Low gain DHT 01A valve single ended stereo preamplifier with valve rectified power supply.

With modern DACs pushing upwards of 2V output you may wonder what benefit a preamplifier could provide beyond input switching and a volume control? The 01A valve in your signal path will certainly convince you otherwise.

Each 01A has its own individual DC regulated power supply heating the thoriated tungsten filaments, bringing a glow to the valves and to the sound. You won’t want to listen without them.

Volume control is implemented via high quality autotransformers, the final word in signal attenuation. One per channel, preserving dynamics and signal quality down to whisper quiet levels.

A separate choke rectified power supply with the highest quality film capacitors provides a noise free foundation for the 01As to do their magic.

Default Configuration

• Lundahl transformers
• 2 x 01A valves
• Choice of 816 mercury (2 x 816/2 x 6AX4) or 6AX4 (4 x 6AX4) full wave bridge rectifier power supply. Mercury vapour valves require careful handling; preheating of the condensed mercury prior to applying power to the anodes is required. For the 816 valve this is approximately 30 minutes after any transportation and then 20 seconds each time the amp is switched on thereafter
• Coleman regulators for each filament DC supply with precision voltage adjustment via top mounted controls. DHT filament current draw can vary significantly between valves - adjustable regulation ensures low noise, great sound and long life for your valves
  
• High gloss finish available in any RAL Classic colour (see RAL Colour Charts)
• Solid hardwood 2/3 width format cases in high grade ash, beech, cherry, maple, oak, sapele or walnut
• Dual mono Intact Audio autotransformer volume controls - stereo option available upon request
• ClarityCap TC polypropylene film capacitors
• Charcroft Z-Foil bias resistors
• Teflon valve sockets
• Point to point UP-OCC 99.999% copper wired
• Black anode caps, black knurled solid aluminium knobs
• 4 x RCA Inputs (active wired - passive options available)
• 1 x RCA Output
  
• Lifetime warranty to first owner

Custom Options

The design has been optimised to showcase the very best of the 01A however the platform will accommodate components from other manufacturers, including transformers, capacitors, resistors etc. Let us know what you have in mind.

Inputs can be wired passively, i.e. direct to the volume transformers, not requiring power and useful if you don't require any extra gain.

Technical Specification

• Gain: 5dB
• Input impedance: 100k ohms
  
• Frequency Response 20Hz - 25KHz (+/- 1dB)
• Cathode biased
• Zero negative feedback
  
• Dimensions (including valves): PSU: 28cm wide/32 cm deep/27cm high. Amplifier: 28cm wide/32 cm deep/25cm high
• Weight: PSU: 14kg. Amp: 13kg