Option filters can be installed in the analyzer section of any Audio Precision instrument with analog domain analysis (2700 series, Portable One and ATS-1, and legacy System Two and System One instruments), adding filtering for weighted noise or other special measurements. 2700 series instruments accept up to seven option filters; Portable One and ATS-1 accept up to two. In operation, only one option filter can be selected at a time.
Audio Precision makes a wide variety of Option Filters, including low-pass and high-pass filters, bandpass filters, weighting and other noise measurement filters, sharp cutoff filters, de-emphasis filters and receiver testing filters. We make a “blank” filter circuit card so you can create your own filter, and for 2700 and System Two instruments you can obtain a kit that provides for an external filter connection. If you need a filter that we don't make, contact us and we'd be glad to quote a custom filter for you.
In addition to the plug-in Option Filters, two special multi-stage filter modules are also available, the S-AES17 Low-Pass Filter and the OPT-2020 Pre-Analyzer filter. Both of these filters have a section that is installed previous to the analog analyzer input, reducing out-of-band noise that may impair the measurement.
Bandpass Filters 1/3-Octave (Class II) View Graph
Family response: Class II (4-pole)
± 0.2 dB from 0.97 fo to 1.03 fo, < –12 dB at 0.8 fo and 1.25 fo, < –32 dB at 0.5 fo and 2.0 fo. These filters permit measuring specific frequencies in the presence of white noise. Contact Audio Precision if you have requirements for filter frequencies not listed here.
- FBP-120 Bandpass Filter fo = 120 Hz
- FBP-180 Bandpass Filter fo = 180 Hz
- FBP-250 Bandpass Filter fo = 250 Hz
- FBP-300 Bandpass Filter fo = 300 Hz
- FBP-400 Bandpass Filter fo = 400 Hz
- FBP-500 Bandpass Filter fo = 500 Hz
- FBP-500HQ Bandpass Filter (Hi-Q) fo = 500 Hz (for linearity measurements)
- FBP-600 Bandpass Filter fo = 600 Hz
- FBP-666 Bandpass Filter fo = 666 Hz
- FBP-800 Bandpass Filter fo = 800 Hz
- FBP-945 Bandpass Filter fo = 945 Hz
- FBP-1000 Bandpass Filter fo = 1.00 kHz
- FBP-1200 Bandpass Filter fo = 1.20 kHz
- FBP-1500 Bandpass Filter fo = 1.50 kHz
- FBP-2000 Bandpass Filter fo = 2.00 kHz
- FBP-3000 Bandpass Filter fo = 3.00 kHz
- FBP-3150 Bandpass Filter fo = 3.15 kHz
- FBP-4000 Bandpass Filter fo = 4.00 kHz
- FBP-4500 Bandpass Filter fo = 4.50 kHz
- FBP-5000 Bandpass Filter fo = 5.00 kHz
- FBP-6000 Bandpass Filter fo = 6.00 kHz
- FBP-8000 Bandpass Filter fo = 8.00 kHz
- FBP-10000 Bandpass Filter fo = 10.0 kHz
- FBP-12500 Bandpass Filter fo = 12.5 kHz
- FBP-15000 Bandpass Filter fo = 15.0 kHz
- FBP-16000 Bandpass Filter fo = 16.0 kHz
- FBP-20000 Bandpass Filter fo = 20.0 kHz
- FBP-22000 Bandpass Filter fo = 22.0 kHz
Low-pass Filters (bandwidth-limiting)
- FLP-300 Low-Pass Filter 300 Hz ± 3%, 5-pole Butterworth
- FLP-400 Low-Pass Filter 400 Hz ± 3%, 5-pole Butterworth
- FLP-500 Low-Pass Filter 500 Hz ± 3%, 5-pole Butterworth
- FLP-1K Low-Pass Filter 1 kHz ± 3%, 5-pole Butterworth View Graph
- FLP-3K Low-Pass Filter 3 kHz ± 3%, 7-pole Butterworth
- FLP-4K Low-Pass Filter 4 kHz ± 3%, 7-pole Butterworth
- FLP-8K Low-Pass Filter 8 kHz ± 3%, 7-pole Butterworth View Graph
- FLP-12.7k-1 Low-Pass 12.7 kHz, 1-pole Butterworth
- FLP-20K Low-Pass Filter 20 kHz ± 3%, (per AES-17)
- FLP-50K Low-Pass Filter 50 kHz ± 5%, 3-pole Butterworth View Graph
High-pass Filters (bandwidth-limiting)
- FHP-70 Bandwidth-Limiting, High-Pass Filter 70 Hz ± 3%, 8-pole
- FHP-400 Bandwidth-Limiting, High-Pass Filter 400 Hz ± 3%, 9-pole View Graph
- FHP-2K Bandwidth-Limiting, High-Pass Filter 2 kHz ± 3%, 9-pole
- FIL-D50 De-emphasis Filter 50 µs ± 1% View Graph
- FIL-D50E De-emphasis Filter 50 µs ± 1% + 15.625 kHz notch
- FIL-D50F De-emphasis Filter 50 µs ± 1% + 19.0 kHz notch View Graph
- FIL-D75 De-emphasis Filter 75 µs ± 1% View Graph
- FIL-D75B De-emphasis Filter 75 µs ± 1% + 15.734 kHz notch
- FIL-D75F De-emphasis Filter 75 µs ± 1% + 19.0 kHz notch
Weighting and Noise Measurement Filters
- FIL-AWT Noise Measurement Filter “A” weighting per IEC Standard 61672-1 (2002) (Replacement for previous standard 179 and 651) View Graph
- FIL-CCR Noise Measurement Filter Weighting per CCIR Rec 468 and DIN 45404 (Also for CCIR/ARM) View Graph
- FIL-CIT Noise Measurement Filter Weighting per CCITT Rec P53 View Graph
- FIL-CMS Noise Measurement Filter “C-message” per BSTM 41004 and ANSI/IEEE Std 743-1984 View Graph
- FIL-CWT Noise Measurement Filter “C” weighting per IEC Rec 179 View Graph
Receiver Testing Filters
- FIL-RCR Receiver Test Filter 200 Hz–15 kHz + 19.0 kHz notch
- FIL-FMP 15 kHz low-pass filter + 19 kHz notch filter.
- FIL-IECR Receiver Test Filter 20 Hz-15 kHz + 15.625 kHz notch View Graph
- FIL-VID De-emphasis Filter 12.6 kHz sharp low pass filter with notch at 15.7 kHz to reject the Hsync pilot tone in TV stereo
Miscellaneous Option Filters
- FBP-500X Bandpass Filter. High-Q 500 Hz bandpass for CD DAC linearity measurements. View Graph
- FLP-B20K 20 kHz “Brickwall” Filter. The FLP-B20K filter offers negligible effect below 20 kHz, but very high attenuation above. Its purpose is to remove sampling frequencies, typically 44.1 kHz or higher, as well as switching components.
- FLP-B40K 40 kHz “Brickwall” Filter. Similar in purpose to FLP-B20K, but with knee at 40 kHz, typically used for removing sampling frequencies at 88.1 kHz, 96 kHz or higher.
- FIL-USR User-buildable Filter. This blank circuit board with connector allows building building custom active or passive filters.
- System Two External Filter. This kit allows a user-designed filter to be connected externally to a 2700 series or System Two instrument.