6B4G tube amplifier with a CS4397 DAC: one owner’s Demograf Audio system

One forum member, known as Bahobaho, has lived with Demograf Audio electronics for years. His system is built around a DAC on the Cirrus Logic CS4397 and an amplifier on 6B4G triodes. This article brings together two moments: a 2013 session in which a guest heard the 6B4G amplifier with the Fostex TH900, and the owner’s own notes on his system and his music from 2014, written on the day a new Demograf Audio amplifier went into his rack.

These impressions are summarised and translated from owners’ posts on an audiophile forum. They are the subjective views of their authors, not measurements or claims of Demograf Audio. The units are earlier builds. The CS4397 DAC is offered today as Hyperion; there is no current catalogue model on 6B4G tubes.

The owner and his music

The owner listens to a great deal of music, mostly jazz and other improvised music, some experimental electronics and, from his younger years, some heavy music. Among the artists he names are John Zorn, Miles Davis, Bill Frisell, John Coltrane, Bill Evans, Tom Waits, David Sylvian, Carcass and Slayer. What he values in the sound of these units is dynamics, stage and space, timbre and a sense of life, and every listening session with other equipment, he writes, confirms his choice for him.

He describes the system’s looks as stern: a black rack, black or dark-wood cases, black knobs and no badges or ornaments. In his words, it looks severe but is gentle in reality.

The same day he had guests who helped him install and update the amplifier, and they compared several sets of cables and headphones on it.

The 6B4G amplifier with the Fostex TH900

In 2013 a guest, borlebsin, listened to the Fostex TH900 through the owner’s CS4397 DAC and 6B4G amplifier, after spending the morning with his own loudspeakers. He compared what he heard with those loudspeakers and with his memory of the TH900 driven directly from a tube output stage at home.

Bass

He found the TH900’s bass excellent in itself, and noticeably more tangible and realistic through the 6B4G amplifier than straight from the tube output. In richness and depth it matched the bass of his loudspeakers. Next to the loudspeakers, however, the bass took up a little too much of the overall picture.

Midrange

Compared with the loudspeakers he missed some midrange harmonics that fill the centre of the sound.

Treble

Through the 6B4G amplifier the treble was much softer and more balanced than straight from the tube output. In detail and resolution it led the closed-back headphones he knew: the quietest rattles and triangles were clearly audible.

Soundstage

The stage lost some of the width and depth he had heard at home, and was narrower than his loudspeakers’ and than the Sennheiser HD 800’s. In exchange the sound gained a more singing quality, more realism and a better tonal balance.

Summary

The owner values these units for dynamics, stage, timbre and a sense of life, and every session with other equipment, he writes, confirms his choice. A guest heard the 6B4G amplifier tame the TH900’s treble and give its bass more realism, at the cost of some stage width, and gain a more singing, tonally balanced sound in return.

Which Demograf Audio piece fits

• A directly heated triode amplifier close to the 6B4G: Eurybia, a single-ended Class A integrated on 2A3 triodes, 2 W per channel, for headphones and high-sensitivity loudspeakers. The 6B4G is an octal-base relative of the 2A3 with a 6.3 V filament.
• The CS4397 DAC: Hyperion, with a solid-state or tube output stage. Owners’ reviews of the DAC on its own are collected in Hyperion CS4397 tube DAC: owners’ reviews.
• Faster bass for rock and metal: Solaria on 45 triodes, or Atlas on 300B triodes for a warmer midrange. Our guide to power triodes in single-ended amplifiers compares the tubes.

Every unit is made by Dmitriy Gubchenko. Each is made to order with a one-year warranty (extra warranty available: +1 or +2 years), and the tube types are agreed before the build starts.