Wow and flutter on recordings and TT's combined

[Trackside]

Here's a question - to what extent is wow and flutter cumulative in the recording and playback system. Analogue master tape and cutting lathe will have some wow and flutter even if it's too low to actually hear but if the tolerances get very close to being audiable and you then throw into the replay chain an TT with average W&F will this tip it over the threshold and make it audiable. Similarly if its played on a TT with very low W&F will it remain acceptable and inaudible? Could it be argued that for very good pitch stability you may actually need a TT that has lower W&F than the limits of human perception in this area in order to avoid these cumulative errors ( if they exist).

[cats squirrel]

when things like this are random, then adding together the phenomena usually results in a root 2 increase, and not the expected 2x increase.

I don't think the human hearing is that exact, meaning the level at which we perceive w&f is person dependant, not absolute. And one's musical aptitude has something to do with it. I own several Lenco turntables because, to my ears, they provide a constant speed, whereas I can detect w&f in other turntables, especially low/mid priced belt drives, even some Linn's.

[cafe latte]

As i said in the topic i posted IMO there is no absolute with wow and flutter, just a theory of mine that the frequency of the wow is also an issus as 0.1% seems to me at least more audable on the cheap a direct drives than on cheap belt drives. Maybe the wow is more gradual on the belt than on the cheap DD's making it more obvious, or maybe owning a reasonable direct drive has made me more sensitive to wow.
Regards
CL

[SupaWales]

I've found that the onset of "something wrong" is extremely variable, it depends on the listener.
My Garrard 401's plinth is away for a modification so the 401 is having a rest and I've been using a Dual CS505-3 instead.
I can detect a small amount of wow especially on classical organ pieces on the belt driven Dual compared to the absolutely rock solid idler driven Garrard.
The wow isn't noticeable on material that doesn't have long drawn out solo passages so most rock / pop music sounds fine.
My wife can't hear anything wrong at all, so small amounts of wow or other defects are not perceived by some listeners.

I suppose the perception of a problem depends on training as well, for example the test pressing quality control listeners who would often throw away what many people would consider perfectly useable styli because they could hear the distortion caused by very small amounts of wear to the diamonds' polished surfaces.
I once worked as QC at a small pressing / tape duplication plant.. on the 8 track & cassette side mainly but also looked after the Garrard 401 / SME 3009 / Shure M75ED decks in the record test room.

Regards..

Paul.

[Trackside]

Also it may be possible for a listener to be aware of something a bit uncertain or unconvincing about a replay quality without actually being able to hear the pitch varying in a classic wowing. This is why it could be described as 'pitch insecurity' rather than wow and flutter. BTW flutter ( high frequency pitch instability) I think is very rare in TT replay due to the forces needed with anything but a very low mass platter.

[cocoabaroque]

Wow and flutter are two seperate issues-- wow is often primarily caused by off-center pressings or warps in the vinyl. Any turntable that has audible wow has serious problems, such as a damaged idler wheel or slipping belt, unstable electronic circuit, etc. Musicians tend to be more aware of wow as it can sound like a vibrato at 33.3 rpm-- very disturbing if it was not intended in the original recording.

Flutter is easiest to detect when compared to a lower-flutter table. Tones may sound or "feel" smoother or more solid on a lower flutter table. Idler decks typically use 1800rpm motors, and their fast rotational speed makes motor cogging (flutter) less audible. Slower 300rpm (Linn, Thorens, etc) motors on suspended-type tables have much higher audible flutter.

Whats really interesting is the flutter of the 300rpm motors make wow less audible. The micro-cogging makes the pitch of the notes less centered, and less susceptable to perceived wow. It's a pleasing effect when it masks the defects in the original recording. This, I believe-- is the draw to Linn, Thorens, even Rega. Most of your records sound great when the problems are masked.

With regard to the original post, I would think the defects are additive. Older records whose master was cut on an idler-drive lathe may have less flutter, while masters cut on later direct-drive lathes may have more flutter (or might mask the wow in your off-center pressing!)

[duficity]

I would suspect that the combination of tape master wow, record off center wow and turntable drive mechanics wow is so random as to never conicide, and therefore the worst example of wow would be limited to which of those three sources has the worst deviation.

[Trackside]

Wow and flutter are two seperate issues-- wow is often primarily caused by off-center pressings or warps in the vinyl. Any turntable that has audible wow has serious problems, such as a damaged idler wheel or slipping belt, unstable electronic circuit, etc. Musicians tend to be more aware of wow as it can sound like a vibrato at 33.3 rpm-- very disturbing if it was not intended in the original recording.

Flutter is easiest to detect when compared to a lower-flutter table. Tones may sound or "feel" smoother or more solid on a lower flutter table. Idler decks typically use 1800rpm motors, and their fast rotational speed makes motor cogging (flutter) less audible. Slower 300rpm (Linn, Thorens, etc) motors on suspended-type tables have much higher audible flutter.

Whats really interesting is the flutter of the 300rpm motors make wow less audible. The micro-cogging makes the pitch of the notes less centered, and less susceptable to perceived wow. It's a pleasing effect when it masks the defects in the original recording. This, I believe-- is the draw to Linn, Thorens, even Rega. Most of your records sound great when the problems are masked.

