QR 2010
• Ultimate Analogue Test LP
• Tacet Vinyl Check
• CBS STR 100
• CBS STR 130
• Ortofon Test Record

I've put the ones I can provide data for in italics. I'd really like to be able to easily compare these records as I often wonder how much distortion, crosstalk or wow&flutter is actually caused by the record/pressing/wear instead of the cartridge being tested.

Denon had some excellent test records too...

 

[USER]

How do you guys feel about making a catalog of the all the commonly used test records with all of their specs, strenghts and weaknesses? There's a lot of info on all of them, spread across lots of threads on all the different audio forums. What there is not is a conclusive list of all of them.

I wouldn't mind capturing sweeps of the test records I have so we can compare how the same system measures up on the various available test discs.

Of course wear is a factor here, but given enough data from different people comparing the same system playing different test discs, I imagine we could even that out to some degree.

I'd be interested in seeing

• frequency response
• distortion graphs
• crosstalk/channel separation figures
• wow and flutter
• EQ requirements, possibly with biquads

... compared across the usual suspects:

• JVC TRS 1007
• Clearaudio CA-TRS 1007
• HiFi News
• Elipson
• B&K QR 2010
• Ultimate Analogue Test LP
• Tacet Vinyl Check
• CBS STR 100
• CBS STR 130
• Ortofon Test Record

I've put the ones I can provide data for in italics. I'd really like to be able to easily compare these records as I often wonder how much distortion, crosstalk or wow&flutter is actually caused by the record/pressing/wear instead of the cartridge being tested.

A couple of quick thoughts:

First, I don't think we are quite ready for such a project. While we can take measurements now (and please do!), it may be best to wait for JP's finalized script and/or comparison tool. When it is ready one will be able to bang out some direct comparisons and additional measurements (e.g. crosstalk) of the same cartridge on different records or with different variables. Then we can reach some sort of consensus on things such as optimal EQ. I agree that a test record overview will be helpful as a sticky for this thread, however we will not be able to consider it conclusive and it would be good to approach it that way. The medium is too much of a pain in the ass. But if you want to take the lead and start keeping track of these things it would be appreciated.

Some of the information is available on the test records themselves, granted JP has been pushing past their limits recently. A measurement like wow and flutter is difficult here because test records innately have loads of problems that affect its measurement hardest. To name but one example: I have seen different pressing issues on the Tacet records. On recent pressings the test tone is simply off, and the older, better ones have centering issues. It's likely going to be the case that we will just say it's near impossible to find a test record for that W&F number many look for. This doesn't mean that the older Tacet and other records are not useful, as has been discussed in the Fun with Measurements thread. And I wouldn't want my findings stopping someone from finding a Tacet holy grail that works if it exists out there.

As I have posted on this thread, record wear may not be the biggest issue. But it would be good for others to test this as well. Indeed, in my view, what we really need to do first is present and look at as much data as we can. Another thing to consider that certainly affects the eBay CBS records is warping. But how much does it affect the measurements? Does it create those large discrepancies between them above 10kHz? I just received a record flattener and am currently looking at its effects. After the first pass the record is not yet totally flat but I am seeing some smoothing that I can't say is a huge deal. Unfortunately, those issues above 10kHz (here that huge bump between 14-18kHz) don't seem to be smoothed out.

The differences aren't big enough for the graph above so I tried this:

I'll update this graph once I fully flatten the record. The biggest difference here is the 3rd harmonic. If, when I try out other warped CBS records, I see this as a trend, does it invalidate most CBS measurements? The FR does seem more smoothed out, which makes sense to me, but I would be fine with the one on first graph.

If you are itching to see a comparison graph of your different test records feel free to send me the files. I'd need them in stereo, however.

 

[morillon]

the problems of wear, except for very intensive use of our test discs, concerns the overmodulated tests known as torture at more than +15db +16db +-70um 80umetc.

 

[ariendj]

First, I don't think we are quite ready for such a project.

IMHO we need data, lots of data. Better start now and find a home for what we have already learned.

While we can take measurements now (and please do!), it may be best to wait for JP's finalized script and/or comparison tool.

I'm still playing around with it but I'm no good as a programmer. I'll try to contribute as much as I can, but it will probably not amount to much more than housekeeping and usability stuff.

When it is ready one will be able to bang out some direct comparisons and additional measurements (e.g. crosstalk) of the same cartridge on different records or with different variables. Then we can reach some sort of consensus on things such as optimal EQ.

Agreed, we're not there yet.

I agree that a test record overview will be helpful as a sticky for this thread, however we will not be able to consider it conclusive and it would be good to approach it that way.

True, but I think we need to start to gather the info we do already have in one place. This way, maybe more people can join in. I wasted a lot of money on nearly useless test discs. If I can save one person from spending $50 on a crappy test disc I'd call that a win.

The medium is too much of a pain in the ass.

Isn't that the challenge we all enjoy?

But if you want to take the lead and start keeping track of these things it would be appreciated.

I'll give it some more thought and make a start.

Some of the information is available on the test records themselves, granted JP has been pushing past their limits recently.

So have I. And with the amount of crappy test discs, it's bound to happen to anyone who tries.

A measurement like wow and flutter is difficult here because test records innately have loads of problems that affect its measurement hardest.

Agreed

To name but one example: I have seen different pressing issues on the Tacet records. On recent pressings the test tone is simply off, and the older, better ones have centering issues. It's likely going to be the case that we will just say it's near impossible to find a test record for that W&F number many look for. This doesn't mean that the older Tacet and other records are not useful, as has been discussed in the Fun with Measurements thread. And I wouldn't want my findings stopping someone from finding a Tacet holy grail that works if it exists out there.

Information like this is what I think we should be gathering, in the first step. Should help a lot of people starting out. Personally, I regret buying the Tacet and the HiFi News.

