Adding filtering for weighted noise and other special measurements
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 plugin 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 the measurement of 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.