Civilized life is the last retreat of the unpliable mind.
For me the primordial soup is an aspiration and an ascension toward untethering and freedom, not a state of decrepitude.
I take it there’s no Ornette Coleman on your shelf either...
To each their own.
However this does show that including some well recorded music tracks might not be the best course of action, given that many disagree completely on what should be considered music at all.
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Hi folks
Just occurred to me if anyone thought of checking Canadian based plants. Currency is favourable aganst US and Euro and postage out of the country too.
No affiliation.
RIP-V | Montreal, Quebec
Precision Record Pressing. State of the art record pressing plant.
Paba
Just occurred to me if anyone thought of checking Canadian based plants. Currency is favourable aganst US and Euro and postage out of the country too.
No affiliation.
RIP-V | Montreal, Quebec
Precision Record Pressing. State of the art record pressing plant.
Paba
Locked groove: modulation step response
Just saw/commented on some a speed stability discussion on
http://www.diyaudio.com/forums/analogue-source/309349-turntable-speed-stabilty-104.html#post5359273
So was thinking the lock groove 3150Hz test signal discussed here: is a harmonic steady state response signal (well locally for a part of the revolution sufficient to estimate 'instant' frequency).
What if we could have one locked groove w 3150Hz BUT, w a step up/down response in modulation depth. Would'nd that expose possible problems wrt record slippage/insufficient platter inertia etc?. I.e. ½ revolution high modulation, then step down to rest ½ revolution low modulation. IF modulation effects matter they should show up in the polar plots. Though for heavy platters the inertia might be so high that single revolution changes are not enough to capture this effect.
/wolf_skate
Just saw/commented on some a speed stability discussion on
http://www.diyaudio.com/forums/analogue-source/309349-turntable-speed-stabilty-104.html#post5359273
So was thinking the lock groove 3150Hz test signal discussed here: is a harmonic steady state response signal (well locally for a part of the revolution sufficient to estimate 'instant' frequency).
What if we could have one locked groove w 3150Hz BUT, w a step up/down response in modulation depth. Would'nd that expose possible problems wrt record slippage/insufficient platter inertia etc?. I.e. ½ revolution high modulation, then step down to rest ½ revolution low modulation. IF modulation effects matter they should show up in the polar plots. Though for heavy platters the inertia might be so high that single revolution changes are not enough to capture this effect.
/wolf_skate
Member
Joined 2009
Paid Member
Hi Chris
Well yes ok .. but some of the analysis thought to be done w this LP is apparently not all for standard test equipment use but, w dedicated instant freq. estimation algorithms (taking sampled raw signal in from phono amp).. so in this case a level step could be used?
/patrick
Hi Pano
Well personally I'd like a 1step locked groove: 50% high level - 50% low level..Difference in modulation levels as much as can be reasonably be considered plausible for most cartridges to just cope but also being sufficiently stressed (20dB or 30dB?.. too low a level an we have noise problem, but with a locked groove we can average that out). Thread on
http://www.diyaudio.com/forums/analogue-source/309349-turntable-speed-stabilty-105.html#post5361385
post #1047-1048
suggest it is more the arm/cartridge instability which looks like drag induced speed changes (opposed to actual platter speed change). The posters on above thread will likely know more about what is best practical levels/procedure.
Such Locked grove only makes sense if the expected step responses are shorter than ½ revolution .. else open track is needed over several revolutions (loosing the possibility to coherently suppress noise etc)
None the less such a test seems valuable for the 'tool box' supplied by the LP (which should provide things other did not .. as well as classical test need to there)
Other thing I was asking at some point .. markers are considered on some tracks as I could under stand. Is it possible to have markers placed on exact same radial across different tracks? (so on test track we could cross transfer some test result to clean up another test on another track.. like estimating record off-centring on one track (constant pitch/level locked groove) to compensate for other pitch sensitive test tracks in post processing) ??
/Patrick
Pano and I discussed this a little. There is an inherent problem with a few of our ideas like trying to get exactly 5670 cycles (3150Hz) with one missing as a marker in a single locked groove. This would require the lathe to be perfect. We will probably need to leave a space as a position marker so we have a cycle count plus a delta t that can be read by simply counting sample clock cycles. Having any markers on different tracks align at exact radii is probably hopeless.
(I'm back, some unforeseen problems with my 94yr. old mother)
Right Scott. We don't know how locked grooves are cut, and it may be that each engineer has his own ideas. E.G. if the track lasts longer than 1.8 seconds, is there an over cut of the beginning of the track, or does the lathe engineer stop short?
We need to know that before we know exactly what we can cut.
We need to know that before we know exactly what we can cut.
No, but the exact number of cycles actually cut does depend on the lathe and the source being exactly synced. If you supply a cut exactly 1.8sec long (@ 96k, 172800 samples) and the lathe is .05% slow that's an 86.4 sample gap. If the lathe is fast you overrun the end.
IMO we need to leave a gap that covers the max spec on lathe speed and take it into account.