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Hello Up for sale is a Bryston 2BLP that has been restored and upgraded. For many Brystons being restored, it means replacing the Electrolytic Capacitors. That certainly is important, but using the Best capacitors can actually improve the Amplifiers Sound. I used Nichicon KG capacitors which were the best ones that would Fit. Another important thing to do is to Tighten the Power Transistors – and I did that too. It turned out they were not loose. A Re-Capped Bryston is a wonderful thing, but there are 2 other CRITICAL things that should be done, and are normally NOT Done. And of course – I did them. One is the Bias Adjustment Pot. Everyone has trouble with this adjustment, mainly because the Open Frame ¾ Turn Trimmer after 20+ years develops issues at its set point that makes a touchy adjustment even harder to manage. Turning the adjustment is TOO MUCH, with luck, just applying Turning Force without turning is what most people do to “adjust”. Results are usually poor and not stable with time. I replaced the Open Frame ¾ Turn Trimmer with a Sealed 24Turn Trimmer. This makes it Much More Reasonable to adjust the Bias, The set screw can be used by actual Turning (not just applying pressure) to adjust bias. And its Stable. The Trimmers I chose have the adjustment screw facing up, so bias can be set with the Cover on the amplifier with a PLASTIC Adjustment tool (the bias is better set with the top on, after an hour or two of being on.) You can see the Blue Bias Trimmer that is close to the Power Transistors on the photo of the board.. I think Bryston recommends setting the Bias at 12mV, I found the amplifier sounds better at 15-17mV, but it runs hotter. My room is typically 72Deg, and if the Amplifier is sitting on a table with its heat sinks over the edge of the table – it never gets too hot. If you dont like this Bias setting, Ill set it to whatever you want. The other thing I never see on restored Brystons is that no one addresses the DC Offset at the output, and ALL 20+ Year Old Brystons suffer from that. DC Offset is bad for Speakers, and the Differential Amplifier circuit works better if it is properly balanced. The input transistors were matched at production, and there would be very little DC Offset at its output when new. But Transistors have something called Vbe drift. The Vbe is normally about 700mV, if it changes 1mV in 20 years and the amplifier has a gain of 30, there will be 30mV of DC Offset at its output. That is FAR too much. This amplifier was in the 40mV range when I got it. Good is generally considered less than 10mV. I installed a DC Balance circuit very similar to what Bryston included in their later amplifers. It is the Other Blue Trimmer near the coil (Inductor). Unfortunately the cover, or amplifier board, needs to be removed to set this 24 Turn Trimmer. But the measurement will change once the cover is on and thermally stabilizes. Getting below 10mV (What is considered “Good”) is easy, but I try to get in in the several mV range. This takes a few iterations of cover on – cover off and waiting for thermal equilibrium. Once you are below 5mV, its probably not worth the trouble getting it any better. I “Burned in” this amplifier for over 2000Hrs to eliminate any sort of “Infant Mortality” after I Re-Worked the unit. (Im from the defense industry, and 2000Hr burn-Ins are always required) This unit had the following measurements - seen in the photos before I packed it: There is a Photo included showing the Bias Voltage of both channels. There is an other photo showing the DC Offset of both channels. 2 Photos 5 minutes apart Interesting Note: Moving the amplifier location will have a slight change in measured Bias because a different location will have different air currents for cooling and this will change Bias by up to a few mV. So will the line voltage because the Power Transistors will have more voltage across them at “Hi Line” which will cause the Bias to lower a bit. I recommend (To the Extremest) resetting bias in the amplifiers final location if you worry about this sort of thing, but if you never measure anything and just use it as is – its good for another 20 years. Just like from the factory I enclosed several pictures to indicate what I did and the condition of the Chassis. I bought this unit from a recording studio in Canada. They get new units when the Bryston 20 year warranty expires. That is why some are marked with a Room Number or something similar. The Amplifier boards are screwed in place with the 4 screws at the corners of the Heat Sinks. Then you pull and they slide out. Another think I did to this unit was replace ALL the ceramic Caps with better caps, Mica and Polystyrene depending on its circuit function This auction is for ONE Stereo Amplifier. One other thing about this Bryston 2B. It was a Studio unit and had XLR Input connectors as inputs on the rear. I replaced them with RCA Connectors which are a much smaller Diameter. I made some Polycarbonate Mounting plates for the RCAs, you should be able to see them in a photo. XLR Cables are great for Long Runs across a studio, but is a silly concept for home audio. Especially with a Bryston 2B. XLR is a Balanced Input. The Bryston Circuit is a Single Ended Design (Input and Gnd) So There was an additional Circuit in this 2B that converted the Balanced XLR Input Signal to a Single Ended Signal – it was a fairly complex circuit that was actually AC Coupled to the 2B input. So – converting the XLR Input Connectors with RCAs allowed the removal of all that additional circuitry, so it will sound the same as a unit that was built with RCAs at the factory Also, this studio unit does not have an On/Off switch, it has a Dynamic Headphone Jack in its place. So it is also a Headphone amplifier. Its better to leave it on anyway, for many years the Brystons were not furnished with an On/Off switch. And there is more. You can see the Green “On Indicators” on the unit. The Studio unit had “Level Controls” where the red LED Clipping Indicators are on a home unit. I removed the Level Control Knobs (Replaced them with screws) and also removed the low quality Pot that was turned with a long shaft. The Input Level Pot is gone and replaced with a High Quality Wire. So, this Fully Refurbished and Broken In Unit is set up for Home Stereo Use. You might think this is a lot for a Bryston 2BThere are businesses that will do this for you, look in to it and see what they charge to upgrade a 2B you provide. If you have any other questions, just ask. Thanks for looking!!
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