It seems to me, from memory, that you can make LPs containing music at about 18 mins/side without compromising on fidelity, and run up to about 25 minutes with low frequency limiting (by that I'm referring to equalization on tracks to remove LF information that otherwise would be cut-able. Example the "25 hits" compilations by K-Tel, which were not the same sonically as the songs as released on the artist's original albums). So I would think that we could easily exceed 12 minutes, especially since not every track will have substantial LF information.
Obviously that's a question that should be posed to a mastering engineer or pressing facility.
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That both mechanics of motion and performance of cartridge generator electro-magnetics are uniform for all vectors........ it's a cartridge performance/setup indicator, in principle.
Perhaps also useful for setup checks, if there are included markers for true vertical, true lateral, and both true 45 deg vectors?
LD
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Folks:
I'm interested in a test LP though, since I lack any test equipment (other than DVMs), it's unclear how useful it will be for me. Are you anticipating providing thorough documentation to enable those of us with limited technical skills or equipment to make the most of the LP?
Also, is there any advantage to making this a multi-LP set where the LPs are one-sided (and/or include 33 and 45 rpm variants)? I imagine the incremental cost would be relatively low.
Regards,
Scott
I'm interested in a test LP though, since I lack any test equipment (other than DVMs), it's unclear how useful it will be for me. Are you anticipating providing thorough documentation to enable those of us with limited technical skills or equipment to make the most of the LP?
Also, is there any advantage to making this a multi-LP set where the LPs are one-sided (and/or include 33 and 45 rpm variants)? I imagine the incremental cost would be relatively low.
Regards,
Scott
Could someone volunteer to be a SPoC for answering such questions and keep contact with the mastering engineer at the selected record company?
I have begun contact with GZ mastering, we shall see how it goes. They seem like the first mastering house to approach.
I wasn't sure what that test would show, but Scott explained it to me. It shows all possible angles the cut.
What would you use as the marker? And should the tone be 1kHz?
What would you use as the marker? And should the tone be 1kHz?
The goal would be for all tests to be done with a soundcard. I don't have the adaptor to make my laptop stereo, but I assume something like the free Soundcard Scope would work. Special tests would need the algorithms wrapped into some freely distributable environment. I have never done it but there is a process to make Python scripts into a .exe.
I assume every OS has something similar that displays/records sound card IO that's free. I know they all support Python. I have the code for a Python scope but It's fairly involved.
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I've been thinking, and it's an interesting proposition here: whether two slightly dissimilar frequency tones L, R, is the same as two FM modulated tones where the small modulation is opposite sense L,R........
I'm not certain but think they're effectively similar, but for sure the FM method gives a true solution and is the way to fly.
LD
I just remember the old quadraphonic SQ records encoded the surround information in the L and R channels with 90° phase shift. It could be decoded by an all-pass network, and the stylus wiggled in a circular way. I still have a couple of Czech Supraphon SQ LPs. Steady 1 kHz or frequency sweep in all LF, RF, LB, RB channels can be encoded in SQ, so I assume it cold be worth adding such signals for stylus mechanical testing in all directions, even though not used for real SQ. Not sure what markers could be used.
(revised my previous post where I wrote L+R, L-R, L, R would be enough)
(revised my previous post where I wrote L+R, L-R, L, R would be enough)
I would think something like L = sin(omega*t + phi) and R = sin(omega*t - phi) where phi cycles from 0 to pi in 1.8sec might work.
Yes. That's of the form L = sin(at + bt) and R =sin(at - bt)
Which is the same as L =sin((a+b)t) and R =sin((a-b)t)
Then effectively L channel tone frequency is fixed at sum of test tone frequency+ rotating frequency, and R channel frrquency is the difference. 1kHz +/- 0.55Hz would be the two fixed test tones.
Et voila !
LD
Which is the same as L =sin((a+b)t) and R =sin((a-b)t)
Then effectively L channel tone frequency is fixed at sum of test tone frequency+ rotating frequency, and R channel frrquency is the difference. 1kHz +/- 0.55Hz would be the two fixed test tones.
Et voila !
LD
Yes, I think you want .55Hz/2 the above cycles twice in 1.8sec from a quick look but does the right thing. Pano there's something off in yours not sure what. Darn CoolEdit does not let me do 1000.275Hz too many digits I'll have to get back to this and do it in Python.
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Updated track list
In no particular order:
Please comment. Giving 10 secs to the sweeps and 1 minute to everything else doesn't even fill one side.
In no particular order:
- 3150Hz Speed, wow+flutter
- 1kHz Reference level 5cm/sec, distortion, phase
- Pink Noise (level?)
- White noise (level?)
- Full range sweep @5cm/sec - FR and EQ As extended FR as possible.
- same 24dB below reference
- same 18dB below reference
- same 12dB below reference
- same 6dB below reference
- same @ reference
- same 6dB above reference
- same 12dB above reference (if possible)
- Rotating phase
- L+R
- L-R
- Crosstalk test
- Silent Groove for Rumble (maybe locked)
- Low frequency sweep for cart & arm resonance
Please comment. Giving 10 secs to the sweeps and 1 minute to everything else doesn't even fill one side.
I'll check on what others have thought best on the pink noise. BTW many test LP's gobble up space with voice announced spot frequencies and I have several with 1/2 a side blank.
Yes, I was thinking about voice announcements. They could be useful as a warning for the increasing amplitude sweeps.
Scott - more like this? It doesn't seem to rotate far enough, but maybe that's all we need.
