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Philosophy of Electrical Protection vs. Hum
I use cheater plugs for hum reduction. To understand why, we must enter the
realm of Engineering Philosophy. While I have only a few really high end
components, I am very fond of three old surround processors, two external
DACs, two analog preamps, five basic amplifiers, and miscellany. The more
parts in the system, the harder it is to deal with audible hum. As the
Jensen article points out, it is virtually impossible to eliminate hum loops
when unbalanced interconnects are used.
Nevertheless, at one point, my system was pretty hum-free even though two
components, an Acoustat TNT-200 and a Hafler pre have three wire power
cords. Then, one day, it was back. I went through the drill of disconnecting
pieces until the hum went away, but it did not. Facing a very simplified
system, I stared in astonishment at the Parasound SCAMP power switchers,
which I had installed to be "green." I took them out and the hum went away.
Apparently, the relay contacts had unbalanced the potentials in a very
slight way, enough to increase the level of hum significantly. I don't know
whether it was contact resistance or contact rectification. But my
conscience would not allow me to live without the SCAMPs in the system.
Putting a cheater plug on the Acoustat amp knocked the hum down.
From the dawn of the electrical age, people have lived with single levels of
protection in consumer electrical equipment. Residential table and floor
lamps are vulnerable to internal shorts that can put lethal potentials on
the metalwork. The National Electrical Code continues to allow this because
such lamps are supposed to be used in rooms with little exposure to
electrical grounds. Following a similar philosophy, amplifiers built until
the 90's frequently had two wire cords. Such amplifiers are still in wide
use.
More recently, the NEC reflects a preference for two levels of electrical
protection. Although the NEC sanctions only passive measures, such as a
protective ground, or special transformer construction known as "double
insulation", a GFCI (Ground Fault Circuit Interrpter) replaces the
protection lost by disconnecting the protective ground with a cheater a
plug. It could be argued that, since the GFCI is an active device, it is not
as reliable as the passive protection provided by a passive ground. However,
such arguments are difficult to quantify. The GFCI detects a problem
anywhere in the system, while the Acoustat passive ground protects only the
Acoustat. The GFCI detects nascent problems, while the protective ground can
silently mask transformer leakage until the transformer burns up.
Audiophiles face a serious challenge in eliminating hum from their systems,
because the interconnect system devised seventy years ago looks fine, but it
doesn't work reliably. It works best when components made by the same
manufacturer are hooked together in simple configurations. Those who prefer
to mix/match among manufacturers and genres according to their taste can
encounter apparently insuperable obstacles. It is much to the shame of
consumer hi-fi manufacturers that they did not adopt professional balanced
standards. This will become moot in the transition to an all digital world,
but it doesn't help those of us who have substantial investments in
equipment that may have sonic virtues.
Bob Morein
(310) 237-6511
realm of Engineering Philosophy. While I have only a few really high end
components, I am very fond of three old surround processors, two external
DACs, two analog preamps, five basic amplifiers, and miscellany. The more
parts in the system, the harder it is to deal with audible hum. As the
Jensen article points out, it is virtually impossible to eliminate hum loops
when unbalanced interconnects are used.
Nevertheless, at one point, my system was pretty hum-free even though two
components, an Acoustat TNT-200 and a Hafler pre have three wire power
cords. Then, one day, it was back. I went through the drill of disconnecting
pieces until the hum went away, but it did not. Facing a very simplified
system, I stared in astonishment at the Parasound SCAMP power switchers,
which I had installed to be "green." I took them out and the hum went away.
Apparently, the relay contacts had unbalanced the potentials in a very
slight way, enough to increase the level of hum significantly. I don't know
whether it was contact resistance or contact rectification. But my
conscience would not allow me to live without the SCAMPs in the system.
Putting a cheater plug on the Acoustat amp knocked the hum down.
From the dawn of the electrical age, people have lived with single levels of
protection in consumer electrical equipment. Residential table and floor
lamps are vulnerable to internal shorts that can put lethal potentials on
the metalwork. The National Electrical Code continues to allow this because
such lamps are supposed to be used in rooms with little exposure to
electrical grounds. Following a similar philosophy, amplifiers built until
the 90's frequently had two wire cords. Such amplifiers are still in wide
use.
More recently, the NEC reflects a preference for two levels of electrical
protection. Although the NEC sanctions only passive measures, such as a
protective ground, or special transformer construction known as "double
insulation", a GFCI (Ground Fault Circuit Interrpter) replaces the
protection lost by disconnecting the protective ground with a cheater a
plug. It could be argued that, since the GFCI is an active device, it is not
as reliable as the passive protection provided by a passive ground. However,
such arguments are difficult to quantify. The GFCI detects a problem
anywhere in the system, while the Acoustat passive ground protects only the
Acoustat. The GFCI detects nascent problems, while the protective ground can
silently mask transformer leakage until the transformer burns up.
