The Audio industry
supports a number of specific line conditioning devices
to improve AC line "quality".
Many of these devices do improve sound reproduction sometimes
at the expense of other sonic qualities. An example is
AC isolation transformers. A good isolation transformer
floats the neutral so that it is no longer in a circuit
path with the earth ground. This will give a balanced
power source. In AC lines contaminated with RF or HF
noise this type of transformer does help a great deal
to open up the sound by reducing stress on active devices.
It does so at the expense of power factor loss. Power
factor is the term for wattage delivery by the in phase
alignment of current with voltage. Any loss of power
factor is stated as a percentage below 100%, and is caused
by misalignment of current and voltage phase since wattage
equals voltage times current. Inductance (an isolation
transformer) shifts the phase causing current to lag
behind voltage reducing the total power in watts available.
The sound reproduction suffers by reducing the equipment's
ability to track power hungry dynamics. Lower range percussive
impacts are affected the most, examples; timpani, lower
What is needed is to reduce earth ground
noise through a more effective sink for the power line
neutral and ground without any power factor loss. Certain
research facilities needing a low noise environment accomplish
this with ground grid screens laid underground covering
an area to give as much conductor surface area as economically
possible. This screen is then connected to the AC power
grid ground potential to create a low impedance ground
for sinking noise. This would be impractical for homes
but an alternative is to run multiple copper clad ground
rods. I presented this idea to a client who has a perfectionist
system in that he uses Wadia with Goldmund components
and has had dedicated 20 amp services for each component.
Initially we installed 10 new ground rods all sharing
the feed for the existing ground rod. The difference
this made was easily apparent, more so than any AC line
conditioning he had previously tried except for the dedicated
service runs he had previously done. The cost per ground
rod with wire clamp is around $10.00. After this experience
I knew that I would do my own home and to try some measurements
to see what is happening.
My existing home wiring is copper circa
1963 construction with the ground connection only having
been made to the copper water line. For a listening room
finished in the basement I installed a 100 amp subpanel.
This afforded me the space for running dedicated circuits
and six #6 wire ground feeds to six 8 foot 5/8 inch copper
clad rods. Before this new room was completed my stereo
used single 15 amp household service shared with some
light feeds. A modified TRIPPLITE LC2400 line stabilizer/conditioner
fed the preamp and CD source only. Note, the stock TRIPPLITE
gave a hard edge to the sound. Once the subpanel with
its low impedance earth ground was connected to the existing
main panel the sound improvement was more apparent than
any isolation conditioning device I had tried. I must
point out that this improvement is all the more impressive
considering the mediocre condition of the AC service
that the system was using. Now the system is in the new
room with the individual AC runs and the sound leaped
in improvement as if I purchased upgraded electronics.
I measured the effects using a 50 MHz
digital storage scope by placing the probe lead on a
AC receptacle ground connection and the scope ground
on the water main. With the subpanel (new earth grounds)
disconnected I measured an AC waveform with a lot of
harmonic noise on it that was 6 mV peak to peak. This
waveform had 2 mV of DC offset and RF noise that was
3 mV peak to peak. After connecting the subpanel the
distorted AC waveform now had over 10 mV peak to peak
but no DC offset and the RF noise was now less than 1
mV peak to peak. Why the increase in the AC waveform?
I summarize that the lower impedance ground connection
was now allowing more voltage noise to flow to ground,
increased current flow of noise thus an increase of voltage
(V=IR). And this lower impedance path to earth ground
eliminated the DC offset (a capacitive charge) and improved
the RF sink to ground.
You must check with local codes and, If
you are not a qualified electrician, hire a contractor
since the connections are made at the distribution breaker
box where lethal voltages are present.
In summary, if at all possible do this
upgrade. Start with at least six 8 foot ground rods.
My client recently added four more for a total of fourteen
rods and still heard a small improvement. Consider that
a higher moisture content in the earth will further improve