Mezmerize DCB1 Buffer
The 'Mezmerize' is an implementation of the famous B1 unity gain buffer by Nelson Pass on a new board designed by CFT and Salas. It is a direct coupled layout so is getting rid of the coupling caps of the original circuit and reduces the already low parts count even further.
The Mezmerize DCB1 is powered by a pair of onboard Salas shunt regulators to provide +/- 10V. The board (currently available through the Diyaudio store) also offers provisions for 6 input relays and an output relay for delayed start-up muting.
The build of my Mezmerize took no longer than about 20 months... with the building of the case taking the longest stretch of time. It all started out on the breadboard with the populated circuit board that was gently hotrodded. I was using TO220 rectifiers on it to run the CCS's at a higher setting as what the board was designed for. I settled on a CCS setting of about 350mA that just barely gets the bottom plate warm to the touch. The rest of the parts are pretty much as per BoM... finely selected LED's for the voltage reference, Elna Silic caps and Amtrans AMRG carbon as output resistors.
Other deviations are two capacitor banks for the power supplies with no less than about 50 pieces of 330uF capacitors in parallel... each side. The volume attenuator is based on a digital stepped attenuator using japanese mini relays that was hand built by a nice guy from Hungary (running a website called 8th Note blog). The digital attenuator is controlled by an Alps mono 10K potentiometer and is doing its job absolutely beautiful. It is extremely smooth with only a soft clicking noise of the relays but no audible noises through the headphones, has what feels like infinite steps while, thanks to the simple Alps mono pot, offers that detented feeling of a high end quality attenuator. I actually couldn't be more happy with this solution! Source selection is done via a swiss Elma switch.
It all was cased up in a custom case with two simple black sides, a rear panel with an aluminum insert for the IEC inlet and the assorted RCA's and a front piece crafted from a block of moroccon Thuya wood that was sanded forever and then coated in several layers of clear coat. Both front and rear are visually floating on stainless steel dowels. The top plate is 3mm aluminum and was CNC cut at the german 'Frontpanel Express' in Berlin. The two front knobs are (my trademark) white Delrin knobs turned on a lathe by a friend.
The Mezmerize DCB1 Buffer is replacing my former all tube preamplifier as the head of my audio chain...Nothing is coming in the way of the music could be a conclusion! :)