Nude Turntable Project

Hi Lewm - you posted

Lewm - From the photo, and the two smaller inset photos which I cannot get my computer to enlarge for me, I think I see that the SP10 sits on spikes that are inverted such that their pointy tips are going up into the threaded bolt inserts on the bottom surface of the SP10 escutcheon. I don't see anything "compliant" in that.

Sorry for the confusion.
The photo was my feeble attempt at a type of collage showing the latest setup Version 5.
But the previous pic also showed the previous version SS legs which confused things.

Here is an updated pic.

http://cgim.audiogon.com/i/vs/i/f/1377781727.jpg

Version 4 is the bottom right pic.
Moving clockwise

Version 4.5 can be seen and then the latest Version 5.

Version four uses the pointy Solid Stainless Steel legs - the points are matched to the indentation of the cone footers They are heavy enough couple pounds each; add in the sp10 weight - and you easily indent the shelf they are placed on. In this case its a Mennonite made maple block (acting in the plinth role in this setup). The threaded flat holes at the other end of the SS pointy legs use a threaded joiner and that side gets screwed into the sp10 (in all versions) Various different materials can be wrapped around the threaded joiner before inserting and will affect sound.

The latest setup shown - bigger pic - has everything rigidly bolted in SP10 and Armpod. The SS legs in this version have threaded holes both ends (with threaded joiners at both ends for bolting into the sp10 and the black shelfl which in this set up, is now in the plinth role. The same maple block is no longer playing the plinth role and has been decoupled. My definition of a plinth (so no confusion with my post)the immediate base structure that holds all the TT system goods. :^)

You had posted earlier

Just by eyeball, your brass pod appears to be canted with respect to the SP10 platter surface. Probably an optical illusion.

isnt this whole hobby a sort of audible illusion ? Its probably the phone camera shot in low light but even if it was a mini version of a leaning tower a pisa it would not matter. The ET2 mounted on it has three leveling spikes and can be leveled on any surface. I have also had the top mounted Dynavector tonearm on this solid brass armpod. Now a tower of pisa would be a problem with it.

I'd like to mention a small but very significant point. I add some oil in the one hole at the top of the brass arm pod that is used to secure the ET2.

I hear the difference. I believe the oil works (with resonances) in a similar fashion to the actual damping trough on my reference ET 2.5 which is in my main room.

Cheers

Hi Richard - thanks for sharing those ideas.
If I understand you are using three leg supports under your triangle TT.

One is the "alpha" leg the leader for energy transmission, while the other two are slower followers? Are you not worried about energy in the plinth getting built up in those two areas with the pvc legs? Did you have a way to test this other than by listening?

My sp10mkII when being set up on my SS legs clearly shows a very heavy "weight bias" to the front left when viewed from the front - where start/stop switch is. Is the Sp10mkIII similar in weight distribution?

Would this mean the alpha leg goes on the heavier corner of your plinth ?

also I am curious.

Do you have an opinion on how your theory would work with a turntable that does not use a thrust bearing?
Air Bearing or Magnetic propulsion for levitation?

thanks

heavy "weight bias" to the front left when viewed from the front

maybe its the front right side now that I think about ..... its been too long.

Chris.

Like your Alpha leg analogy. Actually, with the other two feet, we are trying to block energy transmission as much as possible although in practice I doubt that this can truly be done. The PVC feet are softer than the plinth and the shelf, acting like a road block.

I have tried this approach on all of my home brew and some commercial TT's, it doesn't seem to matter if there is weight asymmetry.( That said, my current triangular TT is virtually weight symmetrical) In all cases IMO, the one spike and two "feet" arrangement was better than 3 spikes. A trend is that, for a conventional plinth type TT, the spike goes close to where the tonearm is. I don't see any issue with energy build up in a suitably rigid, hard chassis.
The idea is to get mechanical energy out of the system quickly and cleanly.

Also I don't think that there would be any issue with this approach on an air or magnetically levitated platter.

No figures to back all of this up. Just listening.

Cheers.

08-26-13: Richardkrebs
From reading here it seems that those that prefer hard supports make them all out of the same material. I believe that this arrangement can be improved, if your goal is to wick energy out of the TT structure. By using, say, three identical hard feet you are creating multiple paths to the shelf (ground). This is the electrical equivalent of an earth loop.

This is certainly not new.
The seminal article for mechanical grounding in audio equipment as applied to turntables was the Technical Report by Martin Colloms of the Goldmund Reference published in Volume 51 of The Absolute Sound magazine in 1988. Colloms undertook a complete dissection of the design of the Goldmund Reference including the single point grounding methodology that Goldmund employed. I would highly recommend anyone interested in TT design obtain a copy for reference. Some of these mechanical grounding principles were deployed to their entry level products such as the Goldmund Studio that richardkrebs owned.
Each time there is a change in materials some energy passes through and some gets reflected back. For example if you have a mat on a platter, then some energy will pass through from the mat to the platter, but some energy will reflect back to the record/stylus and smear the sound. This is basic materials engineering.
Providing properly designed pathways to drain unwanted energy from the stylus, record interface through the platter to ground in order to prevent coloration from energy reflecting back into the record and stylus has been around since the 60's, moreso in Japanese audio circles.
The Final Audio Parthenon from Japan released in 1971 is essentially a nude turntable with defined energy paths from stylus to ground. The designer Kitamura explains that the amount of energy generated by the interaction of stylus and groove is much higher than required to drive the coils, and therefore unless the balance of energy is drained to ground, it rebounds and resonates the turntable, arm and cartridge, superimposing resonances back into the playback. This is documented in a review of the Final Audio TT in TAS Volume 8 #30 in 1983. The absence of resonance, which results in a clarity and density of tone unparalleled by other TT's I have auditioned such as the Goldmund, Micro Seiki's. SP10's, L07D's etc is one of the primary reasons I purchased the Final Audio Parthenon.

08-29-13: Ct0517
If I understand you are using three leg supports under your triangle TT.
One is the "alpha" leg the leader for energy transmission, while the other two are slower followers? Are you not worried about energy in the plinth getting built up in those two areas with the pvc legs? Did you have a way to test this other than by listening?

08-29-13: Richardkrebs
Like your Alpha leg analogy. Actually, with the other two feet, we are trying to block energy transmission as much as possible although in practice I doubt that this can truly be done.

Actually it does work.
With electrical grounding the signal always finds the path of least resistance.
With a mechanical ground, as discussed, providing a single path to ground results in a cleaner dissipation of energy. Mechanical resonances and disturbances will find the path of least resistance to some degree, but there must be a logical path in terms of materials selection, transmissibility etc from platter to ground to minimise backward reflections. In the richardkrebs example the resonant behaviour of the hard footer will result in a specific resonance absorption and transmission/reflection profile, whereas the soft feet will attract a resonance absorption and transmission/reflection profile that is quite different. If one were able to put together a mathematical model of the structure and materials composition, then minimising the resonant behaviour and backward reflections can be calculated quite easily and would be more reliable than listening since no system exists without colourations due to room or other equipment..