【傳(chuan)聲器(qi)】專業麥克風的要求(qiu) 使用傳(chuan)聲器(qi)的注意(yi)事項

對專業麥克風的要求

高保真和專業(ye)用傳聲器(qi)的(de)(de)失(shi)真度要小(xiao)于0.3%，寬(kuan)頻響范圍，良好的(de)(de)信噪比(bi)性能，良好的(de)(de)聲電(dian)轉換能力，即有較(jiao)高的(de)(de)靈敏(min)度。

傳聲器使用要點

（1）使用傳聲器之前，應先了解傳(chuan)聲(sheng)器(qi)的類型和(he)特性(xing)(xing)，往往靜態(tai)(tai)(tai)技術指標(biao)稍低而(er)瞬態(tai)(tai)(tai)特性(xing)(xing)好(hao)的傳(chuan)聲(sheng)器(qi)，要比靜態(tai)(tai)(tai)指標(biao)較高而(er)瞬態(tai)(tai)(tai)特性(xing)(xing)較差的傳(chuan)聲(sheng)器(qi)更好(hao)一些。電容式傳(chuan)聲(sheng)器(qi)還(huan)應注(zhu)意需加供電電源(yuan)。

（2）傳聲(sheng)器(qi)位(wei)置附近不應有大(da)的反(fan)射面，如墻壁(bi)等(deng)，以避免強烈的反(fan)射聲(sheng)引起聲(sheng)音(yin)相位(wei)干涉而破壞聲(sheng)音(yin)的自然(ran)度(du)。傳聲(sheng)器(qi)與音(yin)箱(xiang)之間的布位(wei)也(ye)十分重要，一般要求(qiu)將傳聲(sheng)器(qi)安放在音(yin)箱(xiang)的后(hou)面，避開音(yin)箱(xiang)輻射方(fang)向。

（3）傳(chuan)(chuan)(chuan)聲(sheng)(sheng)(sheng)(sheng)(sheng)器(qi)(qi)的(de)插(cha)接(jie)件(jian)要牢固可靠。作(zuo)為(wei)傳(chuan)(chuan)(chuan)聲(sheng)(sheng)(sheng)(sheng)(sheng)器(qi)(qi)插(cha)接(jie)件(jian)的(de)卡儂或大二芯插(cha)頭(tou)、插(cha)座(zuo)與傳(chuan)(chuan)(chuan)聲(sheng)(sheng)(sheng)(sheng)(sheng)器(qi)(qi)線(xian)(xian)(xian)(xian)焊接(jie)要求(qiu)很規范。傳(chuan)(chuan)(chuan)聲(sheng)(sheng)(sheng)(sheng)(sheng)器(qi)(qi)必須使(shi)用(yong)優質屏(ping)蔽(bi)電(dian)纜傳(chuan)(chuan)(chuan)送信號(hao)(hao)。由于(yu)傳(chuan)(chuan)(chuan)聲(sheng)(sheng)(sheng)(sheng)(sheng)器(qi)(qi)輸(shu)出信號(hao)(hao)很微弱，所以(yi)一(yi)旦竄入干(gan)(gan)擾(rao)(rao)信號(hao)(hao)就(jiu)會(hui)產生雜(za)音(yin)，為(wei)此(ci)必須選用(yong)金屬(shu)屏(ping)蔽(bi)線(xian)(xian)(xian)(xian)傳(chuan)(chuan)(chuan)輸(shu)信號(hao)(hao)，并應將屏(ping)蔽(bi)線(xian)(xian)(xian)(xian)的(de)一(yi)端(duan)與傳(chuan)(chuan)(chuan)聲(sheng)(sheng)(sheng)(sheng)(sheng)器(qi)(qi)的(de)外(wai)殼良(liang)好(hao)連接(jie)，另(ling)一(yi)端(duan)接(jie)音(yin)響設備(bei)的(de)外(wai)殼。屏(ping)蔽(bi)線(xian)(xian)(xian)(xian)的(de)長度也應盡量短。因為(wei)傳(chuan)(chuan)(chuan)聲(sheng)(sheng)(sheng)(sheng)(sheng)器(qi)(qi)線(xian)(xian)(xian)(xian)越(yue)長，分布(bu)電(dian)容(rong)越(yue)大，這不僅容(rong)易引起(qi)干(gan)(gan)擾(rao)(rao)信號(hao)(hao)，而且會(hui)引起(qi)人聲(sheng)(sheng)(sheng)(sheng)(sheng)信號(hao)(hao)（特(te)別是(shi)高音(yin)）的(de)損耗。一(yi)般說(shuo)來，不平衡(heng)連接(jie)（單芯屏(ping)蔽(bi)線(xian)(xian)(xian)(xian)）時，傳(chuan)(chuan)(chuan)聲(sheng)(sheng)(sheng)(sheng)(sheng)器(qi)(qi)連線(xian)(xian)(xian)(xian)的(de)長度不宜超過(guo)10m，若必須加長連接(jie)線(xian)(xian)(xian)(xian)，則應采(cai)用(yong)平衡(heng)接(jie)法（即用(yong)雙芯屏(ping)蔽(bi)線(xian)(xian)(xian)(xian)），以(yi)減少外(wai)來干(gan)(gan)擾(rao)(rao)。