With regard to the original post, I would think the defects are additive. Older records whose master was cut on an idler-drive lathe may have less flutter, while masters cut on later direct-drive lathes may have more flutter (or might mask the wow in your off-center pressing!)

Huh? http://en.wikipedia.org/wiki/Wow_and_fl ... easurement

[Trackside]

I would suspect that the combination of tape master wow, record off center wow and turntable drive mechanics wow is so random as to never conicide, and therefore the worst example of wow would be limited to which of those three sources has the worst deviation.

Each of those sources of WOW will by cyclic and non random and thus it's a certainty that they will coincide in the way described.

[steve195527]

I would suspect that the combination of tape master wow, record off center wow and turntable drive mechanics wow is so random as to never conicide, and therefore the worst example of wow would be limited to which of those three sources has the worst deviation.

Each of those sources of WOW will by cyclic and non random and thus it's a certainty that they will coincide in the way described.

they could cancel each other out if things worked in your favour!
No it is not a certainty as the wow in the recording will affect the music in the same way no matter how the record is placed on the TT how the wow from the turntable affects the music will most definitely be affected by how the record is placed on the deck,both how central it is and also its orientation to the cyclic problem the deck has

[cocoabaroque]

Further clarification of my earlier post: Play the same off-center pressing LP on 2 different decks-- a Thorens (or Linn), and an idler-drive Rek o kut or similar. You may not even notice the pitch fluctuations in the Thorens/Linn, it will sound basically fine-- or at least not too bad. You probably WILL hear the wow with the ROK. Both decks play the same LP with the same issue. Why is the wow less evident on the 300rpm motor tables? Because of the flutter. Incidently, nearly ALL LP's are pressed off center, but many are "close enough" considering the technology of vinyl playback at the time the record was released. As motor speed-stability improves with massive platters, flywheels and low-cogging motors, pitch variations (wow) will become more intrusive.

[Trackside]

Further clarification of my earlier post: Play the same off-center pressing LP on 2 different decks-- a Thorens (or Linn), and an idler-drive Rek o kut or similar. You may not even notice the pitch fluctuations in the Thorens/Linn, it will sound basically fine-- or at least not too bad. You probably WILL hear the wow with the ROK. Both decks play the same LP with the same issue. Why is the wow less evident on the 300rpm motor tables? Because of the flutter. Incidently, nearly ALL LP's are pressed off center, but many are "close enough" considering the technology of vinyl playback at the time the record was released. As motor speed-stability improves with massive platters, flywheels and low-cogging motors, pitch variations (wow) will become more intrusive.

So you are saying flutter (high frequency pitch oscillation) will mask wow ( low frequency pitch oscillation)?

[cocoabaroque]

Trackside: Yes, exactly-- although I do not agree with the definition "high frequency pitch oscillation". Flutter may be within the audio band too. Anyone who has seen their Grado cartridge "wiggle" in the groove can also hear flutter in the low frequency range with oscillations about 10-20hz. Presumably, a 300rpm motor may flutter at 300hz, or multiple thereof (1200 in a 4-pole motor). If the flutter or motor cogging is mild enough, such as with the low-torque but smoother running Rega motors, the flutter is less audible.

[Trackside]

Trackside: Yes, exactly-- although I do not agree with the definition "high frequency pitch oscillation". Flutter may be within the audio band too. Anyone who has seen their Grado cartridge "wiggle" in the groove can also hear flutter in the low frequency range with oscillations about 10-20hz. Presumably, a 300rpm motor may flutter at 300hz, or multiple thereof (1200 in a 4-pole motor). If the flutter or motor cogging is mild enough, such as with the low-torque but smoother running Rega motors, the flutter is less audible.

Flutter is any pitch variation >4hz
Wow is pitch variation <4hz
Sorry but I don't believe in your theory of it masking wow however 'vibrato' is a known phenomena which some like in instruments and voices which may make the sound of a TT sweeter. A significant flaw in this theory is that a large rotating mass like an LP12 platter would need a lot of torque in the drive system to alter the speed of it's rotation at these frequencies. In short a low torque AC motor connected to the platter with a stretchy rubber belt cannot accelerate and decelerate the plater that fast. The main aim of a high mass platter is to prevent flutter. WOW however can be induced easily by any number of factors which change the speed of the stylus through the groove over a longer time frame - off centre record, uneven drag in the main bearing, loose tolerances and/or wrong viscosity in the oil causing the spindle to roll around the journal and not rotate on it's axis, uneven elasticity in the belt or belt slip, an unbalanced platter causing the suspension to rock , unbalanced suspension springs which introduce lateral movement when damping vertical input from structural or acoustic feedback. There is also dynamic stylus drag when loud or complex passages are traced. Direct drive and idler drive TT's however do have enough torque in their drives to create flutter but are conversely unaffected by most of the problems that create WOW in suspended subchassis and belt driven TT's. Flutter is not inevitable in the design though and is symptomatic of a fault. Likley a low level of constant flutter is more acceptable than wow if it creates a subtle vibrato within a tone rather than varying the tone like wow.