Some Technical details about the DAC:
Features
ESS Sabre32 Reference (ES9018) DAC Chip
Twisted Pear Legato Discrete Balanced output and Single Ended I/V Output Board
Headphone Out (Dynamic Headphones)
32 Bit Volume Control (Defeatable)
Twisted Pear Shunting Power Supplies
Salas Power Supply for Modules
Arduino Uno I2C Serial Control w/ LCD Screen Display
LCD Dimmer Control
Front Panel Manual Encoder Control
Apple Remote Control
HiFi2000 / Modushop Pesante 2U Chassis w/10mm Front Panel
Two S/PDIF Inputs (BNC and RCA)
Up to 32 Bit 192Khz Via S/PDIF
USB to I2S Input - Amanero Combo384 Module USB Class 2 to I2S 32bit and DSD
USB 44.1Khz – 384Khz and Native DSD Possible
Shurter Filtered/Fused/Switched IEC Power Entry Module
The all important DAC chip is the ESS Sabre 32 Reference DAC chip.
Some note from Rich:
Buffalo III DAC Overview
This DIY Twisted Pear Buffalo III DAC incorporates the ESS Sabre 9018 DAC chip. Twisted Pear is a boutique type online retailer that claims pursuit of good sound quality as their goal. There are many satisfied Twisted Pear customers that are no longer trying different DAC’s after building one.
The ESS Sabre DAC chip handles S/PDIF input differently than other DAC chips which results in better sound quality when playing S/PDIF. More info can be found by reading the ESS Sabre white paper. This DAC is configured to play direct DSD via USB, I2S via USB and S/PDIF. I2S is the serial communication found in CD players where clock and data are separate. S/PDIF has clock embedded with data and the DAC must sort it out. DAC supports up to 32 bit 192KHz S/PDIF playback. Higher rates including DSD can be played via the Amanero OEM USB input module.
The ESS Sabre DAC chip has been highly optimized by Twisted Pear (TP). It is configured as a current output DAC and requires a current to voltage or I/V output board. Three separate series shunt regulator modules (Tridents) are used for digital supplies with a dual series shunt voltage regulator module used for the AVCC supply. TP provides access to all DAC chip settings along with 32 bit volume control. This is normally done with a firmware chip and dip switch settings, however this DAC uses I2C serial control with open code allowing easier and remote operation.
32 bit volume control is part of the ESS Sabre DAC chip options and does not degrade sound quality like 16 bit volume control. You also have the option to disable the DAC’s volume control if desired. NOTE: IF you disable volume control, headphones and output will be at full volume. If you don’t use headphones often and would rather use your remote control pre amp to control volume, you have the option of selecting the highest volume (99) and the DAC will send full output to your pre amp. If you switch to headphones, turn the volume down before connecting the headphones.
Two TP shunting power supplies provide power for the DAC and I/V output stage. A Salas power supply provides power for the TP Sidecar, input board and USB input modules. Powering the input modules with separate power supply reduces load and heat from the 5v DAC power supply.
The installed TP Sidecar is a digital switch. When the relays are not powered, it passes S/PDIF from the input board to the DAC. When powered, it switches to the USB input to DAC. This switching is automatic. When you select Input 3, the Arduino supplies 5v to the Sidecar board which activates signal relays connecting the USB input to DAC board.
A TP Placid HD power supply powers the DAC board (5.25v) while a TP Placid HDBP (bipolar) PS powers the Legato I/V board. The Legato can be run from 12 to 15 volts, with 15 providing the best dynamics. The HDBP PS is set at 15v+ and 15v-. The drawback of shunting power supplies is heat thus the fully vented top cover. The DAC should have sufficient space around it to allow cooling. Nothing should be placed on top of DAC. It draws air from slots in bottom panel. The chassis has HiFi2000 anti-vibration feet installed. Power supplies are adjusted to shunt the TP suggested ~50mA of current.
The Legato output board has pots to null DC output on the single ended and balanced + and balanced - out. However, the Legato has common mode DC which is DC measured between balanced + and balanced ground and balanced – and balanced ground. Some amps can handle common mode DC, some cannot. For that reason, AC coupling caps are installed in the balanced + and - output. High quality 2.0uf Dynamicaps metalized Polypropylene film capacitors are used.
The DAC is controlled via I2C serial control using an Arduino UNO controller board and LCD display with modified HiFiDuino code for the ESS Sabre DAC chip. It is powered by an internal wall wart power supply. DAC settings, input and volume are controlled by manual rotary encoder on front of DAC and via an Apple remote. Changes to code can be made with Arduino software on a computer which can be uploaded to the Arduino UNO.
The I/V (current to voltage) output stage is a Twisted Pear Legato. The Legato is a fully discrete balanced active I/V line stage with both balanced and single-ended outputs. Balanced out is discrete output while single ended is op amp based. It also has a headphone out that can drive dynamic headphones. The LME49600 output buffer is capable of delivering 250mA.
The Amanero USB adapter Supports DSD and 44.1Khz – 384Khz playback.
