What is vinyl 'roar'

[Trackside]

Roar.jpg (152.98 KiB) Viewed 960 times

This is what it looks like but what are the main culprits;
1,Residual noise from the cutting or pressing that is actually 'recorded' or imprinted in the groove.
2,The texture of the vinyl itself and or any impurities.
3,Noise generated by the friction of the stylus against the vinyl.
4,Mechanical noise from the turntables drive and bearing system.
5, ?
The attached is taken from the following setup;
HFN test record residual groove, pink noise and phono system noisefloor (cart off the surface of the spinning record.
Cart is DL-103, TT SL-1200 MK2, Phono stage is V-LPS + V-PSU, A-D is E-MU 0404 usb, Recording at 44/16 using Adobe Audition CS5 using ASIO. FFT frequency analysis set to 65536 Blackman-Harris averaged L+R channels, Frequency window 20hz to 20khz in Logarithmic scale.
Additional notes;
Drive system / bearing of the Sl-1200 is very quiet - probably as good as it gets unless you spend serious sum of money and mine's modded and quieter than stock. HFN residual groove is not the quietest silent groove - other records show less peaks in below 50hz. HFN Pink noise track is not clean in the upper frequencies - recording at 45rpm pushes these irregularities past 20khz so it's not the cart / phono stage.

[duficity]

my definition of vinyl roar is that constant noise that is not part of the recorded sound or damage to the disc. So something other than tape hiss, ticks, pops, music, microphone artifacts etc. I could be the stylus friction in the groove, but I would also include any sound from a grooveless disc, which would probably be coming from the bearing and drive system.
anything else the stylus picks up, it is meant to, whether music, ticks, pops or other artifacts. The stylus doesnt know the difference between a scratch and music. It just responds. but if there is sound beyond that, I count that as roar.

By the way, does a silent groove have any modulation? At a microscopic level, what do the groove walls look like. Is there an accepted tolerance for groove walls.

And as for records which are eccentric with respect to the spindle hole, is the master also cut with that eccentricity, or does that only happen in the final stamping stage?

[Trackside]

IMO Vinyl roar is everything picked up by the stylus that is not in the original recording. Mic noise, tape hiss etc are other issues.

[youngdand]

The quality of the vinyl used is i think quite a big factor. I have the Hi Fi For Pleasure Stereo Test Disc, and although quiter than most records in my collection, still has substantially more roar than some japanese pressed records i have.

I have some direct to disc recordings that are so quiet that i have to check that i have put the cue lever down.

[lensmanMK2]

i quite like groove roar,i use it as a tool to evaluate changes to a tt/cart

for me more groove roar on a bit of vinyl i know will result in a better sound,seems to work with multiple turntables and cart combinations.

why i dont know,but i use it and it works.

by the way young,what is "direct to disc"? do they record direct to a master disc like the 60s?

[youngdand]

They Cut the disc alongside the performance. A couple of the discs have got good inserts explaining the process and equipment used, if i get time i will try and scan some in.

http://en.wikipedia.org/wiki/Direct_to_disc_recording

I have a couple of Jun Fukamachi and a lee ritenour. i have a couple of others somewhere, but those stck out in my head.

jun fukamachi "at Steinway" is a fantasticall recorded album, but belt drives dont do it justice!

[satanfriendly]

IMO Vinyl roar is everything picked up by the stylus that is not in the original recording. Mic noise, tape hiss etc are other issues.

I agree to some extent. What confuses the issue though is a change of cartridge can reduce/increase the 'roar' experienced. Surely it can be attributed to a number of other issues associated with the cartridge itself, stylus profile, materials used in the cartridge body and general rejection/absorption of other influences by the cartridge itself.

I am not sure it could be associated to bearing noise etc as a change of cartridge bringing about a change in the level of 'roar' using the same turntable would indicate not. A change of mat can often reduce additional and unwanted noise levels.

Certainly the quality of the pressing itself should be a consideration figured in. I have had a number of duff vinyl discs which were in reality unusable due to the level of surface noise/interference on the disc itself.

So nothing to say 'this is the cause?' or 'what is it?', but I've thrown together a number of possible influences.

[missan]

FWIW, normally the noise floor above, let´s say 500-700, is very even. The level might vary, but the curves look very much the same. This points to me that this is not really a 'tracing' floor, but a result from how the friction is varying at lower freq. And as a result from how the friction varies this will introduce different noise levels, but with rather similar appearance. If I understand LD correctly that is, but it makes sense to me I think. It´s difficult to see how the level at higher freq can 'work on it´s own', as there is practically no variation in level.
Even with very low friction there still is 'roar', but the noise floor at higher freq is significantly lower. Maybe how still the cartridge can be in relation to cantilever pivot has some influence, it´s just a thought, or if it´s possible for the pivot to move differently depending on design.
missan

[analogaudio]

............vinyl roar is one of the reasons CD was invented.............

