Indeed, ~10Hz resonant system content shows up strongly even on a silent groove - which ought to be a huge clue (one might think) about what then provokes the cart/arm system ...............
As to impulses, there's nothing to stop us having a test track with a series of separated loud 'clicks' recorded as a sound file, so long as we get the amplitude right so it's huge but also cutable/trackable........ that's a great idea, Bill.
LD
Hi Kevin,
The HP whatever it was that you passed up on from work.
I could really use an RF generator, like an HP 8642, 8657 or 8664. Anything in that area. Newer? Hell yes! A spec-an that reaches 6 GHz would be nice too since I am starting to work with GPS signals. HP/Agilent/Keysight strongly preferred. That stuff won't help with a test LP though. I'm hoping the RTX will look after the low frequency end because the best thing I have now is an HP 339. It is drastically improved over the Leader THD meter and oscillator I was using, and that wasn't that long ago. But as your skill and ability improves, the test equipment has to keep pace.
I've done similar things that you have to get rid of gear. I gave my surplus equipment to a few people I've know a long time, and that has really helped them a lot. At least I know it is going to a good place. The problem is of course that I rebuild (if needed) and calibrate equipment before it goes away to someone else. That limits these activities somewhat.
-Chris
The HP whatever it was that you passed up on from work.
I could really use an RF generator, like an HP 8642, 8657 or 8664. Anything in that area. Newer? Hell yes! A spec-an that reaches 6 GHz would be nice too since I am starting to work with GPS signals. HP/Agilent/Keysight strongly preferred. That stuff won't help with a test LP though. I'm hoping the RTX will look after the low frequency end because the best thing I have now is an HP 339. It is drastically improved over the Leader THD meter and oscillator I was using, and that wasn't that long ago. But as your skill and ability improves, the test equipment has to keep pace.
I've done similar things that you have to get rid of gear. I gave my surplus equipment to a few people I've know a long time, and that has really helped them a lot. At least I know it is going to a good place. The problem is of course that I rebuild (if needed) and calibrate equipment before it goes away to someone else. That limits these activities somewhat.
-Chris
Most of the salient papers have been discussed on other threads that lead to this one. There is a lot that is true, but also a lot that has been taken on trust as starting assumptions and doesn't always hold up. If you assume everything you read in a magazine or on the internet about vinyl is wrong, then you are in a good place to start with what is going on here.
There is still the point that a test LP is very useful if not critical in aligning the stylus/motor assembly and diagnosing the basic TT setup issues. Providing one at a fraction of the going rate seems a good thing. I think the CBS labs AES papers on the STR series of test LP's is in the anthology. OTOH I doubt there is much there on the wet/dry play "mystery" and a cheap test LP would allow some to be sacrificed in the cause.
The technical discussions are partly a side show over one or two tracks that might or might not be useful. We are not designing new stylus geometries or reinventing the technology as far as I know.
The technical discussions are partly a side show over one or two tracks that might or might not be useful. We are not designing new stylus geometries or reinventing the technology as far as I know.
Yes Scott, quite. There might be a track or two what is novel, but mostly it's an inexpensive way to get a test LP that we know exactly what went into it, and why. If we play our cards right we'll know what had to be altered to be cut onto the master, and can include that in our notes and files.
That said, should we include a track that is 3150Hz when played at 45 RPM for speed and stability there, too? Or is a multiple of 45 better - like 3600Hz?
That said, should we include a track that is 3150Hz when played at 45 RPM for speed and stability there, too? Or is a multiple of 45 better - like 3600Hz?
With modern scrutiny, and with the benefit of modern analysis tools and methods, much of the then contemporary explanation and understanding just doesn't hold up - and there are significant ommissions and oversights without which a proper self-consistent understanding can't happen. Maybe it's easier to see with the benefit of hindsight and without baggage of an industry and press with massive resources and an attitude of certainty about such things? The upshot is that much of the remaining common-wisdom/lore that survives around certain forums, for example, either isn't true or is incomplete and can be bettered. To a profound extent...........!Many of the problems discussed in this thread have been analyzed by professionals 40-60 years ago. A lot of info can be found in the AES disk recording anthology volume 2 (disk playback and testing).
500+ pages of engineering jargon.......
The upshot is that there remain significant performance improvement opportunities in vinyl playback, even after multiple decades comprising an era of development.
Moreover, one needs the right test record to explore and exploit the latent playback oppportunities: there's little point just duplicating what has gone before.
A bit like the Bohr model of the atom: it's almost right and useful in a sense, but once one pulls on the loose ends there are better explanations that might actually lead somewhere better.
Yes, for my sins. Read mostly anyways and I understand it.......anyone participating here who has read the whole damn thing and understood it? I haven't......
LD
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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
Yes, it has been addressed. Still waiting for an answer to that and other questions.
It nice to say "let's not repeat what's on other test LPs" - but it would be much nicer to come up with a list of test signals you actually want on the LP. Give us a list a specific test signals, and they will be incorporated into the track list. There are only a few essential tracks; reference 1K, full frequency sweep, silent groove. The rest is up for grabs. Specify what signals you want and why - so that we can get them on the track list.
Hi Pano,
Why not copy a track list that looked complete? We can use that as a starting point instead of going through it all again. The technical tracks are the ones I'm interested in, and some common ones like channel identification. If there is such a thing as a reference level, it should be included as well. They would have used either 1 KHz or 400 Hz as a guess. If we use the 1 KHz tone, then the hum filter on test equipment can be used.
-Chris
Why not copy a track list that looked complete? We can use that as a starting point instead of going through it all again. The technical tracks are the ones I'm interested in, and some common ones like channel identification. If there is such a thing as a reference level, it should be included as well. They would have used either 1 KHz or 400 Hz as a guess. If we use the 1 KHz tone, then the hum filter on test equipment can be used.
-Chris
OK, I'll post another list, this one more sparse. Please add to it what you would like see on the test LP. Once we get a long list, we can start paring down and deciding on track order.
In no particular order:
Full range sweep @5cm/sec
3150Hz Speed, wow+flutter
1kHz Reference level 5cm/sec
Left identification
Right identification
Pink Noise
Rotating phase
Crosstalk test
Silent Groove for Rumble (maybe locked)
Low frequency sweep for cart & arm resonance
In no particular order:
Full range sweep @5cm/sec
3150Hz Speed, wow+flutter
1kHz Reference level 5cm/sec
Left identification
Right identification
Pink Noise
Rotating phase
Crosstalk test
Silent Groove for Rumble (maybe locked)
Low frequency sweep for cart & arm resonance
Hi Pano,
Please add another 3150 track near the last tracks so speed and W&F can be checked at the beginning and end of an LP.
Is the silent groove better at the ends, or in the middle?
-Chris
Edit: Here is a more complete list that maybe could be a starting point unless there is too much disagreement
http://www.diyaudio.com/forums/analogue-source/313335-test-lp-buy-11.html#post5252022
Please add another 3150 track near the last tracks so speed and W&F can be checked at the beginning and end of an LP.
Is the silent groove better at the ends, or in the middle?
I think now we should get serious about the track list. Mostly I was happy with it and didn't have a comment for tracks I wasn't interested in - unless we begin to run out of room.
-Chris
Edit: Here is a more complete list that maybe could be a starting point unless there is too much disagreement
http://www.diyaudio.com/forums/analogue-source/313335-test-lp-buy-11.html#post5252022
I've thought about that one. Will defer to others as to whether or not it's important.
I think middle or end. Anyone have other ideas? Does track position or linear speed have any useful information?