Twinings Tea Box Preamp

Twinings Tea Box preamps are genuinely made from Twinings Tea boxes. Four fine and lightly scented teas come with the well presented box. Though the box timber is light weight and velvet lined, the adding of bituminous Al foil to the inside increases box weight and provides a RFI and EMI shielding.

No screws scar the the timber box top by the use of internal adhesive "stand offs" to mount the component boards. The two circuit boards are component-2-component wired. In a preamplifier, keeping the signal path as short as possible is essential. Only clean DC power enters the preamplifier section. With a remote power supply and valve rectification a very quite and detailed sound reproduction can be ensured. Not to mention the addition of a very cool looking timber preamplifier.

Fostex FE206E back loaded horn

Retro-thermionic not only produces valve amplifiers and preamplifiers but also some finished speakers. Currently retro-thermionic is having constructed the back loaded enclosures to accommodate the Fostex FE206E drivers. After evaluating the the Fostex driver in a simpler two chamber enclosure, retro-thermionic, decided to have the more complex labyrinth style enclosures made. A CNC cutting machine was employed to make the most efficient cuts from the expensive and heavy 21mm multiply timber. Some panels are double layers of 21mm multiply. Panel bracing is extensively carried-out to control box colouration.

Sandbags can be layed in the bottom of the horn to tailor the bass to the listening room. Sandbagging can also be performed in the driver chamber to alter the level of other low frequencies. With efficiencies of the drivers reaching 96db the retro-thermionic amplifiers can produce high sound levels easily.

Fostex FE206E back loaded horn

At this point the enclosures have not been stained. It is easy to see the excessive bracing which goes into these speakers. A large amount of internal dampening is used and the cabinets are held together with stainless steel screws, doweling and glue. Large clamps were used when two panels were attached to ensure a rigid and tight fit of all panels. These speakers will be stained a dark teak.

Sound stage is pin-point. Stage depth is is very evident. Bass weight can be tuned by placing the speakers closure or further from the wall. Placement is critical.