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CD-R and Audio Hardware => Vinyl => Topic started by: Pepzhez on 2010-09-09 13:08:28

Title: Inner Groove Distortion
Post by: Pepzhez on 2010-09-09 13:08:28
As compared to vinyl, CD/FLAC/MP3/AAC are extremely handicapped when it comes to producing inner groove distortion.

In other words, if distortion is your thing, vinyl cannot be beat; nor can said distortion be eliminated from the format.
Title: Inner Groove Distortion
Post by: doctorcilantro on 2010-09-09 15:47:18
As compared to vinyl, CD/FLAC/MP3/AAC are extremely handicapped when it comes to producing inner groove distortion.

In other words, if distortion is your thing, vinyl cannot be beat; nor can said distortion be eliminated from the format.


Not that simple.  Some sides are cut a 10 minutes, and why people use linear trackers.
Title: Inner Groove Distortion
Post by: Pepzhez on 2010-09-09 16:35:14
Ten minute sides are a solution of sorts, albeit not very common, practical, or particularly good value for money. Such releases cover, oh, I'd guess .0000000000000000000000000000000000000000000000000000001 of recorded music, if even that.

Likewise, linear tracking tables in theory work to minimize inner groove distortion, but in actual practice this is not so easy to accomplish. There were a slew of linear tracking turntables on the market in the early 1980s. Most were mediocre, or worse, performers, and these devices are not held in very high esteem today -- nor are they particularly sought after.

This isn't to say that vinyl cannot be an enjoyable listen, and, yes, a vinyl version of a particular recording may for a variety of reasons be preferable to its CD counterpart, but there are inherent limitations to the format that one ought to be aware of and will have to live with, one way or another. Inner groove distortion and wobbling pitch were always annoyances to me. If such things do not bother you, then you needn't worry about them.
Title: Inner Groove Distortion
Post by: botface on 2010-09-10 09:33:28
Inner groove distortion and wobbling pitch were always annoyances to me.

Sounds like your turntable was pretty poor quality and not set up properly
Title: Inner Groove Distortion
Post by: Pepzhez on 2010-09-10 12:28:24
You are incorrect on both counts. Early on I owned the usual substandard Gerard phonographs that young kids tended to have. Later on I owned top shelf model (and highly regarded during their era) turntables from the likes of Dual and Linn. Without a doubt those tables were big improvements, and while they can help tremendously to minimize the inherent shortcomings of the format, they certainly cannot eliminate them.

Yes, I do know how to set up a turntable properly, thank you. That was a necessary acquired skill at the time for anyone desirous of decent vinyl playback.
Title: Inner Groove Distortion
Post by: botface on 2010-09-10 12:36:46
You are incorrect on both counts. Early on I owned the usual substandard Gerard phonographs that young kids tended to have. Later on I owned top shelf model (and highly regarded during their era) turntables from the likes of Dual and Linn. Without a doubt those tables were big improvements, and while they can help tremendously to minimize the inherent shortcomings of the format, they certainly cannot eliminate them.

Yes, I do know how to set up a turntable properly, thank you. That was a necessary acquired skill at the time for anyone desirous of decent vinyl playback.

That's curious. I've never heard "wobbling pitch" from a decent turntable that's been properly maintained. I've also never been unduly troubled by inner groove distortion on most records. If you know how to set up a cartridge/arm properly you will appreciate that inner groove distortion can be reduced to insignificant levels - not totally eliminated, you're right. Having said that the degree of distortion also depends on programme material. Maybe you just have better ears than me
Title: Inner Groove Distortion
Post by: Fedot L on 2010-09-10 14:58:54
…linear tracking tables in theory work to minimize inner groove distortion

No. The so-called "inner groove distortion" has nothing to do with neither tone-arm type (pivoting or linear tracking) nor cartridge alignment adjustment. Even with the best cartridge alignment adjustment, the "tracing distortion" will be present, as not depending on it.

The distortion that increases as the stylus passes from the “outer” to the “inner” grooves, is not an “inner groove distortion”, the so-called "inner groove distortion" is the "tracing distortion", non-linear distortion proper fundamentally to the mechanical reproduction of any groove (and not only "inner") of a gramophone record, and by any stylus, due to the difference between the shapes of the cutter chisel and the stylus. But to a variable degree, depending, at equal signal frequency and amplitude, on the radius of the groove. And in the same groove, on the shape of the stylus' surface in contact with the groove.

