bhi Dual In-Line
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| Frequency | n/a (audio-frequency DSP noise-cancelling module) |
| Bands | n/a (works on receive audio from any band) |
| Power | Not an RF device. It is an audio unit with a built-in 7 W mono speaker amplifier (plus a 0.5 + 0.5 W headphone amp). It runs on 10-16 V DC, drawing about 800 mA nominal and 2.5 A maximum. |
| Modes | amplified DSP noise-cancelling audio module (receive audio cleanup, dual-channel/stereo) |
| Weight | 380 g (13.4 oz) |
| audio in | 3.5 mm stereo jack (accepts speaker-level or line-level; a Combine/Separate switch lets the two channels be used as stereo or as two separate mono inputs) |
| speaker out | 3.5 mm mono jack - amplified 7 W mono speaker output (into 4-8 ohms) |
| line out | 3.5 mm stereo jack - line-level output (about 0 dBV) to a powered speaker, EQ unit, or recorder |
| headphone out | 3.5 mm stereo jack - 0.5 + 0.5 W headphone amplifier (the speaker is not muted when headphones are used) |
| power | 2.1 mm coaxial DC jack (centre positive), 10-16 V DC |
| power req | 10-16 V DC, 800 mA nominal / 2.5 A maximum, via a 2.1 mm centre-positive coaxial jack. A fused DC lead is supplied; a 12 V desktop supply is recommended. |
A flexible, effective receive-audio cleaner: bhi's DSP is well regarded for pulling readable speech out of hiss and crashes, and the eight filter levels let you trade noise reduction against naturalness. The dual-channel design is unusual and genuinely useful - you can run stereo or feed two radios - and the three simultaneous outputs (amplified speaker, line, headphones) make it easy to drop into almost any shack. Low 38 ms latency means no distracting delay.
It only cleans up receive audio; it does nothing for transmit and is not a substitute for a good antenna or a quiet location. Aggressive filter settings can add artifacts or a slightly processed sound to voices, the unit is a separate box needing 12 V and cabling, and at around GBP 190 it is a meaningful add-on. Everything is on 3.5 mm jacks, so users with phono/quarter-inch gear need adapters.
The bhi Dual In-Line is a fully featured DSP noise-cancelling speaker amplifier that drops between a radio and its speaker and cleans hiss, static and tones out of receive audio, with eight filter levels, dual-channel/stereo handling, and amplified speaker, line and headphone outputs. It is a strong choice for operators who struggle with a noisy band or weak signals - especially those wanting to monitor two radios; it cleans only receive audio and very high filter levels can sound processed.
The bhi Dual In-Line is a digital signal processing (DSP) noise-cancelling module that sits between a radio and an external speaker and cleans up what you hear. bhi, a UK company, is well known for DSP units that separate speech from background noise, and the Dual In-Line is the flagship of its in-line range. Switch it in and band hiss, static crashes and tuning whistles drop away while voices stay readable; you choose how hard it works using eight filter levels, giving 8 to 40 dB of noise reduction plus up to 65 dB of tone (heterodyne) suppression.
What sets this model apart from a basic in-line filter is that it is dual-channel. A Combine/Separate switch lets it process a true stereo pair or two completely separate mono inputs, so you can feed two radios into it and monitor both at once. It is also amplified and generously connected: there is a 7-watt mono speaker output, a stereo line-level output (for a powered speaker, an equaliser, or a recorder), and a stereo headphone output, and you can use the speaker and headphones at the same time. Everything is on 3.5 mm jacks, and front-panel knobs set input, filter and output levels, with overload indicators for each channel. Processing latency is a negligible 38 milliseconds.
It is housed in a compact impact-resistant case (165 by 78 by 50 mm, about 380 grams) and runs from 10-16 volts DC through a 2.1 mm centre-positive jack, drawing 800 mA nominally. It replaces bhi's older NEIM1031MKII and sells for around GBP 190. Note that it only improves received audio - it does nothing on transmit - and very high filter settings can give voices a slightly processed sound.
It is an alternative to analog noise cancellers such as the Timewave ANC-4, and pairs naturally with a digital-modes interface like the SignaLink USB when you want clean audio both by ear and into the computer.