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The SC480 50W RMS Amplifier Module - Part 1

At last!- an amplifier module to replace the venerable ETI-480.It has less distortion, is much quieter, has inbuilt protection and sounds a lot better.

By Peter Smith and Leo Simpson

Back in the October 2002 issue we noted that we intended to produce a replacement module for the very popular ETI-480 amplifier module which was published back in December 1976 - 26 years ago.

In the same note we stated, somewhat controversially, that the ETI-480 was a dog of an amplifier and that it was not a good performer, even by 1976 standards.

Having made that outrageous statement (to some readers, at least), we had to come up with the goods. Fortunately, we were pretty confident that we could, and we are pleased to state that this new module is even better than we had hoped.

It uses the same power output transistors as in the ETI-480 and just one more low-cost transistor has been added to the overall component count. Kit cost should be about the same as for the ETI-480.

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But the SC480 is as modern as tomorrow - with performance to match.
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The transmogrification of an amplifier. Many readers will recognise the venerable (26-year-old!) ETI-480.
Performance
Output Power50 watts into 8Ω 70 watts into 4Ω
Music Power77 watts into 8Ω ;105 watts into 4Ω
Frequency response-1dB at 14Hz and 70kHz (at 1W- see Fig.1)
Input sensitivity0.875V for 50Ω into 8Ω
Harmonic distortion<.05% from 20Hz to 20kHz; typically <.003%
Signal-to-Noise Ratio-114dB unweighted (22Hz to 22kHz); -119dB A-weighted, both with respect to 50W into 8Ω
Damping factor>140dB at 100Hz & 1kHz, with respect to 8Ω and without PTC thermistor
Protectionfuses plus "Polyswitch" PTC thermistor
Stabilityunconditional

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