The only way to reduce it very considerably with "mechanical" cartridges: the use of styli types designed and manufactured for CD-4 discrete quadraphonic reproduction (“Shibata”, “Pramanic” etc.), or their modern analogues (“Fine-line”, “Line contact” etc.) having the finest possible radius of contact with the groove sides.

http://www.answers.com/topic/tracing-distortion (http://www.answers.com/topic/tracing-distortion)

Good illustrations:
http://www.speakerbits.com/speaker-repairs...article-24.aspx (http://www.speakerbits.com/speaker-repairs/about-cartridges-stylus-types/article-24.aspx)

A general link:
http://www.google.ru/search?hl=ru&neww...q=&gs_rfai= (http://www.google.ru/search?hl=ru&newwindow=1&q=known+by+the+name+%22tracing+distortion%22&btnG=%D0%9F%D0%BE%D0%B8%D1%81%D0%BA&aq=f&aqi=&aql=&oq=&gs_rfai=)
Title: Inner Groove Distortion
Post by: doctorcilantro on 2010-09-11 03:17:19
…linear tracking tables in theory work to minimize inner groove distortion

No. The so-called "inner groove distortion" has nothing to do with neither tone-arm type (pivoting or linear tracking) nor cartridge alignment adjustment. Even with the best cartridge alignment adjustment, the "tracing distortion" will be present, as not depending on it.

The distortion that increases as the stylus passes from the “outer” to the “inner” grooves, is not an “inner groove distortion”, the so-called "inner groove distortion" is the "tracing distortion", non-linear distortion proper fundamentally to the mechanical reproduction of any groove (and not only "inner") of a gramophone record, and by any stylus, due to the difference between the shapes of the cutter chisel and the stylus. But to a variable degree, depending, at equal signal frequency and amplitude, on the radius of the groove. And in the same groove, on the shape of the stylus' surface in contact with the groove.

The only way to reduce it very considerably with "mechanical" cartridges: the use of styli types designed and manufactured for CD-4 discrete quadraphonic reproduction (“Shibata”, “Pramanic” etc.), or their modern analogues (“Fine-line”, “Line contact” etc.) having the finest possible radius of contact with the groove sides.

http://www.answers.com/topic/tracing-distortion (http://www.answers.com/topic/tracing-distortion)

Good illustrations:
http://www.speakerbits.com/speaker-repairs...article-24.aspx (http://www.speakerbits.com/speaker-repairs/about-cartridges-stylus-types/article-24.aspx)

A general link:
http://www.google.ru/search?hl=ru&neww...q=&gs_rfai= (http://www.google.ru/search?hl=ru&newwindow=1&q=known+by+the+name+%22tracing+distortion%22&btnG=%D0%9F%D0%BE%D0%B8%D1%81%D0%BA&aq=f&aqi=&aql=&oq=&gs_rfai=)



So now you're suddenly equivocating 'innner groove distortion' with 'tracing distortion'? One being a function of tonearm alignment, and the other due to stylus shape. Not new concepts, and often addressed by today's designers.

And then admit something like an Optimized Contour Contact Line diamond will function great.

Sure, you may have to match up a linear tracker more carefully to cart., and worry about lateral effective mass, but do it right, and you can achieve more than acceptable fidelity.

Sure vinyl has it's limits, but there are some damn good implementations these days.

Troll?
Title: Inner Groove Distortion
Post by: Arnold B. Krueger on 2010-09-11 09:47:19
As compared to vinyl, CD/FLAC/MP3/AAC are extremely handicapped when it comes to producing inner groove distortion.

In other words, if distortion is your thing, vinyl cannot be beat; nor can said distortion be eliminated from the format.


Not that simple.  Some sides are cut a 10 minutes, and why people use linear trackers.


Linear trackers do not resolve most problems with inner groove distortion, or inherent LP distortion in general.  They do address two kinds of distortion that I can think of, one of which does not absolutely need a linear tracker to address. But, there are plenty other kinds of distortion that linear trackers don't help with at all. That's one reason why they did not take over the marketplace - they were only a fractional solution.
Title: Inner Groove Distortion
Post by: Arnold B. Krueger on 2010-09-11 10:02:58
So now you're suddenly equivocating 'inner groove distortion' with 'tracing distortion'? One being a function of tonearm alignment, and the other due to stylus shape. Not new concepts, and often addressed by today's designers.


What he's saying is that inner groove distortion has two major causes, only one of which is addressed by linear tracking tone arms. This is fact. You can't play divide and conquer unless you actually conquer both of them.

Quote
And then admit something like an Optimized Contour Contact Line diamond will function great.


Great compared to what? Compared to less-optimal styli, they trade reduced but not vanishing tracing distortion for other problems, including a need for increased mounting precision.

Quote
Sure, you may have to match up a linear tracker more carefully to cart., and worry about lateral effective mass, but do it right, and you can achieve more than acceptable fidelity.


I don't think that anybody is saying that vinyl can't have acceptable fidelity if you are tolerant enough of audible noise and distortion. Some of us happen to not be so tolerant, and will only find it to be acceptable when other generally superior alternatives fail, mostly for non-technical reasons like disagreeable mastering or the simple fact that much great music was recorded before digital.

Quote
Sure vinyl has it's limits, but there are some damn good implementations these days.


I have yet to see any significant improvements in basic vinyl playback in the past 20 or 30 years.  Just different trade-offs or more often, just a lot of hype.
Title: Inner Groove Distortion
Post by: doctorcilantro on 2010-09-11 12:19:29
Fair enough. Just seemed like the poster was equivocating.

So avoiding Pinch Effect is impossible with any modern arm/tonearm?

I have read arguments against LTs because of possible mistracking on off-center pressings which 'should' cause mistracking. Haven't noticed that myself, yet.

