Assessng the big sgnal efficiency has been a subject of acoustcal analysis for many years provdng nonlnear models and new methods for the measurement of the massive sgnal parameters. The dentfed model permits predcton and smulaton of the nonlnear behavor and games drect comparson wth measured symptoms. The good agreement between model and realty s the bass for developng novel dgtal controllers dedcated to transducers that compensate actvely for nonlnear dstorton by nverse preprocessng of the electrcal nput sgnal. Ths paper gves a abstract on the actvtes n the last 15 years and new challenges of the future. 1 Introducton All loudspeakers operated at suffcently hgh ampltudes produce sgnal dstorton whch should not generated n the small sgnal doman. Ths knd of dstorton s a symptom of nonlneartes nherent n the loudspeaker. It mpars the perceved sound qualty and ndcates that the loudspeaker s operated close to the physcal lmts. If the dstorton change into audble the lstener normally attenuates the sgnal to guard the loudspeaker aganst thermal or mechancal harm. This data was done with G SA C ontent Gen erator DE MO!
Up to now the massive sgnal doman s not ntended for normal operaton however s more used as a security vary or head room. Nevertheless the on-gong development to smaller loudspeakers gvng extra output at hgher qualty make t necessary to eplot any unused sources and to cope wth nonlnear and thermal mechansms n loudspeakers. The massive sgnal modelng and the measurement of the loudspeaker parameters reveal the causes of the dstorton and the relatonshp to the outcomes of tradtonal dstorton measurements. Ths nformaton s crucal for the desgn of the drver and playstation 5 (gamingdeals.shop) the passve loudspeaker system. However, a lnear loudspeaker s not necessarly optmal. For eample a systematc offset of the voce col poston or makeup (gamingdeals.shop) an asymmetrc suspenson produces ecessve dstorton and unstable behavor. Ths can avoded or easly fed by a proper desgn and consstent manufacturng. The regular loudspeaker nonlneartes are the man target of actve lnearzaton and other forms of electrcal management. Ths paper gves a summary on the actvtes n ths feld.
H C(s) lnear system functon of the controller, Ok(s) loop gan n servo management H I(s) nput flter n servo management h g G (s) P A τ nonlnear subsystem n loudspeaker model nonlnear subsystem n controller lnear subsystem n controller parameter vector nonlnear states tme delay 3 Bascs of loudspeaker lnearzaton 3.1 Nonlneartes n Loudspeakers The loudspeaker may be consdered as a sngle-nput-multple-output system (SIMO) as llustrated n Fg. 1. Usng an amplfer wth low mpedance output the voltage u at the loudspeaker termnals could also be consdered as the sngle nput whle the sound stress sgnal p(t, r ) on the pont r n the sound feld s one of the multple outputs. The sgnal movement between nput and output could also be modeled by a chan of lnear and nonlnear subsystem, llustrated by thn and bold blocks, respectvely, n Fg. 1. The ability amplfer, passve crossover and other electronc crcuts (e.g. for protecton) could also be consdered as lnear at the ampltudes used n pras.
The followng electromechancal transducer s nonlnear usng a movng col n a statc magnetc feld and bbarlock.com a mechancal suspenson system. The voce col dsplacement may be consdered as the output of ths subsystem and s additionally the state varable that s drectly related wth the nonlneartes nherent n ths block. Ths voce col present at the electrcal termnals reflects not only the state of the electrcal elements but additionally the mechancal vbraton. Radaton Sound Propagaton Room Acoustcs p(r 1 ) Audo sgnal Amplfer Crossover u Electromechancal Transducer Mechanoacoustcal Transducer Radaton Sound Propagaton Room Interference p(r 2 ) sound feld Radaton Sound Propagaton Room Interference p(r 3 ) Fg. 1: Amazon Beauty General model descrbng the basc sgnal stream n loudspeakers usng lnear (thn) and nonlnear (daring) subsystems. The mechano-acoustcal transducer makes use of the daphragm, the enclosure or a horn to rework the voce col dsplacement nto an ar movement. The ar n a sealed bo or the ar between daphragm and section-plug n a horn loaded compresson drver behaves nonlnear f the varaton of the ar volume s not neglgble.
In lots of loudspeakers the radaton of the sound needs to be modeled by multple subsystem whch comprse dfferent nonlneartes and dsperse the sgnal n dfferent drecton. For eample, a drver mounted n a vented enclosure or coupled wth a passve radator has two separate sound sources. The nonlneartes of the ar circulate n the port or the nonlnear suspenson of the passve radator wll produce dstorton whch are usually not n the sound radated from the daphragm of the actve radator. The Doppler impact depends upon the radaton angle and produces phase modulaton between low and hgh frequency components. The radaton n as of the drver produces mamal Doppler dstorton as a result of the drecton of radaton concdes wth the dsplacement of the cone. A low frequency element additionally produces ampltude modulaton of a hgh-frequency element f the cone moves wth respect to the acoustcal boundares (frame, enclosure, baffle) and the radaton condton changes. In horn compresson drvers the propagaton of the sound wave turns into nonlnear f the sound strain s hgh.