Manley Stingray II - Manual (Page 12)

You may have bought a great system but there is a good chance that you are only getting a fraction of its po-
tential. Very frequently we have experienced top quality electronics sounding unimpressive simply because acous-
tics were ignored. Even amongst studio engineers, few can really tell the difference between good speakers in a
bad room and bad speakers in a good room - but they all know good speakers in a good room and very likely so do
you. Acoustic techniques are better explained in books on recording studio construction. You can buy good ready-
made acoustical materials and/or build them yourself for a fraction of the cost. Dollar for dollar, you can expect far
greater improvement with acoustic treatment than expensive interconnects.
Most people think acoustics is about sound-proofing but there is a lot of info available for improving the
reproduction of music. Sound-proofing is usually expensive. Luckily just improving the acoustics in a room can be
pretty painless. You may be able to change or move what is on the floors and walls (without getting expensive or
ugly). The improvements may be dramatic.
Number One on the bad list is parallel surfaces. That pretty much includes most rooms. Parallel surfaces can
support a very short echo that is known as a standing wave. It boosts some frequencies and cuts others. This effect
is often called comb filtering because of the multitude of peaks and dips. One cure is breaking up the big surfaces
with a variety of smaller ones. The good news is that book shelves, curtains, wall hangings or macrame, plants, fur-
niture and lamps all help. Not only does this balance live surfaces with dead ones but “checker-boarded” areas also
act as a sort of diffuser. You can probably build low cost effective and attractive diffusers or have them made if you
want something better (and more efficient).
Number Two is very unbalanced room treatment. Both too “live” and too “dead” is generally bad. One might
think that wall to wall carpets & curtains is going to be fine but watch out. All that stuff only eats highs and a little
mids, but doesn’t do anything to the lows. The lows end up very live in contrast to very dead highs. One way to
balance this is get some thick absorbsion into the corners. Thick absorbsion in the corners is most effective to
lows. The idea is to balance high and low absorbsion. Even normal speech sounds weird in near empty rooms with
plain painted gypsum walls and hardwood floors. The simpler the decor the more intense the acoustic problems.
The only hints we can offer is that the wall behind the speakers and behind you are often the most important. You
can build some simple absorbers. Simply cut two 4’X8’ pieces of 2” rigid fiberglass or open cell foam rubber into
16”X8’ strips and wrap some white cloth around them. Easy, clean looking and cheap. Experiment, lean them
against the wall at various places. Even very experienced acoustic designers experiment, listen then decide rather
than attempting to predict every result. A variation is to use “perf-board” as a backing if you intend to stretch the
fabric reasonably tight. It may also help with hanging the strips to the walls. Perfboard with a one or two inch space
behind it is an alternative front surface to increase diffusion or can do double duty as a simple helmholtz absorber
(for the low mids) and can be effective on the ceiling. You can hang a few up there either flush or dropped a few
feet if you have the height to absorb lower frequencies. The wall behind the listening position is usually responsible
for too much or too little lows compared with the rest of the room. Read up on slat and membrane absorbers for
problems there - the panels described above won’t help much for that.
Number Three is lack of left/right symmetry. In order to get the left and right similar sounding and getting
a rock-solid center you should have identical left and right walls and distances. The ideal is a perfectly symmetri-
cal room but this may not be practical. Again, try to achieve this with positioning. Some of the “test” CDs have
a variety of low frequency tones or sweeps. Use them to find rattles and buzzes in the room. Lamps and fixtures,
some cabinets and components can do this. A little tape or glue can often fix these types of things. If you are getting
serious about this kind of thing you can get a variety of test gear from measurement mics to real time analysers or
computer software. These are useful tools but do not depend on the readings unless you are very experienced using
them. Best to use your ears and use the test gear to verify what you hear and to document the changes. Remember
that test gear neither makes records nor listens to music. Frequency measurement often ignores “time”, and exager-
ates some factors while glossing over others. Steady tones are virtually useless in real rooms. The more comprehen-
sive tests give complex data that needs to be correctly interpreted to be useful. Use ‘em but don’t jump to conclu-
sions. Always use ears too.
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