Below you will find a few measurements done using the Room Analyzer. We have included the bass frequency repsonse and spectrum analysis. The difference between near field and in room response from a subwoofer is clearly shown.
Room 1 - a room with nasty room resonances
Room 2 - an ok room but it can be improved
Room 3 - a very good room built by an acoustic expert
Different placement of a product read more >
The difference with and without room influence read more >
Room 1
A room decorated in a modern fashion - walls built from single layer of gypsum, only a little furniture and plain walls. Surface 30 m2.
We see an uneven frequency response. Around 50 Hz and 100 Hz there are peaks of +15 dB. This ruins most of the music. The bass will probably feel "slow" and lack distinctive punch.
To the left of the picture we see the frequency response of the room. This is not an unusual result, actually this is what many living rooms look like. The peaks at 50 and 100 Hz are the results of standing waves in the room, so this is a less fortunate speaker placement.
The picture to the right shows the frequency response as a function of time. We can also call it decay. The two peak frequencies remain during the complete measurement, something we do not want. Preferrably they should be as short as possible.
Room 2
A room that from the beginning have good relations between lenght, width and height and a decay time thatīs good with only small amounts of remaining energy after 100 ms. In this room the owner has put some effort into placing his subwoofer. This resulted in a good frequency response, but also a short decay time. Compare to the example above.
The room is heavily furnitured and the placement of the hifi components have taken several hours to get right.
Room 3
A listening room designed by an acoustic engineer. For example, this means no parallell walls, sloping ceiling, absorbing materials and thick walls with several layers of gypsum. The room has got a perfect balance between absorbing and reflecting materials. A room as good as this cost about the same as a decent car, but the result is a short decay time with very good frequency response.
The system uses a 18" woofer, which explains the very low frequency contents fo the measurement. Note the difference in the freq axis compared to the measurements above. Despite the large membrane area used the room doesnīt play along the way it would usually do.
Very few rooms posses this kind of acoustic qualities.
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An example of different placement of the subwoofer in the same room, with regular dimensions os 6 x 4.2 meters:
The first picture shows a subwoofer placed near the middle between the front speakers, about 1 meter from the back wall. A customer with a room like this would probably complain about the capacity of the subwoofer. Look at the picture below.
Here is the measurement with another placement of the subwoofer in the same room, now placed near the wall behind the stereo rack. The resonance at 30 Hz is still present but not at all as much, and the big dip is also evened out.
The room influence of a product
This measurement is a so called near field (done at 5-10 cm) and shows the subwoofer frequency response (this is what it would sound like if played in a infinite room without room influence. The subwoofer used in this measurement is a SVS SB12-Plus)
This is no unique response curve - itīs rather common.
The next measurement shows how the freq response can look using the same subwoofer in a common setup, placed next to the TV, between the front speakers. This is done at approx 3 m. We get a BIG dip in the listening position. Any difference from the measurement above is due to the room influence, and clearly shows how important the room is and why the effort of finding a good placement usually pays off very well.
Room Analyzer is a great tool for this.
