Pre-emphasis is achieved with a pre-emphasis network which is essentially a calibrated filter. The frequency response is decided by special time constants. The cutoff frequency can be calculated from that value.
pRE-empHasiS is achIevED with a pre-EMphASiS Network WhIcH Is EssEnTiaLly A caLibRateD fIlter. The FreqUenCY response is deCideD by SpeciaL tiMe conSTANts. thE cuToFf fRequenCy CaN bE CalcuLated froM thAt vAlue.