Weird bass sounds/skipping on T560

[mxlusky]

Hi trolls,

I have a problem with my T560. It makes weird skipping/bass sounds at 12" diameter (even with quiet groove). When I get around 10" diameter it stops and cuts normally. Heating of stylus made it worse. Is here anyone who have this issue and fixed it? First I thought that the problem is faulty stylus, but it isn't. Help will be much appreciated. Thanks.

[Dub Studio]

This could be chatter, “humping”, subsonic frequencies, too much stereo width.. the list goes on. Without seeing the lathe set up, inspecting the disc, and hearing the audio, it's hard to say. But here are some pointers:

When the stylus hits a warp in the disc, like a car hitting a hump in the road, it can cause the cutting head to start oscillating uncontrollably, and warps are always worse around the edge due to the break in surface tension, which might explain why it’s not happening further into the disc. Let's call this humping to differentiate it from chattering (which looks similar but has a completely different cause).

Assuming the disc is flat and smooth (i.e. little or no detectable ripple on the outer edge of the disc), then it's probably not humping. BTW its not necessarily the amplitude of the hump, but the length that is the issue here. The cutting head suspension has a resonant frequency and if your hump hits that frequency, it will sing.

Some audio, especially slowed down samples from vinyl or other sources, contains lots of sub sonic content which is just messing with your cut and doing nothing useful at all. Your tonearm also has a resonant frequency which is normally set below the human hearing range for obvious reasons, but again, if your subsonic content hits that frequency, the tonearm itself will start to sing (you can sometimes see this if you slow down the record on playback and observe the tonearm). Assuming you have a high pass filter applied at a reasonable frequency (try 20Hz, but your personal default is up to you), then its probably not subsonic.

Assuming you have centred the low end (try 300hz downwards, but again, your personal default is up to you), then its probably not stereo width.

If all the above are eliminated it could be chatter, and this is probably the most complicated to deal with.

NB: chatter is a factor of surface speed (not rpm) … so that could be why its only happening around the edge.

Other factors that combine with surface speed to cause chatter are: too much heat (stylus and or plate), bad rake angle, too much weight, too little weight, bad dash pot, bad counterweight, etc.

Some things to try:

- set the counterweight to 50 grams, then adjust the dashpot spring to give you a net weight of around 12.5 grams on the spring scales. If that doesnt work, add a little more until you reach 15. If that still doesn’t work, it’s probably not your stylus weight.

- adjust the rake angle in a more negative direction (making it more perpendicular to the plate, but not as far 90 degrees). Chances are your rake angle is just too positive, so the stylus is just digging in too much and then bouncing back out. BEWARE, changing the rake angle will mean repeating the previous step again, because the net weight will now be very different.

- check your dashpot to ensure the plunger is free moving, and completely immersed in oil AT ALL TIMES. If the end of the plunger goes too near to the surface of the oil, it can sometimes suck air underneath itself and dramatically reduce its ability to dampen the resonance of the suspension. If this happens, you can either top up the oil (if you have some) or raise the height of the cutting head. BEWARE, raising the cutting head height means you also need to raise the turntable height using the four supporting feet.

- try cutting without any heating lamps. Sometimes the surface of the disc can be hotter around the edge than it is in the middle, which will again cause the cutting stylus to go too deep.

- try reducing the heating coil temperature, for similar reasons as above.

Good luck!

[Dub Studio]

BTW the above answer covers all the possible causes of low frequency skipping that I can think of at the time of writing... but looking at the picture it looks like its mainly a disc temperature issue.

[tragwag]

Like Dub Studio I'm going to assume a lot of details about your setup to give you lots of options:
If it's the stock 1200 turntable, I'd guess it's a torque issue.
If the blank is warped at all, it's that. Check for the head moving up and down when cutting, even slightly.
Like DS said, excessive heat during cutting or too close heat lamp could cause a warp of an otherwise flat blank.
Next down the line - head weight is too heavy, which causes torque issues or worse, disc slippage from the turntable.

best of luck hunting down the issue!

[mxlusky]

This could be chatter, “humping”, subsonic frequencies, too much stereo width.. the list goes on. Without seeing the lathe set up, inspecting the disc, and hearing the audio, it's hard to say. But here are some pointers:

When the stylus hits a warp in the disc, like a car hitting a hump in the road, it can cause the cutting head to start oscillating uncontrollably, and warps are always worse around the edge due to the break in surface tension, which might explain why it’s not happening further into the disc. Let's call this humping to differentiate it from chattering (which looks similar but has a completely different cause).

Assuming the disc is flat and smooth (i.e. little or no detectable ripple on the outer edge of the disc), then it's probably not humping. BTW its not necessarily the amplitude of the hump, but the length that is the issue here. The cutting head suspension has a resonant frequency and if your hump hits that frequency, it will sing.

