In that time I have learned a great deal through practical experimentation and
listening.
The lessons are many but the most significant one I believe, is this:-
- Isolated armpods around a 'nude' turntable is one of the most difficult (and problem-frought) solutions to the turntable design imaginable...
There are only two advantages I believe, for this solution:-
- Ability to easily adjust geometry for every (and any) tonearm
- Potentially better sound
The pitfalls are numerous:-
- Stability of the turntable
- Isolation of the turntable
- Levelling of the turntable
- Stability of each armpod
- Isolation of each armpod
- Levelling of each armpod
- Maintenance of the geometric relationships
- Elimination of ground-loop hums
- Elimination of EMI/RFI interference
- Cost
The fact that it has taken me seven years to fully resolve
all these issues (and the multitude levelling processes are still not perfect)
should be enough to discourage all but the foolhardy from following....
HERE is the final resolution
of my Copernican Nude Turntable...
You will notice that the whole assemblage now sits on a Herzan TS140 Active Isolation
Platform which weighs 28.5Kg(62.8lbs).
This platform in turn sits on a propped and cantilevered 33mm wall shelf made
of laminated stressed-skin MDF.
The circular blue plastic discs under the spiked footers are poker chips which
were needed to prevent a ground-loop hum caused by all the armpod and turntable
metalwork, conducting through the Herzan aluminium top-plate to the electronics
below.
These poker chips are Superglued to the Herzan aluminium top-plate to prevent
movement and 'lock' the overall geometry in place.
The Herzan provides sub-hertz active vibration isolation in all six degrees of
freedom.
Performance Details:
- Active vibration isolation from 0.7 – 1,000 Hz
- Passive vibration isolation from 1,000 Hz and beyond
- 90% vibration isolation at 3.5 Hz
- 99% vibration isolation at 10 Hz
- 99.9% vibration isolation at 20 Hz and beyond
- Up to 55 dB of vibration reduction beyond 20 Hz
This Active Isolation Platform has highlighted a major
weakness in the Copernican philosophy....
Because the armpods are separated from the turntable motor, they are all
subjected to the maximum Structure-Borne Acoustic feedback experienced by the
supporting floor/shelf/rack system.
With a 'normally' designed turntable.....the
tonearm mounting points are attached to the turntable's plinth and are thus
'shielded' from structure-borne feedback by the turntable's own isolation
footers and mass/material of the plinth design. The levelling of the arm
supports is also integrated with that of the plinth.
Here is a readout of the vibrations experienced by the Herzan with the Isolation 'OFF' and the
turntable/arm at REST.
The top line is vibration in the vertical plane and there are two directions of
horizontal vibrations below.
These vibrations are purely Structure-Borne Sound Transmission caused by the
flexural stresses in the supporting shelving material and are entirely ultra
low-frequency (2-10Hz). They are there ALL THE TIME....
These ultra-low frequencies can pass through and affect ALL materials
regardless of their mass or densities, and they are not successfully absorbed
or reflected by normal isolation stands, footers or springs.
Only specialised stands designed for applications such as electron microscopes
(able to provide isolation down to 2Hz or below) can prevent these damaging
frequencies affecting the turntable/platter/arm/cartridge interface.
Here is a readout with the Isolation 'ON' and the turntable at REST.
You can see how the Herzan has 'actively' absorbed and nullified these ultra
low-frequency vibrations and prevented them entering the turntable system.
All the following readouts contain vibrations of higher frequencies (mostly
above 1000Hz) which are able to be absorbed, reflected or dissipated (to a
degree) within the normal provinces of footers, stands, isolation devices and
depending on design....within the plinth, platter, feet and mass of the
particular turntable.
Here is a readout with the Isolation 'OFF' and the turntable
REVOLVING.
Here is a readout with the Isolation 'ON' and the turntable
REVOLVING.
Here is a readout with the Isolation 'OFF' and MUSIC PLAYING.
Here is a readout with the Isolation 'ON' and MUSIC PLAYING.
The Herzan has been integrated in my system for 6 months now, and not only is it the final 'piece' of the jigsaw for the 'Copernican'
puzzle.....but it singularly is the most significant contributor to the elimination
of 'distortions' and the elevation of sound quality that I have experienced in 40 years of
audio.
