Power Cord Revelation

Neal, yes, the one I tested was Sig

Stealth V10 preamp power cord one of the best!!

We investigated this interesting problem
years ago and found that the power cord(s) affect
the 'ground-floor' noise of the equipment.

SWR has been over-looked as the culprit, due to the
length of the cord being 'too-short'. None the less
the power cord has a different 'resistance' than the
equipment in use. The resultant mis-match will still
cause a reflected energy, of about 250-375 m-Volts.
This reflected energy - noise - is impressed upon the
ground plane of, for example, the CD player.
The circuitry of the CD player is affected by this - noise -
causing / changing the audio signal enough to be heard by
many individuals.
We have a complete white paper written up we could send
to you about this process and pictures of the
- measured noise- .

We, as posted before, investigated this problem and
were amazed that power cords made a difference.

We used a network analyzer to check power cords
for the low end testing of common L,C,R measurements
are of little value as we found out. Our first tests
were to measure SWR - SMITH Chart - displays. Wow
what a difference in SWR and cable designs - geometries
in particular. ZIP cords and regular 3 wire power cords
were our first cables tested.
LONG story short - we eventually designed an
award winning power cord - but more importantly
learned why the short power cord affects(ed) the audio
systems. Noise from the resistive mis-match of the
power cord and the equipment in use. Even though the
generated noise is low about 250-375 m-Volts this
is enough to cause havoc with the audio signal.
We have a white paper if you would like to see our
full details of how we did this test.

Mootsdude,

here is a follow up with more details...

Audio Grade Power Cords - AGPC

We investigated this interesting problem years ago and
found that the power cord(s) affect the 'ground-floor'
noise of the audio equipment being used.

The question is then how ?

By trying different home made power cords we could hear
differences in the music we listened to. We then made up
high impedance probe to see if there was any noise on the
power cords. The spectrum analyzer showed that there was noise
from 8 MHz to 13 MHz. We tested other power amps and cd-players
and found this same 'noise' on all tranformer power supplies.

This lead us to reconsider the power system', which is the wall socket,
the power cord and the equipment's power transformer.

Intuitively we all know that the wall socket's impedance/resistamce
is different from the power transformer's impedance/resistance.

So we decided to measure the wall sockets 'resistance'.

By using a salt-water-bath-load [old RF trick] we came up with the following
information: [see our AGPC white-paper for more details]

1.) Copper wire feed sockets have about .23 Ohms of impedance
2.) Aluminum wire feed sockets are about .45 Ohms of impedance.

This give us the source 'resistance'.

A power transformer 'resistance' that we used ranged from
11 Ohms to 14 Ohms. The ratio of the source with the transformer
is then from 50 to 58 to 1. This SWR of 50-58 at full wave lenght
would have a 90% reflection level.

The concurrent argument is that the power cord is too short !

Very true; compared to the miles at 60 Hz / 6 feet is very
insignificant,- almost-.

Looking at the power applied we know it is 60 cycles per second
or 120 pulses per second. The measured nosie is in the low MHz
range. Looking at the harmonic relationship of the 60/120 cycle/pulse
with the noise frequency we can see that they are related.
From 3MHz to about 30 MHz the pulsing energy is:[examples]
3 MHz : 60Hz 50k-1; 120pps 25k-1
12 MHz : 60Hz 200k-1; 120pps 100k-1
and are evenly harmonically related with the 'measured' 'noise'.

Then the next step is to determine how much noise is 'generated'
from this resistive mis-match.

By looking again at the spectrum analayzer we can see how much
noise-energy is being produced.

The graph on the analyzer showed a range of 250 - 375 mVs of noise.

Now what, how does this affect the audio signal.

This nosie is of very high frequncy energy and should be filterd easily
by the power supplies. But remember the low-side the -white-wire- of
the power cord and the -green- ground wire are tied to the equipment's
low side!

The Hot-wire and nosie are in a long-shaped 'capacitor' with the
white and green wire; the nosie can easily pass through this natural
'capacitor' since the 'noise' is of very high frequency.

The 'ground-plane' then has extra 'energy' of high frequencies that can
pass onto the solid state parts of the audio systems.
Transistor's control volatages are from about .4 v to .66 v and this low
level of voltages can easily be affected by this high 'Frequncy-Noise'.

With this information we can see why the CD-player is far more likely to be
affected by the 'power cord' than the power amplifier.

The power cord itself has an affect on the nose being generated due to
the changes in the differnt 'materials' used in their consruction.

- - -

Well hope this information will lead to better Fidelity!