Background
The Groove
RIAA stage is the result of over 10
years R&D into disk replay. The
project started with the original
ISO in 1989 and continued through
the HR ISO, with its various board
and component revisions to include
work on the Eikos project. Although
Eikos was an essentially digital source,
lessons learnt and R&D completed
paid huge dividends when the time
came to start work on the Groove.
Even given the limits of 16Bit resolution,
Tom realised that it was not the mathematics
that was holding back what was theoretically
achievable from CD, but more fundamentally,
the fuel that the components ran on.
He argued that as long as the voltage
regulators supplying the board were
noisier than the quietest passages
recorded, and their transient response
time was slower than the devises were
capable of, there was no point in
improving the circuit topology until
these fundamental problems were solved.
Two years later, he had developed
the Lithos regulator, which removed
if you will the existing carburettor
on the engine, and replaced it with
fuel injection a competition chip
and a turbo charger. The device is
53 times faster, 1000 times quieter
and 5 decimal places more accurate
than the best regulators available.
From this new base line, Tom started
to design the Groove Phono stage.
Description
The groove
is of dual mono construction. Channel
separation is therefore only limited
by the specifications of the cartridge
used. At the front end Tom has used
very low noise I/C's (less noise than
a 50-Ohm resistor). This stage is
followed by a very accurate passive
RIAA EQ circuit. The third stage is
an ultra linear gain amp, around this
he has placed the active low frequency
filter to roll off subsonics. The
fourth stage is the output stage,
which is capable of driving several
meters of interconnect. Tom recommends
that the best results are obtained
with the Groove Tube interconnect as its low screen to core
capacitance, solid core and stable
characteristics to 200 Mhz. help to
maintain accurate signal transfer
to a line output.
Air vents in the base and the rear
of the box must not be blocked, as
they are crucial in allowing the four
class A regulators to dissipate heat.
It will take on average 72 hours to
reach correct operating temperature
as the errors caused by the temperature
coefficient fall from 100 to +/- 1
part per million. The case, if made
of any metal other than copper would
have a deleterious effect on the sound
quality, as field effects even non-ferrous
materials would interfere with electron
flow within the unit. It must be remembered
that the unit is preserving and amplifying
almost immeasurable small changes
of voltage from the cartridge that
are all easy to corrupt. The phono
stage is providing the majority of
gain in the system, therefore any
corruption at this point will be multiplied
by the gain of the phono amp (+60dB
for the phono amp +6dB for the pre-amp
+30dB for the power amp) and is for
this reason the case work is of Perspex,
a material with no inductive capacity.
The Groove is internally shielded
by double sided ground planes both
top and bottom, even so it is advisable
to site it with caution, avoiding
areas of large field effect, e.g.
near large transformers used in power
supplies.
By careful design and application
of the new Lithos technology, The
Groove brings vinyl re-play into a
new era, as previously unattainable
levels of resolution are revealed,
coupled with a speed of transient
response and increase in dynamic range.
You will discover you own a new record
collection.
Always switch off before connecting
or disconnecting to other devices.
Clean using a damp chamois leather.
For stubborn stains use Mykal Sticky
Stuff Remover. Never spray with cleaner/polish,
as this can enter the unit and cause
damage. Brasso will remove scratches.
Replacement front panels and boxes
are available on request.
• All impedances and cartridge output
voltages are available to order.
• Each Groove is hand built to your specification
in Great Britain. (See order form with
shopping cart)
Dimensions:
Width = 33cm (12.87 inches)
Height = 9cm (3.5 inches)
Depth = 18cm (7.02 inches)
