Crown Preamplifier IC 150
The Crown IC 150 was a state-of-the-art preamplifier when it came out in 1971. It offered an unheard of level transparency due to its ultra-low noise levels.
This is a top-quality American-made preamplifier, listing for the equivalent of over $1,500 when new.
The IC 150 has an entirely passive input selector and tape monitor and recording system. The volume control and loudness compensation circuits are entirely passive. The Balance and Panorama controls are completely passive. Even the HIGH and LOW filters are completely passive. To get 12 dB/octave for the passive HIGH filter, the IC 150 uses one inductor in each channel to make a classic LC filter.
The advantage of passive circuits is that they add no distortion and no noise, and have unlimited dynamic range and output level.
The only active circuitry in the entire line-level audio path is a single LM301AN operational amplifier in each channel, which provides 20 dB of gain. The tone controls work in the feedback loop of this one op-amp. This simplicity is how Crown got this to work and sound so well.
How simple is it? Even with the phono preamp and all the relays and other control logic and power light, the entire preamp draws only an actual measured 2.7 watts from the wall — less power when ON than most modern HiFi gear wastes while it’s off!
The tone controls have separate left and right adjustments, popular back in the day. With mono records still in most people’s collections, we boosted the bass and cut the treble on the right, and boosted the treble and cut the bass on the left, to simulate stereo. This put the violins on the left and the basses on the right.
The separate phono preamp board, mounted right at the phono input connectors, has several discrete transistors. It’s also a gem, using 1% resistors and 2.5% capacitors for precise adherence to the RIAA curve. It also has rear-panel adjustable gain for each channel from 30 ~ 50 dB so your turntable’s level and balance can match your other components.
It runs from regulated ± 18V supplies giving this Crown an output of 11.7 V RMS of hot, clean audio, not the wimpier ± 15 V supplies more popular today that limit their output levels to about 8 V RMS.
Specifications Crown Preamplifier IC 150
Input Impedance 100 kΩ.
Output Source Impedance 600 Ω.
Output Slew Rate 4.25 V/µS.
Weight 10 pounds.
Quality Hand-made in Elkhart, Indiana, USA.
Power Power cord is flexible 2/16 heater cord.
Power switch rated 25 Amperes.
Switched outlets rated 1,200 watts.
2.7 watts, measured power consumption. 2 W rated.
1/8 A fuse (1/16 when set to 240 VAC).
1971: $1,550 list price, corrected for inflation in 2015.
Specifications Crown DC 300A Power Amp
Description: Solid-state stereo power amplifier. Rated power: 100Wpc into 16 ohms (23dBW), 150Wpc into 8 ohms (21.8dBW), 250Wpc into 4 ohms (21dBW), all at <0.1% IM distortion. Frequency response: DC–20kHz, ±0.1dB; DC–100kHz ±0.6dB. IM distortion: <0.1%, 10mW–150W into 8 ohms; typically below 0.05%. Input sensitivity: 1.75V in for rated power out.
Dimensions: 7″ (178mm) H by 9¾” (229mm) D by 19″ (483mm) W (standard rack-mount panel). Weight: 40 lbs (18.2kg).