Quartz Lock
- Thread starter jeff2369
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Yes, it is considered by some to be the best way of keeping on speed. I think it is. However, some individuals claim that it will create micro-variations in speed as it is constantly checking the accuracy. This is bull, IMO. But people can live their lives however. 
Ben aka MacKat
Ben aka MacKat
lini
just me...
chupwally: The quartz crystal doesn't actually regulate anything - it just makes a very stable oscillator (or a very precise reference clock, one might say just as well). So in an analogue motor control circuitry one would use it to produce a certain reference frequency against which the information about the actual motor or/and platter speed in form of a generated frequency can be compared...
Greetings from Munich!
Manfred / lini
Greetings from Munich!
Manfred / lini
Stacker45
Active Member
Hmmm...so you mean,that when the red light is on,the speed is off?
Blue Shadow
Waiting for Vintage Gear from this century
The HK TTs and the Sansui SR-838 sound better with the quartz lock off.
for the HK, the speed of the platter is check and the motor speed adjusted but the belt absorbs this adjustment a bit and the adjustment may be exaggerated causing the table to sound less smooth (single extended note of a piano).
The SR-838, I don't know but maybe it doesn't check enough.
As for the tables that I know do well with quartz lock, the KD-600/650, well that platter weighs so much a little bump in speed or drop in motor power is going to be absorbed by the moment of inertia. Kenwood also had available at the time a 600 gram center weight, 1350 gram ring weight and 1200 gram platter mat. Added to the 2600 gram weight of the platter, there was 5.75 kilograms of rotating mass, about 12.7 pounds.
for the HK, the speed of the platter is check and the motor speed adjusted but the belt absorbs this adjustment a bit and the adjustment may be exaggerated causing the table to sound less smooth (single extended note of a piano).
The SR-838, I don't know but maybe it doesn't check enough.
As for the tables that I know do well with quartz lock, the KD-600/650, well that platter weighs so much a little bump in speed or drop in motor power is going to be absorbed by the moment of inertia. Kenwood also had available at the time a 600 gram center weight, 1350 gram ring weight and 1200 gram platter mat. Added to the 2600 gram weight of the platter, there was 5.75 kilograms of rotating mass, about 12.7 pounds.
This was a good question and I'm glad it was asked as I wondered about this myself.
I thought it was just a marketing gimick for a long time, it's good to now know the science behind it.:thmbsp:
The quartz lock tables I have are always on, no on/off switch. I was not aware some tables had a "quartz-lock" on/off switch.
I thought it was just a marketing gimick for a long time, it's good to now know the science behind it.:thmbsp:
The quartz lock tables I have are always on, no on/off switch. I was not aware some tables had a "quartz-lock" on/off switch.
Yes, it is considered by some to be the best way of keeping on speed. I think it is. However, some individuals claim that it will create micro-variations in speed as it is constantly checking the accuracy. This is bull, IMO. But people can live their lives however.
Ben aka MacKat
Completely agree with you MacKat. When I was shopping for a TT for my modern system (because I'm a gluton for punishment or something), I was told the same thing. "Oh, get a belt drive, the direct drives with quartz-lock are terrible at maintaining speed accurately because they have to constantly adjust themselves all the time." That didn't make sense to me either because if it were true there would be tens of thousands of used quartz-locked DD TTs on the market for $1 due to people trying to get rid of them in a market were nobody wants them. I have 3 DD quartz-locked TTs and no complaints.
FWIW I ended up with an extremely near new condition Denon DP47-f instead of a modern belt driven table.
SDA SRS 1.2
Well-Known Member
thedelihaus
Nocturnal transmissions
If you are indeed activating the quartz function and the speed goes crazy, something electro-mechanically is amiss with your table.
illini
The Past is Alive
It provides a reference frequency for the servo system.