Axon noted:

Quote
Tracking and tracing distortion are rather similar mathematically, so I strongly suspect that what most people refer to as "mistracking" really is mistracing or tracing distortion. Mistracking only happens when the stylus physically loses contact ("tracking") with one or both sides of the groove. That's usually not what's going on with IGD.


I take you believe that IGD remains with linear trackers because of exactly ...?

If the stylus is tangential to the groove, what happens when using a linear tracking with an off-center pressing as it approaches the end of an LP?

thanks

So now you're suddenly equivocating 'inner groove distortion' with 'tracing distortion'? One being a function of tonearm alignment, and the other due to stylus shape. Not new concepts, and often addressed by today's designers.


What he's saying is that inner groove distortion has two major causes, only one of which is addressed by linear tracking tone arms. This is fact. You can't play divide and conquer unless you actually conquer both of them.

Quote
And then admit something like an Optimized Contour Contact Line diamond will function great.


Great compared to what? Compared to less-optimal styli, they trade reduced but not vanishing tracing distortion for other problems, including a need for increased mounting precision.

Quote
Sure, you may have to match up a linear tracker more carefully to cart., and worry about lateral effective mass, but do it right, and you can achieve more than acceptable fidelity.


I don't think that anybody is saying that vinyl can't have acceptable fidelity if you are tolerant enough of audible noise and distortion. Some of us happen to not be so tolerant, and will only find it to be acceptable when other generally superior alternatives fail, mostly for non-technical reasons like disagreeable mastering or the simple fact that much great music was recorded before digital.

Quote
Sure vinyl has it's limits, but there are some damn good implementations these days.


I have yet to see any significant improvements in basic vinyl playback in the past 20 or 30 years.  Just different trade-offs or more often, just a lot of hype.

Title: Inner Groove Distortion
Post by: Saucerful on 2010-09-11 17:13:35
I've been into vinyl casually for about 2 or 3 years. I have a Stanton T.120C turntable, that's the version with the S-shaped tonearm. My cartridge is a Shure M97xE. Despite being quite inexperienced with vinyl, my ear is pickier than some, and so I consider the inner groove distortion produced by my rig to be bothersome.

At first I thought it was because of the way I set the cartridge up, but I had it taken off and reinstalled by the DJ/PA equipment specialist at my local music shop. Same issue with very noticeable inner groove distortion. Granted, it seems to be much more noticeable on some records than on others, and most of my vinyl is used, which leads me to believe that part of the issue can be blamed on the poor tracking of previous owners' cartridges. I know something is definitely wrong though, because I experience the distortion even on new vinyl close to the inner groove and especially on 7" vinyl where the tonearm is consistently on a more extreme angle.

If you're wondering about the rest of my rig, for now I'm just using the built-in phono preamp on my turntable and going line-in to my Asus Xonar Essence STX sound card and out to my Sennheiser HD 555 headphones.

So, notwithstanding any sound quality issues inherent in using the built-in preamp or any of that sort of thing, I'm wondering what my best course of action would be to reduce inner groove distortion. For now, I'm just getting ideas, so price isn't really an object. I'll sort out what I can afford later. I just want to know what are the likely culprits. Should I replace my cartridge? Or should I toss my Stanton and get an entirely different turntable? I'm not looking to replace my entire rig just yet, so suggestions for headphones and preamps/amps aren't really what I'm looking for today. I'm just wondering what I should do with my turntable/cartridge setup.

Thanks in advance.
Title: Inner Groove Distortion
Post by: Fedot L on 2010-09-12 18:39:19
…linear tracking tables in theory work to minimize inner groove distortion

No. The so-called "inner groove distortion" has nothing to do with neither tone-arm type (pivoting or linear tracking) nor cartridge alignment adjustment. Even with the best cartridge alignment adjustment, the "tracing distortion" will be present, as not depending on it.

So now you're suddenly equivocating 'inner groove distortion' with 'tracing distortion'? One being a function of tonearm alignment, and the other due to stylus shape.

The so-called "inner groove distortion" is not a function of tone-arm alignment. Any pivoting  tone-arm alignment leaves variable horizontal tracking angle errors and in “outer”, and in “medium”, and in “inner” grooves.

And linear tracking tone-arms reduce horizontal tracking angle errors to negligible levels.

Concerning what I’ve written about tracing distortion, proper to ANY groove, and not to “inner ones”, and why it is so, I’ve nothing to add to what I’ve written (and studied by specialists since 1940s).
And then admit something like an Optimized Contour Contact Line diamond will function great.
Sure, you may have to match up a linear tracker more carefully to cart., and worry about lateral effective mass, but do it right, and you can achieve more than acceptable fidelity.

You are right. That’s just what I wrote in my first post.
So now you're suddenly equivocating 'inner groove distortion' with 'tracing distortion'? One being a function of tonearm alignment, and the other due to stylus shape. Not new concepts, and often addressed by today's designers.

