The TeddyXPS is a power supply which was designed to improve the performance of
Naim CD players such as the CDX, CDX2, CDS2, CDS3, Naim HDX, and Naim DAC. It
is compatible with the original Naim XPS but uses superior circuitry to provide
even better performance. Many people who bought the TeddyCap asked me if I can
build a similar power supply to substitute the original XPS. After a long
design and test period I’m happy to present the new TeddyXPS.
CDX/CDX2
and DAC Background
The CDX
CD player and the Naim DAC incorporate a built-in economical power supply, but
were designed to accept an external power supply, the XPS, which significantly
improves its performance. The Naim XPS uses the same circuitry as the internal
power supply, and the main reason for the improvement is related to the fact
that the internal power supply has only three power rails while the external
has six. In addition to proving six power rails, the TeddyXPS uses a superior
regulation circuitry, the SuperTeddyReg. This power supply can also be used to
power other Naim CD players such as the CDS2 and CDS3, and the Naim HDX.
The CDX
requires four power rails:
1. +15V
for the CD drive control circuits, panel lights etc
2. +15V
for the clock, servo processor, etc
3. +/-
10V for the digital to analogue converters
4. +/-
22V for the analogue output circuits (I/V converter and filters)
When
using the internal power supply circuits 1 and 2 are driven from one rail, and
circuits 3 and 4 are driven from the second rail. The problem is that noise
from one circuit is affecting the other circuit and vice versa. The use of four
independent power rails eliminates this problem and provides a significant
improvement.
The power
supply is one of the most important and critical factors in sound quality. As
described above, a significant improvement can be achieved, even by simply
splitting the power supply to independent power rails. This effect can also be
demonstrated by adding a second HiCaps with the NAC82/282. The original XPS
uses however a basic regulation circuit, the same circuit used in all Naim
power supply, which is based on a monolithic linear regulator the LM317 (or the
LM337 for the negative rails). More improvement can be achieved by using an
ultra low noise power supply such as the SuperTeddyReg. This regulator which
was originally designed for the TeddyCap and demonstrated great success was
later adapted to be used for the TeddyXPS.
Cable
The
TeddyXPS is equipped with a very high quality Burndy replacement cable. This
cable is made of three independently screened cables, each of them is made of
PTFE/Silver plated wires. One cable carries the power for the analogue
circuits, one for the DAC circuits, and one for the motor and control circuits.
Having each cable independently screened gives better separation between them.
The
effect
Better
soundstage, more details, extended and more open sound (cymbals last longer),
extended and firmer bass, human voices sound more natural, and an overall
smoother, and less aggressive and fatiguing sound.
