Hi all I have just got my SL-1200 mk2 out of storage and started using it.
Think I can hear wow on piano and other sustained notes. Did the easy fix of changing the bearing but no real difference.
The strobe is steady, the pitch fader is clean and seems to work ok - although I only ever have it in the centre position/green led on.
Is there a fault with my deck or have I just become used to CDs being pitch perfect?
It's been suggested that I should replace the an6682 or the an6680. Does this sound right?
Any or all input welcomed.
Thanks
Adrian.
Think I can hear wow on piano and other sustained notes. Did the easy fix of changing the bearing but no real difference.
The strobe is steady, the pitch fader is clean and seems to work ok - although I only ever have it in the centre position/green led on.
Is there a fault with my deck or have I just become used to CDs being pitch perfect?
It's been suggested that I should replace the an6682 or the an6680. Does this sound right?
Any or all input welcomed.
Thanks
Adrian.
Certain records have the hole punched off center, which can cause wow. Did you try more than one record?
Hi, yes. I am aware this could be an issue. I have tried several records and tried the same records on another TT. I'm fairly sure it's not the records.
Borrowing a test record with some single tone bands on it would be the next step just to confirm. The Mk2 should be quartz locked at all speed settings but can you confirm the little green light on the 0 of the pitch slider is lit?
Hmmm…
First … the 1200 mk 2 is a direct drive turntable that uses a quartz reference oscillator and a phase locked loop frequency synthesizer to drive the magnetics within the direct-drive motor housing.
Second … the strobe of the 1200 is referenced nominally to line frequency in your region. 60 Hz in the Americas, and 50 Hz most-everywhere else.
Third … relatively modest amounts of wow and flutter (below 4 Hz and above 4 Hz respectively) aren't easily seen on the strobe. Gross rotational rate approaching line frequency is what you get. A WOW of 0.1% is considered audible to most critical listeners, especially (as you note) on long-decay of complex-harmonic instruments.
0.1% is 1 part per thousand. You'd think that the several hundred edge strobe spots would show 1 PPT as a slight precessing forward and reverse of the pattern … but unless you sit there looking at it really carefully, 0.1% is easy to overlook.
NOW, the 'shortcomings' of the SL–1200 mk₂…
That slider for controlling pitch. Its a variable resistor. Its been in storage (and existence) for years. Decades. Coming up on a half-century (wow!). Slider-type pots are notorious for unavoidably admitting small amounts of dust and 'stuff' from the environment through their slider-slot housing. This gets on the pot, and makes it 'scratchy' (if it were a volume control). This scratchiness in turn - even though it is not being piped to the audio output - causes the set-point of voltage to the phase-locked loop to change, which in turn induces flutter into the rotational rate of the motor drive circuit.
EVIDENCE for this would be if the wow/flutter pattern … wasn't a pattern. Wasn't synchronous with the rotational rate of the vinyl disk sitting on top. If is sounded subtly different each time a particular notable passage was played (without stopping the rotation, but just lifting and resetting the tone arm!).
If it isn't reproducible, then the cause is very likely the slider. There's plenty of advice out there as to how to fix that.
If however, the effect is reproducible and synchronous with the rotational rate of the record, then it suggests the other effects that people have already noted. Center-hole not punched nicely exact on the recording. Subtle warping of the disk itself. Etc.
Oh yes… the last thing that I remember is to ask, does the audio signature go away when you play-back through headphones? This is important: much of the research done on wow and flutter indicated that the natural reverberations of the room or listening theatre were to 'blame' for heightening how noticeable (or 'detectable') the effect of mid-frequency wow and flutter would be. Headphones eliminate room reflections of course (if the speakers are muted!). Hence why the question.
GoatGuy
First … the 1200 mk 2 is a direct drive turntable that uses a quartz reference oscillator and a phase locked loop frequency synthesizer to drive the magnetics within the direct-drive motor housing.
Second … the strobe of the 1200 is referenced nominally to line frequency in your region. 60 Hz in the Americas, and 50 Hz most-everywhere else.
Third … relatively modest amounts of wow and flutter (below 4 Hz and above 4 Hz respectively) aren't easily seen on the strobe. Gross rotational rate approaching line frequency is what you get. A WOW of 0.1% is considered audible to most critical listeners, especially (as you note) on long-decay of complex-harmonic instruments.
0.1% is 1 part per thousand. You'd think that the several hundred edge strobe spots would show 1 PPT as a slight precessing forward and reverse of the pattern … but unless you sit there looking at it really carefully, 0.1% is easy to overlook.
NOW, the 'shortcomings' of the SL–1200 mk₂…
That slider for controlling pitch. Its a variable resistor. Its been in storage (and existence) for years. Decades. Coming up on a half-century (wow!). Slider-type pots are notorious for unavoidably admitting small amounts of dust and 'stuff' from the environment through their slider-slot housing. This gets on the pot, and makes it 'scratchy' (if it were a volume control). This scratchiness in turn - even though it is not being piped to the audio output - causes the set-point of voltage to the phase-locked loop to change, which in turn induces flutter into the rotational rate of the motor drive circuit.
EVIDENCE for this would be if the wow/flutter pattern … wasn't a pattern. Wasn't synchronous with the rotational rate of the vinyl disk sitting on top. If is sounded subtly different each time a particular notable passage was played (without stopping the rotation, but just lifting and resetting the tone arm!).
If it isn't reproducible, then the cause is very likely the slider. There's plenty of advice out there as to how to fix that.
If however, the effect is reproducible and synchronous with the rotational rate of the record, then it suggests the other effects that people have already noted. Center-hole not punched nicely exact on the recording. Subtle warping of the disk itself. Etc.
Oh yes… the last thing that I remember is to ask, does the audio signature go away when you play-back through headphones? This is important: much of the research done on wow and flutter indicated that the natural reverberations of the room or listening theatre were to 'blame' for heightening how noticeable (or 'detectable') the effect of mid-frequency wow and flutter would be. Headphones eliminate room reflections of course (if the speakers are muted!). Hence why the question.
GoatGuy
Wow. Pun intended. Some food for thought there. And yes the slider is on the centre detent and the green led is on. I have noticed that although the illuminated dots do not precess (noticeably), they do not seem as crisp as I remember them. I am using only the strobe for illumination. I'll look further tomorrow evening and report back.
Well, there you are then. “Artificial 50 Hz line frequency” so to speak. Solves the “will it work in North America” problem pretty easily. I think the rest of the commentary I penned still holds, just with a single continent-independent reference.
BTW - reading up on this, the 100 Hz strobe reference also appears to be its own source of not-quite-absolute pitch variation, as it is not exactly 100.00 Hz, but can vary by as much as 0.5%. Not that this would cause the OP's perceived issue. Most of us aren't terribly accurate in the absolute-pitch department.
GoatGuy
As I don't use DD turntables, I am not sure if this would work or not... but what about adding weight to the inner rim of the platter? Equal weight all the way around the inside edge? A friend of mine had an Onkyo turntable with the same issue and that is what he did to solve the issue.
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