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The
Power FAQs
Straightforward answers with no spin!
Puzzled about power? If you want answers you've come to the right place. Our technical experts have decades of experience in solving tough power problems and their power quality engineering expertise is sought worldwide.
The items below were all
questions asked by Audiophiles. We are happy to answer yours. Just email your question to support@PurePowerAPS.com and we'll do our best to give you a clear, straightforward answer with no spin.
Q: Is there a difference between the PS Audio Premier AC regenerator and the
Pure Power APS?
Q.
When is the Premier the best choice for your AV system?
Q.
What about current limiting?
Q.
Does PurePower offer variable frequency control?
Q.
Will balanced power technology do what PurePower does?
Q:
Will an isolated receptacle provide clean AC power?
Q.
Won't an isolation transformer make a new clean power supply?
Q.
Why aren't the PurePower receptacles isolated from each other?
Q: Can an ordinary, off the shelf, computer UPS product do the same thing as an AC regenerator?
Q: Can a dimmer switch
be placed in the same circuit as my PurePower?
Q: Is there a difference between the PS Audio Premier AC regenerator and the
Pure Power APS?
A:
The fact is there is one important similarity between the two; both dispense with the idea of “conditioning” or cleaning up the incoming AC utility power because no amount of tinkering with bad power can match the purity of a brand new AC sine wave generated at the point of
use. PurePower’s “transformerless” AC Regenerator uses solid-state components and proprietary software, with an unsurpassed efficiency of over 90%. The efficiency and intelligence are both crucial to the optimum operation of high power
amplifiers, and plasma TV’s. Premier uses a power amplifier
design that incorporates a large torroidal transformer to maintain output voltage.
The
Primary difference between the two is PurePower's auxiliary battery that
allows PurePower units to be 100% isolated from all utility based power.
PurePower produces 120 volts, 60 cycle output no matter what the input -
even if the input is zero volts. Premier is unable to be completely
isolated from the incoming power quality - so when the incoming power
drops below certain values or the load is high, or both, Premier's
output follows the utility voltage drop and its distortion reflects the
input distortion. Simply put, when the utilty sags, the Premier sags.
When the input power is below 95 V or above 135V the Premier simply
shuts down.
Q.
When is the Premier the best choice for your AV system?
A: The are so many instances it is hard to count them all. For example
Premier is the best choice:
When you know the utility voltage is reliable.
When you only have a small load to support.
When you never have brownouts or blackouts.
When you have no projector.
When you don't have tube amplifiers or don't care about maintaining tube
bias.
When your spouse never turns on the (a) dishwasher (b) clothes dryer (c)
air conditioner while your listening to a sublime passage.
When dynamics aren't a real issue.
Q.
What about current limiting?
A:
The logic of current limiting is simple. If the wall outlet of a typical 15-amp circuit is capable of delivering 1750 watts, and your AC regenerator is 50% efficient – obviously the
RMS current is limited by 50% . The PurePower APS is 90% efficient. The PurePower 1050 keeps delivering its full rated output of 1050 watts continuously even when the inbound utility voltage drops to 60 volts – and keeps on delivering it even if the utility voltage drops to 0 thanks to its integral high energy battery back up
system.
Long term, short term and instantaneous power.
Power amplifiers require different amounts of current under different conditions. They have an RMS requirement that draws a steady wattage over time. They have short term start up requirements for as much as 150% of the rms value that may last from 5 to 30 seconds and they may have an instantaneous requirement for 200 to 300% of the rms value for milliseconds when they have to drive the speakers during a sharp peak (think cannons in the 1812 overture).
The PurePower is designed to support the start up inrush by delivering 150% of capacity for up to 30 seconds and 110% for 2
minutes. The PurePower design is capable of delivering instantaneous power up to 300% of its rated output, even when utility voltage drops. For our PurePower 1050, that means instantaneous
current of over 37 Amps.
Voltage drop and circuit “intelligence”
Supplying the current an amplifier wants when it wants it is a demanding task because the amplifier can change its power needs very dramatically very quickly – in fact in a fraction of a cycle. The PurePower AC Regenerator circuit is designed to be “smart” about maintaining voltage no matter what, and maintaining voltage during high current draw is exactly what allows the amplifier to meet its wattage needs and provide the best dynamic range without clipping. By contrast, a normal wall outlet actually experiences a voltage drop that reduces an amplifier’s current draw under the same conditions. The performance improvement provided by the
PurePower design can be impressive in terms of amplifier performance as illustrated on our
technology page and attested to by our customer and reviewer comments.
Q.
Does PurePower offer variable frequency control?
A: The PurePower APS matches the frequency of the new regenerated sine wave to the utility power frequency automatically. PurePower maintains an exact 50 or 60 Hz frequency +\- .1Hz%.
PurePower does not allow operation of components at any frequency other than the frequency for which they were
designed.
Q.
Will balanced power technology do what PurePower does?