Audiophiles face a serious challenge in eliminating hum from their systems,
because the interconnect system devised seventy years ago looks fine, but it
doesn't work reliably. It works best when components made by the same
manufacturer are hooked together in simple configurations. Those who prefer
to mix/match among manufacturers and genres according to their taste can
encounter apparently insuperable obstacles. It is much to the shame of
consumer hi-fi manufacturers that they did not adopt professional balanced
standards. This will become moot in the transition to an all digital world,
but it doesn't help those of us who have substantial investments in
equipment that may have sonic virtues.
Bob Morein
(310) 237-6511
You hit upon an interesting topic even though it's sorely obvious you
don't know your ass from a hole in the ground.
Audio equipment design is a curious mishmash between arbitrary safety
requirements imposed in various jurisdictions-which may or may not be
appropriate for audio equipment and may or may not be adequate, entrenched
notions of proper practice -ditto, the ever present obsession with slashing
build cost, and compliance with existing standards such as they are. Add in
a dollop of customer control strategies and the electrical ineptitude of
the majority of status-seeking WGBD yuppie buyers that make up the
majority of actual buyers of expensive audio equipment and you have a
vicious stew.
Since the user of hi-fi equipment is generally not in continuous contact
with the system and is not, as in medical practice, specially vulnerable
to leakage currents, simply testing the primary loop of the power supply
(assuming it's a transformer linear supply and not an AC-DC or switchmode
system) with common IR equipment or even a common VTVM if used properly
for leakage, initially and at reasonable intervals is sufficient. One and
only one earth ground path is necessary for hum and RF noise reduction as
well as safety.
In my opinion, anyone who buys a Parasound SCAMP system in preference to
the time tested alternatives of fitting a locally accessible circuit
breaker or just _pulling the plug_ on a power strip has too much money and
should be relieved of it by some scam artist. Oh wait, that's what is
happening in that very case.
--
Message posted using http://www.talkaboutaudio.com/group/rec.audio.opinion/
More information at http://www.talkaboutaudio.com/faq.html
don't know your ass from a hole in the ground.
Audio equipment design is a curious mishmash between arbitrary safety
requirements imposed in various jurisdictions-which may or may not be
appropriate for audio equipment and may or may not be adequate, entrenched
notions of proper practice -ditto, the ever present obsession with slashing
build cost, and compliance with existing standards such as they are. Add in
a dollop of customer control strategies and the electrical ineptitude of
the majority of status-seeking WGBD yuppie buyers that make up the
majority of actual buyers of expensive audio equipment and you have a
vicious stew.
Since the user of hi-fi equipment is generally not in continuous contact
with the system and is not, as in medical practice, specially vulnerable
to leakage currents, simply testing the primary loop of the power supply
(assuming it's a transformer linear supply and not an AC-DC or switchmode
system) with common IR equipment or even a common VTVM if used properly
for leakage, initially and at reasonable intervals is sufficient. One and
only one earth ground path is necessary for hum and RF noise reduction as
well as safety.
In my opinion, anyone who buys a Parasound SCAMP system in preference to
the time tested alternatives of fitting a locally accessible circuit
breaker or just _pulling the plug_ on a power strip has too much money and
should be relieved of it by some scam artist. Oh wait, that's what is
happening in that very case.
--
Message posted using http://www.talkaboutaudio.com/group/rec.audio.opinion/
More information at http://www.talkaboutaudio.com/faq.html
"Soundhaspriority" <nowhere@nowhere.com> wrote in message
news:0uednbNNtacMe7TVnZ2dnUVZWhednZ2d@giganews.com
> I use cheater plugs for hum reduction.
Known by professionals as the idiot's easy way out.
> To understand why,
> we must enter the realm of Engineering Philosophy.
No, using cheaters to reduce hum is like anti-engineering.
> While I have only a few really high end components,
Automatic proof of engineering naivate - being fooled by high end audio
weirdness.
> I am very
> fond of three old surround processors, two external DACs,
> two analog preamps, five basic amplifiers, and
> miscellany.
Sounds like a few sales on eBay are in order.
> The more parts in the system, the harder it is to deal with audible hum.
Hence the use of balanced, high-level connections in professional audio.
> As the Jensen article points
> out, it is virtually impossible to eliminate hum loops
> when unbalanced interconnects are used.
Virtually impossible, but not totally impossible.
> Nevertheless, at one point, my system was pretty hum-free
> even though two components, an Acoustat TNT-200 and a
> Hafler pre have three wire power cords.
So far so good.
