Veridian Utopia

Digital to analog converter

Sirius

Balanced R2R ladder · Valve output stage

No oversampling and no digital filter. Everything after the ladder is valve, and every unit is specified before it is built.

Sirius signal path Digital inputs feed a rotary selector, then a dual AD1865 R2R ladder, a valve buffer stage, and balanced XLR plus RCA outputs. USB · AMANERO S/PDIF · TOSLINK AES/EBU SELECTOR DUAL AD1865 · NOS R2R SIGNAL VALVE BUFFER HOT + COLD − XLR BALANCED RCA · SE ANODE SUPPLY · CHOKE FILTERED · VALVE OR SILICON RECTIFICATION

Fig. 1 — Signal path, single channel shown

Digital section galvanically isolated

Full block diagram, both channels
ISOLATION BARRIER USB · AMANERO S/PDIF TOSLINK AES/EBU ROTARY SELECTOR AD1865 LEFT · NOS R2R NO OVERSAMPLING AD1865 RIGHT · NOS R2R NO OVERSAMPLING VALVE BUFFER L BALANCED HOT / COLD VALVE BUFFER R BALANCED HOT / COLD XLR LEFT RCA LEFT XLR RIGHT RCA RIGHT POWER SUPPLY MAINS 115/230 V RECTIFICATION VALVE OR SILICON CHOKE FILTER ANODE RAIL HEATER SUPPLY REGULATED DIGITAL RAIL SEPARATE WINDING
Sirius DAC with a copper top plate and black front panel, the model name engraved in gold

The idea

A resistor ladder converts a number into a voltage and nothing else. No oversampling, no digital filter, no correction of the signal after the fact.

Sirius uses two Analog Devices AD1865 ladder converters, one per channel, running without oversampling. The digital section is galvanically isolated from the analog side, and the path from the converter to the first valve is kept as short as the layout allows.

The output stage is a balanced valve buffer. Anode supply is choke filtered, with either a valve rectifier or silicon diodes depending on how you want the power supply to behave. All boards use ENIG gold plating.

Sirius is the successor to the Excellence DAC. It can also be built single-ended rather than balanced — ask, and the price comes down.

Sheet 01

Specification

Converter
Dual AD1865 R2R ladderNon-oversampling, isolated board
Resolution
PCM up to 192 kHz
Output stage
Balanced valve bufferSignal valve, type chosen at build
Outputs
XLR balanced, RCA single-ended
Inputs
Up to fiveUSB (Amanero), S/PDIF, Toslink, AES/EBU, one spare
Selection
Front rotary selectorActive input shown by LED
Rectification
Valve or siliconChoke filtered anode supply
Boards
ENIG gold plated throughout
Standby
Manual
Mains
115 V or 230 V
Price
On requestDepends on the specification chosen
A signal valve on the copper top plate of a Sirius, with four more behind it
Close view of a 6SN7 signal valve seated in the copper top plate
Sirius in a copper finish, rear three-quarter view showing the valve apertures and vent pattern

Fig. 1 — Signal valves seated in the top plate, and the copper finish from behind

Rear panel of the Sirius: balanced XLR and RCA outputs, rotary input select, AES/EBU, S/PDIF, Toslink and USB
The valve output board inside the Sirius, with the relay ladder of the volume control alongside
Internal wiring in cotton sleeving running between the output board and the power supply

Fig. 2 — Rear panel, valve output board and internal wiring

Sirius DAC in a silver finish, valves visible behind the chassis
Inside the Sirius: valve output board above, converter and supply boards below
Detail of the Sirius front panel, engraved logo and volume control

Fig. 3 — The same converter in a silver finish

Sheet 02

Built to order

Each unit is specified before it is built. These are the choices that change how it sounds and what it costs.

  • Silicon rectification in place of the valve rectifier
  • Choke or resistor filtering
  • Output capacitor selection
  • Input capacitor selection
  • Volume control fitted
  • OS-CON capacitors where the layout allows
  • Pure silver internal wiring
  • Direct digital path, no signal buffer
  • Single-ended build instead of balanced
Sirius DAC in red and black, output valves lit

Sheet 03

Written elsewhere

Norway · 2018

A long listening report on the Sirius, written after several months with the unit rather than a weekend.

rognlien.wordpress.com →

Sweden · Comparison

Two Sirius units placed against a Lampizator, with the listening notes written up in full.

Download the write-up (PDF) →

Germany · Since 2023

A thread on the Analogue Audio Association forum, running since March 2023 and past three thousand posts. Reading it needs a free forum account.

analog-forum.de →

Ordering

Tell me what you want it to do

There is no shopping cart. Write to me with the sources you use, the amplifier it will feed, and whether you need balanced or single-ended. I will come back with a specification and a price.

Each unit is built after it is ordered, so allow time between the order and the delivery.

Or write directly to info@veridian-utopia.com

  • WorkshopCentral Slovakia
  • Emailinfo@veridian-utopia.com
  • PriceOn request, depends on specification
  • ShippingWorldwide, insured
  • ServiceFor the life of the unit