May 26, 2000
Subject: Power confusion
Congrats on the new site. And thanks to SoundStage!
for pointing me to it.
My question concerns powering two remote amps. Since these
two 100Wpc amps are best placed in a well-vented but difficult to access spot on the
floor, can I plug in their power cords directly into the switched outlets on my preamp? Or
will I be creating some kind of current/voltage choke point? These amplifiers have no 12V
trigger.
Thanks for your help on this.
John Woltemate
Dear John:
I figured as long as I had API’s Les Edelberg on the line, I’d ask
him your question as well. He said, "It's OK to power the amps through the switched
outlets of the preamp as long as they don't exceed the maximum rating of those outlets and
the user would like the convenience of the automatic turn on of the amps when the preamp
is turned on. If the automatic turn-on is not really needed or desired, then I'd recommend
that the amps be plugged directly into the wall, eliminating an additional plug connection
and switching device from being in the circuit (always a good idea to keep things as
simple as possible)."
I agree with Les, but I think you’re saying
that the convenience of the preamplifier switch is something you’d like to keep. So I
have a question for you -- have you considered leaving your system on all the time? Unless
you’re running tubes (in which case, you obviously don’t wish to reduce tube
life just for convenience’s sake) or really hefty Class A amplifiers, it won’t
cost all that much in electricity, and your system will always be ready to sound its best.
I seldom turn off solid state gear around my house -- unless we’re talking about
refrigerator-sized amplifiers. That’s when I’m around the house, of course. When
I go on vacation, I not only turn everything off, I actually unplug everything from the
wall.
ATB...Wes
May 16, 2000
Subject: Dedicated circuits
Hello Wes:
I would like to get a dedicated circuit for my system, but
have several questions. I have 2 Hubbell 15A hospital grade receptacles.
My dealer recommended 10awg wire (30A circuit). So:
a) Is this ok to have a 30A circuit through 15A
receptacles?
b) Should the circuit breaker be changed to a 30A one if
the recommendation above is ok?
c) Is it better to daisy chain the two receptacles or have
separate lines (on the same phase)?
d) Would I need to change/modify my equipment/power cords
for 30A current (I have Simaudio gear)?
Thanks for any info you can give me,
Pete Chin
Dear Pete:
You’re right to be concerned about fooling
around with electrical circuits. I always like to get an expert’s opinion on
questions like these, so I called in Les Edelberg of Audio
Power Industries (API).
Les is a big believer in dedicated circuits.
According to him, there are several reasons they’ll make your system sound better. If
you live in an older house, its terminations, receptacles and circuit breakers may have
existed untouched for many years. As a result, connections may have become corroded or
loose. The contacts inside receptacles may have become worn, and circuit breakers may have
been tripped many times and become less effective. In cases where wiring is aluminum,
connections almost certainly have loosened -- in this situation, he cautions that you
should establish a program of routine tightening, especially of the neutral connections.
A new dedicated circuit provides all new, clean,
tight connections, receptacles and circuit breakers. It also eliminates other household
devices from being directly on that circuit, which puts even more distance between the
audio or video system and them.
Like me, Les is adamant that you have a qualified
electrician perform the work. This ensures both the safety and quality of the work. As far
as materials, high-grade commercial components will perform just fine. Les says, "if
you want to use specialized components, just be sure they meet local electrical
codes."
Les offered me the following tutorial on wire gauge
and current capacity: Wire gauge is all about current carrying capacity. A standard 15 amp
household circuit is usually wired with 14 gauge wire. A 20 amp circuit is wired with 12
gauge wire and a 30 amp circuit (very rare in households) calls for 10 gauge wire. Those
wire gauges are specified in the United States by the National Electrical Code (NEC).
Les recommends a minimum of 12 gauge copper wire be
used for the dedicated line whether it be a 15 or 20 amp line. 10 gauge can be used, but
many electricians will not run it as it is much more difficult to run, especially in an
existing dwelling. 12 gauge is sufficient for almost all audio and video applications
unless professional equipment will be used, requiring higher current circuits and special
AC connectors. It is OK to use 10 or 12 gauge wire in a 15 amp circuit.
Les opined that a 30A circuit breaker should not be
necessary for normal audio and video systems. Since a circuit breaker is designed to pass
the rated current and trip when the current demand exceeds its rating by a certain amount,
if a much higher rated breaker is used, it will take longer to trip when there is an
overload -- a potentially dangerous situation! The breaker rating should be sized to the
needs of the equipment it will be supplying power to, and no higher. Almost all consumer
audio and video equipment is designed to run on a typical 15 amp household circuit.
