Rumble from Turntable Bearing?

[Balle Clorin]

It happens on all records

Well all records are warped to some degree. I see the same in most records , on every of the 4 turntables I have, and also on Mike Fremers most expensive systems( audio rip from YouTube). A tiny irregularity triggers the arm-cartridge 8 hz resonance.. A bump of 1/100 of a millimetre can trigger it. This is why any good RIAA must have a sharp filter at 20hz or so

First time I saw that pattern you see I thought I had a problem too, but since it is appears every where on any system I realised is is just the nature of vinyl playback

Get a good clamp Michell type and use a rumble filter to remove it

 

[Thomas_A]

One can do this before the filter well. Moerch DP-8 tonearm excels at reducing LF noise and other tonearms with damping as well. Also of course flattening records.

 

[AndyMorris]

Well all records are warped to some degree. I see the same in most records , on every of the 4 turntables I have, and also on Mike Fremers most expensive systems( audio rip from YouTube). A tiny irregularity triggers the arm-cartridge 8 hz resonance.. A bump of 1/100 of a millimetre can trigger it. This is why any good RIAA must have a sharp filter at 20hz or so

First time I saw that pattern you see I thought I had a problem too, but since it is appears every where on any system I realised is is just the nature of vinyl playback

Get a good clamp Michell type and use a rumble filter to remove it

That's interesting. I'm thinking of ways to see if that is so.

 

[Frank Dernie]

A phono cartridge is a seismic type transducer.
The sensing element needs to "measure" the movement between the stylus and what should be the stator - ie the cartridge body which should be motionless.

In fact it is obviously not motionless at low frequencies, which is just as well otherwise it wouldn't be able to trace the groove, and as frequency increases and approaches the resonance of the cartridge/headshell on the stylus suspension the cartridge body begins to move more than the stylus so its output is coming from cartridge body bouncing, not music on the record.
At resonance there is a phase shift and the cartridge body movement starts to reduce and, by about a frequency 2x the resonance the cartridge body on the suspension, is an near enough to being an acceptable stator and the cartridge output becomes an accurate reproduction of what is on the record.

All this spurious output should be removed since it is inaccurate.
It is possible to add enough damping to transducer these lower frequencies more accurate but, depending where this damping is, and what type it generally makes the cartridge less accurate at the audible frequencies so is a pretty bonkers thing to try

 

[Waveform Fidelity]

DSP can kill super low frequencies without affecting music.

Well, yes but sharp cut-off frequency introduce horible phase shifts that affect good bass response. Aslo recall here is RIAA equalization !

 

[EJ3]

Well, yes but sharp cut-off frequency introduce horible phase shifts that affect good bass response. Aslo recall here is RIAA equalization !

Would the "horrible phase shifts" at the frequencies in ? be noticeable at or below 10 Hz?
Or above 20 Hz? Remembering that we are dealing with records and phono stages.

 

[Waveform Fidelity]

Depends on the filter design. Most amplifiers have a low frequency roll-off anyway typically 5-10Hz so there is already some rejection of the sub-sonic signal

 

[Frank Dernie]

Well, yes but sharp cut-off frequency introduce horible phase shifts that affect good bass response. Aslo recall here is RIAA equalization !

Yes but the physics of how all seismic transducers function guarantees a phase shift at low frequencies so IMO that is commonly used straw man reasoning.
It doesn't need to be that sharp, just at around 25 to 30Hz.
The reality is that bass response is one of the weak points of the way the disc/arm/cartridge system works and is hard-wired in by physics and is therefore inevitable.
People who just like "more bass" may like listening to a bass boosting flank of a resonance curve but accurate or "good bass response" it ain't, and physically can not be.

 

[EJ3]

Depends on the filter design. Most amplifiers have a low frequency roll-off anyway typically 5-10Hz so there is already some rejection of the sub-sonic signal

Bassed on your statement, I guess that I'm just lucky:
Mine (perhaps in 1979 my APT/Holman Pre Amp was designed correctly):
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

And I guess that in 1988 my NAD 2200 amp was also correctly designed (the green lines FR):

From what you say, it's not statistically probable that 2 pieces of gear, from different manufacturers and from different decades would have good low end FR. H'MM?

