rajapruk skrev:Många surroundhögtalare som spelar samma signal som varandra borde ge en massa negativa kamfiltereffekter, eller?
Det här kan andra svara bättre på men min gissning är både avstånd och antal avgör om detta får negativa effekter eller inte. Det finns väl ett antal tidsfönster som avgör hur interferenser och reflexer uppfattas? Jämför med Calzone högtalarna som nyttjar tidiga reflexer.
Det här skulle möjligen då tala för att många surroundhögtalare är bra. (Utöver argumentet är de ska täcka 270 grader).
Edit, artikeln av Flöjt Tool som Calleberg länkade till har några enkla sammanfattningar i början (vet ej hur relevanta de är för hemmalyssnare?), tex
Flat on-axis frequency response is clearly the engineering objective for most of these systems. Those that deviate significantly earn lower ratings in double-blind subjective evaluations. Although there is more to be considered, a flat direct sound delivered to listeners is the basis for most reproduced sound.
The on-axis curve by itself is insufficient data. Full 360◦ data, appropriately processed, is important information.
With sufficient anechoic data on a loudspeaker it is possible to predict withreasonableprecisionmiddleand high-frequency acoustical events in a listening space with known properties.
In normal rooms the on-axis frequency response is not the dominant physical factor. However, the direct sound has a high priority in perception, establishing a reference to which later arrivals are com516 pared in determining such important perceptions as precedence effect (localization), spatial effects, and timbre. In this example, the poor off-axis performance dominated the in-room measurements and in listening tests caused audible timbral degradation. Equalization of the room curve will destroy the only good performance in the loudspeaker—the on-axis/direct sound response. Equalization cannot change loudspeaker directivity; the remedy is a better loudspeaker. Adequateanechoicdataontheloudspeaker would have revealed the problem in advance of measurements or listening. • Below the transition/Schroeder frequency the room resonances and the associated standing waves are the dominant factors in what is measured and heard. These are unique to each room and are strongly location-dependent.
Equalization is very limited in what it can “correct,” yet the notion that changing the signal supplied to a sound system consisting of an unknown loudspeaker in an unknown room can “equalize” or “calibrate” a system is widespread. In the context of a practical application where there is an audienceofseverallisteners conventional equalization cannot:
• Addorremove reflections
• Change reverberation time
• Reduce seat-to-seat variations in bass
• Correct frequency dependent directivity in loudspeakers
• Compensate for frequency dependent absorption in acoustical materials and furnishings. The exception is in the highly reflective sound field at very low frequencies.
In conclusion, there are reasons to exercise great caution in the application of equalization based on conventional inroommeasurements.However,itisdefinitelyadvantageous at lower frequencies, and later discussions will show that equalization based on anechoic data is also useful in the creation of superior loudspeakers
Kanske hittar fler citat om jag orkar läsa vidare.
Edith 2:
Peter, kurvan som Calleberg klippte in är vad de kallar steady-stste, vilket jag antar är någon form av tidsintegrering. Då kanske fallet på 7 db blir lite mindre förvånande?
Fig. 14. Subjectively preferred steady-state room curve targets in a typical domestic listening room
Det viktigaste måste vara det man hör.