Turntable resonance

[Jeb98]

The technology deployed in gramophones tells us that engineers at least tried to do something to dampen resonance and halt soundwaves mechanically propagating through the machine's body. The felt covering the turntable and the rubber isolators between soundbox and tonearm are the most evident ones. They clearly show, in any case, that they considered and tried to put a limit to issues concerning resonance.

So a dead turntable would be preferable to a live one?

With modern day turntables, the platter is often made to be with no ringing or resonances. But also, every section of the turntable is made to very high tolerances with isolation of noise, reducing of friction, and damping of resonances.

I figure that there is not enough sound fidelity for resonances to matter that much in a gramophone but I don't know. If you look at the average gramophone, these were mass produced and not precision made machines. There is motor noise and vibration that makes it's way to the turntable or platter. Regardless of that, the short tonearms of most gramophones introduce considerable tracking error on records, and it can be heard during certain dynamic passages where a lot of distortion or sibilance comes through.

If you look at the EMG and Expert gramophones it looks like they took considerable measures to make precision machines and the tonearms are longer, I would assume to decrease tracking error. I wonder if their platters ring. It seems they took a lot of considerations into the sonics of their machines, and if they damped their turntable platters I guess that would give credence to it having a positive effect.

Sorry for the long reply!

Jonas

[Daithi]

With modern day turntables, the platter is often made to be with no ringing or resonances. But also, every section of the turntable is made to very high tolerances with isolation of noise, reducing of friction, and damping of resonances.

There is motor noise and vibration that makes it's way to the turntable or platter.
If you look at the EMG and Expert gramophones .....I wonder if their platters ring. It seems they took a lot of considerations into the sonics of their machines, and if they damped their turntable platters I guess that would give credence to it having a positive effect.

Sorry for the long reply!

Jonas

Your reply was as long as it needed to be. I guess it only remains for someone to tap the side of an EMG turntable and report the results.
Very informative, thanks.

[AudioFeline]

So a dead turntable would be preferable to a live one?

• An acoustically-dead turntable will sound lifeless, an acoustically "live" turntable may have unacceptable resonances. The best balance between the two is ideal - the unwanted resonances are tamed but the music still lives.

• Alternately, a "live" (working) turntable is always preferable to a dead ("non-working") turntable!

[Marco Gilardetti]

This turntable resonance conversation and relative comments recall to some degree what is usually said about the reverb in a listening room. Too much reverb will mush the sound and will kill some frequencies due to cancelling resonance. On the other hand, however, there is a general consensus that an over-treated, almost anechoic room feels unnatural to the ears and would kill the life out of music.

However, it has also to be said that depending on the specific appliance, recommendations vary. When it comes to loudspeaker cabinets, usually everything is done in order to kill unwanted resonances. I don't remember ever reading an article in which anyone recommended to leave a bit of spurious resonance in loudspeaker cabinets.

Coming to Hi-Fi record players, the cabinet is generally very highly damped, with coil suspensions plus other passive materials (again: never read anywhere that the cabinet might resonate) that would isolate the cabinet from soundwaves fed back from the speakers. The arms are usually engineered in such a way that, matched with the appropriate pickup, the resonance is out of the hearable frequency range (it is usually set very low, ideally around 10 Hz). The turntable is usually highly damped with an overabundant rubber mat. Sometimes rubber is replaced with a felt mat, or with a carbon fibre / synthetic foam mat, or with a cork mat, or for the more demanding ones with a leather mat. All of these materials are vibrations-dampener to various degrees. But then, at least in this case, there's today's extravagant person who say he listens with a copper "mat" and reports "improvements" in sound quality. Personally I never tested a copper "mat" and I believe that, as a material, it is unfit for the purpose, with issues concerning the record/mat contact surfaces etc.; but I thought to report that a minority of people claim that a non-dampening metal mat is OK.

[Daithi]

The turntable is usually highly damped with an overabundant rubber mat. Sometimes rubber is replaced with a felt mat, or with a carbon fibre / synthetic foam mat, or with a cork mat, or for the more demanding ones with a leather mat. All of these materials are vibrations-dampener to various degrees. But then, at least in this case, there's today's extravagant person who say he listens with a copper "mat" and reports "improvements" in sound quality. Personally I never tested a copper "mat" and I believe that, as a material, it is unfit for the purpose, with issues concerning the record/mat contact surfaces etc.; but I thought to report that a minority of people claim that a non-dampening metal mat is OK.

Heavymetal fans always breaking the rules .... of physics.

[VanEpsFan1914]

Daithi--are you building a phonograph?

[Daithi]

Daithi--are you building a phonograph?

Yes ....
As we speak...so to speak.

[VanEpsFan1914]

Daithi--are you building a phonograph?

Yes ....
As we speak...so to speak.

Neat! Good luck with it; I am very curious what it will look like.

[Marco Gilardetti]

there's today's extravagant person who say he listens with a copper "mat" and reports "improvements" in sound quality.

Heavymetal fans always breaking the rules .... of physics.

Well, my take on this is that the "improvement" has little or nothing to do with resonance, but it's instead due to the fact that copper is a conductive material, that quickly discharges to ground static electricity.

As a matter of fact, after having tried a half dozen of different mats, the one I seem to like the most is a carbon fibre, non-woven fabric, which is conductive and literally eats out all static. Unfortunately it is extremely light, so all the weight of the rubber platter is subtracted to the turntable. I'd be happy if I could have a mat as thick and as heavy as a rubber one, but as conductive as the mentioned carbon fibre mat.

[Daithi]

As a matter of fact, after having tried a half dozen of different mats, the one I seem to like the most is a carbon fibre, non-woven fabric, which is conductive and literally eats out all static. Unfortunately it is extremely light, so all the weight of the rubber platter is subtracted to the turntable. I'd be happy if I could have a mat as thick and as heavy as a rubber one, but as conductive as the mentioned carbon fibre mat.

How about a sandwich of carbon fiber and some heavy material?