Rube Goldberg would be proud.
Is this amount of record/tonearm bobbing "normal"
Most records sound fine, but a few of them (shoegaze, Interpol) with extended chords sound bad, uneven.
This could all be in my head. I'm new to this.
Kindly take a look at a brief video and tell me whether my platter is warped?
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Oh, I didn't pay enough attention, a TD124 you say! It is DEFINITELY the 'liftable' thin lightweight easily distorted cover that is slightly warped as mijostyn said. I LOVED mine, best BASS ever! EXCEPT, it's bearing is very susceptible to vertical movement, not good match for my too flexible floors. http://www.soundfountain.com/amb/td124page.html
Why a liftable platter cover? TD124's motor/bearing/lube need to warm up/loosen up, then you adjust the speed, then, every once in a while you re-check/refine it's speed, using the mirror showing the strobe dots on the underside of the main platter. More people join the party, room warms up, go check again! Clever 'no-contact- speed solution: Adjuster moves a shield that alter's a magnet's pull (more or less) on the underside of the platter to achieve perfect speed. It ain't direct drive, it ain't quartz locked. That cast iron platter weighs 4.5 kg (nearly 10 lbs), it's magnificently machined bearing, there is NO WAY it is warped. If it was misaligned to the bearing, it would be more pronounced than OP has. Remove the platter, drop it back into the bearing sleeve, go make toast, it might have dropped all the way down when you return. The clearances are so refined the air has to escape before the bearing can lower. Push down, it won't go. Just wait. First time you do it, you think something is wrong. During play, you do not want to turn it on/off, you don't want to wait for such a heavy platter with magnificent bearing to stop spinning, SO, their clever solution: a thin platter cover that you can raise/lower to disengage/engage the constantly rotating platter below. Raise, flip/change LP, lower lightweight platter down onto the main rotating platter, spin it does, instantly correct speed. Trying to 'fix' the slight warp in the platter cover may worsen it. Live with it's slight warp? Have a long peek at this, listen to specific frequencies on test lp https://www.vinylrecorder.com/stereo.html Know this: it is more important that your anti-skate is correct.
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Mijo, I don’t know enough about the workings of a TD124 to cast any doubt on your explanation of the mechanism of what we observe here, but back in the late 50s and early 60s the TD124 was the cat’s pajamas for any well heeled serious audiophile, not merely “made for commercial use”. They may have been used at radio stations too, but probably because of rugged construction. At audio salons in New Haven the TD 124 was slotted into McInosh and Marantz-based systems as a matter of course. |
This is an age old problem with Td 124s. The table was designed for commercial use which meant immediate cuing of records which it does with a clutch that lifts the very light outer platter off the heavy inner platter which keeps rotating while the other is stationary. The outer platter is soft metal and can easily be deformed which is what has happened here. I hate to be the one to tell this to the OP but this is a terrible design for a modern audiophile turntable and should be kept aside as a interesting side path in audio antiquity. Time to get a new turntable. Do yourself a favor and steer clear of antiques. Get yourself a modern up to date design. If you do not want to see your tonearm bob at all get a table with vacuum clamping. |
Hello, I would say this is going to be bad for the bearing. |
+4 for MC, slaw, and Dover. Watching the bottom edge of the platter as it rotates through the window for the speed sensor, it looks to be moving up and down, as MC notes. The top edge of the platter proper (not the mat or the LP) appears to be unevenly machined. The champhered edge changes shape a bit as it rotates if you concentrate on one point. I'd worry about the platter first; no big deal if an LP is warped or off-center; they are nearly all imperfect. Could be the platter is askew with respect to how it should sit on the spindle; that would be the easiest thing to fix. |
Thanks for the feedback. In this case there is a lower platter, an upper platter, a mat, and the record. The lower platter is about 48 hundredths "tall" and you can see it in this video:
The runout (probably the wrong word) seems like it's about ~three hundredths. I can hear it on some records. I guess my choices are a new platter or a better turntable.
Yes, millercarbon, it is a graham tonearm. I love it.
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Might not realize this, the ones above certainly missed it, but there are four different things going on here. From bottom to top: platter, mat, record, and arm. Watching the first few seconds it is clear the bottom edge of the platter is oscillating up and down. But the top edge is what counts and hard to tell for sure with your camera bouncing around but it looks like the top is off too just maybe not as much. Anyway for sure your platter is a contributing factor. Then you have the mat, but it is way too out of focus and jittery. What you should do, place a piece of cardboard or something along side the platter with a mark as reference and watch the TOP SURFACE of the mat. If you are lucky the mat may not be flat. The reason I would call this luck, it is like balancing a tire you might be able to improve it by rotating the thick part of the mat to the lower part of the platter. Then there is the record. Perfectly normal looking record. Some are dead flat, some are not. This one is well within the norm. That’s not your problem. The platter, that’s your problem. Finally the arm. It is tracking well not bobbing, nothing wrong there. Bottom line, if it sounds good it is good. This is all within the range of normal LP playback. In other words I’ve seen worse. I’ve had them where the record was so warped it hit the cartridge causing it to go airborne. That’s a bad record! Nice arm by the way. Graham? Had one myself. Deserves a table better than this. Do what you can, upgrade when you can, other than that don’t sweat it. |