What he's saying is that inner groove distortion has two major causes…

Who is that “he”?
As for me, I never said this. Once more, I’ve repeated in this post above that what is popularly called “inner groove distortion” is not “inner groove distortion”, but the distortion proper to the playing of ANY groove by a stylus that has not, and cannot have, the profile of the cutting chisel, but aggravating on the shorter radii of the record. Thus having ONE cause.
Title: Inner Groove Distortion
Post by: Arnold B. Krueger on 2010-09-13 10:19:10
So now you're suddenly equivocating 'inner groove distortion' with 'tracing distortion'? One being a function of tonearm alignment, and the other due to stylus shape. Not new concepts, and often addressed by today's designers.

What he's saying is that inner groove distortion has two major causes…

Who is that “he”?
As for me, I never said this. Once more, I’ve repeated in this post above that what is popularly called “inner groove distortion” is not “inner groove distortion”, but the distortion proper to the playing of ANY groove by a stylus that has not, and cannot have, the profile of the cutting chisel, but aggravating on the shorter radii of the record. Thus having ONE cause.


That "he" is me, Arnold B. Krueger.

I see you are playing with personalities rather than deal with the question that I asked.

Here it is again:

"Inner groove distortion has two major causes, only one of which is addressed by linear tracking tone arms. This is fact. You can't play divide and conquer unless you actually conquer both of them."

The two causes of inner groove distortion are:

(1) Cartrdige not being held tangent to the groove

(2) Wavelengths on disk shortened by smaller groove radius

Linear tracking can address (1) but not (2).

Pinch effect is only part of (2).


Title: Inner Groove Distortion
Post by: Fedot L on 2010-09-13 13:26:35
What he's saying is that…

Who is that “he”?

I see you are playing with personalities rather than deal with the question...

I see it’s quite mutual.
…the question that I asked.
Here it is again:
"Inner groove distortion has two major causes, only one of which is addressed by linear tracking tone arms. This is fact. You can't play divide and conquer unless you actually conquer both of them."

The question that I already answered. There is no “inner groove distortion”. What is popularly called “inner groove distortion” is not “inner groove distortion”, but the distortion proper to the playing of ANY groove by a stylus that has not, and cannot have, the profile of the cutting chisel, but aggravating on the shorter radii of the record. And called “tracing distortion”.
The two causes of inner groove distortion are:
(1) Cartridge not being held tangent to the groove

Cartridge not being held tangent to the groove is not a cause of the tracing distortion that some people call "inner groove distortion", because such a bad cartridge adjustment causes considerable horizontal angle errors and in “outer”, and in “medium”, and in “inner” grooves.
(2) Wavelengths on disk shortened by smaller groove radius

The tracing distortion that some people call "inner groove distortion" is present on ANY groove radius played by styli, and being caused by the difference between profiles of the cutting chisel and of ANY stylus, that have not, and cannot have, the profile of the cutting chisel. This distortion increases with groove radius decrease, because, you are quite right, of wavelengths on disk shortened by smaller groove radius, thus making the stylus more and more incapable of following the grooves’ micro-convolutions.
Title: Inner Groove Distortion
Post by: doctorcilantro on 2010-09-13 13:54:55
So now you're suddenly equivocating 'inner groove distortion' with 'tracing distortion'? One being a function of tonearm alignment, and the other due to stylus shape. Not new concepts, and often addressed by today's designers.

What he's saying is that inner groove distortion has two major causes…

Who is that “he”?
As for me, I never said this. Once more, I’ve repeated in this post above that what is popularly called “inner groove distortion” is not “inner groove distortion”, but the distortion proper to the playing of ANY groove by a stylus that has not, and cannot have, the profile of the cutting chisel, but aggravating on the shorter radii of the record. Thus having ONE cause.


That "he" is me, Arnold B. Krueger.

I see you are playing with personalities rather than deal with the question that I asked.

Here it is again:

"Inner groove distortion has two major causes, only one of which is addressed by linear tracking tone arms. This is fact. You can't play divide and conquer unless you actually conquer both of them."

The two causes of inner groove distortion are:

(1) Cartrdige not being held tangent to the groove

(2) Wavelengths on disk shortened by smaller groove radius

Linear tracking can address (1) but not (2).

Pinch effect is only part of (2).

@ Fedot

I quoted you above, confusing your comments with those of Pepzhez, thus was very confused. Thanks for your insights.


@ ABK

Sorry for any confusion, my spacebar tore off my laptop and I was being lazy. I was speaking to Fedot (mistakenly) as I simply thought it was unclear what he meant, or rather what I'm glad we are now discussing. I understand you can't write a dissertation and it's fair to summarize your experience with these technicalities, but it seemed to me (most likely simply as a result of my ignorance on these matters compared to you) you had wrapped everything into vinyl = distortion = bad. I understand vinyl has very real and measurable defficiencies, I just wonder how audible these defficienices are.

What are some of the systems you have used or tested in the last 20 years?

So tracing distortion and pinch effect are aggravated at the inner grooves; for "music" or a sine wave?

