Quote:
Originally Posted by DSJR
My Oracle Delphi mk4 got from Gamepath has never missed a beat. Keeps its set-up, works perfectly and sounds wonderful. Oh yes and spare parts are not a problem :)
Regards D S D L
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Quote:
Originally Posted by DSJR
My Oracle Delphi mk4 got from Gamepath has never missed a beat. Keeps its set-up, works perfectly and sounds wonderful. Oh yes and spare parts are not a problem :)
Regards D S D L
That is a brilliant idea !Quote:
Originally Posted by Dalek Supreme D L
Try also adding a bit of removable silicone on the 3 extremities of the suspended chassi; changes everything you heard before...
Oracle now uses a similar idea with 3 vertical pieces dipped into silicone with their latest TT model.
Quote:
Originally Posted by Citation16
The weird thing about this is that Oracle are now doing what Project did with their first turntable which was a copy of an Oracle Delphi but on the cheap, with no nice fit and finish or metal work. It had a little pot under it and adjustable paddle. Silicon sat in the pot.
Regards D S D L
It will make a difference. It alters (reduces) the amount of isolation afforded by the suspension system. But it also reduces the amount that the motor is able to pull the suspended part around so that the platter's rotation actually follows the motor pulley's rotation more accurately.
A fair point.Quote:
Originally Posted by pure sound
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Well, I've also experimented with this and I would say; yes you are right but only up to a point. In theory it does reduce isolation but this is very frequency dependent and, not surprisingly, partly depends on the specific implementation. I use a silicone damped suspension on my current deck and it has made it virtually immune to footfall whilst maintaining good rejection at higher frequencies. I'm still experimenting but, at present, I would say there are more pros than cons to such a design. Your second point regarding motor and platter stability I entirely agree with. The damping system I use has relatively low resistance in the vertical plane and increasingly greater resistance in the horizontal dependant on deflection.Quote:
Originally Posted by pure sound
Keith Howard did an interesting piece on isolation/suspension systems a year or two back in HiFi News. While damping the resonance of a suspension did improve its behaviour in terms of the time taken to return to rest it did also compromise the attenuation afforded by the filter aswell. There's unfortunately no such thing as a free lunch. The effectiveness of filters is always frequency dependent.
I suppose the values you choose depend how much attenuation is enough at any particular frequency.
Max Townshend always posits an optimum Q but I can't recall the value he uses. For home use I'll tolerate a high Q suspension with a longer settling time for the better isolation it offers but it certainly wouldn't be very 'commercial' *
* NB. this only applies in turntables where the drive system doesn't have a significant role in the suspension system. A sloppy High Q suspension wouldn't be much use on an AR/Linn/Thorens type deck.
True, true and true.Quote:
Originally Posted by pure sound
Tom took great pains to ensure that his designs ran close to true speed, BUT, the motors are still synchronous I believe, and isolating the mains frequency with a re-generated one which is variable if necessary, must be a good thing for these motors.Quote:
Originally Posted by pure sound
Does the Wave Mechanic regenerate the 50Hz cycle then?
I quote-
NOTTINGHAM ANALOGUE STUDIO
128 CORDY LANE, UNDERWOOD, NOTTINGHAM NG16 5FD
Design and Manufacture of Quality Audio Equipment
Telephone: +(44) (0) 1773 762947
Fax: +(44) (0) 1773 533566
V.A.T. REGISTRATION NO. 667 3729 92
WAVE MECHANIC POWER SUPPLY
Why a power supply? But first, why an AC turntable motor? Nottingham Analogue turntables excel by virtue of their almost elemental simplicity, relying as they do on the fact that a rotating platter will continue to do so at absolutely constant speed unless acted upon by outside forces. By coupling this steadily rotating mass to an arm base that is stable around the axis of
rotation of the platter, the result is a truly integrated unit.
By giving the platter adequate moment of inertia, the effects of any variability in outside forces are minimized. However, the most important force, bearing friction, should if the bearing is correctly made and lubricated remain essentially constant; hence, all that is required is to supply a small amount of energy to the platter at a constant rate – just sufficient to counter the friction and maintain a steady speed.