（4）聲源與傳聲器(qi)(qi)的距(ju)離(li)要適當。當演唱(chang)抒情歌曲(qu)時(shi)，演員(yuan)常(chang)常(chang)將傳聲器(qi)(qi)靠(kao)近嘴邊，以充分利用近講效(xiao)應，提升低(di)(di)音。近講傳聲器(qi)(qi)與嘴部(bu)的距(ju)離(li)可在1～20cm。作演講時(shi)，為提高(gao)語言清晰度，傳聲器(qi)(qi)離(li)嘴部(bu)宜在20～30cm，甚至還要專門切除些低(di)(di)頻效(xiao)果。

（5）由(you)于演唱或演講大(da)多使用單指向性(xing)傳聲(sheng)器，此時應注意(yi)嘴(zui)部(bu)與傳聲(sheng)器中(zhong)心軸(zhou)(zhou)線之間的夾(jia)角(jiao)大(da)小會(hui)影響(xiang)拾(shi)取聲(sheng)音信號的頻(pin)率(lv)特(te)(te)性(xing)。演唱時，嘴(zui)部(bu)對(dui)準傳聲(sheng)器中(zhong)心軸(zhou)(zhou)線夾(jia)角(jiao)為0°，傳聲(sheng)器輸出的頻(pin)響(xiang)特(te)(te)性(xing)最(zui)佳；嘴(zui)部(bu)偏離中(zhong)心軸(zhou)(zhou)線越遠，頻(pin)率(lv)特(te)(te)性(xing)變差(cha)，高(gao)音損失越嚴重，且傳聲(sheng)器輸出電壓也會(hui)減少。一般心形傳聲(sheng)器，嘴(zui)部(bu)與中(zhong)心軸(zhou)(zhou)線的夾(jia)角(jiao)宜保持在(zai)45°范圍內(nei)，對(dui)強指向性(xing)傳聲(sheng)器則應保持在(zai)30°之內(nei)。

（6）良好(hao)的減振(zhen)裝置(zhi)(zhi)。拾音單元固定在套架(jia)上，高(gao)檔傳(chuan)(chuan)聲(sheng)器(qi)(qi)有(you)減振(zhen)裝置(zhi)(zhi)，防止傳(chuan)(chuan)聲(sheng)器(qi)(qi)因振(zhen)動而產生(sheng)(sheng)振(zhen)動噪聲(sheng)或因傳(chuan)(chuan)聲(sheng)器(qi)(qi)意外(wai)掉在地上或因磕(ke)碰(peng)產生(sheng)(sheng)強(qiang)大的聲(sheng)沖擊，損壞(huai)功放或音箱的高(gao)音單元。常用的減振(zhen)裝置(zhi)(zhi)有(you)橡膠減振(zhen)支架(jia)、橡膠傳(chuan)(chuan)聲(sheng)器(qi)(qi)夾子、橡膠傳(chuan)(chuan)聲(sheng)器(qi)(qi)夾子墊、彈簧傳(chuan)(chuan)聲(sheng)器(qi)(qi)夾子．使用手持傳(chuan)(chuan)聲(sheng)器(qi)(qi)時(shi)，不要握(wo)住傳(chuan)(chuan)聲(sheng)器(qi)(qi)網罩，以(yi)免(mian)堵(du)塞(sai)后面進氣(qi)孔，造成失真，影響效果。使用無線(xian)傳(chuan)(chuan)聲(sheng)器(qi)(qi)時(shi)，其載頻(pin)應避開當地調頻(pin)廣播或無線(xian)電話通信的頻(pin)率，以(yi)免(mian)相互串擾。

