Typical applications and use
For use in confined spaces
High frequency measurements
High pressure measurements
Sound intensity measurements
All G.R.A.S. microphone preamplifiers are based on a small ceramic thick-film substrate with avery high input impedance. The ceramic substrate is shielded by a guard ring to minimise the influence of stray capacitance and microphonic interference. The casing is made of stainless steel for maximum strength and durability. The small dimensions of this preamplifi r ensures reliable operation under humid conditions owing to the heat generated by internal power dissipation.
Type 26AR can handle both single and dual-sided power supplies. The supply can vary between 28VDC and 120 VDC single-sided or ±14VDC and ±60 VDC dual-sided. When using the high supply voltage (120VDCor ±60VDC), the dynamic range exceeds140 dB.
The electrical circuit in Type 26AR is built on a ceramic substrate using selected low-noise components to gain very low self-noise. The electrical self-noise is so low that system noise is mainly determined by the microphone capsule’s thermal noise.
The low-frequency cut-off of the G.R.A.S. 26AR preamplifier is mainly determined by the input impedance of the preamplifier and the capacitance of the microphone capsule. The capacities 20 pF,6.4 pF and 3 pF equal the typical capacitances of ½″, ¼″ and ⅛″ microphone capsules respectively.
The high-frequency cut-off is determined by the preamplifier’s ability to drive capacitive loads (slewrate), caused by the cable. For large-signals, the effects of these parameters must be accounted for when measurements are performed. The large-signal response for Type 26AR for various capacitive loads corresponding to different cable lengths is shown in the data sheet. The output level is in decibels relative to1 Volt. Typical capacitance for the cable is 100pF/m (30pF/foot).
Type 26AR is supplied with a 3-m light-weight cable (AA0057). Its 4-pin LEMO plug connects to the preamplifier and its 7-pin LEMO to a power module. The cable is only 2.5 mm in diameter and will withstand temperatures from -40 oC to +150 oC. An adapter GR0010 for G.R.A.S. ½″ microphones is included.
Ext. view of 4-pin LEMO plug 00 male and 7-pin LEMO plug 1B male (ext. view)
|Frequency response (±0.2 dB) with 18 pF microphone dummy and 4.7 nF cable load||Hz||2.5 to 200 k|
|Input impedance||GΩ // pF||20 // 0.4|
|Output Voltage Swing, max. @ ±14V/+28V power supply||Vp||10|
|Output Voltage Swing, max. @ ±60V/+120V power supply||Vp||50|
|Noise (A-Weighted) maximum||µV||2.5|
|Noise (A-Weighted) typical||µV||1.8|
|Noise (Linear 20 Hz – 20 kHz) maximum||µV||6|
|Noise (Linear 20 Hz – 20 kHz) typical||µV||3.5|
|Power supply, single||V||28 to 120|
|Power supply, balanced||V||+-14 to +-60|
|DC-offset, minimum, single suppy||V||0.5 x Vs - 1|
|DC-offset, maximum, single suppy||V||0.5 x Vs + 4|
|Temperature range, operation||°C / °F||-30 to 70 / -22 to 158|
|Temperature range, storage||°C / °F||-40 to 85 / -40 to 185|
|Humidity range non condensing||% RH||0 to 95|
|Humidity coefficient @250 Hz||dB/% RH||TBD|
|Connector type||7-pin LEMO (FGG.1B.307)|
|CE/RoHS compliant/WEEE registered||Yes / Yes, Yes|
|Weight||g / oz||TBD / TBD|
|Weight with cable and connector||g / oz||TBD / TBD|
|G.R.A.S. GR0010||¼″ to ½″ adapter for use with G.R.A.S. ½″ microphones|
|G.R.A.S. AA0057||3-m cable, 4-pin LEMO 00 male to 7-pin LEMO 1B male|
|G.R.A.S. RA0001||Right-angled (90º) Adapter for ½″ microphone and ¼″ preamplifi er|
|G.R.A.S. RA0003||Adapter for ½" microphone and¼" preamplifier|
|G.R.A.S. RA0006||Angled (90º) Adapter ¼! to ¼"|
|G.R.A.S. AA0008||Extension cable, 3 metres|
|G.R.A.S. AA0009||Extension cable, 10 metres|
|G.R.A.S. AA0012||Extension cable, 30 metres|
|G.R.A.S. AA0014||Extension cable, 100 metres|
|G.R.A.S. AA0020-XX||Extension cable, XX metres(customer-specified length)|
|G.R.A.S. AA0013||Tripod adapter for ¼" preamplifier|
|G.R.A.S. RA0096||Tripod adapter for ¼" preamplifier with angular adjustment|
|G.R.A.S. 12AK||1-Channel Power Module incl. SysCheck Generator|
|G.R.A.S. 12AA||2-Channel Power Module incl. SysCheck Generator|
|G.R.A.S. 12AQ||Computer-controlled Power Module incl. SysCheck Generator|