How do we remember 1970s amplifiers?

Dynaco Stereo 300 / QSA300 Power Amplifier



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Description:

Specifications:

Rated 4-channel Power Output: 75 watts continuous average power per channel into 8 ohms (40 watts per channel into 16 ohms) 20-20,000 Hz, at less than 0.25% total harmonic distortion. Distortion reduces at lower power outputs.

Available 4-channel Output Power:

20-20,000 Hz, all channels driven, 0.25% maximum THD:

75 watts continuous average per channel @ 8 ohms;
100 watts continuous average per channel @ 4 ohms;
40 watts continuous average per channel @ 16 ohms.
Stereo Operation Available Output Power:

Low Impedance Mode Connections:

80 watts continuous average per channel @ 8 ohms;
150 watts continuous average per channel @ 4 ohms;
200 watts continuous average per channel @ 2 ohms;*
High Impedance Mode Connections:

80 watts continuous average per channel @ 16 ohms;
150 watts continuous average per channel @ 8 ohms;*
* 5 minutes sustained full power limit without a fan.

Power at Clipping, 1 of 4 channels, 2500 Hz, less than 1% distortion:

90 watts @ 8 ohms;
130 watts @ 4 ohms;
45 watts @ 16 ohms.
Power at Clipping, Each Stereo channel, 2500 Hz, less than 1% distortion:

Low-Z mode:

95 watts @ 8 ohms;
160 watts @ 4 ohms;
240 watts @ 2 ohms.
High-Z mode:

160 watts @ 8 ohms;
90 watts @ 16 ohms.
Intermodulation Distortion: Less than 0.25% at any power level up to 75 watts rms per channel into 8 ohms with any combination of test frequencies. Distortion reduces at lower power levels.

Half-power bandwidth: 37.5 watts per channel at less than 0.25% total harmonic distortion from 5 Hz to 50 KHz into 8 ohms.

Frequency Response: +0, -1 dB, 10 Hz to 40 KHz @ 1 watt into 8 ohms; ±0.5 dB, 20 Hz - 20 KHz @ 75 watts into 8 ohms.

Hum and Noise: Greater than 95 dB below rated output, full spectrum.

Input: 35,000 ohm load; 1.0 volt for 75 watts into 8 ohms.

Semiconductor Complement: 52 transistors, 40 diodes.

Slewing Rate: 7 volts per microsecond.

Damping Factor:

Greater than 80 to 1 KHz into 8 ohms;
Greater than 50 to 10 KHz into 8 ohms.
Channel Separation: Greater than 70 dB by IHF standards.

Connectors: Inputs: phono jacks. Outputs: Color coded 3-way binding posts with standard 3/4" spacing.

Dimensions: 18-1/4" wide, 14-1/2" deep;, 7" high panel, 17-1/2" wide. Add 1/2" for feet.

Shipping weight: 58 lbs. Net weight: 52 lbs.

Power Consumption: 120 VA quiescent; 10 amps maximum; 50/60 Hz, 120/240 VAC.

Designed by:

Harry Klaus

Year Introduced:

1976

Price:

$269.00 kit
$399.00 assembled

Comments:

Basically two ST-150 units in a single chassis, with separate power supplies. Usable as four independent channels or as a bridged stereo amplifier with 300 watts per channel. The MC2/MC3 meter kits provided output monitoring.

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This page created and maintained by Greg Dunn.
Copyright © 2000 Greg Dunn

I originally purchased this as a 4 channel amp which I used with my "Quad" Phase Linear 4000 pre. At that time, I thought it was "hot stuff".

Now, it is in use as a bridged stereo amplifier with 300 watts per channel. It sounds like what it is, "A big powerful mid fi amp". It works fine in our entertainment room where at least three conversations are always going on at the same time.

The music was so much better back then that we didn't know the equipment was lousy, and a good time was had by all.

Since everything is relative, and none of us had rigs much better or much worse than the next guy; we all thought our rigs were killer at that time.

I'm still using the the Dynaco. It was a "Quad" when I used it in the 70's. I had it mated with my "Quad" Phase Linear 4000. Since that time I converted it to stereo.

Without a doubt I thought everything I had was "hot stuff" at that time. Now, I use the still powerful Dynaco in the entertainment room where nobody listens anyway, but it bangs out that bass.

I guess your question is how we remember, as opposed to how we compare with today's amps; and I remember it as "all good".

While I remember it as "all good", compared to today; that stuff would be junk.

Either Hafler, or Dynaco could be transformed into true "high end" amps by simply substituting their existing parts for the best parts available today.

Successful businesses were created doing just that. When "Black Gate" capacitors were available, I replaced every electrolytic in every piece of equipment I own with Black Gates. That was with the exception of huge capacitors in power amps, but all other lytics in everything from reels to DACs were replaced with Black Gates.

If the replacement of a single part can upgrade a piece of equipment, imagine how replacing all of the parts would affect that piece of equipment. It's quite possible that some highly regarded "high end" amps are essentially "Haflers" or "Dynacos" with different parts.