Is it true as the groove speed decreases distortion rises? The wavelength shortens, and coupled with shape of the "inadequate" playback stylus, we get tracing distortion? Is this audible enough to detract from the fidelity in a meaningful way given an optimized setup (contact line stylus, tangential tracking). Many modern records, on 2 LPs seem to be cut a 10 minutes per side, or cut at 45rpm (which I assume would help?)


thanks for all the great discussion so far
Title: Inner Groove Distortion
Post by: Leigh on 2010-09-13 15:24:23
The two causes of inner groove distortion are:

(1) Cartrdige not being held tangent to the groove

(2) Wavelengths on disk shortened by smaller groove radius

Linear tracking can address (1) but not (2).

Pinch effect is only part of (2).


Yes. (2) is not hard to understand at all if given even a small amount of thought. Take one revolution of an LP and measure the length of the vinyl groove the needle passes through. It's simply 2*pi*r where r is the radius (distance from the spindle to the location of the needle). As you approach the end of an LP side you have all that musical information squished into a smaller amount of groove length. It is difficult if not impossible to have the same amount of fidelity in the last song on a side compared to the first. As I understand it, cutting engineers reduce the high frequencies in songs towards the end of a side to reduce the chance of "overloading" the stylus. This in and of itself isn't distortion, but it is a reduction in fidelity and one of the reasons vinyl drives me nuts. Some needle designs are better than others in "tracking" correctly. "Microline" styli seem to do a good job. I am immensely pleased with the Audio Technica AT440MLa in this regard. It has virtually eliminated that spitting sound on vocal S's etc., which is what I most closely relate to IGD, and it's reasonably priced (non-audiophile price).
Title: Inner Groove Distortion
Post by: doctorcilantro on 2010-09-13 15:50:42
Quote
The top two rows of values in Table 1 are taken from Shure literature and some of the reviews that were published when the V15/III was released. Shure used to publish ‘trackability’ graphs, etc, that showed the peak modulation velocities their cartridges could track. The data shown is for a playing weigh of 1 gram. Knowing the velocity and frequency we can calculate the acceleration required. Then use this to work out the maximum allowed stylus curvature and tip mass which would allow the stylus to perform as specified. Shure themselves claimed that their V15/III stylii had a tip mass of no more than 0·4 milligrams. Their chief engineer of the time also wrote an article that appeared in Hi Fi News[1]. This said that they had surveyed a number of LPs and that the highest accelerations they could find were around 1500g, so they designed the V15 series to track these discs. From the values in the above table we can see that the requirements include a tip mass of less than or equal to 0·6 milligrams and a minor radius of less than or equal to 3·5 microns. If the V15/III stylus had a higher mass or radius it would be unable to perform as specified across the frequency range and right to the end of an LP side.

In fact although the Shure VN35MR stylus for the V15/III had a ‘Micro Ridge’ with a claimed radius of 3·5 microns, earlier stylii had larger contact radius values. For example the VN35E was an elliptical shape with a minor radius of 5 microns. The measurements Shure quoted were often obtained using 45 rpm test discs, and using test tones recorded well away from the end-of-side region. Increasing the rotation rate from 33 to 45 rpm stretches the modulation out along the groove, reducing the curvature of the bends. At the end of an LP side it means that a stylus contact radius of 4·7 microns would allow the V15/III to fully meet its specifications.

And as you can see from Figure 5, if we keep away from the end of the LP side we don’t need such a small tip radius. So although the VM35MR shape might have coped with 1500g accelerations right up to the end of side, the VN35E and some of the earlier shapes may not.

Overall, the above tells us that if we wish to be able to play real-world LPs without mistracking we really need a tip mass of around half a milligram or less, and a minor radius of curvature (or equivalent) of around 3-4 microns or less. Larger values may be fine for most of the playing time of most discs, but could run into trouble in extreme cases. In theory, even lower masses and curvatures may seem desirable, but in practice they may only be needed for test tones, not music. Indeed, the cutter used to create the groove shape may have had an effective contact radius of a few microns, so it simply makes no sense to try to reach a stylus radius smaller than this. More extreme modulation may simple never appear on real-world discs of music. Although who knows, maybe it does – at least up until it is played for the first time!...

So although theory tells us we’d need to cope with 6000g and very tight curves to obtain a 0dB 20kHz test tone, the reality seems to be that practical LPs of music don’t normally have modulations which reach such extreme levels. This agrees with the results in the previous article and explains the difference between the theoretical requirements and reality!


http://www.audiomisc.co.uk/HFN/LP3/aroundthebend.html (http://www.audiomisc.co.uk/HFN/LP3/aroundthebend.html)

My emphasis added. It would seem given modern contact line styli, audiophile pressings ("10 minute sides" or 45rpm), linear tonearms, low effective tip mass, etc. etc. all could add up to effectively mitigate IGD (tracing distortion) to a great degree???
Title: Inner Groove Distortion
Post by: cliveb on 2010-09-13 15:54:25
As you approach the end of an LP side you have all that musical information squished into a smaller amount of groove length. It is difficult if not impossible to have the same amount of fidelity in the last song on a side compared to the first.

