Fantastic condition Doshi Audio v2.1 Alaap Full Function Preamplifier with external power supply. Unit comes with external power supply and includes original packaging, all tubes, umbilical cord, power cord, and manual.Unit is rated 8/10 for light use and minor cosmetic wear consistent with age. Features:
Simple Circuits, Minimal Gain Stages and elegant execution with respect to power supply and interstage loading provide results that are true to the spectral power and dynamic envelope of the audio signal.
The audio circuitry in the phono stage consists of a balanced pre-preamplifier section for Moving Coil pickup cartridges that provides 20 db of gain. This section feeds the first tube preamplifier section which comprises of 4 parallel triode section that drive a passive RIAA equalization network. The de-emphasized signal is then amplifier by another section made up of parallel triode sections. The phono and line inputs are then switched into the primary of a 31 position transformer volume control manufactured by Sowter (UK) for Doshi audio. The advantages of using a transformer volume control are isolation between stages, consistent loading into the line section, and noise immunity. The Secondary of the transformer is connected to a 31 position Shallco rotary switch. The line section is a low output impedance line driver capable of driving low (for a tube output stage) input impedances. In practice, loads as low as 10k ohms can be driven without an output transformer. With the appropriate output transformer, 600 ohm loads can be accommodated.
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