Recording - August 2018 - 26

GIK Acoustics

Gotham N23
5" Quadratic
Diffuser

A beautiful solution to a
perplexing acoustics problem
REVIEW BY PAUL VNUK JR.

ongtime readers will know that I am one of those
annoying people, both on gear forums and in
print, who will always suggest spending money
on treating your room prior to spending money on
expensive gear. Yep, I'm that guy.
As a studio owner with a room full of gear and a more
than healthy complement of room treatment, I am constantly
reminded to keep preaching this to myself as well. I always
consider: is my control room-which started life as a dog
kennel and was then turned into office space before its current incarnation-treated properly?
Even though I've considered my room well-treated for over
a decade, I decided to answer that question decisively. I
used James Lindenschmidt's 2-part article on the use of
Room EQ Wizard and a measurement mic ("Beyond The
Clap Test," November 2017 and March 2018) to gather
data about my room and see for myself.
This led me back to the folks at GIK Acoustics, where
James works as one of their acousticians. I ended up
adjusting my speaker positioning, adding another GIK
Monster Bass Trap, installing two more Impression Series
Panels (reviewed November 2017) at my second reflection
points, and taking the old 242 Acoustic Panels that were in
their place and using them to create a second ceiling cloud
in the back of my room.
At this same time, the folks at GIK asked if I would consider
reviewing their new Gotham Diffusion panel. So armed with
a measurement mic in hand, and taking measurements
before and after installing four Gotham Diffusors in the rear
of the room, here is what I learned.

Holy diffusers, Batman!

With a name like the Gotham, there was no way I could
not use a Batman reference! Anyway: the Gotham N32 is a
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RECORDING August 2018

17.5" x 17.5" x 5.5" all-wood diffusor made of medium density
fiber board and weighing 20 lb. Although many similar
diffusors on the market-often called skyline diffusors because
they look like a cityscape from above-look like random
patterned wood blocks glued on a base, the best ones are
not random at all. Ideally, each block adheres to a specific
mathematic measurement. In the case of the Gotham it uses
a 23-root quadratic sequence made to provide, according to
the GIK website: "true, even diffusion from 1250 Hz to 9500
Hz, with scattering effects down to 650 Hz."
I was a straight-C math student with an art degree, so let me
just say the Gotham diffusers are geometrically balanced and
look fantastic, alone or in groups. They are almost hypnotic-looking;
everyone who has seen them in my room notices them instantly and
comments on how cool they look! My wife, an interior decorator,
thinks they look like great sculptural wall art.

What does a diffuser (or diffusor) diffuse?

Most of the time when folks discuss room treatments, the conversation centers around absorption-usually bass traps, because
nobody can ever really have enough bass traps, right? Often most
of us suffer from rooms that are too live and reverberant and we
need to deaden them. But what about diffusion?
I asked noted acoustician (and another frequent Recording
contributor) Bruce Black what diffusers do and what I should
listen for. His answer was, "Diffusion is a time domain thing,
having to do with reflections, and how they interact and influence a room's sound. Diffusors are quite handy to break up
flutter echoes, enhance the sense of space ("air"), and help in
localization. How much you will hear depends on how much
diffusion you've installed, where you've installed it, and the
quality of the diffusor."
In simple terms, bass traps and acoustic panels absorb
sound waves while diffusors scatter sound waves. In other
words, they work hand in hand to balance out the sound of a
room: one by eating up unwanted frequencies and the other

Table of Contents for the Digital Edition of Recording - August 2018