You missed tracks discussed in posts 602, 604, 612, 614, and perhaps others that were discussed in text but didn’t specifically appear on someone’s list.
Ray K
Yes! Cut this and press it. It comprises tracks that I don’t have on any of the other test LP’s in my library.
Ray K
I've gone back and looked at each and every post mentioned above in 661. One is a list from an existing test LP, a few are my compiled lists and others are suggestions for tone bursts and tracking tests.
I was hoping that the tone bursts would be added to the list, but no one added them. There is a debate about whether tracking tests are needed, since they are so frequent on other test LPs.
I was hoping that the tone bursts would be added to the list, but no one added them. There is a debate about whether tracking tests are needed, since they are so frequent on other test LPs.
The FM demodulator, needed to build the previously discussed VTA Patent circuit, uses a VCO to keep track of the 3150Hz frequency coming from the LP.Sure.
The most important factor about the 3150Hz tone is to get the centre hole precisely located and accurately toleranced - needs to be far better than standard specs allow. Not sure that's been addressed with any of the candidate production houses yet?
I keep returning to the scene from 'A mighty wind' where the band has a record pressed without a centre hole to save money............
LD
The signal steering the VCO is a direct measure of the frequency stability of this incoming tone.
The Image below shows the VCO steering signal for almost 4 LP revolutions.
It's quite easy to see that the Adjust+ test LP has an non centric hole, making the 3150Hz tone going slightly up and down in frequency
1mV in this image corresponds to exactly 0.1% change in pitch, corresponding in this very case with a hole that is 0.1mm off centre.
One tenth of a millimeter seems almost nothing, but is still very easy to detect.
Looking at the image, I would say that the hole eccentricity for this test LP should be a factor 10 better, i.e. within 1/100 of a millimeter.
Hans
Attachments
Well done,
This is the first time I get the feeling that a test LP with this material might be something for me.
Hans
How would that be done in practical terms? The hole punch is not part of the mastering, but part of the stamping process. AFAIK, it's done after stamping and before the label. How does one get a record stamping plant to be accurate to within 1/100mm? Not saying it can't be done, but how do you get the production line to adhere to that?
I just off the phone with Rainer Maillard of Emil Berliner Studios in Berlin. I had sent him a list of questions that Pano gave me as these were also sent to GZ. Here's the list:
1) Levels.
We want a 1kHz reference tone cut at 5 cm/s. At what level should we set this reference in our digital files?
For a full frequency sweep, what is a recommended level? We don’t want to over drive the cutter at high frequencies .
2) EQ and compression.
Of course we don’t want EQ or compression for any files. These are test tones straight cut.
Can we apply our own RIAA curve to the files and you turn off yours? Or does this cause you problems?
(Scott would like to apply the RIAA to our files. He can make it extremely precise. I don't know if this is possible or even easy for the mastering house. I wonder if the mix RIAA with their cutter head EQ)
3) Frequency Reponse
What are your frequency limits with pure tones and sweeps? We’d like to get all you are capable of cutting and hope to go above 20 kHz.
Is it advisable to use 1/2 speed mastering?
4) File format.
Is there any real advantages to 192K bitrate, or is 96K enough?
(Scott and I think that 24bit 92K is a good choice)
5) Hole centering. How precise can it be? It’s important for a test disc.
We didn't answer all questions, but here's what I got:
The frequency limit of their cutting head is 40kHz when cutting half speed. So 96kHz is good enough.
Beyond 15kHz linearity is really difficult because of feedback in the cutter head.
He said that he has some test records that the Deutsche Grammophone manufactured for their own use that are extremely linear even beyond 15k and that he has no idea how they did it.
Linearity of the cut master needs to be checked with an optical pickup system as a mechanical pickup system is too non linear.
He said that mastering a test record is a really difficult job that takes a lot of time and effort (which translates to expensive) and he is not crazy about doing that job. He told me a college of his in another facility is currently mastering a test record (didn't get info about what facility or who that customer is) and he has one of his two lathes blocked for that one job.
Center hole centering is business that needs to be discussed with the pressing plant.
1) Levels.
We want a 1kHz reference tone cut at 5 cm/s. At what level should we set this reference in our digital files?
For a full frequency sweep, what is a recommended level? We don’t want to over drive the cutter at high frequencies .
2) EQ and compression.
Of course we don’t want EQ or compression for any files. These are test tones straight cut.
Can we apply our own RIAA curve to the files and you turn off yours? Or does this cause you problems?
(Scott would like to apply the RIAA to our files. He can make it extremely precise. I don't know if this is possible or even easy for the mastering house. I wonder if the mix RIAA with their cutter head EQ)
3) Frequency Reponse
What are your frequency limits with pure tones and sweeps? We’d like to get all you are capable of cutting and hope to go above 20 kHz.