Does anyone know if there have ever been experimental LPs that were cut "inside out" - starting at the centre and moving towards to outer edge. For some classical music, where the beginning is quiet and the climax has all-guns-blazing, I'd have thought that might help.
Title: Inner Groove Distortion
Post by: Leigh on 2010-09-13 18:49:03
As you approach the end of an LP side you have all that musical information squished into a smaller amount of groove length. It is difficult if not impossible to have the same amount of fidelity in the last song on a side compared to the first.

Does anyone know if there have ever been experimental LPs that were cut "inside out" - starting at the centre and moving towards to outer edge. For some classical music, where the beginning is quiet and the climax has all-guns-blazing, I'd have thought that might help.


It's easy to press an LP that way. I can't recall off the top of my head any specific examples, but some LPs have been released that way but as a novelty.

I can't find the link, but there was an early phonograph design where constant linear velocity was maintained. Obviously, the record would spin faster and faster as the needle made its way to the center (or slower as it moved away from the center if it were designed that way), and the record would have to be cut this way also. However this would obviously lead to much less program time per side. I would imagine getting the speed/pitch right would be a real challenge with a design like this.
Title: Inner Groove Distortion
Post by: pdq on 2010-09-13 21:24:42
I can't find the link, but there was an early phonograph design where constant linear velocity was maintained. Obviously, the record would spin faster and faster as the needle made its way to the center (or slower as it moved away from the center if it were designed that way), and the record would have to be cut this way also. However this would obviously lead to much less program time per side. I would imagine getting the speed/pitch right would be a real challenge with a design like this.

Actually quite the opposite is true. If currently LPs have to rotate at 33 1/3 in order to have sufficient fidelity at the innermost groove, then that is much faster than it needs to be at the outermost groove. This would result in increased capacity.

This is very reminiscent of Laser Discs and their CAV vs. CLV modes.

I completely agree about the difficulty of getting the speed/pitch right.
Title: Inner Groove Distortion
Post by: splice on 2010-09-13 23:15:06
Does anyone know if there have ever been experimental LPs that were cut "inside out" - starting at the centre and moving towards to outer edge. For some classical music, where the beginning is quiet and the climax has all-guns-blazing, I'd have thought that might help.


The BBC "Transcription Series" (radio programs that were recorded on disc for distribution to affiliates for later broadcast, such as syndicated serials) were cut alternately "outside in" to "inside out". (The first disc in the set would play "outside in" as usual, then the second disc in the set would play "inside out".) This avoided the sudden change in sound quality that would otherwise occur when changing discs. Broadcasting studios usually used spherical stylus profiles for reasons such as longer stylus and disc life, reduction in surface noise and ease of cueing, but the profile made inner groove distortion worse.
Title: Inner Groove Distortion
Post by: Leigh on 2010-09-13 23:49:18
I can't find the link, but there was an early phonograph design where constant linear velocity was maintained. Obviously, the record would spin faster and faster as the needle made its way to the center (or slower as it moved away from the center if it were designed that way), and the record would have to be cut this way also. However this would obviously lead to much less program time per side. I would imagine getting the speed/pitch right would be a real challenge with a design like this.

Actually quite the opposite is true. If currently LPs have to rotate at 33 1/3 in order to have sufficient fidelity at the innermost groove, then that is much faster than it needs to be at the outermost groove. This would result in increased capacity.

This is very reminiscent of Laser Discs and their CAV vs. CLV modes.

I completely agree about the difficulty of getting the speed/pitch right.

I was thinking that if the magic of vinyl is on the outer edges, then in order maintain that magic you'd have to have the linear velocity of the outer groove as the baseline, not the inner groove, and hence you'd have less program time per side.

It's all academic, though, as nobody is going to do anything like this!
Title: Inner Groove Distortion
Post by: Axon on 2010-09-14 05:05:54
Yikes, this topic again?

OK, so that reminds me. Since we're well past April, I've finally gotten off my duff and uploaded my tracking error simulator paper from last year: here (http://files.audiamorous.net/trackingerrorsimulator/tollerton127stripped.pdf). (Suitably modified to avoid confusion with the AES preprint.) Those of you curious about the finer points of tracking distortion as it relates to inner groove distortion are highly encouraged to read it.

Title: Inner Groove Distortion
Post by: Axon on 2010-09-14 05:52:29
The so-called "inner groove distortion" is not a function of tone-arm alignment. Any pivoting  tone-arm alignment leaves variable horizontal tracking angle errors and in “outer”, and in “medium”, and in “inner” grooves.

I'm kinda confused by what you're saying here (and in other posts). If you're saying that when IGD is demonstrated to exist, an improved stylus is a much more effective solution than a realignment, you're very right. If you're saying that tracking distortion can never be the cause of IGD, or that it is not inversely proportional with radius, or that it is not a nonlinear distortion in the same way that tracing distortion is nonlinear, you're very wrong.
Title: Inner Groove Distortion
Post by: Arnold B. Krueger on 2010-09-14 13:23:58
I understand you can't write a dissertation and it's fair to summarize your experience with these technicalities,


The technical details related to vinyl production and playback were pretty thoroughly discussed in the JAES amd IEEE journals back in the day. Thse articles are in the respective archives for posterity. 