A: No, balanced power is an ingenious technique that uses
transformer technology to cancel noise and distortion in the AC sine
wave. However balanced power transformers are notoriously inefficient,
can crush system dynamics and they have no effect on voltage drops, brownouts or
blackouts. (See our comparison chart.) Balanced power systems in which the normal 120 volt line and grounded common wire are replaced with a 2 wire +/- 60 volt scheme. They
are non-standard compared to house wiring and must be isolated to make sure they do not cause dangerous voltages in other household power systems. We do not have
a
professional opinion on their safety, but tend to think that it is always preferable to operate electrical equipment in the simplest way possible that fully meets local
standards.
Q:
Will an isolated receptacle provide clean AC power?
A: An isolated ground
receptacle has no effect on AC power. There is a great deal of confusion
about the term “isolated receptacle” and the term is often
misapplied. An isolated outlet is
better described as an “isolated ground” outlet. Its purpose is to
make sure the safety ground wire has the best direct connection to the
supply ground at the service entrance. This is critical to prevent
unwanted currents or noise from being carried between the common and
ground wires. Ideally there is zero potential between them, and
therefore no unwanted signal, but bad connections can create an
opportunity for “common mode noise” to exist.
Q.
Won't an isolation transformer make a new clean power supply?
A: Expensive
isolation transformers can be used to create a new “clean” ground at
the point of use and this will fix a common mode noise problem – but
at a high cost and a risk of dampening audio system dynamics. It will
not correct voltage sags or spikes. It is better, and cheaper, to run
new, uninterrupted wiring from the service entrance to a single
“isolated ground” receptacle. This simple step will almost always be
effective at cleaning up common mode noise that can cause hum.
Q.
Why aren't the PurePower receptacles isolated from each other?
A:
All AC circuits in a single residence are connected together, and a
power problem that exists at one outlet will be experienced at all
outlets served by the same distribution transformer. This often means
you are sharing power problems with several of your neighbors. The only
way to truly isolate one receptacle from another is to provide separate
power sources for them. This can be done by individual isolation
transformers, or by separate AC Regenerators.
When
you see the term “isolated outlets” in receptacles in the same
enclosure or on the same power bar you should take the term with a grain
of salt. Many power conditioners have
an added low pass filter – basically a small coil and capacitor –
attached to each receptacle. The theory is that this will filter high
frequency noise generated by a device plugged into one receptacle and
prevent “cross contamination” to other devices.
These
inexpensive filters may have some efficacy, but there are 10 different
“power gremlins” that can reduce AC power quality, and a filter can
only affect 1 of the 10, so perhaps “1/10 isolated receptacle” might
be a better descriptor. If you plugged your amplifier into one outlet,
and a light dimmer switch into the other, some of the high frequency
noise from the dimmer switch could be attenuated by the filter. If you
own a CD player or preamp that makes noise like a dimmer switch, it
could likewise attenuate that noise. (Our advice to all audiophiles is
to not let a dimmer switch come anywhere near your house, and if you
bought a piece of high quality audio gear that radiates noise like a
dimmer switch, send it back.)
There
are two flaws in the filter plan. 1: most audio system component power
supplies either do not radiate such noise into the AC line, or they are
so small a contributor as to be negligible. 2: The distortion they do
tend to generate is harmonic distortion. This distortion is completely
unaffected by a low pass filter.
PurePower’s
engineers considered adding low pass filters to our output receptacles,
but discarded the idea. We believe it is just as likely for the filters
to reduce current flow and diminish sonic performance as it is to remove
harmful high frequency noise. We think they are of small benefit –
other than to use as a marketing point.
We
do continually test customer systems to look for examples of cross
contamination. So far we have not detected any, but we will keep an open
mind.
Q: Can an ordinary, off the shelf, computer UPS product do the same thing as an AC regenerator?
A: No. Computer grade UPS systems are designed to support the specific requirements of computer power supplies and while they do an excellent job of protecting from surges and provide continuous power during blackouts (power failures) they have either no or very insensitive voltage regulation, do not remove harmonic distortion, allow some noise and transient voltages through and provide less than ideal sine wave AC output.
Computer UPS systems such as the APC SmartUPS do not perform full continuous power conditioning, but pass through the AC power from the wall outlet, turning on their battery powered AC inverters only in low voltage (usually <95 volts) or blackout conditions. Their battery life tends to be limited. They also tend to be noisy and intrusive unless housed in a separate room or electrical closet.
Q: Can a dimmer switch be placed in the same
circuit as my PurePower?
A: Dimmer switches are one of the worst offenders in adding noise to household electrical circuits. They can generate low frequency noise in the wiring and radio frequency noise by radiation and conduction. They should definitely not be placed near sensitive audio and video components and certainly not in the same circuit. Solid State dimmer switches operate by chopping current into very fine steps. This can interact with
audio equipment in unpredictable ways. If you insist on using a dimmer, make sure it is on a completely separate circuit from your audio and home theatre equipment. For more info on dimmer behavior see:
http://www.lutron.com/product_technical/FAQ.asp
The
PurePower
APS will completely remove all dimmer switch noise from the ac line supply to your system.
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