MFJ-655B - Equalizer
Deluxe equaliser and conditioner 8-band for voice
MFJ makes sophisticated Pro Audio gear user friendly, affordable and RF bulletproof. MFJ adapted Pro Audio heart and soul to ham radio communications. The MFJ-655 all-in-one audio console gives you Pro Audio processing that makes your audio professional sounding.
It gives you all the capabilities youll ever need . . . 8-Band Equalizer . . . Downward Expansion noise gate . . . clean Compressor . . . smooth Limiter . . . low noise Preamp . . . universal microphone interfacing . . . impedance matching . . . level control . . . and RF/audio isolation.
Its processing is so smooth and transparent, no one will detect its presence. All they will hear is your outstanding audio that brings you unsolicited compliments.
A built-in headphone monitor lets you hear improvements as you make them and a VU-meter lets you accurately adjust levels.
An auxilary input lets you use other audio sources and a push-to-talk jack lets you use microphones without PTT.
The MFJ-655 uses the Analog Devices SSM2166. This professional quality audio conditioner gives outstanding performance over an exceptionally wide bandwidth with very low noise and very low total harmonic distortion, typically .25%.
An 8 Band Equalizer lets you adjust your voice for full quality ragchewing audio or powerful, pileup penetrating audio.
An adjustable Downward Expansion noise gate gives you transparent background noise reduction.
A clean, low-distortion Compressor gives you more powerful, richer, fuller sounding speech with more talk power.
A smooth Limiter keeps instantaneous audio peaks from overdriving your transmitter and prevents SSB distortion and splatter.
Front panel controls let you easily adjust input and output levels.
You can use nearly any mic-rophone with any transceiver with its Universal Mic-Interface, pre-amp, mic element voltages, impedance matching and PTT jack.
Plug in your headphones to hear your rigs received audio or plug in your MFJ, Heil or computer boom-mic headset to talk and hear.
8 Band Equalizer
The MFJ-655 voice band equalizer divides the speech frequencies into eight bands -- 50, 100, 200, 400, 800, 1600, 2400 and 3200 Hz. You can increase or decrease the gain of each band by 16 dB.
For ragchewing, you can adjust for rich, full quality audio. And for Dxing, you can increase the high and reduce the low frequencies for a highly intelligible signal that lets you punch through DX pileups.
You can turn ordinary, even poor microphones into pricy professional sounding ones.
Equalization compensates and improves your entire audio chain -- from your voice to your microphone and through your radio.
Downward Expansion noise gating
Downward expansion noise gating eliminates or greatly reduces background noise when you stop speaking -- no more amplifier fan noise, dogs barking, kids music or traffic.
Downward expansion is a professional audio technique. When you stop talking it smoothly attenuates low-level noise by reducing gain instead of abruptly cutting off like a noise gate -- background noise smoothly vanishes.
You control the level at which downward expansion starts and the delay when it ends.
Clean, Smooth Compression
Natural unprocessed voice has peaks and valleys. The average power of SSB speech is only 15 to 30 percent of peak power.
If instantaneous peaks are reduced, average power increases significantly.
The superb Analog Devices SSM2166 provides smooth, clean, almost transparent compression over a very wide bandwidth. It reduces speech peaks as much as 15 times.
Just a small amount of clean compression is impressive and gives you more powerful, richer and fuller sounding audio.
For DXing where every ounce of power counts, you can use more compression to increase average power.
Most of the speech power is in the lower speech frequencies.
Attenuating these lower frequencies with the equalizer reduces their power.
This lets you increase compression for weaker high frequencies -- where most of the speech intelligibility lies.
The MFJ-655 compressor does a superb job in creating an exceptionally clean, higher average power SSB signal.
Limiting -- splatter prevention
If occasional large audio peaks exceed a fixed set level, the compressors limiting function quickly attenuates them.
Limiting prevents over-driving your microphone input, transmitter and amplifier causing SSB distortion and splatter.
In the MFJ-655, compression and limiting work jointly to provide a level, constant output.
Standard 8-pin round or modular microphone plugs directly into the front panel. You can also plug in your MFJ, Heil or computer boom-mic/headset.
A PTT jack for a foot switch or other lets you use microphones without push-to-talk.
Its Universal Mic-Interface lets you use any mic with any radio. Internal jumpers configure any microphone to any radio.
A front panel controlled low noise pre-amp gives you up to 20 dB gain.
Select 600 Ohm, 200 Ohm or Hi-Z input impedances to match dynamic, electret or high impedance crystal/ceramic microphones. Has 8, 5, and 11/2 VDC mic voltages.
Use 12 VDC or 240 VAC with MFJ-1312