Is it advisable to use 1/2 speed mastering?
4) File format.
Is there any real advantages to 192K bitrate, or is 96K enough?
(Scott and I think that 24bit 92K is a good choice)
5) Hole centering. How precise can it be? It’s important for a test disc.
We didn't answer all questions, but here's what I got:
The frequency limit of their cutting head is 40kHz when cutting half speed. So 96kHz is good enough.
Beyond 15kHz linearity is really difficult because of feedback in the cutter head.
He said that he has some test records that the Deutsche Grammophone manufactured for their own use that are extremely linear even beyond 15k and that he has no idea how they did it.
Linearity of the cut master needs to be checked with an optical pickup system as a mechanical pickup system is too non linear.
He said that mastering a test record is a really difficult job that takes a lot of time and effort (which translates to expensive) and he is not crazy about doing that job. He told me a college of his in another facility is currently mastering a test record (didn't get info about what facility or who that customer is) and he has one of his two lathes blocked for that one job.
Center hole centering is business that needs to be discussed with the pressing plant.
The tracking tests that appear on so many other test LP's are only at ~300Hz. Tracking ability at 300Hz does not necessarily scale up or extrapolate to higher frequencies and the results seen on a single frequency trackability test can lead to false assumptions of overall performance ranking. Additional tests at say, 1KHz, 5KHz, and 10KHz give a more meaningful overall picture for comparisons. Yes, Shure used these frequencies when they introduced the concept of "trackability" at multiple frequencies and pushed this as part of their advertising campaign. I have seen much anti-Shure sentiment and what seems to be a subliminal rejection of Shure's method expressed on various web forums over the years, but it is a useful objective metric and multiple frequency trackabilty bands are not found on other test records.
Ray K
GZ Vinyl answers to technical questions
Questions are in black, answers in BLUE
1) Levels.
We want a 1kHz reference tone cut at 5 cm/s. At what level should we set this reference in our digital files?
For a full frequency sweep, what is a recommended level? We don’t want to over drive the cutter at high frequencies .
There is no fixed connection between digital level in audio files and analog (mechanical) level on record. We always set cutting level according musical content.
If we know the reference level is supposed to be 5 cm/s we set to cutting level to meet this requirement.
5 cm/s is quite low for reference tone. It corresponds to -9 dB (= 16 µm peak to peak amplitude) of Neumanns reference level at 1 kHz (0 dB = 14,14 cm/s = 45 µm PP).
For real time cutting current, temperature and acceleration are limiting so -20 dB of Neumanns level is safe. For non real time cutting (half speed, 2/3 speed, 3/4 speed) mechanical parameters (groove angle, groove radius, ...) are limiting. In other words it is possible to cut groove that is impossible to play at least without heavy distortion.
To prevent this problem I recommend to use 45 rpm and cut frequency sweep at outer side of the disk from higher to lower frequencies.
2) EQ and compression.
Of course we don’t want EQ or compression for any files. These are test tones straight cut.
Can we apply our own RIAA curve to the files and you turn off yours? Or does this cause you problems?
For test LP we don't use any processing except cutting level settings. There must be clear information about test records and requests in tracklist. To help orientation different width of transition grooves can be used to separate specific signals.
We can switch off upper time constant (2122 Hz) only. There is no benefit if you apply your own RIAA curve. There are several other circuit in the signal path and RIAA curve has to be last one!
3) Frequency Response
What are your frequency limits with pure tones and sweeps? We’d like to get all you are capable of cutting and hope to go above 20 kHz.
Is it advisable to use 1/2 speed mastering?
Generally we are able to cut more than common pickup is able to play. Usually geometric parameters are most limiting, so the best results are achievable for 45 rpm and outer side where should lie most critical signals. Differences between cutting and playback stylus cause several nonlinear distortion, crosstalk up to -6 dB, left and right channel time shift and many more. It depends what you prefer. I did frequency sweep cut till 30 kHz at -16 dB. Frequency response for the SAS playback stylus was almost flat till 25 kHz.
1/2 speed mastering lower current and temperature 4 times so it is no longer problem. On the other hand it causes problems for cutting low frequencies. Sometimes I rather use 2/3 or 3/4 speed.
4) File format.
Is there any real advantages to 192K bitrate, or is 96K enough?
I believe you won't hear the difference even for critical test signals. I measure ears to our every new cutting engineer. The absolute record is 21 kHz, but most people are not able to hear more than 18 kHz. It depends on age and many others factors.
It is TRUE that design of antialiasing filter is easier for higher sampling rates. On the other hand design of the DA converter clock is harder for higher frequencies. It depends on DA converter. We use Prism Sound Orpheus DA coverter for cutting.
5) Hole centering. How precise can it be? It’s important for a test disc.
