G.R.A.S. Type 40HT - Microphone Type 40 AH; Gain and Filter Unit Type 26 HT

G.R.A.S. Sound & Vibration
Single-channel Low-noise Measuring System consisting of: Type 40HT and Type 12HF - Page 5
Fig. 1.3 shows a Single-channel Low-noise Measuring system (as described in this document)
andconsistsof:
• ½-inchLow-noiseLevelMicrophoneSystemType40HT.
• PowerModuleType12HF.
Note:thepowermodulemustbeorderedseparatelyandthetripodandtripodadapterare
optionalextras.
1.1 Microphone Type 40AH
TheType40AHisaspecialhigh-sensitive½-inchmicrophone.Itisexternallypolarizedwith
aspeciallyreducedinherentnoiseoorinordertoachieveahighdynamicrangeandwide
frequencyrange.
1.2 Gain and Filter Unit Type 26HT
ThebodyoftheUnithasanoverload-warningLED,(Fig.1.1),whichisrepeatedonthefront
panel of the chosen power module (see Fig. 2.1).
Thesignalofthemicrophoneisampliedby20dBintheGainandFilterUnitType26HT.
Thetwocompensationltersgivethesystemtwoparalleloutputswhichcorrespondto:
a) linearpressure-frequencyresponse.
b) linearfree-eldfrequencyresponseatanangleof0°incidence.
Fig. 1.2 Power modules available from G.R.A.S. for Type 40HT,
Left: Single-channel Power Module Type 12HF
Right: 10-Channel Module Type 12HM
Fig. 1.3 A Single-channel Low-noise Measuring System as described
in this document, shown here with Tripod and Tripod Adapter
(both available from G.R.A.S.)
To Analyser
Type 12HFType 40HT