 

[AndyMorris]

Thank you for everyone's thoughts and ideas. Very informative.

My Setup has a turntable with a (switchable) phono amp going thru a Behringer UFO202 which can accept either line or phono input to digitise and send up the USB to my PC.

The original screenshots are from a setup where the turntable phono was used to send a line level signal to the UFO202.

When I switched the turntable to output at phone level and used the phono amp built in the UFO the rumble was removed.

 

[Waveform Fidelity]

Thank you for everyone's thoughts and ideas. Very informative.

My Setup has a turntable with a (switchable) phono amp going thru a Behringer UFO202 which can accept either line or phono input to digitise and send up the USB to my PC.

The original screenshots are from a setup where the turntable phono was used to send a line level signal to the UFO202.

When I switched the turntable to output at phone level and used the phono amp built in the UFO the rumble was removed.

I am surprised you could hear it!

 

[NTK]

Any chance the turntable has a 15-pole motor similar to this one (SP10)? Perhaps some out-of-alignment or other problems also magnified the cogging torque.

 

[AndyMorris]

I am surprised you could hear it!

I didn't hear it, I saw it in audacity

 

[EJ3]

Yes but the physics of how all seismic transducers function guarantees a phase shift at low frequencies so IMO that is commonly used straw man reasoning.
It doesn't need to be that sharp, just at around 25 to 30Hz.
The reality is that bass response is one of the weak points of the way the disc/arm/cartridge system works and is hard-wired in by physics and is therefore inevitable.
People who just like "more bass" may like listening to a bass boosting flank of a resonance curve but accurate or "good bass response" it ain't, and physically can not be.

Just curious (since I presume that you are talking about non-linier tracking arm turntables [and my main table is a Technics SL-M3 linier tracking TT]):
Is that true with linier tracking turntables, too?

 

[EJ3]

I didn't hear it, I saw it in audacity

So, it is inaudible & occurs at - how many DB?

 

[EJ3]

Thank you for everyone's thoughts and ideas. Very informative.

When I switched the turntable to output at phone level and used the phono amp built in the UFO the rumble was removed.

Perhaps the built in Phono amp has a built in RUMBLE filter?
That brings a couple other questions about it's FR coverage & slope, if it has a "rumble" filter.
Or does the built in Phono Pre-amp even reach into the low bass region (many don't reach down that far).
So, perhaps further research is warranted.
Hopefully, it's not the bearing (although, that could be a good excuse to get another TT).

 

[AndyMorris]

So, it is inaudible & occurs at - how many DB?

The picture in my original post shows it at around -30db

 

[AndyMorris]

Perhaps the built in Phono amp has a built in RUMBLE filter?
That brings a couple other questions about it's FR coverage & slope, if it has a "rumble" filter.
Or does the built in Phono Pre-amp even reach into the low bass region (many don't reach down that far).
So, perhaps further research is warranted.
Hopefully, it's not the bearing (although, that could be a good excuse to get another TT).

I suspect that as the turntable was a mid price DJ style TT that they added a phono preamp to get into the 'vinyl rip' market. I suspect that mpost professional DJ mixers and/or PA systems have a pretty good LF filter to stop the PA stacks walking across the floor. Vinyl Studio does have a pretty good rumble filter.

A new TT would be very shiny, but the money would also buy a lot of records.

 

[EJ3]

The picture in my original post shows it at around -30db

That is potentially (actually, for younger [and safely kept but utilizing ear plugs and such]) probably audible at times in a relatively quiet room.
Does your TT have a spec on what the rumble is supposed to be? If so, compare it to what you are seeing.
Many,(perhaps most) do not maintain their TT properly. (I am/have been guilty of this, too).
Personally: I would lube the bearing with a proper TT bearing lube & check again. (after a few hours of use).
If it went down, great, if it did not, then I would be looking into either replacing the bearing or getting a better TT.

 

[Frank Dernie]

Just curious (since I presume that you are talking about non-linier tracking arm turntables [and my main table is a Technics SL-M3 linier tracking TT]):
Is that true with linier tracking turntables, too?

It is a function of the way any cartridge works so is unavoidable with any arm.