sure you have the alternative to switch off any machines and/or mechanical
ventilations.
Consider this: how can you hear the finest musical details if your noise floor is high?
Advanced Acoustics
Books, shelves and paintings are much better than nothing, but they in turn are
nothing compared to properly designed acoustical products.
So what is a "properly designed acoustical product"? Think of them as mirrors,
although the analogy limps a little! The acoustical products will create a (acoustical)
mirror image of your speaker. How do you prefer that image to be? A smaller version
of the speaker? A brighter one? A darker? A bluer one? A taller one? A wider one?
We are convinced that the image should be a replica of your speaker. This implies that
properly designed acoustical products are highly effective in a large frequency band.
There are for instance coefficients describing the absorptive efficiency as well as
coefficients for the diffusing efficiency. Often a number between 0 and 1 which should
be read as 0.5 equals 50% efficiency. Sometimes the number is greater than 1.0 and
this is a good signal for testing the sales people! Ask them how the product can
absorb more than 100% of the sound! The answer is that not only the surface facing
outwards is included in the calculation but also the sides of the absorber. Got another
answer? Look for another product or sales man.
Another good thing to look for is any recommendations as to how near the product
you can sit. Some recommendations say "recommended distance is more than 1.0
meter/3 ft". Again – perfect opportunity to ask sales person a question as to why! For
diffusers the answer often is that the diffuser has a strong lobe effect. This is a
contradiction - diffusers must not have peak lobe, they should diffuse the sound! A
good diffuser is the one you can sit close to, closer than a 0.3 m / 1 feet!
Around a certain frequency, depending on room volume and reverberation time, wave
lengths change in nature. This is usually referred to as Schroeder frequency (2000 √
(T/V)). This is a transition, not a distinct frequency. In practice this is the shift above
which diffusers are used and below which bass absorbers are used. In normal rooms
this is between 100 and 500 Hz. The problem gets worse the lower the frequency.
The solution to low frequency problems spells Helmholtz absorber. Efficiency is tightly
connected to the size of the Helmholtz. All other bass absorber types are poor in
efficiency and not recommended.
We recommend properly designed diffusers on the walls and ceiling
2
, at reflection
points. This will clear up the mids and highs at the same time as creating better 3D
image. Corners are often the perfect place for Helmholtz bass absorbers, but
measurements are very helpful not to say necessary.
The Three Sweet Spots
To get the best performance out of solo, you must locate the three sweet spots and
position your listening positioning and your solo speakers there. This is a task with
cm / ½-inch precision.
Solo is designed to be placed some distance away from walls. The radial room mode
(“standing wave”) will add bass into the tonality. Decrease the bass by increasing
distance from wall behind solo.
2 Ceiling reflection is not as important for solo thanks to dispersion pattern.
by engelholm audio
Revision A
www.engelholmaudio.com
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