Trust me, all of the reasonable technical alternatives were flogged to death before the decision was made to scrap vinyl for mainstream use.

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but it seemed to me (most likely simply as a result of my ignorance on these matters compared to you) you had wrapped everything into vinyl = distortion = bad. I understand vinyl has very real and measurable defficiencies, I just wonder how audible these defficienices are.


It is impossible to produce and playback a recording using vinyl media and have something that is very close to audibly facsimile reproduction of the origional recording. It is easy to accomplish the same thing with 44/16 digital.  While high speed wide track magnetic tape comes far closer to facsimile reproduction than the LP, it is still possible to distinguish one generation of analog tape in an ABX test.

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What are some of the systems you have used or tested in the last 20 years?


I decline to answer such questions because vinyl advocates can and will usually dismiss any reasonable and even many unreasonable vinyl playback systems as being inadequate based only on myth and rumor.

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So tracing distortion and pinch effect are aggravated at the inner grooves; for "music" or a sine wave?


Music is just a collection of sine waves. If its bad for sine waves, its bad for music.

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Is it true as the groove speed decreases distortion rises?


Yes.

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The wavelength shortens, and coupled with shape of the "inadequate" playback stylus, we get tracing distortion?


Yes. This was well known and documented in the 1960s. Nothing has signficantly changed since then. We still don't play records with cutting styluses for pretty obvious reasons. We may or may not have playback stylii that are better approximations of the cutting stylus, but that approach can't compensate for the fact that the vinyl springs back after being cut, and always has a shape that is different from our intentions.

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Is this audible enough to detract from the fidelity in a meaningful way given an optimized setup (contact line stylus, tangential tracking). Many modern records, on 2 LPs seem to be cut a 10 minutes per side, or cut at 45rpm (which I assume would help?)


If you measure the may different at are inherent in vinyl production and playback, they are large enough so that they look on paper like they would be audible. If  you simulate them, they are audible. If you try to ABX vinyl playback and the origional recording you will be able to hear a difference in almost every case you try.  Most extant recordings on vinyl were produced using magnetic tape, and audible flaws were introduced to the process before the LP was cut. Cutting and playing back the LP is even worse than analog tape.

My point is that facsimile reproduction was lost before the vinyl was even cut.  That all said, vinyl sounds pretty good given how bad it measures. And measurements do matter, when used and judged intelligently.


Title: Inner Groove Distortion
Post by: Axon on 2010-09-14 20:32:52
The technical details related to vinyl production and playback were pretty thoroughly discussed in the JAES amd IEEE journals back in the day. Thse articles are in the respective archives for posterity.  Trust me, all of the reasonable technical alternatives were flogged to death before the decision was made to scrap vinyl for mainstream use.
You seem to be suggesting that the technology behind vinyl (and alternative ways of playing it) was completely exhausted by the time CDs were introduced. I submit that the literature admits no such interpretation - that some people continued vinyl research at least a few years into the 80s as JAES back issues will attest, that vinyl technology did continue to advance until about ~1987 at the earliest, and that like any paradigm shift, the observation that vinyl research slowed to a trickle as the digital epoch began merely reflects that researchers perceived digital to be a vastly more fruitful topic than vinyl at the time - that is, the reasons are sociological rather than technical. (Even if that reason was founded on technical justifications which were true, ie, that digital really was a more fruitful research effort, because of its intrinsically higher fidelity.)

It is true that the literature is a lot more accurate and meaningful to the nature of the medium than a lot of audiophiles give it credit for. <cue Clark ranting about the evil AES cabal...> But it's very important to distinguish between that point, and the incorrect premise that the existing literature has exhausted the field. Very few if any dead fields have a research literature which wholly explore the subject.

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It is impossible to produce and playback a recording using vinyl media and have something that is very close to audibly facsimile reproduction of the origional recording. It is easy to accomplish the same thing with 44/16 digital.  While high speed wide track magnetic tape comes far closer to facsimile reproduction than the LP, it is still possible to distinguish one generation of analog tape in an ABX test.

I don't believe that comparison of vinyl vs tape is correct. IIRC, if I'm remembering my old JAES articles right, one of the papers from the 60s compared the dynamic range of vinyl vs 15ips tape, and concluded that lacquer trounced tape, and that well-pressed vinyl was extremely competitive, beating out tape at some frequency ranges. I'd imagine that 30ips tape could be extrapolated to have numbers roughly 3-6db better compared to 15ips, except below 100hz, which I think would make it a reasonably valid comparison. And of course, that paper was before Dolby A which changes the comparison significantly, but adds its own drawbacks. I do recall a couple records I own having significant tape hiss on the record, being distinguishable from groove noise due to the change in overall noise timbre on the leadin/leadout. Obviously they are not examples of fine recording practice but they certainly disabuse one of the notion that vinyl noise is so high as to make tape noise almost certainly inaudible.