Stacker45
Active Member
That's odd,mine is steady as a Swiss watch,whe the QL is switched ON,and for those who didn't know they're were TT with switchable QL,if you zoom the pictrue,you'll be able to see the QL button
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Is quartz more useful with DD tables that have very light platters? I only own one such machine, but its not a quartz lock table. Everything else I have is belt or idler drive and those simply rely on line frequency for stability. Oddly enough, the featherweight non-QL table is rock solid for speed. I'd expect it to be subject to drift but I haven't been able to detect any. It is about a cheap feeling POS but it performs way better than you'd expect.
ETI_5000
Super Member
Just to be clear, it just provides a very stable oscillator reference frequency, set by a quartz crystal, but you still have to adjust or calibrate the setting so that the speed will be correct. Once it’s calibrated (which is normally done at the factory), it should be spot on for speed accuracy, unless components in the oscillator drift in their specifications, or variable components (e.g. trimpots) get moved or vibrated so that their setting is changed.
Quartz crystals provide a very stable source for setting frequencies, which hardly moves with changes in temperature – see http://en.wikipedia.org/wiki/Crystal_oscillator . The quartz locked turntable was originally developed by JVC in about 1974, and was traditionally used on the most expensive turntables from many Japanese, American and European manufacturers.
The service manual (unfortunately not available on vinylengine for the Marantz 6350Q) usually describes how to calibrate the quartz lock. Calibration sometimes is simple, requiring only a screwdriver and digital multimeter, if a stroboscope is included in the turntable as standard, but in other cases may require a stroboscope card to check speed, and more complicated and expensive instruments such as a CRO (Cathode Ray Oscilloscope), which only electronics service people commonly possess. It just depends on the manufacturer as to how easy it is, and they vary quite a bit – companies such as Sony, who are at the forefront of electronics, usually made it quite hard – their engineers were obviously more attuned to inventing than making things easy for service people!
In some cases, manufacturers such as Marantz may have left it up to their local distributors to calibrate before sale, and if that wasn't done, then they may have not been accurate for speed even when new, when the quartz lock was switched on.
Quartz crystals provide a very stable source for setting frequencies, which hardly moves with changes in temperature – see http://en.wikipedia.org/wiki/Crystal_oscillator . The quartz locked turntable was originally developed by JVC in about 1974, and was traditionally used on the most expensive turntables from many Japanese, American and European manufacturers.
The service manual (unfortunately not available on vinylengine for the Marantz 6350Q) usually describes how to calibrate the quartz lock. Calibration sometimes is simple, requiring only a screwdriver and digital multimeter, if a stroboscope is included in the turntable as standard, but in other cases may require a stroboscope card to check speed, and more complicated and expensive instruments such as a CRO (Cathode Ray Oscilloscope), which only electronics service people commonly possess. It just depends on the manufacturer as to how easy it is, and they vary quite a bit – companies such as Sony, who are at the forefront of electronics, usually made it quite hard – their engineers were obviously more attuned to inventing than making things easy for service people!
In some cases, manufacturers such as Marantz may have left it up to their local distributors to calibrate before sale, and if that wasn't done, then they may have not been accurate for speed even when new, when the quartz lock was switched on.
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Pio1980
AK Member
A quartz clock time standard for the platter motor PLL circuit provides the most stable and long-term consistent speed control, the stability can be compromised by drifted component values that affect free-run center locking and also create time constant element conflicts in the PLL, causing the TT to not sound right with quartz locking engaged. As long as readjustments aren't required afterward (see previous post) a recap and checking of restive elements and solder pad integrity should restore proper functioning.
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QL on the PL-9 is always 'on'; no option to disable it. One of the several that I own is a parts-unit that, among other issues, has a really funky QL problem. QL inidicator light will show steady on and be spot on for about 30 mins, then, with nary a flicker drops below speed. If I cycle the speed selector and select 33 it remains spot on for 30 mins. Several doses of deoxit on all of the contacts and the motor board trim pots has zero effect. Probably an issue in the PLL circuit as Pio1980 suggests.
If I ever get the time I'll see if I can track it down. Otherwise, it remains on the parts unit shelf.
If I ever get the time I'll see if I can track it down. Otherwise, it remains on the parts unit shelf.
