Is a single 20 amp dedicated circuit enough to run mono blocks

Power Consumption (Watts)
600 watts 8 ohm 1100 watts
75 watts 8 ohm 750 watts

Note the data plate on the back says ,
120V 60 Hz 1100W
http://www.bryston.com/PDF/Manuals/7B3_Manual.pdf

It’s not a question whether you can plug them both into outlets fed from the same 120V 20 amp dedicated circuit. The question should be how will they preform? Will they be starved for power if they are pushed hard any where near their full rated available output power?

What is the distance, length, of the 20 amp dedicated branch circuit? (Up, down, over, and around.)

What size of AWG wire did you use? Bare minimum #12awg or #10awg?
If you used #10 you should be fine if the length of the branch circuit is not too long.

If the branch circuit wiring is #12awg and the length of the branch circuit is over, say 50ft or so, then when you push the amps hard playing music with a lot of dynamics you may experience fluctuations in the AC mains voltage. As the amps are trying to draw more current, amps, (in gulps), to replenish, recharge, the electrolytic capacitors in the DC power supplies the mains voltage will/may dip. A power amp’s power supply need a steady state voltage. It doesn’t like the voltage fluctuating with the beat of the music.

You could use a volt meter and watch the meter as you push both amps hard to see if the voltage is holding steady or fluctuating, bouncing all over the place. You might even try a table lamp using a 60 watt incandescent light bulb. If you see the brilliance of the lamp changing with the beat, dynamics of the music, when you are pushing the amps hard, then that tells you the voltage is fluctuating as the amps are trying to draw more current.

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Speakers are Focus Audio FS-788,i believe that they are 10 ohoms 

New house ,using 12/2 wire at 40 feet from distribution box,,great idea with the lamp

https://www.google.ca/url?sa=t&rct=j&q=&esrc=s&source=web&cd=7&cad=rja&u...


Ohm chart for speaker

Thanks for providing the additional info. The speakers have rather low sensitivity (84.5 db/2.83 volts/1 meter) per the SoundStage measurements, but as you indicated their impedance is high (10 ohms or more aside from the upper treble area, where relatively little power is usually required).

I see also that the manufacturer recommends amplification in the range of 20 to 350 watts per channel. So you probably won’t ever be using more than around half of the amp’s power capability, or the speakers would be over-driven and probably distorting or compressing noticeably.

So I suspect that the amps will function in a reasonable manner when powered by the single 20 amp line you’ve described, assuming no other high current devices are on that line. But as Jim (Jea48) indicated, sonics might not be quite as good compared to having a second line.

To put that into perspective, the two amps are specified as consuming a combined total of less than or equal to 160 watts at idle, and if we assume say 1600 watts at the maximum power level you would be using that is a fluctuation of 1440 watts, or 12 amps at 120 volts. The 80 foot total length of the 12 gauge hot and neutral runs in your wiring from the breaker panel corresponds to a resistance of about 0.128 ohms. 0.128 ohms x 12 amps corresponds to a voltage fluctuation of about 1.5 volts. Not a huge amount, certainly, but perhaps enough to have perceptible consequences depending on the energy storage of the amp and the dynamics of the music.

Good luck with the new amps and the new house! Regards,
-- Al