DC motors and their highly developed control systems may rightly dominate the small motor market for “movement and placement” applications such as robotics, but are they what we need in order to maintain this steady state? For this purpose, an AC synchronous motor backed by the “mass” of the National Grid should be the answer. Unfortunately, although the laws of mechanics show no sign of changing, electricity supplies are – and apparently always for the worse. There are four main areas of concern.
1. Voltage variations
As a case in point, since “harmonizing” with the rest of the EC, the nominal UK domestic supply voltage has fallen from 240V to 230V, but the permissible range of voltage has increased vastly, now being from –6% (216.2V) to +10% (253V). This whole range will not be seen in any one locality, but wide variations do occur between different areas.
For an AC synchronous motor, such voltage variations will not affect its overall speed, but will affect its torque: not what we need for constant energy input (torque x speed = power). In addition, the absolute voltage level has a very distinct effect on the dynamics and detail of the music, with a clearly audible optimum voltage range. We need, then, to be able to optimize the motor supply voltage and to hold it stable.
2. Frequency variations
These, by definition, will directly affect the speed of a synchronous motor. Supply frequency variations are generally slow, but are easily demonstrated using an independent precision strobe illuminator such as the “Zapper”.
Permissible variation in the UK is +/- 1% (6% equates to a semitone). Over 24 hours the frequency must average exactly 50Hz to satisfy users of synchronous clocks, so that if the frequency is slow at one point in the 24 hours, it must be fast at some other point as night follows day (sometimes literally!). For a power supply, some slight adjustment of frequency is desirable for pitch purposes but once set, it must remain stable.
3. Supply waveform
This is an aspect that has been becoming universally and insidiously more of a problem over the years largely as a result of the “switched mode” power supplies that have generally supplanted transformers in much modern electronic equipment.
The supply waveform does not now have a clean sinusoidal shape, but shows drastically clipped peaks – the equivalent of adding numerous high order harmonics to the fundamental 50 or 60 Hz. These can be shown to exist at significant levels far up into the audio frequency range, and even if attenuated by damping in the drive belt will still feed through to the platter. We need to synthesize a new clean waveform; “filtering” is not an answer.
4. Voltage spikes, and other “hash”
These are another part of the fallout from the volume and complexity of modern consumer demands, and are sufficiently worrying to have provoked restrictive regulations on equipment manufacturers. Our AC motor supply needs to be free of all such intrusions.
THE WAVE MECHANIC
The “Wave Mechanic” power supply addresses all of these issues, and provides a clean waveform, stable in voltage and frequency even when run off voltages well below the permissible level. The output voltage is pre-set internally to be in the optimum range, and there is a single control on the front panel to allow minor adjustment of the frequency for pitch control. Other than for this purpose it will probably remain untouched.
Both 50Hz and 60Hz version are available configured to suit local frequency and voltage. For a Turntable speed reference to partner the “Wave Mechanic” power supply, the “Zapper” hand-held battery-operated strobe illuminator is ideal. This is available in 50Hz and 60Hz version, either with the power supply or separately for more general use.
The audible benefits of the power supply are very clear. Detail, dynamics and sound stage are all much improved, but perhaps the most evident feature is the way that the whole pace and rhythm of the music sound natural and true. Pitch stability is impeccable, giving complete confidence and much deeper involvement in the musical performance. The benefits should not be expected to replace those from upgrading the turntable, but rather to complement them. Al of the Nottingham Analogue turntables will benefit, whether your current one or your next upgraded one!
Specifications:
Supply voltage/frequency: Version for 230V/50Hz, 115V/60Hz, 100V/50Hz, 100V60Hz
Power consumption: 6.5W
Fuse: Ceramic HRC 5mm x 20mm T250mA (230V), T500mA (115V and 100V)
Output frequency: 50Hz or 60Hz (depending on model) with control in center position.
Case Dimensions: (H x W x D) 2.55” x 4.13” x 11.22”
Weight: (w/ packaging) 5.6 lbs.