Dionysos

CONTROL AMPLIFIER WITH REMOTE

Dionysos is a remote controlled transformer coupled vacuum tube line level amplifier.

Accepts both balanced and unbalanced input signals on RCA and XLR connectors
Switches ground plane with input selection preventing ground loops
Programmable ground arrangement for large systems powered from different mains
Dual balanced and unbalanced output for bi-amplification or headphone amplifiers

Home Theater bypass feature for integration in Home Cinema systems
Shunt-regulated constant current PSU for lowest noise and best dynamic behavior
Choke input rectifier for lowest switching noise
Late night mode -12db pad
Programmable absolute phase per input and accessible via remote control

Stepped volume control for perfect repeatability of level setting
Inductive volume control for best sound quality
Custom vacuum encapsulated signal relays for ultimate sound and reliability
Modular construction
Microprocessor controlled
Interlocking solid aluminum chassis

The control amplifier is the centerpiece of every high-end audio system. It is responsible for source selection, signal conditioning and volume control. It has the task to match the output of your source to the input of your power amp. Its output stage has to drive any power amplifier through any length of cable with optimal quality via balanced or unbalanced lines, while resisting any interference.

The input of Dionysos provides optimal loading for the source component to develop its full potential, allowing it to extract the maximum amount of information while keeping all noise picked up along the way out of the signal chain. The transformer input provides complete isolation from the rest of the system, rejects common mode signals much better than any active solution, stops EMI/RFI and ensures a truly balanced differential input, while having very low DC resistance.

The volume control of Dionysos adjusts the level of the input signal to the value required by the power amp without burying low level information in noise while transferring enough power to properly drive the amplification stage without affecting its operation. Potentiometers and resistor ladders, as sophisticated as they might be, have a fundamental flaw. They operate by unnecessarily dumping the excess signal across a resistor. It is like driving a car with fixed engine power (signal) and adjusting the speed with the brakes (resistor) wasting most of the engine power! Our solution is fundamentally different and as simple as it gets. We use a transformer with various winding ratios and we switch between them. In the example above it would be illustrated by a gearbox, transferring all the power of the engine at all speeds. In other words remains in CONTROL at all volume settings.

The gain stage is realised by the use of a single low noise dual triode coupled with a transformer, making the output of the control amplifier low impedance, DC free, truly balanced, isolated from the noise sources and decoupled from other components in the system. This is the absolute optimum driving method for the following power amplifier's input stage. To further reduce the astonishingly low noise floor of the unit the active circuit is disabled below a certain volume setting and the attenuator is connected directly to the output providing low impedance noise free signal. This "gearbox" approach guarantees consistent performance at all levels making sure each component operates in it's optimal range.

The power supply of Dionysos uses a choke input rectifier arrangement. This eliminates switching noise and any other disturbance that originates before the choke, so the power reaching the reservoir capacitor is perfectly clean. Audio signal modulates the power supply of all devices, so we opted for a very unique way of power supply regulation eliminating the problem entirely. Dionysos uses a current sourced shunt regulator. In other words the current consumed at any given time is constant. Avoiding any variations makes intermodulation impossible while the shunt element passes all signal currents getting rid of energy storage devices (e.g. capacitors) that might affect the sound thus allowing all the finest textures to be rendered unaffected by signal content or amplitude. All this is governed by a microprocessor switching to the appropriate combination of relays and monitoring the unit’s status and incoming commands.

The chassis is milled from solid plates of different thickness aluminum that are interlocked together to form a ring like rigid structure. We have the power supply mounted on the left sidewall of this structure and the signal transformers on the right side, crossed by two semi-flexible bars on which the motherboard and its heat sink are attached via vibration isolating gel bushings. The top and bottom plates link all sides of the ring with the flexible bars and the feet made from conductive plastic on flexible screws. There are no screws visible anywhere on the chassis. And the chassis feels like a solid block protecting the circuitry from the environment both mechanically and electrically.

Available Finishes

BLACK ANODIZED ALUMINUM

SILVER ANODIZED ALUMINUM

Product History

First introduced in 2010. The first units made used Bent Audio input and attenuation boards. The distinguishing features for those are the seven segment led displays and Tape Out on the back. Their serial numbers are on the bottom plate. The units used a rectifier tube and Lundahl power transformer along with a regulator tube as reference for the shunt regulator. The rectifier and regulator tubes should be changed every year. The signal tube every second year. Those pieces have only 23 steps on their volume controls as they do not have the passive option. Gain can be reduced by rewiring 2 jumpers (please contact us for details)

A revision (v2) was launched 2012. The passive attenuation option was added extending the volume steps to 31 and a lower noise solid state voltage reference was used for the regulators. Those units can be recognized by the dot matrix display while still featuring Tape Out on the back panel. At some stage along the production (mid 2015) the rectifier tube was replaced by solid carbide diodes. The board still has a slot for a rectifier tube.

Next (v3) revision was launched in 2017. The tape output was removed and the -12db attenuation pad was introduced along with small changes in the power supply. Can be recognized by the lack of Tape Out on the back panel and the serial number is printed there now. All older units can be serviced at the factory and we can provide replacement parts for your local technician.