Where do classical vinyl records get their rumble from?

@tablejockey 

can a reflex style clamp be used on the Holbo platter?

Good to see you are still looking at buying a Holbo!  

I have never tried a reflex clamp but had a quick look at a SOTA Reflex LP Clamp. It would seem to fit, provided two conditions are met

1. The Delrin spindle must resist being pulled out of the platter
2. There must be sufficient spindle length protruding for the clamp to grip

The protrusion depends on whether you use a mat, and if so what its thickness is.

Funnily enough, I don’t know much about the internals of the Holbo even though I have one.

I probably know more about Wilson Benesch because they publish so many whitepapers and are backed by government grants and university research.  No doubt they apply for patents around the world - which is not a copy-protection mechanism affordable to most entrepreneurs.  Even patents probably don’t stop counterfeits from Asia! 

I only have one wish for a Holbo improvement, and it is a slightly longer spindle

@hb22  over to you!

I think the whole 6Hz resonance thing is a red herring.  But I am glad the problem is at least ameliorated if not solved. If the Tacet LP cannot make the SME resonate at all, like I said before, there is something fishy about it OR the resonance is below 5Hz (doubtful because it would cause havoc) or above 15Hz. Because all tonearms with all cartridges must resonate at some frequency.

The problem that arises with the horizontal resonant frequency is at 0.5hz. The Holbo in combination with the DS cartridge is at 6hz, so far from the problem. Do not mix the horizontal and vertical resonant frequencies. Also, the tangential tonearm airbearing is very different from the regular pivot tonearm, where the common resonant frequency can be very problematic.

And once again: the rumble has already been recorded on vinyl, there are such copies, and there are not a few of them.

@lewm 

I think the whole 6Hz resonance thing is a red herring

Thanks, agreed if you are looking for tonearm / cartridge resonance!  I realised last night that it is almost certainly caused by sub-plinth resonance instead.   Now I know that, if I were at home, I could just play the Tacet record louder and find out where the arm resonances are. The only instrument I am using with this record is my ear.

I am assuming the Tacet record relies on acoustic feedback to excite the resonance, which has to be big enough to cause audible mis-tracking?  But @billstevenson has caused me to query this assumption?

I am glad the problem is at least ameliorated

The only thing that has changed so far, is that I think that adding downforce makes one record sound slightly cleaner (the music, not the noise) but I doubt if I could pick it in an A/B comparison. Long term, I don't want to keep running an expensive cartridge at 150% of its recommended tracking force.

My original question about varying rumble-like noises from some classical records is still open 

@hb22 

the rumble has already been recorded on vinyl, there are such copies, and there are not a few of them

This strongly supports the contention that nearly identical artifacts are heard on two very different players.  Some records are noisy on both.  Some have nearly silent backgrounds on both.  Unfortunately for me, most of my records have very quiet passages which seem very close to the noise floor.  Some very new recordings from say Decca and DG are among my worst for high noise floors relative to the program - maybe they are trying to realistically capture bigger than usual dynamic ranges.

My test record does not have any test tracks below 5-Hz.  I could invest in better set up tools but in my opinion only azimuth and VTA are of real relevance to the Holbo, and VTA can be adjusted on the fly while listening anyway.