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

goofyfoot

No there are true mono designs made today that play in both right in left channels.

Of course. But if it has vertical compliance consistent with the Westrex 45/45 system, it's not a "true mono" cartridge. It's that lack of vertical compliance that makes a true mono cartridge incompatible with a stereo LP.

@cleeds So Miyajima, Hana, EMT, Ortofon and Audio Technica cartridges are not true mono cartridges because they have two balanced mono coils and play mono in both the right and left channels. That doesn't make any sense to me but you apparently have a definition of what's a true mono cartridge that's different from what everyone else thinks.

To All,

While I may have been impetuous and inaccurate about exactly which mono designed cartridges use two balanced mono coils and which use a single, both designs exist. And both designs can be considered a true mono cartridge. My determination for a true mono design is based on the differences between a strapped stereo cartridge and one that is built from the ground up, for strictly mono.

The Hana mono cartridge is described as a true mono, single coil cartridge that can be used on a stereo pressing without damaging the record.

Here is AI’s response to the single coil to dual coil mono design approach;

Two Coils vs. One: Traditional true mono cartridges rely on a single coil. However, cartridges described as having "left and right mono coils" typically feature dual moving coils (like a stereo cartridge) internally wired or angled to respond only to horizontal movement. This dual-generator configuration allows the cartridge to present a balanced load to your preamp, avoiding the ground-loop hum issues that can sometimes occur when bridging a single-coil mono cartridge to two stereo inputs.

The Audio Technica AT33 Mono as recommended by Jonathon Carr on an earlier Audiogon post. The AT 33 Mono has two distinct, horizontally oriented coils.

 

 

@goofyfoot 

The distinction between true mono cartridges and those that are not, pertains to whether a stereo cartridge was strapped. This has been discussed in past Audiogon posts to great detail

Rather than trawl through umpteen posts, I asked ChatGPT, which of course has already trawled through Audiogon posts angry while building its Large Language Model!

Strapping a cartridge refers to internally wiring the audio pins of a stereo turntable cartridge so that both channels output the exact same signal, converting a stereo cartridge into a mono player. [1, 2]

How It Works

  • The Pins: The back of a standard phono cartridge has four pins: Left (+ / -) and Right (+ / -).
  • The Strapping: A small wire, solder, or connector physically bridges the positive pins together and the negative pins together.
  • The Result: Rather than outputting separate left and right stereo signals, the cartridge combines the audio data into one single, centralized signal, mimicking a true mono setup. [1, 2, 3]

Why People Do It

  • Better Mono Playback: Playing vintage mono records using an unstrapped stereo cartridge can create annoying, out-of-phase surface noise. Strapping eliminates this and reduces background noise and rumble. [1, 2]
  • Cost Savings: True mono cartridges can be expensive. Strapping an affordable stereo cartridge allows you to achieve the benefits of mono playback without buying specialized equipment. [1, 2, 3, 4]
  • Modern Convenience: Many manufacturers offer mono cartridges that are factory-"strapped" for plug-and-play compatibility with standard stereo amplifiers. [1, 2]

As a bit of an aside, current DS Audio optical cartridges cannot be strapped, because two of the four wires carry a DC voltage to power the Light Emitting Diodes in the cartridge. 

Also a bit quirky is my Soulnote E-1 Ver2 Equalizer, which acts as a phono stage for MM and MC cartridges, as well as being an equaliser for DS Audio optical cartridges.  It has a switchable low-cut filter designed to mitigate the audible effects of warps, but the filter only operates on MM and MC inputs wink.

The Soulnote is also a bit unusual because it does not use any negative feedback.  Negative feedback improves distortion numbers in the frequency domain, at the expense of smearing signals in the time domain.

I get the sense that every 'quirk' in the Soulnote has been carefully thought through by the designers, so it is no accident that the extended bass from optical cartridges is kept intact.  Also, there is no mono switch - that is left to the pre-amplifier laugh

When I think about my vinyl playback systems, there are three critical components. I would like my turntables and cartridges to be neutral, minimising added noise and coloration.  Against this quiet background, the Soulnote phono-stage / equaliser seems to make an astonishing difference though I have no rational way of apportioning the plaudits.

@goofyfoot 

This dual-generator configuration allows the cartridge to present a balanced load to your preamp, avoiding the ground-loop hum issues that can sometimes occur when bridging a single-coil mono cartridge to two stereo inputs

It is a bit early in the morning for me, but I cannot see why a single coil (with two wire connections) cannot also present as 'balanced' to a phono stage with suitable mono input.

Another quirk of the Soulnote is that it can accept balanced or single-ended input from MM and MC cartridges over either XLR or RCA connections.  Balanced or single-ended operation is configured by a rear panel 'bridging' switch and the user cannot mix-and-match from the front panel.