[duficity]

trackside,
You said IMO Vinyl roar is everything picked up by the stylus that is not in the original recording. Mic noise, tape hiss etc are other issues
I dont quite understand. are you saying that mic noise, tape hiss etc is not in the original recording, so therefore it is vinyl roar, or that that mic noise, tape hiss, etc are in the recording, so its not vinyl roar. or something else. As far as I know, tape hiss and mic noise are in the recording. Where else would they come from.

[Trackside]

trackside,
As far as I know, tape hiss and mic noise are in the recording. Where else would they come from.

and therefore they are not part of vinyl roar IMO

[Ldg]

Here's some food for thought, self-plagerised from my own posts on this topic, which are fairly scattered to the wind, it pulls them together:

Here's an attempt at an explanation, and an audio simulation that seems pretty plausible, IMO. And perhaps explains all manner of vinyl surface noise effects and events......

If groove-stylus friction randomly changes due to natural vinyl material variation, say, in vinyl surface grain, instantaneous friction would have random flicker noise, (pink). It being by far the most common in nature.

ie friction would vary randomly to an extent, with a noise-time variation like this :



Marked up, is a hypothetical red line, above which a stylus might move (micro-mistrack) due to downforce being inadequate to hold position. Red line position depends on groove modulation forces, and cartridge/stylus specifics.

Cartridge noise output would be just due to the fraction above the line, where the stylus moves. Which might comprise this, for example :



One can see, it looks like random pop/crackle, the correct form for the noise we observe here.

You can hear how remarkably close to the observed noise sound it is ! What I'm suggesting is the effect of loud hf sounds, like Miles' trumpet, or the Tom Petty intro, is to lower the red line. Also this simulation sounds remarkably like surface noise in general. It's spooky.

So I'm pretty enthusiastic about this explanation, can't see a contradiction in fact.

Also, it perhaps opens the door to exploring and explaining the nature of surface noise in general, why and how it varies. For example, how wetting significantly influences surface noise, or why surface noise decreases toward inner grooves, how new vinyl pressing have variable surface noise, why worn styli show more surface noise. This is, of course, enormously interesting.

I think 'micro-mistracking' would always have both some lateral, and vertical motion content, it being a slide up one groove wall, in principle. So not much pure in-phase or out-of-phase L/R content, and a bit of a mixed bag i think. Seems to accord with some of my recordings. Also with the general view that L/R surface noise is not coherent.

The direction stylus would move when downforce isn't enough to hold it (in 'micro' mistracking), would depend upon the momentum and direction it already had, and direction of other forces in play. So it's not easy to analyse, i think, but motion would always have at least some vertical component to it.

Even if friction flicker noise is a 'sometimes' factor in surface noise, it is unlikely to be the only factor. I also like the 'base clearance' theory as to why there can be variance between styli as to surface noise performance.

I thought about how friction flicker noise might apply to silent grooves, and general surface noise. At first, I couldn't see how any upforce could be generated. Then realised there is c 20 deg VTA, and c 25 deg lateral tracking angle (applied to 45 deg wall), through which tonearm drag is applied. Tonearm drag would have flicker varation, of course, it being groove-stylus friction derived. So perhaps it's possible.

I'm curious whether, rather than surface level variation (pits and peaks), variation in vinyl material composition contributes to variation in friction, and so that is a mechanism for normal surface ticks, pops and crackle ? Even in silent grooves.

Just that a bad pressing, eg many from the 70s in the great vinyl famine, seems to show a very similar crackle/pop sound notable even on silent sections, and sometimes throughout the whole pressing. And generally worse on outer tracks, and often fixable by wetting during play.

So perhaps friction flicker and vinyl material variation at least plays a part in general surface noise crackle/pop ? Particularly in bad/degraded pressings.

Some quick calculations suggest that friction flicker noise might be significant in normal surface noise crackle/pop/ticks as follows :

IF stylus-groove friction has natural random variation that follows a flicker law, roughly peak friction would be 12dB above rms level [IIRC]. RMS friction level is known, from Yosh's site/JVC figures and own measurements. Then we can estimate peak (flicker) friction.

Without going into detail for now, applying this peak friction force via a 20 deg VTA, and via a 25 deg tracking offset angle to a 45 deg groove wall, is calculated to be typically just enough to exceed VTF, even on a silent groove, dependant on friction coefficient.

So perhaps micro-mistracking does happen in normal, even silent grooves ? And this might be a significant mechanism for how surface noise crackle/pop arises ?