Some audio, especially slowed down samples from vinyl or other sources, contains lots of sub sonic content which is just messing with your cut and doing nothing useful at all. Your tonearm also has a resonant frequency which is normally set below the human hearing range for obvious reasons, but again, if your subsonic content hits that frequency, the tonearm itself will start to sing (you can sometimes see this if you slow down the record on playback and observe the tonearm). Assuming you have a high pass filter applied at a reasonable frequency (try 20Hz, but your personal default is up to you), then its probably not subsonic.

Assuming you have centred the low end (try 300hz downwards, but again, your personal default is up to you), then its probably not stereo width.

If all the above are eliminated it could be chatter, and this is probably the most complicated to deal with.

NB: chatter is a factor of surface speed (not rpm) … so that could be why its only happening around the edge.

Other factors that combine with surface speed to cause chatter are: too much heat (stylus and or plate), bad rake angle, too much weight, too little weight, bad dash pot, bad counterweight, etc.

Some things to try:

- set the counterweight to 50 grams, then adjust the dashpot spring to give you a net weight of around 12.5 grams on the spring scales. If that doesnt work, add a little more until you reach 15. If that still doesn’t work, it’s probably not your stylus weight.

- adjust the rake angle in a more negative direction (making it more perpendicular to the plate, but not as far 90 degrees). Chances are your rake angle is just too positive, so the stylus is just digging in too much and then bouncing back out. BEWARE, changing the rake angle will mean repeating the previous step again, because the net weight will now be very different.

- check your dashpot to ensure the plunger is free moving, and completely immersed in oil AT ALL TIMES. If the end of the plunger goes too near to the surface of the oil, it can sometimes suck air underneath itself and dramatically reduce its ability to dampen the resonance of the suspension. If this happens, you can either top up the oil (if you have some) or raise the height of the cutting head. BEWARE, raising the cutting head height means you also need to raise the turntable height using the four supporting feet.

- try cutting without any heating lamps. Sometimes the surface of the disc can be hotter around the edge than it is in the middle, which will again cause the cutting stylus to go too deep.

- try reducing the heating coil temperature, for similar reasons as above.

Good luck!

Thanks a lot for sharing your amazing knowledge. In the meantime I set up everything again from scratch and now it is much better. There were probably some problem with counterweight but maybe also with dashpot. I add some oil in it and now it looks to work better. It still occur from time to time, which is weird, but it happened only twice instead of everytime, when I cut stuff before resetting the machine. Temperature should be probably ok, I cut around 40-42 celsius of disk temperature. They are almost flat everytime, so this should be ok too. Audio is also ok because it happens even when I cut silent groove. Well there is still lot to learn about this machine and cutting blanks. I am really grateful that there are people like you in this forum, who are ready to help. Thanks a lot!

[mxlusky]

Like Dub Studio I'm going to assume a lot of details about your setup to give you lots of options:
If it's the stock 1200 turntable, I'd guess it's a torque issue.
If the blank is warped at all, it's that. Check for the head moving up and down when cutting, even slightly.
Like DS said, excessive heat during cutting or too close heat lamp could cause a warp of an otherwise flat blank.
Next down the line - head weight is too heavy, which causes torque issues or worse, disc slippage from the turntable.

best of luck hunting down the issue!

Also big thanks to you. I think that you are on point that it could be combination of torque issue and bad set weight. My Technics is old and weary and I noticed it started to lose speed form time to time. Maybe I should buy external motor for it to prevent this from happening. Thanks!

[Dub Studio]

Audio is also ok because it happens even when I cut silent groove.

Ok this is an important bit of information which helps to narrow down the list of potential causes.. it's definitely mechanical.

Temperature should be probably ok, I cut around 40-42 celsius of disk temperature.

This could be the cause. Personally, I don't heat plates at all (just room temperature) for several reasons:

- it takes time
- it's hard to get consistent temperature across the entire plate
- it can get too hot (causing chatter, which I think is the issue here, or worse still deformation of the disc)

In order to get good flat plates, and very smooth cuts, I use a combination of two things: deburring, and a dished platter.

- deburring removes any small burrs around the edge of the disc that prevent good contact with the platter. This gets rid of any ripples, which can slow the platter and cause wow and flutter.

- a dished platter helps create enough tension in the disc to keep it locked on really well. Just remember, you need to adjust the angle of the Technics slighty so that the height remains constant across the plate (raise the left hand side slightly).

If you don't have a dished platter (or one that is not dished enough) you can easily make one... all you need to do is get a rubber gasket (say 1-2mm in thickness 12" in diameter) and place it on the turnable platter. Then use another disc (a 14" lacquer works really well) and place it on top of the gasket. When you place your disc on top, you just need to push it down in order to dish the disc, and then clamp it in place really tightly (you don't want it springing back up during a cut!).