（7）抗(kang)干(gan)(gan)擾(rao)性能要(yao)好(hao)。聲(sheng)(sheng)(sheng)場中不可避免地(di)存(cun)在著某種磁場和(he)電場，如空調(diao)、電源線(xian)和(he)人(ren)體的(de)(de)靜電感應等。作(zuo)為傳聲(sheng)(sheng)(sheng)器(qi)(qi)的(de)(de)拾(shi)音單(dan)元，很小的(de)(de)雜(za)聲(sheng)(sheng)(sheng)干(gan)(gan)擾(rao)經過(guo)調(diao)音臺和(he)功(gong)率放(fang)大器(qi)(qi)放(fang)大后(hou)，送入揚(yang)聲(sheng)(sheng)(sheng)器(qi)(qi)就(jiu)會形成很強(qiang)的(de)(de)雜(za)音，損害聲(sheng)(sheng)(sheng)音的(de)(de)質量(liang)，所以要(yao)求傳聲(sheng)(sheng)(sheng)器(qi)(qi)結構、外殼要(yao)有良好(hao)的(de)(de)屏蔽作(zuo)用(yong)，要(yao)求全金屬結構，防磁性良好(hao)，要(yao)用(yong)良好(hao)的(de)(de)屏蔽傳聲(sheng)(sheng)(sheng)器(qi)(qi)導線(xian)。

（8）在使(shi)用多個(ge)傳(chuan)聲(sheng)器(qi)(qi)(qi)(qi)進(jin)行(xing)拾音時，首(shou)先(xian)應使(shi)各傳(chuan)聲(sheng)器(qi)(qi)(qi)(qi)的相(xiang)位一致；對一個(ge)聲(sheng)源如需用2支或多個(ge)傳(chuan)聲(sheng)器(qi)(qi)(qi)(qi)進(jin)行(xing)單聲(sheng)道拾音（如會議拾音）時就將傳(chuan)聲(sheng)器(qi)(qi)(qi)(qi)盡量靠近，或保持每(mei)個(ge)傳(chuan)聲(sheng)器(qi)(qi)(qi)(qi)與聲(sheng)源的距離(li)相(xiang)等，以免相(xiang)加時產生(sheng)相(xiang)位干(gan)(gan)涉(she)現(xian)象；對2支以上聲(sheng)源如需用2支以上傳(chuan)聲(sheng)器(qi)(qi)(qi)(qi)拾音時，應使(shi)每(mei)個(ge)傳(chuan)聲(sheng)器(qi)(qi)(qi)(qi)之間的距離(li)大于聲(sheng)源與傳(chuan)聲(sheng)器(qi)(qi)(qi)(qi)間距離(li)的3倍(bei)（即滿(man)足3:1規則），以減小信號相(xiang)加時產生(sheng)相(xiang)位干(gan)(gan)涉(she)現(xian)象。

（9）要(yao)注意防風、防振(zhen)、防潮。露天、室外演(yan)出(chu)要(yao)防風，避免風吹(chui)金屬網產生呼(hu)嘯聲(sheng)；空(kong)氣(qi)中的(de)(de)灰塵進入傳(chuan)(chuan)(chuan)聲(sheng)器(qi)(qi)(qi)(qi)，影(ying)響磁隙的(de)(de)清潔度(du)，會造成失真；近講傳(chuan)(chuan)(chuan)聲(sheng)器(qi)(qi)(qi)(qi)，口(kou)形與(yu)傳(chuan)(chuan)(chuan)聲(sheng)器(qi)(qi)(qi)(qi)很近，口(kou)中的(de)(de)濕氣(qi)損害傳(chuan)(chuan)(chuan)聲(sheng)器(qi)(qi)(qi)(qi)的(de)(de)膜片，要(yao)使(shi)用(yong)防塵防潮罩。