Hole centering together with hole size tolerance and turntable center spindle tolerance also are responsible for eccentricity error. For musical signal eccentricity below 200 µm is acceptable and it not cause problem. For test harmonic signal you can always measure some frequncy fluctuation.
Center hole tolerance is 7.24-7.33 mm.
6) Is there anything you, as a mastering engineer, would like to see on a test LP? Something you think should be included or can be done better than on other test LPs?
I would consider signal for measuring polarity, crosstalk, pink noise, arm resonance, rotation fluctuation, intermodulation distortion, pickup azimuth settings, and many more.
There are many things (cutting lathe, head and stylus selection, non real time cutting, cutting head protection bypass, highly accurate cutting & feedback level settings, endless & closed groove programming, distortion precompensation),that could be done better but they requires additional time to prepare cutting and we charge extra cost for them.
We can create test record according to detailed description only. We use high accuracy 4 tone signal generator special invented for vinyl records.
Here are basic features:
Questions are in black, answers in BLUE
1) Levels.
We want a 1kHz reference tone cut at 5 cm/s. At what level should we set this reference in our digital files?
For a full frequency sweep, what is a recommended level? We don’t want to over drive the cutter at high frequencies .
There is no fixed connection between digital level in audio files and analog (mechanical) level on record. We always set cutting level according musical content.
If we know the reference level is supposed to be 5 cm/s we set to cutting level to meet this requirement.
5 cm/s is quite low for reference tone. It corresponds to -9 dB (= 16 µm peak to peak amplitude) of Neumanns reference level at 1 kHz (0 dB = 14,14 cm/s = 45 µm PP).
For real time cutting current, temperature and acceleration are limiting so -20 dB of Neumanns level is safe. For non real time cutting (half speed, 2/3 speed, 3/4 speed) mechanical parameters (groove angle, groove radius, ...) are limiting. In other words it is possible to cut groove that is impossible to play at least without heavy distortion.
To prevent this problem I recommend to use 45 rpm and cut frequency sweep at outer side of the disk from higher to lower frequencies.
2) EQ and compression.
Of course we don’t want EQ or compression for any files. These are test tones straight cut.
Can we apply our own RIAA curve to the files and you turn off yours? Or does this cause you problems?
For test LP we don't use any processing except cutting level settings. There must be clear information about test records and requests in tracklist. To help orientation different width of transition grooves can be used to separate specific signals.
We can switch off upper time constant (2122 Hz) only. There is no benefit if you apply your own RIAA curve. There are several other circuit in the signal path and RIAA curve has to be last one!
3) Frequency Response
What are your frequency limits with pure tones and sweeps? We’d like to get all you are capable of cutting and hope to go above 20 kHz.
Is it advisable to use 1/2 speed mastering?
Generally we are able to cut more than common pickup is able to play. Usually geometric parameters are most limiting, so the best results are achievable for 45 rpm and outer side where should lie most critical signals. Differences between cutting and playback stylus cause several nonlinear distortion, crosstalk up to -6 dB, left and right channel time shift and many more. It depends what you prefer. I did frequency sweep cut till 30 kHz at -16 dB. Frequency response for the SAS playback stylus was almost flat till 25 kHz.
1/2 speed mastering lower current and temperature 4 times so it is no longer problem. On the other hand it causes problems for cutting low frequencies. Sometimes I rather use 2/3 or 3/4 speed.
4) File format.
Is there any real advantages to 192K bitrate, or is 96K enough?
I believe you won't hear the difference even for critical test signals. I measure ears to our every new cutting engineer. The absolute record is 21 kHz, but most people are not able to hear more than 18 kHz. It depends on age and many others factors.
It is TRUE that design of antialiasing filter is easier for higher sampling rates. On the other hand design of the DA converter clock is harder for higher frequencies. It depends on DA converter. We use Prism Sound Orpheus DA coverter for cutting.
5) Hole centering. How precise can it be? It’s important for a test disc.
Hole centering together with hole size tolerance and turntable center spindle tolerance also are responsible for eccentricity error. For musical signal eccentricity below 200 µm is acceptable and it not cause problem. For test harmonic signal you can always measure some frequncy fluctuation.
Center hole tolerance is 7.24-7.33 mm.
6) Is there anything you, as a mastering engineer, would like to see on a test LP? Something you think should be included or can be done better than on other test LPs?
I would consider signal for measuring polarity, crosstalk, pink noise, arm resonance, rotation fluctuation, intermodulation distortion, pickup azimuth settings, and many more.
There are many things (cutting lathe, head and stylus selection, non real time cutting, cutting head protection bypass, highly accurate cutting & feedback level settings, endless & closed groove programming, distortion precompensation),that could be done better but they requires additional time to prepare cutting and we charge extra cost for them.
We can create test record according to detailed description only. We use high accuracy 4 tone signal generator special invented for vinyl records.
