Recording - February 2014 - 8

Note to faithful writers: When sending your letters by email,
please remember to include your name and where you hail from.
Room Modes: not the whole story
Hi there. I read a very interesting article where Mike
Metlay interviewed Peter D'Antonio in your October 2013
issue of Recording.
In the article, Peter D'Antonio says that RPG Diffusor
Systems, Inc. used to sell a a software programme called "Room
Sizer" and he adds that the ratio calculator for room volume is
all basically done online now. The calculator Peter D'Antonio
refers to works out the most appropriate dimensions for a room
from the maximum and minimum room dimensions. I have
searched the Internet and while I can find a demo version of
Room Sizer, that version is only for Windows 95/98 and XP. I use
an Apple MacBook Pro, running OS X.
Are you able to point me in the direction of a version of
Room Sizer that will work on a Mac? I am about to build a
home studio and I suspect that the calculator will be a very
useful tool when designing the room.
I look forward to hearing from you. Kind regards,
Ian Sweeney
New Zealand

Hello, Ian, and thanks for writing. As far as I can determine,
Room Sizer was never supported for the Mac; you'll want to
cast a wider net for room dimension programs. There are a
bunch easily found with a Google search, including some
online options like www.bobgolds.com/Mode/ RoomModes.htm
and others. But I also encourage you to read what else Dr.
D'Antonio said in his interview!
A room mode calculator, if it doesn't take into account speaker placement and listener location, gives answers that are not
only wrong but misleading. You have to worry about modes
that are excited at the speaker location and heard at the listener location; optimizing for axial mode spread does neither.
And any deviation from a perfectly rectangular room, even by
a couple of degrees, invalidates the calculation. It also doesn't
take into account room materials, assuming a perfectly reflective room with no absorption or diffusion at all.
Dr. D'Antonio's advice is to understand and treat the
room you have. If you're going to truly build a room to
exacting size and shape, with construction contractors and
the like, hire a studio architect who can design the room
perfectly. But if you're going to be working with an existing space, he advises to figure out where your speakers
will go, figure out where you're going to sit, and then
sweep the room and listen for (and treat) frequencies that
vanish or are very strong at the listening position.
Once you know which frequencies are a problem, you can
treat them directly. For example, in an upcoming issue of the
magazine, we will run an article describing how to easily
build a Helmholtz resonator to attack a particular frequency in any size/shape room without taking up a lot of space.
If you insist on finding room proportions that optimize
for modal distribution, here's the easiest way to do it. Go to
the webpage realtraps.com/modecalc.htm and click on the
image there to blow it up to full size. There's a list of eight
recommended room dimension ratios. Pick one and start

there... and be prepared to shoot your room and treat for
bad tones anyway, because you're going to need to.
Thanks for reading and good luck. Please keep us
informed as to how your room is turning out, and remember: treat for the problems you actually have, not the problems a spreadsheet says you might encounter in a perfect
world. Best-MM

Tape for tape's sake?
Dear Scott Dorsey: I got your email address from an article
you did in Recording some years ago, on RMGI tape. I am
new to recording and have a TASCAM 38 reel-to-reel in the
shop getting dialed in.
I was wondering if you think the RMGI 468 tape, for recording anything from classical style stuff with strings to hard
rock stuff with a lot of mid bass, would be the best choice for
that deck? As I'm sure you know, it's a 1/2" x 10.5 reel deck;
I have the 2 noise reduction units. With thanks,
Ron Masterjohn
Yelm, WA

Scott Dorsey replies:
Ron: I would really like to discourage you from using a
TASCAM 38 machine for classical work. All of those narrow-track "semi-pro" machines have noise issues; the noise
reduction system helps but then adds another set of artifacts on top.
That said, as far as I know, the RMGI 468 is the only currently-made tape that the 38 will bias up. It might bias up
RMGI 911 and that could get you a little bit better SignalTo-Noise, but I would first give 468 a try. My inclination is
to keep operating levels fairly low because the heads on
those machines will clip before the tape will... I would stick
with 250 nW/m.
As always with narrow-track machines, be very careful with
track layout! Keep important stuff on center tracks, never
edge tracks; expect substantial bleed between adjacent
tracks, so leave a blank track between a timecode track and
an audio track, etc.. You'll get the hang of it. Peace-SD
Ron, I'd like to elaborate on one of Scott's points for all
our readers' benefit. With all the continuing discussion
about how awesome vintage analog tape is, prospective
buyers should remember that not all reel-to-reels will give
you more magic than grief.
The "pro" tape formats were and are 1" 8-track or 2" 16or 24-track, with each track being 1/8" or perhaps 1/12" wide.
As you shrink the width of each track, your usable dynamic
range drops rapidly. Machines with 1/16" tracks (4 tracks on
1
/4" tape, or 8 tracks on 1/2" tape like your TASCAM 38) can
still give you great recordings if you have the right noise
reduction, follow Scott's tips, and are very careful. But you
won't get the same "tape sound" as a wider-gauge deck
gives you when you hit the tape hard with hot levels.
Understand what you're buying!-MM

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RECORDING February 2014

http://www.bobgolds.com/Mode/ http://www.realtraps.com/modecalc.htm

Recording - February 2014

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