It must also have been a revelation to Frank Kuzma (who shares the remote armpod
design philosophy for his TOTL turntable) as in May 2017 at the Munich
High End Show he demonstrated a Herzan
(Table Stable) as a recommended part of his system.
But as I mentioned....the Herzan is the last piece of the 'Copernican' jigsaw.
Some of the initial 'pieces' have proven to be naive....for instance, originally I had the Victor motor unit (with its metal shroud) supported directly on Tiptoes. Whilst the sound was still good....I was disturbed that there might be movement of the turntable with this primitive supporting method.
I thus designed a skeletal stainless steel cradle which I thought would prevent any possible movement. It didn't....and in the process I had removed the motor's original perforated metal shroud. This shroud (it turns out) was acting as a Faraday Shield (with ground wire attached) in protecting the platter from the motor-induced RFI/EMI which now beset the installation.
It wasn't until I designed a new 8.1Kg (18lb) polished granite plinth, that I was able to reinstate the metal shroud (complete with ground wire) onto the motor unit and eliminate
- Movement
- Ground-loop hum
- EMI/RFI problems
I'm not sure if heavier and heavier is necessarily better and better.....but I may be wrong 🤔. In the current design, 8.1Kg of granite is the best I can do and I think it's adequate.....🤗 It's only necessary IMO, for the cradle/plinth to be heavy enough to prevent the constant centrifugal forces of the revolving platter being able to induce 'movement'.
For Belt-Drive or Idler designs...I can imagine these forces (and thus mass of plinth necessary) to be greater.
One thing I DID get right at the beginning, is the size and weight of the 11Kg (24lb) solid cast bronze armpods which surround the motor unit. These are immovable monoliths and are successful in keeping each arm motionless and rigidly clasped whilst providing total immunity from motor/plinth/platter noise and vibrations. This isolation of the arm-mount is a known phenomenon which Continuum tackled in their Caliburn turntable, by suspending and isolating with magnets, the tonearm mounting plate from the plinth proper.
There are other isolated armpod designs which use lighter, taller and flimsier pods which, apart from defeating the purpose of the 'Copernican' concept....may be susceptible to accidental and/or vibrational movement. Those designs I don't accept, as conforming to the principle 😱.
There are detractors of the isolated armpod solution (and some of them have been prominent in their opposition here, on this Thread).
The theory behind their opposition is valid.....rigid connectivity between the platter spindle and the tonearm pivot is a 'sine qua non'.
I agree with them.....
These theorists usually share two traits:-
- They have never had a functioning isolated pod in their home system
- They refuse to accept that the shelf/rack/stand/base on which the turntable and armpods sit, together with 'gravity' are sufficient to maintain a 'rigid' enough connection
I however DO have a functioning isolated pod system in my home (alongside a normal 'all-in-one' turntable) and believe that they are wrong.
If the turntable 'base' and isolated armpods are sufficiently heavy, gravity is indeed enough (as it is with all the buildings in the world) to RIGIDLY maintain the required geometry without the detrimental effects of transmitted vibrations from the motor/belt, bearing and plinth to the tonearm.
There are some notable advocates and adoptees of the 'Copernican' theory:-
- Gabriel/Da Vinci Reference MkII
- The Onedof
- Triangle Art Signature
- Kuzma Stabi XL4
- Basis Conti Signature
So here I am......seven years later with a turntable system I can honestly attest, is the best I have heard. And I have heard most of the acknowledged 'greatest' of all time.......
Now I don't positively know whether it's because of the isolated armpods, the superb Victor DD motor unit or the Sub-Hz Active Herzan Isolation Stand that the results are so good....?
It's most likely a combination of all three 🤗
Would I recommend others go down this same path....?
In hindsight....only if an Active Isolation Stand was a 'sine qua non'.....and this elevates the cost greatly. But consider this....even WITHOUT the Active Isolation Stand....the sound quality is capable of exceeding that of 'Digital' by a large margin 👅
My turntable system (complete with admittedly expensive tonearms) is in the realm of US$30,000 (with the Herzan close to half the total).
Expensive compared with the average turntable...yet not outrageous when compared to 'Uber Decks' like the Caliburn, VPI Direct, Kronos, Walker Proscenium, SME 30/2 or any of the 'Copernican' decks mentioned above.
I think I'm finally done and am happy to offer help/advice to anyone brave or crazy enough to venture down the same path.....😎🎶
Happy listening.....