Bryston 7B-ST Monoblock Amplifiers - 500W/ch, 19" Rack Version

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Crazy powerful yet neutral amplifiers from legendary maker Bryston who makes all their products in North America.

These are rated at 500W into 8 ohms and a staggering 800W into 2 ohms.

Our test rig maxes out at 200W so thats as far as we were comfortable pressing these, but there is no indication they can't deliver the full 500W. We also tested the balanced inputs and they performed to spec.

Both units are in very nice physical condition with little signs of use. 

Reviews:

https://www.stereophile.com/content/bryston-7b-nrb-thx-st-sst-monoblock-power-amplifier-7b-st-october-1996

https://www.enjoythemusic.com/magazine/equipment/1099/bryston7bst.htm

Recommended Cables:

Kimber Kable - RCA Interconnects - Better

Kimber Kable - RCA Interconnects - Best

Kimber Kable - BALANCED XLR Connectors - Better

Kimber Kable - BALANCED XLR Connectors - Best

Kimber Kable - Speaker Cables - Better

Kimber Summit Series Monocle XL Speaker Cables (PAIR) - Best

Kimber Summit Series BiFocal XL Bi-Wire Speaker Cables (PAIR) - Best If Applicable 

Kimber Kable - Power Cords - Better

Kimber Kable - Power Cords - Best

Our Testing Process:

We start with a visual inspection of all internal components to make sure that there are no signs of heat stress or damage. Capacitors are checked for telltale signs of predictive failure including bulging, shrunken wrappers, or physical leakage. We also inspect the PCBs for discoloration from resistors or transistors that may have been running hot. On vintage units we often spot check select capacitors for value and ESR.

If the amplifier passes visual inspection, we move on to a controlled power on sequence using a Sencore safety analyzer to monitor current draw in real time. Once the amplifier is determined to be safe to operate, we connect it to full AC mains for function and power testing. We connect the speaker outputs of the amplifier to a Sencore PA81 Power Analyzer which acts as a dummy load, DC offset monitor, and oscilloscope interface. We start with a low level 1KHz test signal at the amplifier’s input and slowly increase its amplitude while monitoring the output on an oscilloscope for signs of noise, clipping, distortion, or improper channel balance. We continue increasing the signal level until the amplifier reaches clipping. At this point we take an output power measurement and compare it to the spec sheet of the amplifier to verify proper performance. If the device under test has both balanced and single ended inputs they are both tested at this time. We finish off the bench evaluation with a 1KHz square wave check and a 20Hz to 20KHz sine sweep to assess the amplifier’s frequency response characteristics. This battery of tests will usually reveal if the amplifier has any issues that need further attention.

Before the device leaves the bench, we perform a listening test with actual music using a variety of preferred test tracks. Our benches are outfitted with familiar monitor speakers which help us identify inconsistencies that will not always show up on our test gear. The main things that we are listening for are hum or noise with no signal present, proper center image, clicks, pops, or any other obvious undesirable audio characteristics.

If the unit passes all of these tests it is moved to our long term testing rig where we simulate real word operating conditions for 6-8 hours. This allows us to monitor the unit for signs of thermal runaway or intermittent issues that only crop up when the unit has fully come up to temperature.

Specifications:

Solid-state monoblock power amplifier. Class of operation: AB2. Balanced and unbalanced inputs. Rated power output: 500W continuous sinewave power into 8 ohms (27dBW), 800W continuous sinewave power into 4 ohms (26dBW). Distortion: less than 0.01%, 20Hz-20kHz at 500W, IM or THD. Rated slew rate: greater than 60V/µs, parallel mode, 120V/µs, series mode. Sensitivity: 1V for full output. Rated input impedance: 10k ohms. Rated full-power bandwidth: 1Hz-100kHz. Damping factor: over 300 at 20Hz, ref. 8 ohms.

Dimensions:

19" W by 5.25" H by 15.5" D

Weight:

42 lbs