Here's a paper illustrating how (1/f or flicker) variation in friction force might arise in the stylus-groove interface. Stick-slip friction being often mooted as the vinyl-stylus mode, as referenced below.

In any event, it shows (perhaps) analogous test results and a model with a steady state friction element, plus a variable random element that has a 1/f or flicker profile. It is particularly interesting, because it also discusses the role of debris and loose material, which has obvious relevance to a vinyl-stylus environment. eg for debris read thin film of surface contaminant say from washing. However, the tests and model are not in a vinyl environment. But here's enough to be interesting, enlightening, and suggestive by analogy, IMO.

DEBRIS AND 1/f NOISE IN SLIDING FRICTION UNDER WEAR CONDITIONS
M. Duarte et al

http://www.gef.es/Congresos/26/PDF/89.pdf

I also found this literature search which Klaus made and posted about 6 years ago here on VE (!) :

W.r.t. an issue that was mentioned below, i.e. noisy records, here's what I could find in related literature:

SURFACE NOISE

Factors responsible for surface noise are:

Major contributor is the master tape recording.

Factors directly to vinly factors are :
1. Surface roughness : filler
2. Welding and shearing of asperities (roughness, harshness)
3. The associated plastic deformation : microscale intermittency of plastic flow : volumetric version of stick slip behaviour, slipping of molecular aggregates from one position of equilibrium with their neighbours to another, discontinous motion on microscale.
4. Thermal agitation of cutting stylus
5. Lead screw vibration transmitted to cutting head
6. Vibration of stylus induced by frictional drag, stick slip motion during sliding friction : each asperity (roughness) will first stick, then progressively experience elastic deformation in shear produced by the gross sliding motion, until finlly the shear stress becomes high enough to produce a slip either by rupturing the asperity or by casuing the adhering surfaces to separate. Note that stick-slip motion is capable of generating timing errors similar to digital jitter.

[1] Barlow : Limiting factors in gramophone reproduction, Wireless World, 1957, vol.63, p.228
[2] Hunt : On stylus wear and surface noise in phonograph playback systems, JAES, 1955, Jan., p.2

Perhaps there's insight into one of the causal mechanisms behind surface noise crackle&pop here. ie through flicker variation in friction force and resultant micro-mistracking. Then the noise phenomenum of the OP might be simply explained by reduced nett downforce, increased friction, and so degraded tolerance to normal variation in surface friction. Under conditions of tracing high acceleleration grooves (loud hf).

If so, quite a few other surface noise 'oddities' begin to make some sense too, IMO.

Here's a markup of one of the test result plots from the Duarte et al paper. It shows the model I think might apply to vinyl-stylus friction. ie a steady state friction element (1), and a random variable element (2) which follows a flicker law :



If so, one might improve surface noise (with this origin), either by improving 1 or 2. Or by improving overall cartridge/setup tolerance to coping with it. Some elements will be intrinsic to the vinyl pressing or treatment thereof, some to the stylus/cartridge, and some to the setup.[/quote]

Anything that improves stable downforce without increasing friction should help. I also think these would be very fast, short mistracking events, no time for the headshell to move, and so it's all about cantilever rigidity, suspension, and tip inertia, i think. Holding the stylus put, and delivery of the downforce.

[Trackside]

If micro mistracking is occurring in silent unmodulated grooves ( which I'm sceptical about) then increasing velocity would change it's nature seeing that all other factors are equal - VTA, VTF etc. Recording a silent groove at 45rpm and 33rpm would show either a shift of the roar spectrum up the frequency range in line with a pitch change or change it's character in some other way in the nature of an increase in mistracking without a pitch change?

[Ldg]

If micro mistracking is occurring in silent unmodulated grooves ( which I'm sceptical about) then increasing velocity would change it's nature seeing that all other factors are equal - VTA, VTF etc. Recording a silent groove at 45rpm and 33rpm would show either a shift of the roar spectrum up the frequency range in line with a pitch change or change it's character in some other way in the nature of an increase in mistracking without a pitch change?

I think that would depend on exactly what stylus-groove tribology is going on, but generally friction coefficient is taken not to be related to velocity within reasonable limits. There's bound to be some effect, but it appears small in the context of change in rpm. AFAIK what is going on in tribolgy of stick-shift friction is the random making and breaking of tiny adhesions between surface asperities. Neither click & crackle noise nor flicker noise spectrum should pitch shift with 33/45 velocity, I think if anything these naturally would just change level slightly if tribology remains the same.

It will be easy to confirm via silent track spectrum at 33/45 rpm. Rumble due to bearing surface irregulaties, certain mechanical arrangements, or groove irregularities will pitch scale though, so that would need to be seperated somehow.........