Obvously, you need to then raise the cutting head and torque tube, and adjust the angle of the TT (as mentioned above). But once this is done, you will get flat cuts every time.

[Dub Studio]

If it's the stock 1200 turntable, I'd guess it's a torque issue.

I have never noticed torque creating stability issues (other than wow and flutter) so I would be surprised if that's the cause. In any case, you need to do the resistor mod to get good results with a Technics 1200 / 1210 so I would look into that as a separate issue.

I have never tried the external motor, but I would try the mod first because I have used it with good results.

[808fiend]

If it's the stock 1200 turntable, I'd guess it's a torque issue.

you need to do the resistor mod to get good results with a Technics 1200 / 1210 so I would look into that as a separate issue.

Do you have a link with more information on how to do this mod?

Thanks

[SueDenim]

Check out page 14 of the original Vinylium DubplateCutter manual:
https://www.lathetrolls.com/viewtopic.php?t=4709

[mxlusky]

Audio is also ok because it happens even when I cut silent groove.

Ok this is an important bit of information which helps to narrow down the list of potential causes.. it's definitely mechanical.

Temperature should be probably ok, I cut around 40-42 celsius of disk temperature.

This could be the cause. Personally, I don't heat plates at all (just room temperature) for several reasons:

- it takes time
- it's hard to get consistent temperature across the entire plate
- it can get too hot (causing chatter, which I think is the issue here, or worse still deformation of the disc)

In order to get good flat plates, and very smooth cuts, I use a combination of two things: deburring, and a dished platter.

- deburring removes any small burrs around the edge of the disc that prevent good contact with the platter. This gets rid of any ripples, which can slow the platter and cause wow and flutter.

- a dished platter helps create enough tension in the disc to keep it locked on really well. Just remember, you need to adjust the angle of the Technics slighty so that the height remains constant across the plate (raise the left hand side slightly).

If you don't have a dished platter (or one that is not dished enough) you can easily make one... all you need to do is get a rubber gasket (say 1-2mm in thickness 12" in diameter) and place it on the turnable platter. Then use another disc (a 14" lacquer works really well) and place it on top of the gasket. When you place your disc on top, you just need to push it down in order to dish the disc, and then clamp it in place really tightly (you don't want it springing back up during a cut!).

Obvously, you need to then raise the cutting head and torque tube, and adjust the angle of the TT (as mentioned above). But once this is done, you will get flat cuts every time.

Well, this is interesting. It's not the first time I read you are not heating the blanks. I also saw other people saying it these days. It is little bit confusing after all that people saying you need to heat it in the past. So why there is instructions that you should heat them? Is it because of extending lifetime of the styli? I tried to cut blank in room temperature (about 25°C) and I was amazed that it really has no noise at all. I thought it would be noisy as hell )

Also thanks for the Technics mod info, I did not know about it. Seems great.

Maybe I finally found the main reason why I have this problem. When you setting up the weight, first you need to set up back counterweight for about 50g, then you need to set up dashpot for about 15g, right? What I did not know or maybe forget is, that even when you have a cutting head up, dashpot still have influence on the weight of back counterweight. So you can basically set up these two values on every position of the back counterweight. That can cause that I put back counterweight too close to cutting head and there was created some disbalance. So I put it back somewhere in half length of the screw which holds it and things start to get much much better. I don't have much time to experiment with it right now, but it looks this is the way how to solve this problem.

[PMST]

I do not heat discs, if you check any plastic manufacturers specs for PETG, or even PC or PVC, unless you heat to 85 degrees it has no structural benefit apart. Maybe back in the day Souri used a different plastic, but the ones currently on the market for the last 10 years do not need heating and it can cause more problems than benefits.

For example excessive heat can dry the air around the disc causing static. I run a business in the UK selling blank discs made from PETG, I have worked with plastic manufactures over the past few years and so far found no evidence that heating will help a diamond cut whatsoever, this is not only my tests, but info direct from the manufacturers and their opinions.

[Dub Studio]

Well, this is interesting. It's not the first time I read you are not heating the blanks. I also saw other people saying it these days. It is little bit confusing after all that people saying you need to heat it in the past. So why there is instructions that you should heat them? Is it because of extending lifetime of the styli? I tried to cut blank in room temperature (about 25°C) and I was amazed that it really has no noise at all. I thought it would be noisy as hell )

Also thanks for the Technics mod info, I did not know about it. Seems great.

Maybe I finally found the main reason why I have this problem. When you setting up the weight, first you need to set up back counterweight for about 50g, then you need to set up dashpot for about 15g, right? What I did not know or maybe forget is, that even when you have a cutting head up, dashpot still have influence on the weight of back counterweight. So you can basically set up these two values on every position of the back counterweight. That can cause that I put back counterweight too close to cutting head and there was created some disbalance. So I put it back somewhere in half length of the screw which holds it and things start to get much much better. I don't have much time to experiment with it right now, but it looks this is the way how to solve this problem.