As I have posted on this thread, record wear may not be the biggest issue. But it would be good for others to test this as well. Indeed, in my view, what we really need to do first is present and look at as much data as we can. Another thing to consider that certainly affects the eBay CBS records is warping. But how much does it affect the measurements? Does it create those large discrepancies between them above 10kHz? I just received a record flattener and am currently looking at its effects. After the first pass the record is not yet totally flat but I am seeing some smoothing that I can't say is a huge deal. Unfortunately, those issues above 10kHz (here that huge bump between 14-18kHz) don't seem to be smoothed out.

View attachment 270320
The differences aren't big enough for the graph above so I tried this:
View attachment 270321
I'll update this graph once I fully flatten the record. The biggest difference here is the 3rd harmonic. If, when I try out other warped CBS records, I see this as a trend, does it invalidate most CBS measurements? The FR does seem more smoothed out, which makes sense to me, but I would be fine with the one on first graph.

CBS and invalidation... Hmm... They are off at the very top end and with crosstalk, two things I'm most interested in. I'd like to have a crack at trying to find a way to compensate for the cutter head crosstalk, maybe then they'd be more useful. But I need to tweak my setup some more first, I just reconfigured my entire setup.

If you are itching to see a comparison graph of your different test records feel free to send me the files. I'd need them in stereo, however.

I'll grab some data as soon as I have the preamp setup I'm aiming for. I'll upload some files when I do.

the problems of wear, except for very intensive use of our test discs, concerns the overmodulated tests known as torture at more than +15db +16db +-70um 80umetc.

I feel the same way, yet there are lots of posts claiming that you'd have to throw away a B&K QR2010 after 5 plays. I can see how that would make sense when doing QC on a ceramic cartridge production line in the 70s. With my 1.25g T4P setup and either ellipticals or Line Contact / Shibata I have not noticed any degradation.

 

[MaxwellsEq]

Buckle up.

I'd mentioned here that the script can be used on 'contrived' sweeps. The script slices the audio and runs FFTs on the slices, grabbing the largest bin for each slice. Slices at the same frequency are averaged. This gives us a lot of leeway on test signals.

The big question has always been, how accurate are the test records?

If we playback a spot frequency and slow down the 'table, the amplitude of the signal will decrease 6dB/octave. Likewise, if we speed it up the amplitude will increase 6dB/octave. Thus, if we playback a 20kHz spot frequency at half-speed, we'd end up at 10kHz at -6dB. I've modified one of my SP-10MK3 to do +20/-50%.

By taking 20, 10, 5, 3, and 2kHz spots we can record each one while sweeping the turntable speed from -0% to -50% and stitch together a "sweep" from 1-20kHz. The exact frequency and amplitude of each spot doesn't matter as long as they're both consistent throughout the track. If they are, a 10-20kHz "sweep" made from a single spot frequency track, for instance, will be the true response of the cartridge.

We could then use a variation of the script to create a spot track "calibration" to correct any amplitude errors in the track within the dynamic consistency of the cartridge. This calibration could then be applied to the spot "sweep" to give a corrected frequency response sweep for the cartridge. In turn, this data could then be used to validate sweep tracks on test records, and in the creation of transfer functions to correct them.

EDIT - to be clear, the below is just a comparison of the rundown method vs. the TRS-1007 record - no corrections have been applied to the TRS-1007 plot.

View attachment 264170

View attachment 264171

That's ingenious!

 

[Balle Clorin]

How do you guys feel about making a catalog of the all the commonly used test records with all of their specs, strenghts and weaknesses? There's a lot of info on all of them, spread across lots of threads on all the different audio forums. What there is not is a conclusive list of all of them.

I wouldn't mind capturing sweeps of the test records I have so we can compare how the same system measures up on the various available test discs.

Of course wear is a factor here, but given enough data from different people comparing the same system playing different test discs, I imagine we could even that out to some degree.

I'd be interested in seeing

• frequency response
• distortion graphs
• crosstalk/channel separation figures
• wow and flutter
• EQ requirements, possibly with biquads

... compared across the usual suspects:

• JVC TRS 1007
• Clearaudio CA-TRS 1007
• HiFi News
• Elipson
• B&K QR 2010
• Ultimate Analogue Test LP
• Tacet Vinyl Check
• CBS STR 100
• CBS STR 130
• Ortofon Test Record

I've put the ones I can provide data for in italics. I'd really like to be able to easily compare these records as I often wonder how much distortion, crosstalk or wow&flutter is actually caused by the record/pressing/wear instead of the cartridge being tested.

We could add on here..

Frequency Response Test Records

Frequency Response Test Records I was wondering how my few test records measure compared to each other and which one is the best for measuring crosstalk. Used Pickup: Ortofon Vinyl Master Silver (47K//240pF, 17,5mN) Used Turntable: Mitsubishi LT-20 First I adjusted the pickup exaktly...

www.audiosciencereview.com

 

[Balle Clorin]

My new AT33PTG/ii, Left and Right overlaid, since I do not know how to fixate the scale, The other plotstyles rescales the axes making visual comparion difficult
The PTG has much more small wiggles/resonances than my OC9, I wonder why

 

[USER]

I finished testing another batch of CBS STR-100 records (all flattened) and am happy to note that they are all consistent and look good!

Here is a comparison of these new ones and the two records I used for the graphs I previously posted:

I was able to make a correction curve so that I can correct measurements I took of cartridges I no longer have:

Good enough. Now whenever a final correction curve is out all my results should be reliable--as reliable as they can be anyways. It's good to know there are some good copies out there. All are from eBay but this good batch was purchased months ago so I don't know what the current crop looks like. Regardless, I do think that with a flat enough cartridge it is easy to tell which are off.