The Phædrus Audio PHAMULUS is based upon the classic design of the Altec Lansing 436C Compression Amplifier.
Read Sound on Sound magazine's review of the PHAMULUS.
The Altec Lansing 436C δμ compressor amplifier (above) dates from the nineteen-sixties. The circuit of the Phædrus Audio PHAMULUS is based upon this circuit.
A famous, but rare variant of the Altec Lansing 436 is the Abbey Road studio RS124 which included a modification to the Altec input circuit to include a matched-impedance attenuator. Importantly, from an artistic point of view, the original Altec circuit only included a variable release time preset, so this was added as a user-control by the Abbey Road engineers too. This greatly increased the scope of the compressor's duties to which has been attributed some of The Beatles' magic. The entire unit was retro-fitted with a house-designed escutcheon which disguised its Altec heritage.
The variable release user control has also been adopted in the design of the Phædrus Audio PHAMULUS such that the control allows for adjustable release times between 0.1 sec (much faster than the original Altec) and 1.3 sec. This faster response widens the applications of the Phædrus Audio PHAMULUS to include compression duties for - amongst other things - drums.
Type: Compressor Amplifier
Gain: +30dB (reduced to +20dB with output attenuator engaged)
Frequency Response: ±1.5 dB, 40Hz to 15kHz
Max Output Level: >+20 dBu (as straight amplifier at 1kHz)
Harmonic Distortion: At 25 db of compression: Less than 1.5%
Noise Level: 74 dB below rated output (—111 dBm equivalent input noise)
Input Impedance: 15k bridging transformer (earth-free)
Load Impedance: Normally bridging: 600 ohms if ordered specially
Maximum Compression: 30 dB
Attack Time: 50 milliseconds
Release Time: 0.1 to 1.1 seconds
Threshold: Adjustable: 0 dBm to -16 dbm output
Compression Ratio: 2:1 at 0 dBm threshold; 4:1 at +16 dBm threshold
Controls: Gain, Threshold, Release Time, Output atten', meter-trim,
Power Supply: 12V AC, 4 Watts
Tubes: 6BC8, 12AU7
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