I am not sure why heating is recommended, perhaps someone who does know can offer some advice here. In my experience it doesn't help to keep the disc flat, or increase the lifetime of the stylus enough to make it worthwhile spending the time, but some people may disagree.

You don't need to worry too much about the accuracy of the initial 50g... its the dashpot that does the accuracy. I recommend 12.5g.

[tragwag]

interesting discussion going on about the blank heating, my personal experience is that heat makes a huge difference when embossing.
I started with embossing, then started cutting and kept heating the blanks to a reasonable level (70-80 deg F) for cutting with diamond.
Embossing I still heat closer to 90 deg F and notice a difference in surface noise.

[mushroomjesus]

i use heat to flatten the blank and help dry the surface denoiser.

i find blanks are sometimes bowled.ex- heating black souri blank @ 45 can help flatten the blank.

i typically heat blank then let it cool sometimes wait 20 mins after heating before cutting.

after cooled back too room temp then i use surface denoiser and will only use heat lamp to dry up the denoiser before turning light back off to begin cutting.

if you are applying a correct amount of denoiser it will dry up in 3 seconds


for me when cutting depending on the time of year blanks sit around 28-30 with no lamp room temp


i use a red reptile light at 75 watts no dimmer

30 room
+10 or +15 on heat wire =40 or 45

that’s my logic and works for me

too much heat lamp = bad swarf

heat = static build up. i find more static build up using rubber mat combined with lamp.


souri black has a polycarbonate like center so more heat for souri black blanks to flatten vs pure petg

2mm vs 1mm seems to be better for overall blank flatness…. so 2mm less heat.


blanks are shipped on airplanes and might have some flux do to temperature changes and packing and travel.then how we store them also effects the blanks etc. a little heat helps flatten them.


how do you all store your blanks? do you keep all 50 warped in cellophane on a flat surface ? rotate them ? break into smaller piles ?



funny but serious observation - heating a “pvc” blank- if your blanks are pvc - DO NOT HEAT

you can not heat a pvc blank seriously chloride is dangerous to your health. if you are not sure what material you are cutting on please read the Beilstein PVC Burning Test.




is heating any kind of plastic healthy ? petg is used in the food industry but i try to not eat microwave food .


so i think heat lamp has important role and is used to mostly maintain flatness and dry up denoiser,

i will mention in the winter it got a little colder and depending on how i heated the studio sometimes the lamp would help add a little room temp consistency year round.


a hot platter and a cold blank can also warp or bowl the blank i try to wait 20 mins for platter to cool down before deciding if the new cold blank is flat enough or needs heat. i use the turntable and the blank to observe its flatness. if it looks uneven spinning- heat, cool then cut.



i have seen these vinyl record flatness online now. i want to try one to replace lamp.

my observation on vinyl record flatting machines…..it’s heating pvc lol but for petg sounds like an option.

[Dub Studio]

How warped are your blanks!?

There should be minimal warping on arrival, I always unwrap them and store them upright on a shelf (as with any vinyl) but I never get the sense that storage is an issue in that regard.

Of course, there will always be a certain amount of deviation from flat, which is why its best to have a slightly concave platter. The clamp will pull the center down and keep the edge pressed against the platter. If the turntable is slightly tilted, the cutting head will still traverse at the same height relative to the disc. You can use the suction tube and eyeball the amount of tilt as it passes over.

If the discs are not deburred, you will still get ripples because the burrs will prevent the disc from making proper contact with the platter. No amount of heat will fix this.

One solution is to use rubber gaskets, slightly smaller in diameter than the disc you are cutting. I made a set (14 inch, 12 inch, 10 inch and 7 inch) and they worked pretty well, although there was always a fair amount of space under the disc towards the center.

The other solution is to deburr of course, but that takes time.

I am a party animal so I prefer to use an alcohol-based home brew for getting rid of static. Dries much quicker than water-based (obviously), requires no heat and leaves practically no residue so no cleaning needed afterwards.

[spinnertownblanks]

Discs should always be taken out of their plastic wrap immediately, and stored on their sides if possible like you would your record collection but not a huge deal as long as the discs are stacked neatly and on a totally flat surface. Our discs are PETG and we can confirm that PETG does not need heating, and heating can cause more issues than solve. This is information from working with the manufactures too, not just opinion based.

For anti-static liquid, we find the best is just Isopropyl Alcohol like Dub Studio said, its strong, so can be diluted, we was selling it in bottles at a 75% Iso to 25% Distilled Water ratio, we got amazing reviews so we just gave out the recipe for free, worth trying and very cheap to make.