The number of circuits used is dependent on the
needs of the equipment and the preferences of the owner. In most cases Les feels a single
dedicated circuit is sufficient to power all of the components. However, since the current
demands of amplifiers is significantly higher than that of source components, some people
prefer to run a separate dedicated circuit for the amplifiers, rated at 20 amps, and
another for source components, rated at 15 or 20 amps. Both circuits should be on the same
electrical phase, and a qualified electrician can ensure that. Finally, there should be no
need to change or modify equipment or AC cords. They were designed by the manufacturer to
supply the needs of the equipment. There are, of course, after market power cords and
connectors which many consumers use in place of standard issue, but that is a different
issue.
ATB...Wes
May 11, 2000
Subject: Modest Questions
Hey, Wes. The site looks GREAT, and it seems like a winning
endeavor, but that photo of you has got to go! I'd recommend one where you're shown with
both a neck (less spooky) and a smile (more characteristic)!!
My questions are of the audio/social type. My husband is an
audiophile pack rat, and in the interests of marital harmony, I'd like you to verify that:
- it doesn't compromise the quality of sound to dust around
your stereo cables once every five years or so; and
- it doesn't compromise the quality of sound to lift the
dozens of boxes containing the hundreds of CDs up off the floor.
Awaiting your learned judgment.
Jezra in Brooklyn
Just to let readers know, this letter's from a
celebrity -- Jezra Kaye's a professional speechwriter/screenwriter/producer and the wife
of Jerome Harris, the renowned jazz guitarist/bass player/composer whose Rendezvous
CD [Stereophile STPH013-2] I produced. (There are still some copies left at: www.stereophile.com and your local specialty music
store).
Dear Jezra:
Thanks for the kind words about the site. Your
questions involve a variety of audio and psychoacoustic ramifications, but I'll try to
sort through the technicalities and give you straight answers.
About dusting the cables/rear areas of components:
There is a school of thought which claims that dust has excellent dielectric properties
and that dusting the cables will affect sound quality, but I think that's just
rationalization.
The biggest problem with dusting the cables is that
one needs to be careful not to knock any connections loose, so one must dust carefully.
I'd tell you that I have discovered that a lambswool wand type duster is the perfect tool
for this, but since I haven't actually dusted my cables, this is only speculation on my
part. (In my defense, I'd like to point out that I'm constantly connecting and
disconnecting cables, so there's no dust on mine.) Well, not too much. Okay, there's cat
hair everywhere, which is why I'm moving again.
The best way to get an audiophile to clean up back
there is to remind him that periodic cleaning of the cable and component connections is an
inexpensive way to improve sound quality. (Really! Scraping oxidation off the connectors
by plugging them in and out of one another several times actually improves conductivity
and signal transfer.) Of course, there are also audiophile approved tools and liquids to
do this, if hubby requires further temptation.
You write "It doesn't compromise the quality
of sound to lift the dozens of boxes containing the hundreds of CDs up off the
floor." You got your audiophile to put his CDs in BOXES? You are a lucky woman. He
probably puts his underwear in the laundry hamper, too. Count your blessings on this one.
ATB...Wes
May 7, 2000
Subject: Balanced vs. unbalanced interconnects
I have another question! Super high-end companies such as
Krell and Mark Levinson always supply balanced inputs and outputs on their components.
Many praise the incredible clarity and openess achieved with balanced connections. Based
on your experience, is this true? All things being equal in a system, let's say in an all
Krell system, if I switched out all the single-ended connections with balanced connections
(using the same cable models of course), will there be a noticeable or more importantly, a
musical difference?
James Adams
Dear James:
This is a matter of some debate, actually. Some
high-end manufacturers, such as Conrad-Johnson's Lew Johnson emphatically state that
in the lengths employed in home audio cables, there are no performance benefits to be
accrued from balanced cable operation and, in fact, the addition of amplification circuits
will only add to a product's cost. That's why no CJ products offer balanced operation --
not even their $15,000 ART preamplifier.
Other companies, such as Mark Levinson, Balanced
Audio Technologies, and Ayre take great pains to maintain a totally balanced signal chain
from source to output -- although they also offer non-balanced operation within their
components. However, most of these companies refer to the "theoretical"
superiority of balanced operation.
If you read Tom Norton's older reviews in Stereophile
and Stereophile Guide to Home Theater, he always compares balanced and single-ended
operation of the components under review and he has seldom -- if ever -- discovered
significant differences. This corresponds with my experience.
That said, if I'm reviewing or listening to a
system that allows for balanced operation, I tend to use balanced interconnects. I figure
the designers went to so much effort to give me the option, I might as well use it.
However, the most magical sounding system I've ever had running was Krell KPS-20, C-J ART,
Mark Levinson No. 33H, B&W Silver Signatures -- where the C-J ART meant I had to run
the whole thing singled-ended..
And that's all I can tell you on the subject.
ATB...Wes
|