> Then, one day, it
> was back. I went through the drill of disconnecting
> pieces until the hum went away, but it did not. Facing a
> very simplified system, I stared in astonishment at the
> Parasound SCAMP power switchers, which I had installed to
> be "green."
Now out of production, I wonder why.
> I took them out and the hum went away.
A real engineer would be cable to take them apart, find out why they added
hum, correct them and get on with the rest of his life. Or do what I have
done, and that is to engineer a properly-designed device with the same
function, build it, and enjoy its services for the past nearly 30 years.
> Apparently, the relay contacts had unbalanced the
> potentials in a very slight way, enough to increase the
> level of hum significantly.
Nahh, it was probably about how the outlets were wired. Relay contacts are
things that dilettantes worry about.
> I don't know whether it was
> contact resistance or contact rectification.
Probably neither. BTW my remote switching box has a big old ugly relay in
it, too. I salvaged it from a circa 1958 Kenmore washer/dryer.
> But my
> conscience would not allow me to live without the SCAMPs
> in the system. Putting a cheater plug on the Acoustat amp
> knocked the hum down.
The lazy man's way out, and into the dangerous world of lifting grounds.
> From the dawn of the electrical age, people have lived
> with single levels of protection in consumer electrical
> equipment. Residential table and floor lamps are
> vulnerable to internal shorts that can put lethal
> potentials on the metalwork. The National Electrical Code
> continues to allow this because such lamps are supposed
> to be used in rooms with little exposure to electrical
> grounds. Following a similar philosophy, amplifiers built
> until the 90's frequently had two wire cords. Such
> amplifiers are still in wide use.
Amplifiers still often have two wire cords. Building a piece of electrical
gear with a 2-way cord takes extra care in engineering, that many short-run
manufacturers are unwilling to do.
> More recently, the NEC reflects a preference for two
> levels of electrical protection. Although the NEC
> sanctions only passive measures, such as a protective
> ground, or special transformer construction known as
> "double insulation", a GFCI (Ground Fault Circuit
> Interrpter) replaces the protection lost by disconnecting
> the protective ground with a cheater a plug.
In a last-ditch sort of way. It's a safety net. A grounding plug is a
safety harness. Ever work in high places? I have. Trust me, you'd rather
stake your life on the safety harness.
> It could be
> argued that, since the GFCI is an active device, it is
> not as reliable as the passive protection provided by a
> passive ground.
A GFCI is a safety net, not a safety harness. When you activate a GFCI,
you've already fallen off the mountain. Me, I like my safety gear to be very
specfic, reliable, and quick-acting. I wanna stay on the mountain.
> However, such arguments are difficult to
> quantify. The GFCI detects a problem anywhere in the
> system, while the Acoustat passive ground protects only
> the Acoustat. The GFCI detects nascent problems, while
> the protective ground can silently mask transformer
> leakage until the transformer burns up.
More to the point, it is possible to build a transformer that has enough
high-quality insulation that it doesn't need a safety ground to be code.
> Audiophiles face a serious challenge in eliminating hum
> from their systems, because the interconnect system
> devised seventy years ago looks fine, but it doesn't work
> reliably.
More to the point - audiophiles with high end gear face paying high prices
for poorly engineered gear.
> It works best when components made by the same
> manufacturer are hooked together in simple
> configurations.
High end gear mostly works best if left in the store!
> Those who prefer to mix/match among
> manufacturers and genres according to their taste can
> encounter apparently insuperable obstacles.
Or, they have to use their brains.
> It is much to
> the shame of consumer hi-fi manufacturers that they did
> not adopt professional balanced standards.
So what's wrong with buying equipment that has adopted professional balanced
interconnection standards? OK, so you miss out on the bragging rights that
come with buying gear that is being reviewed this month in Stereophile.
> This will
> become moot in the transition to an all digital world,
> but it doesn't help those of us who have substantial
> investments in equipment that may have sonic virtues.
Or may not have sonic virtues, or may have sonic virtues that are easy to
obtain for a far lower price in the form of well-engineered equipment.
news:0uednbNNtacMe7TVnZ2dnUVZWhednZ2d@giganews.com
> I use cheater plugs for hum reduction.
Known by professionals as the idiot's easy way out.
> To understand why,
> we must enter the realm of Engineering Philosophy.
No, using cheaters to reduce hum is like anti-engineering.
> While I have only a few really high end components,
Automatic proof of engineering naivate - being fooled by high end audio
weirdness.
> I am very
> fond of three old surround processors, two external DACs,
> two analog preamps, five basic amplifiers, and
> miscellany.
Sounds like a few sales on eBay are in order.
> The more parts in the system, the harder it is to deal with audible hum.
Hence the use of balanced, high-level connections in professional audio.
> As the Jensen article points
> out, it is virtually impossible to eliminate hum loops
> when unbalanced interconnects are used.