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I decline to answer such questions because vinyl advocates can and will usually dismiss any reasonable and even many unreasonable vinyl playback systems as being inadequate based only on myth and rumor.
Arny, haven't I already told you that HydrogenAudio is not rec.audio.opinion?

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My point is that facsimile reproduction was lost before the vinyl was even cut.  That all said, vinyl sounds pretty good given how bad it measures. And measurements do matter, when used and judged intelligently.
Very, very true.
Title: Inner Groove Distortion
Post by: Arnold B. Krueger on 2010-09-15 13:59:21
As you approach the end of an LP side you have all that musical information squished into a smaller amount of groove length. It is difficult if not impossible to have the same amount of fidelity in the last song on a side compared to the first.

Does anyone know if there have ever been experimental LPs that were cut "inside out" - starting at the centre and moving towards to outer edge. For some classical music, where the beginning is quiet and the climax has all-guns-blazing, I'd have thought that might help.


It's easy to press an LP that way. I can't recall off the top of my head any specific examples, but some LPs have been released that way but as a novelty.

I can't find the link, but there was an early phonograph design where constant linear velocity was maintained. Obviously, the record would spin faster and faster as the needle made its way to the center (or slower as it moved away from the center if it were designed that way), and the record would have to be cut this way also. However this would obviously lead to much less program time per side. I would imagine getting the speed/pitch right would be a real challenge with a design like this.


CLV is an interesting design feature for the LP. In modern times we'd cut a inaudible carrier into the groove along with the music and use a PLL or something like it at playback  to ensure it was being played back consitently. Along the way we might also vastly reduce the massive FM distortion that is inherent in vinyl - many different sources. 

The real problem is using a fairly gross mechanical means to reproduce and distribute media - digital/optical is doing far better right now.  Mechanical playback might come back, but then we'll be playing back recordings that were made by rearranging things at the atomic level.
Title: Inner Groove Distortion
Post by: 2Bdecided on 2010-09-15 16:03:32
It's easy to press an LP that way. I can't recall off the top of my head any specific examples, but some LPs have been released that way but as a novelty.
http://78rpmrecord.com/centerst.htm (http://78rpmrecord.com/centerst.htm)

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I can't find the link, but there was an early phonograph design where constant linear velocity was maintained. Obviously, the record would spin faster and faster as the needle made its way to the center (or slower as it moved away from the center if it were designed that way), and the record would have to be cut this way also. However this would obviously lead to much less program time per side. I would imagine getting the speed/pitch right would be a real challenge with a design like this.
I think it was from world record company, but google doesn't confirm this.

It ran slower than normal at the edge, not faster than normal in the middle. It was an early attempt at an LP, not an attempt to improve sound quality.

Cheers,
David.

Title: Inner Groove Distortion
Post by: Slipstreem on 2010-09-19 22:53:52
I'm wondering what my best course of action would be to reduce inner groove distortion. For now, I'm just getting ideas, so price isn't really an object.

Then buy the albums on CD. That should eliminate the problem.
Title: Inner Groove Distortion
Post by: Saucerful on 2010-09-19 23:28:50
Then buy the albums on CD. That should eliminate the problem.


Yes, this has worked quite well. However, there are still things that are only available on vinyl or particular vinyl pressings that include exclusive tracks, etc.
Title: Inner Groove Distortion
Post by: Leigh on 2010-09-20 03:31:35
I am a big fan of the Audio Technica AT440MLa. It's inexpensive and tracks like a champion. It solved (almost) all of my IGD issues. That, and make sure you've aligned your TT (protractor etc.).

You will probably find the hoffman forums more helpful, as there are a lot of vinyl nuts there who live for this sort of thing.
Title: Inner Groove Distortion
Post by: Saucerful on 2010-09-20 07:36:48
If the OP is buying mostly used vinyl due to being unable to source new vinyl...


Indeed it is mostly used vinyl and possibly permanently damaged, though I must clarify that I do have some brand new vinyl and the problem persists. It's not as bad as some of my used vinyl, no, but it is still noticeable and particularly so on some new 7" singles that I have.


I am a big fan of the Audio Technica AT440MLa.


Thanks for the suggestion. I'll do some research on that cartridge. Also, thanks for the heads up about the other forums, I'll go check that out as well.
Title: Inner Groove Distortion
Post by: 2Bdecided on 2010-09-20 09:44:00
Am I to understand one school of thought is that it is unavoidable and inherent in vinyl playback
How could that possibly be true? Linear tracking eliminated the problem, though it's quite rare these days. It's quite expensive to implement well, and good sized / well designed / well set-up conventional arms are good enough. I think it's rare for the alignment to be more than 2 degrees out at the end of the record.

The inner grooves are lower quality due to lower speed, but they're still "good enough" (assuming you find the middle grooves of a record good enough!) - if the turntable is decent and set up correctly.

I'd say it's far more common than not to find this problem on used vinyl. If you're tracking correctly, "solutions" to damaged records include different profile styli, an altogether poorer quality set-up appropriate for lousy used records, digital noise reduction (e.g. some decrackling algorithms can reduce, but not completely solve, this problem) or buying the CD

Cheers,
David.
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