傳聲(sheng)器(qi)(qi)的(de)(de)結構(gou)比較(jiao)精密，強烈的(de)(de)振(zhen)(zhen)動不僅會使傳聲(sheng)器(qi)(qi)的(de)(de)輸出太大，使擴聲(sheng)系統嚴重過載，而(er)且還(huan)容(rong)易(yi)損(sun)壞其機械結構(gou)，使磁(ci)鐵退磁(ci)、降低(di)靈敏度，使音(yin)圈與磁(ci)路相碰等，所以要注意(yi)防振(zhen)(zhen)。尤其是電容(rong)傳聲(sheng)器(qi)(qi)，電容(rong)傳聲(sheng)器(qi)(qi)應先關閉電源后(hou)再移(yi)動為好。此外(wai)，注意(yi)不宜(yi)用吹(chui)氣或(huo)用手敲打傳聲(sheng)器(qi)(qi)的(de)(de)方法來試音(yin)。在(zai)傳聲(sheng)器(qi)(qi)的(de)(de)保管中，應注意(yi)防潮，保持清潔(jie)衛生(sheng)。

（10）傳(chuan)(chuan)(chuan)聲(sheng)(sheng)(sheng)器(qi)(qi)的(de)(de)(de)(de)相(xiang)(xiang)位(wei)(wei)。如果(guo)一部調音臺同(tong)時(shi)有多只傳(chuan)(chuan)(chuan)聲(sheng)(sheng)(sheng)器(qi)(qi)輸入，若(ruo)有2支傳(chuan)(chuan)(chuan)聲(sheng)(sheng)(sheng)器(qi)(qi)相(xiang)(xiang)位(wei)(wei)相(xiang)(xiang)反，當(dang)2支傳(chuan)(chuan)(chuan)聲(sheng)(sheng)(sheng)器(qi)(qi)信號送(song)入調音臺混合(he)電路中，則信號會相(xiang)(xiang)互抵消，其聲(sheng)(sheng)(sheng)音反而會減(jian)小，需進行調整。因(yin)此，使用(yong)多個(ge)傳(chuan)(chuan)(chuan)聲(sheng)(sheng)(sheng)器(qi)(qi)時(shi)，尤其是各種(zhong)不同(tong)型號的(de)(de)(de)(de)傳(chuan)(chuan)(chuan)聲(sheng)(sheng)(sheng)器(qi)(qi)同(tong)時(shi)混合(he)使用(yong)時(shi)，傳(chuan)(chuan)(chuan)聲(sheng)(sheng)(sheng)器(qi)(qi)的(de)(de)(de)(de)相(xiang)(xiang)位(wei)(wei)要一致。相(xiang)(xiang)位(wei)(wei)鑒(jian)別可用(yong)下述(shu)方法進行。先將所用(yong)的(de)(de)(de)(de)2支傳(chuan)(chuan)(chuan)聲(sheng)(sheng)(sheng)器(qi)(qi)放在(zai)一起，同(tong)時(shi)接收一個(ge)聲(sheng)(sheng)(sheng)源，送(song)出(chu)聲(sheng)(sheng)(sheng)響增(zeng)大(da)，說(shuo)明(ming)2支傳(chuan)(chuan)(chuan)聲(sheng)(sheng)(sheng)器(qi)(qi)同(tong)相(xiang)(xiang)，如果(guo)送(song)出(chu)聲(sheng)(sheng)(sheng)響減(jian)小，并出(chu)現失真，說(shuo)明(ming)傳(chuan)(chuan)(chuan)聲(sheng)(sheng)(sheng)器(qi)(qi)反相(xiang)(xiang)。將其中1支傳(chuan)(chuan)(chuan)聲(sheng)(sheng)(sheng)器(qi)(qi)接線調整過來，以達到同(tong)相(xiang)(xiang)聲(sheng)(sheng)(sheng)。