Here are basic features:
- 64 bit floating point
- cutting lathe rotation synchronization
- 1 ns signal period settings resolution
- 0,000001 dB level settings
- 10 nm amplitude settings
- 4 simultaneous signals
- special signals (pink and white noise, polarity, impulses, linear and logarithmic sweep, trapezoidal & triangle groove shape)
- modulated signal
- constant amplitude sweep
Pano, if I understand the answer to no.6 it is a major change in our methodology and we might lose having an exact digital version of what was cut. I take "detailed description only" to mean they won't take a set of .wav's and cut them???
The biggest worry here is the synchronization to the lathe offered by their system. I can think of all kinds of issues here. Let's say they cut the ref tone and save off a digital version as a .wav. The speed/wow/flutter of the lathe now appears in the data and all I can see is a can of worms trying to get any use out of it.
BTW the specs are impressive but he must realize that any computer can generate 64 bit double precision data files.
The biggest worry here is the synchronization to the lathe offered by their system. I can think of all kinds of issues here. Let's say they cut the ref tone and save off a digital version as a .wav. The speed/wow/flutter of the lathe now appears in the data and all I can see is a can of worms trying to get any use out of it.
BTW the specs are impressive but he must realize that any computer can generate 64 bit double precision data files.
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Well Scott I think #6 means that they can generate tones for a client from just a description of the signal wanted. As nice as that is, it does present the problems you mentioned. We would just use our own signals, unless someone sees utility in one of theirs that we could add the mix.
I like having published files for anyone to download and use as a reference.
What I don't understand in the answers is the reference levels. Any thoughts?
I like having published files for anyone to download and use as a reference.
What I don't understand in the answers is the reference levels. Any thoughts?
Answer to the level question: this was shortly answered in my phone conversation and as I didn't take a note of that I have to give an "I believe he said" answer: it doesn't matter, elemental part of the mastering process is the setting of levels.
This would also work with the answer from GZ.
This would also work with the answer from GZ.
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I just think they don't pay any attention to the correlation of file level to groove modulation amplitude. After all the cart is velocity sensitive and there is no direct correlation. I sense that sending files and noting that a certain file represents 1kHz 0dB and/or X cm/sec, "set that and just let it rip", would be problematic.
I also find the comments on equalization lacking.
Also from reading both sets of comments it's fairly obvious they don't know how, for instance, CBS produced the 50kHz response sweeps.
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Yep, I understand they don't normally do absolute levels, but I'm puzzled by the cutter head levels. He says that 5 c/m second is low, and says:
5 c/m sec is nice because so many cartridges are referenced to that level.
BTW, 2/3 and 3/4 speed mastering are news to me. The GZ engineer seems to prefer them over 1/2 speed. How do they change the source pitch for these speeds?
I'm not sure what that 0dB level is. Is it maximum, or is there room above that?
5 c/m sec is nice because so many cartridges are referenced to that level.
BTW, 2/3 and 3/4 speed mastering are news to me. The GZ engineer seems to prefer them over 1/2 speed. How do they change the source pitch for these speeds?
I just read LD's list and for the sake of keeping him from smelling any more rats I could live with it as is. I think everything I want is there in some form while there are some that I would probably not use or are a little researchy.
Reading the capabilities of GZ I think all of the signals can be put in the context of their 4 signal system, we just need to put detailed numbers on everything in terms of (I think) microns at the groove and time. That would be exact times for each track and octaves per second or Hertz per second on the sweeps. They seem to want settings for all the "buttons, switches, and knobs".
For one thing since they can do tri-waves, maybe LD can translate the G force tracks into times and microns per second.
I don't think we're going to get real 50KHz results from an affordable LP. We make enough demands and it's just going to be another $60 test LP.
Reading the capabilities of GZ I think all of the signals can be put in the context of their 4 signal system, we just need to put detailed numbers on everything in terms of (I think) microns at the groove and time. That would be exact times for each track and octaves per second or Hertz per second on the sweeps. They seem to want settings for all the "buttons, switches, and knobs".
For one thing since they can do tri-waves, maybe LD can translate the G force tracks into times and microns per second.
I don't think we're going to get real 50KHz results from an affordable LP. We make enough demands and it's just going to be another $60 test LP.
He did say Neumann's so I'm thinking mastering engineer and a VU meter. I think some of the finer points here were lost in translation.
BTW I get the impression there is a lot more DSP/digital in the chain than we might think. For all I know the DAC clock and lathe can be synced at any speed they want and the equalization is dynamically adjusted. These are not the guys tweaking in a basement with mullets and beards.
BTW I get the impression there is a lot more DSP/digital in the chain than we might think. For all I know the DAC clock and lathe can be synced at any speed they want and the equalization is dynamically adjusted. These are not the guys tweaking in a basement with mullets and beards.
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