Virtually impossible, but not totally impossible.
> Nevertheless, at one point, my system was pretty hum-free
> even though two components, an Acoustat TNT-200 and a
> Hafler pre have three wire power cords.
So far so good.
> Then, one day, it
> was back. I went through the drill of disconnecting
> pieces until the hum went away, but it did not. Facing a
> very simplified system, I stared in astonishment at the
> Parasound SCAMP power switchers, which I had installed to
> be "green."
Now out of production, I wonder why.
> I took them out and the hum went away.
A real engineer would be cable to take them apart, find out why they added
hum, correct them and get on with the rest of his life. Or do what I have
done, and that is to engineer a properly-designed device with the same
function, build it, and enjoy its services for the past nearly 30 years.
> Apparently, the relay contacts had unbalanced the
> potentials in a very slight way, enough to increase the
> level of hum significantly.
Nahh, it was probably about how the outlets were wired. Relay contacts are
things that dilettantes worry about.
> I don't know whether it was
> contact resistance or contact rectification.
Probably neither. BTW my remote switching box has a big old ugly relay in
it, too. I salvaged it from a circa 1958 Kenmore washer/dryer.
> But my
> conscience would not allow me to live without the SCAMPs
> in the system. Putting a cheater plug on the Acoustat amp
> knocked the hum down.
The lazy man's way out, and into the dangerous world of lifting grounds.
> From the dawn of the electrical age, people have lived
> with single levels of protection in consumer electrical
> equipment. Residential table and floor lamps are
> vulnerable to internal shorts that can put lethal
> potentials on the metalwork. The National Electrical Code
> continues to allow this because such lamps are supposed
> to be used in rooms with little exposure to electrical
> grounds. Following a similar philosophy, amplifiers built
> until the 90's frequently had two wire cords. Such
> amplifiers are still in wide use.
Amplifiers still often have two wire cords. Building a piece of electrical
gear with a 2-way cord takes extra care in engineering, that many short-run
manufacturers are unwilling to do.
> More recently, the NEC reflects a preference for two
> levels of electrical protection. Although the NEC
> sanctions only passive measures, such as a protective
> ground, or special transformer construction known as
> "double insulation", a GFCI (Ground Fault Circuit
> Interrpter) replaces the protection lost by disconnecting
> the protective ground with a cheater a plug.
In a last-ditch sort of way. It's a safety net. A grounding plug is a
safety harness. Ever work in high places? I have. Trust me, you'd rather
stake your life on the safety harness.
> It could be
> argued that, since the GFCI is an active device, it is
> not as reliable as the passive protection provided by a
> passive ground.
A GFCI is a safety net, not a safety harness. When you activate a GFCI,
you've already fallen off the mountain. Me, I like my safety gear to be very
specfic, reliable, and quick-acting. I wanna stay on the mountain.
> However, such arguments are difficult to
> quantify. The GFCI detects a problem anywhere in the
> system, while the Acoustat passive ground protects only
> the Acoustat. The GFCI detects nascent problems, while
> the protective ground can silently mask transformer
> leakage until the transformer burns up.
More to the point, it is possible to build a transformer that has enough
high-quality insulation that it doesn't need a safety ground to be code.
> Audiophiles face a serious challenge in eliminating hum
> from their systems, because the interconnect system
> devised seventy years ago looks fine, but it doesn't work
> reliably.
More to the point - audiophiles with high end gear face paying high prices
for poorly engineered gear.
> It works best when components made by the same
> manufacturer are hooked together in simple
> configurations.
High end gear mostly works best if left in the store!
> Those who prefer to mix/match among
> manufacturers and genres according to their taste can
> encounter apparently insuperable obstacles.
Or, they have to use their brains.
> It is much to
> the shame of consumer hi-fi manufacturers that they did
> not adopt professional balanced standards.
So what's wrong with buying equipment that has adopted professional balanced
interconnection standards? OK, so you miss out on the bragging rights that
come with buying gear that is being reviewed this month in Stereophile.
> This will
> become moot in the transition to an all digital world,
> but it doesn't help those of us who have substantial
> investments in equipment that may have sonic virtues.
Or may not have sonic virtues, or may have sonic virtues that are easy to
obtain for a far lower price in the form of well-engineered equipment.
On 14 Mai, 10:05, "Arny Krueger" <ar...@hotpop.com> wrote:
> A real engineer would be cable to take them apart, find out why they added
> hum, correct them and get on with the rest of his life. Or do what I have
> done,
LOL!!!!
thanks for admiting that yo are NOT a real engineer.
> A real engineer would be cable to take them apart, find out why they added
> hum, correct them and get on with the rest of his life. Or do what I have
> done,
LOL!!!!
thanks for admiting that yo are NOT a real engineer.
