Rumble from Turntable Bearing?

[AndyMorris]

From Vinyl rips I have done and processed in Audacity and Vinyl Studio, I have recently noticed a rumble with a period of 0.12 seconds. This is equivalent to 8 Hz. It beats with a period of 1.8 seconds, which is 33 1/3 times per minute. The rumble amplitude at the maximum of the beat is about -30 db.

Obviously, as I am not an elephant I cannot hear this, but it does raise some questions in my mind:

• Is it reasonable to assume this is caused by the main bearing on the turntable?
• Are the bearings on the turntable on their way out? I estimate, from my collection on Discogs that I have played more than 500 records on this (mid price, DJ style KAM ) turntable. Mostly LPs a few singles and some 78s
• Will this inaudible, which is removed by Vinyl Studio, cause any other distortion?

I would love to hear anyone's opinions oof what is going on here. Do I have a good excuse to get a new TT?


The following screen shots are from the lead-in groove of a good quality LP:

Frequency of rumble

Period of beat

 

[Audio Science Pal]

From Vinyl rips I have done and processed in Audacity and Vinyl Studio, I have recently noticed a rumble with a period of 0.12 seconds. This is equivalent to 8 Hz. It beats with a period of 1.8 seconds, which is 33 1/3 times per minute. The rumble amplitude at the maximum of the beat is about -30 db.

Obviously, as I am not an elephant I cannot hear this, but it does raise some questions in my mind:

• Is it reasonable to assume this is caused by the main bearing on the turntable?
• Are the bearings on the turntable on their way out?

I would love to hear anyone's opinions of what is going on here. Do I have a good excuse to get a new TT?

Once every revolution points to the bearing. If the platter lifts off easily so you can clean and lube the bearing, you could try that. Otherwise, you have a good reason to buy a new turntable.

 

[Waveform Fidelity]

Its just a warped record

 

[Thomas_A]

Most likely it is the resonance frequency of the cartridge + warps and eccentricity.

 

[DVDdoug]

-30dB rumble would be pretty bad, but I would want to make sure it's not the record(s) before replacing the turntable.

Whatever it is, a 20-30Hz high pass filter should reduce it drastically. It's probably a good idea to filter it out. (Most records don't have a lot of energy below 40Hz anyway.)

 

[WDeranged]

Vinyl just has abysmal rumble. It's good practice to hard cut everything below (edit) 15hz.

 

[EJ3]

Vinyl just has abysmal rumble. It's good practice to hard cut everything below 15khz.

YES!
What I do:
My Technics SL-M3's TT Rumble: -82dB
Turn on the 15Hz infrasonic filter:
The low-frequency response is the same with the tone controls either defeated or engaged, for all inputs and all outputs.

The 15 Hz filter is selected with a rear-panel switch.

It's -1/2 dB at 20 Hz, -1 dB at 17.5 Hz, -2 dB at 15 Hz, -3 dB at 14 Hz, - 5 dB at 12 Hz and -10 dB at 10 Hz.

15 Hz filter (only) response.
Problem solved.​

 

[WDeranged]

YES!
What I do:
My Technics SL-M3's TT Rumble: -82dB
Turn on the 15Hz infrasonic filter:
The low-frequency response is the same with the tone controls either defeated or engaged, for all inputs and all outputs.

The 15 Hz filter is selected with a rear-panel switch.

It's -1/2 dB at 20 Hz, -1 dB at 17.5 Hz, -2 dB at 15 Hz, -3 dB at 14 Hz, - 5 dB at 12 Hz and -10 dB at 10 Hz.
View attachment 492238

15 Hz filter (only) response.
Problem solved.​

My preamp (Spartan 15) has a brilliantly deep cut in that area. No point in your speakers pumping for no good reason. Plus, waveforms look so much cleaner without that ripple running through them.

 

[Petrushka]

DSP can kill super low frequencies without affecting music.

 

[EJ3]

My preamp (Spartan 15) has a brilliantly deep cut in that area. No point in your speakers pumping for no good reason. Plus, waveforms look so much cleaner without that ripple running through them.

This is out of my 1977 APT/Holman Pre Amp (the Tom Holman that invented LUCAS sound for the movies, THX, 5.1 surround sound [and more]).

 

[EJ3]

DSP can kill super low frequencies without affecting music.

One day, (if I feel what I have isn't enough) I'll add DSP into my processor loop (maybe). Since I have subs that I built that cover 20Hz-80Hz, they may surprise me and I may determine that I need DSP.
But: I think -92 @ 10 Hz is just fine (TT rumble -82Db + infrasonic -10 Db filter cut.
It's certainly inaudible when taking room noise into account.
I do not use a weight to hold the record flat, I use a pad (from K.A.B.) that grips the spindle and holds the label area flat, thus reducing warp.
That way I avoid having much extra weight on the bearing.
KAB SUPER RECORD GRIP MK2

[td]

[/td]​

• Molded Phenolic
• Color: Black
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• Height: 1"
• Weight: 2 Oz.
• Max Spindle Height: 3/4"
• Bubble Level Accuracy: 1°
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Claims:

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[AndyMorris]

Its just a warped record

It happens on all records

 

[Chrispy]

Easy enough to eliminate at 8hz, so that would be my approach. Just another vinyl issue that comes with the territory, tho

 

[LTig]

Vinyl just has abysmal rumble. It's good practice to hard cut everything below 15khz.

That would be rather pointless.

 

[WDeranged]

That would be rather pointless.

Vinyl isn't that bad

 

[Chrispy]

Vinyl isn't that bad

Otoh it isn't so good to go out of your way for....

 

[WDeranged]

Otoh it isn't so good to go out of your way for....

I dunno. Depends what bands you're into. Some are well served by digital.

 

[Chrispy]

I dunno. Depends what bands you're into. Some are well served by digital.

Not what I meant. I'm saying vinyl is largely not worth it unless you're an old fart like me with an existing tt and collection. To dive in now sounds insane to me.

 

[WDeranged]

Not what I meant. I'm saying vinyl is largely not worth it unless you're an old fart like me with an existing tt and collection. To dive in now sounds insane to me.

It is insane. If I knew how insane I wouldn't have bothered. But I've gotten a lot of joy from it.

 

[Chrispy]

It is insane. If I knew how insane I wouldn't have bothered. But I've gotten a lot of joy from it.

As long as you know. I haven't bought new vinyl in 30 years.