Recording - June 2015 - 8

Note to faithful writers: When sending your letters by email,
please remember to include your name and where you hail from.
Where will you be when the lights go out?
Hello Scott Dorsey: I have been reading your
article on AC Power Handling [available in the
online Resource Library at recordingmag.com]
and I want to thank you for sharing your precious
knowledge. I would be grateful if you could give me
some advice.
Where I live, power cuts happen from time to
time. Could you please advise me on how to protect
my RME interface and my Antelope monitor controller from power cuts in my studio?
I don't care about data loss. I am just wondering
if a power cut can harm my precious audio devices.
What type kind of protection do I need, if any?
Thanks so much in advance,
Stergios Loustas
Greece
www.learningfiddle.com

Scott Dorsey replies:
Stergios, there are actually two different
things to discuss here.
1. Your computer needs an uninterruptible
power supply (UPS) on it. I suggest using a cheap
standby UPS. It will produce a huge amount of
noise when it is actually running on standby
power, but it will be very quiet during normal
operation. The fancier online UPSes, which are
always running their load from the built-in inverter rather than wall current, are usually a better
choice for big data centers, but they will be producing noise all the time. Besides, you don't have
to care if it's noisy when it's running on standby...
because you're not going to be recording in that
case, you're just going to be using the standby
power to shut everything down.
2. The audio equipment itself just needs to be
protected from transients when the power comes
on and off. How much of a problem this is
depends on why the power is going off in the first
place. I lived in a place where the generation
capacity was undersized and there were regular
scheduled blackouts, which were listed in the
morning's paper, so you knew in advance when
you had power. These were very clean power
cuts. On the other hand, if you have outages from
lightning popping big breakers (or just a grid
that's so undersized that power cuts can happen
at any time), you can have substantial junk on
the line.

Get a decent quality surge suppressor with MOVs and gas tubes
in it for your audio gear. Get an electrician (or the power company)
to install a lightning arrestor at the service entry. In some places,
the power company will install an arrestor for free or for a minimal
fee if you ask, but I'm not sure how things work where you are.
Be aware that both the surge suppressor and the lightning
arrestor are only as good as the ground they are connected to.
There are plenty of buildings with minimal grounds that are just
barely what is required to meet the building code. Again, have an
electrician look at it and measure the ground resistance and see
what it takes to get your measured ground resistance down to a
couple of ohms. You'll find this is a general win all around, too.
You can buy a line filter that has a big lowpass filter network in
it and then MOVs and gas tubes, so the lowpass makes the job for
the clamping components easier. These are big and heavy and they
are certainly not a bad thing, but unless you have got the problem
first dealt with before it comes into the building, your money is
better spent on an arrestor and better grounds. Peace-SD
Correction
In our April issue, we reviewed the Soyuz Microphones SU-017,
and in that review we mentioned the forthcoming SU-011 pencil
condenser. Paul Vnuk Jr. mistakenly called the SU-011 a solidstate design, when in fact it uses a subminiature tube. It was an
easy mistake to make; handling the prototypes at NAMM, Paul
saw that they used a conventional XLR connector rather than the
5-pin connector that most tube mics use to connect to their
power supplies.
So if it was a conventional 3-pin XLR, it couldn't be powered
from an external supply, right? A letter from mic guru David
Royer set us straight:
"I enjoyed the review of the Soyuz SU-017 but I have news for
Paul Vnuk-the Soyuz SU-011 is actually a tube microphone. At
their booth at AES they were showing the subminiature tube that
they use in it. What is interesting is that the SU-011 manages to be
a tube microphone and it works with just a 3-pin connector...
One of my employees was gobsmacked at the idea of a tube
microphone that would work with a standard 3-pin cable, until I
drew out a schematic of a Lomo 19a9 from memory; that microphone could be made to work with a standard 3-pin cable. I gave
that hand-drawn schematic to the folks at Soyuz, and then at the
NAMM convention I found out that their engineer was amazed
that I had copied out their circuit almost perfectly... sight unseen.
As I said once: Capacitor microphones obey the same laws of
physics in Barstow as in Berlin."
I'd like to thank David for the clarification, and send our
apologies to the folks at Soyuz for the error. But hey, we got a
cool story out of it!-MM

Write to us at: Talkback, Recording Magazine, 5408 Idylwild Trail, Boulder, CO 80301
Or save stamps and send email to talkback@recordingmag.com
8

RECORDING June 2015

http://www.recordingmag.com http://www.learningfiddle.com

Recording - June 2015

Table of Contents for the Digital Edition of Recording - June 2015