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Where do classical vinyl records get their rumble from?

Recently converted back to vinyl from silver disks, I am struck by how much rumble seems to be inherent in the new and used vinyl I am buying.

A case in point, is a recent Deutsche Grammophon (DG) recording (487 7484) of Mahler’s Second Symphony made at a live performance at the Sydney Opera House (I was there).  The first set I bought was amongst the dirtiest pressings I have ever had, but the second set was much improved.  However, there is a persistent rumble whether played on my Holbo Mk2 air bearing system or my venerable Garrard 301 (new bearing from Classic Turntable Company).

Mahler typically has huge dynamic range, from muted off-stage performers to hundreds of musicians going hell-for-leather.

The rumble could be partly caused by the venue’s air conditioning system, but I hear similar background on a Telarc recording (Stereo 10051) of Saint Saens Organ Symphony made in Philadelphia.  Telarc even arranged to have local roads shut down for the recording sessions.

Similar efforts were made by DG when recording the organ at Notre Dame in Paris, where recording was done late at night to reduce traffic noise.  My copy includes Dolby Atmos on Pure-Audio Bly-ray (DG 486 1466).

I was beginning to think the rumble was inherent in my tables, but then I played a German Direct Metal Mastered (DMM) set from In-Akustik for Clearaudio’s 40th anniversary (INAK 78051 2LP).  It includes some Telarc tracks.  This set has the quietest background I’ve never heard.  There is virtually no rumble, exonerating my tables.

So apart from the recoding venue’s air conditioning and traffic noise, why do so many classical records seem to have built-in rumble?  Could it be from the mastering lathe?

I am really only thinking about classical recordings where the dynamic range approximates the signal to noise ratio of vinyl, meaning that very low-level signals are musically important, while simultaneously bumping against the noise floor.

richardbrand
chrisoshea
602 posts
 

Richard…I didn’t see if you tried 
1. Removing all platter mats 

2.Listened to the same problem recordings on CD/SACD/Streaming to check in that pesky rumble 

If yes, what were the results?

 

Im in the camp that guesses your TTS are the issue. 

 

chrisoshea
602 posts
 

And Richard….Do you hear the rumble through headphones if you have that option?

I agree with the replies the that there is nothing inherently more prone to rumble in classical recordings 

richardbrand's avatar
richardbrand OP
1,475 posts
 

@chrisoshea 

I agree with the replies the that there is nothing inherently more prone to rumble in classical recordings

No, rumble (whether from table or record) is just more noticeable because of the huge dynamic range in some classical music, especially large-scale romantic orchestral / choral works.  When the music is very quiet, it is on a collision course with the noise floor of your gear.  To those who cannot hear the noise floor, turn your volume up until you can.

richardbrand's avatar
richardbrand OP
1,475 posts
 

@chrisoshea 

Im in the camp that guesses your TTS are the issue

How then do you explain how some records exhibit significant rumble-like noise while others are nearly silent, when played on the same turntables?

richardbrand's avatar
richardbrand OP
1,475 posts
 

@atmasphere 

You’ve mentioned the use of a turntable with an air bearing. This is entirely the FWIW Dept.: There should be zero slop between the platter surface and the mounting of the cartridge. As best I can make out, air bearings do not satisfy that requirement

Well, I can only answer on behalf of the air bearing table that I own - the Holbo Mk2.

I agree that zero ’slop’ should be the aim of the game.  A conventional bearing is a central shaft that carries the entire mass of the platter.  It is much shorter than the platter is wide, and runs in a lubricant bath.  Liquid lubricants are effectively incompressible, so any vibrations reaching, or generated by, the bearing are directly passed to the platter.  The effective bearing area is quite small and 'slop' needs to be addressed by precision engineering or adjustment.

Compare that to a platter supported across its entire area by air, which has an impedance mismatch with metal so most vibrations reflect away.  I don’t know the exact internal construction of the Holbo, but the platter and its bearing are machined to 10-microns. They and the tangential air-bearing tone arm are supplied by a low pressure, low volume air supply.  In fact, if I disconnect the air tube from the table, I can feel no pressure or air flow coming from the tube by using my fingertip. 

The platter weighs 5-kgs, about 11-lbs, and is grounded until the unit is switched on, at which point it almost instantly floats on a thin film of air.  There is so little friction, it takes 3 minutes for the platter to stop from 33-rpm if the drive belt is disconnected.

How much pressure is needed?  The area of the platter is about 113 sq inches which makes an easy division by its mass, giving about 0.1 lb per sq inch.  No wonder I cannot feel it.  I also cannot feel the platter rise - my understanding is that the lift is about 1/100th of a millimeter - 10 microns or 1/5 of the groove width of an LP.

How much air is needed?  The displaced volume is 113 sq inches x 10 microns - about 1/20th of a cubic inch.

Unlike liquids, gasses are compressible and make very good springs.  You have one at each corner of your car, running around 40 lb per sq inch.  The best riding cars, from the Citroen DS via the Austin 1800 to high-end Mercedes-Benz also have air in their suspensions.  Air very effectively decouples mechanisms from their surroundings.

The idea that an 11-lb platter somehow ’slops’ on a 10-micron air cushion, relative to the cartridge, is faintly ludicrous to me.  Could the tone arm on its air bearing have significant ’slop’?  Compared with the platter, it has about 1/100th of the mass and about 1/20th of the bearing surface area but also floats on 10 microns of air.  It is virtually friction free.

The tone arm constrains the cartridge so its only possible movements are in a vertical arc about the tone arm bearing, or bodily sideways parallel to the bearing.  Not much scope for ’slop’ there when compared to more conventional tone arms!

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