EAR/Yoshino HP4

EAR/Yoshino HP4

Tim de Paravicini has long had a worldwide reputation for valve preamplifiers and
power amplifiers. Now he has applied his expertise to produce what is arguably the
world's finest headphone amplifier aimed at the highest quality dynamic headphones.

The HP4 uses 6SL7 valves, properly matched to the load through de Paravicini's
renowned transformers, to deliver nearly 1W of high quality, low distortion power into
high or low impedance headphones. The output circuit configuration uses de
Paravicini's 'Enhanced Triode Mode', as employed in the highly successful V20 and
859 integrated amplifiers, while the input is also transformer coupled, giving the
flexibility to accept balanced or unbalanced signals from the preamplifier.

For the greatest user convenience the HP4 has its own volume control, while input
signals can be independently switched through to the power amplifier for headphone
and/or loudspeaker listening. As with all EAR products, reliability is paramount and
valve life is in excess of 10,000 hours.

It has facilities for up to five line inputs, and offers a genuine tape monitoring circuit, making a total of six inputs. A high quality volume control is fitted, as well as a panel mounted power switch. Input and output terminals are gold plated.

Designed by Tim de Paravicini in his usual robust style, the EAR 834L is the perfect match for any high end system, whether biased towards analogue or digital. The electronic architecture is minimalist, so that the absolute minimum sonic degradation takes place. There are three double triode valves, arranged in a classic 'de Paravicini circuit'. Special attention has been given to the input circuitry. All inputs are at the rear of the chassis, on the same circuit board as the selector switches, which are operated remotely by long control shafts.

The power supply is a unique arrangement; a high quality toridal transformer feeds a double DC power supply, that provides the low-tension (LT) heater current, and the high-tension (HT) anode voltage. It is critical in a preamplifier that both the HT and LT supplies are pure DC, and free from AC ripple. This is the case with all EAR products, not just this preamplifier.

The circuit is designed used in such a way as to have a minimum life of five years* continuous operation for the valves.

The preamplifier has more than enough output for any power amplifier, transistor or valve, and is ideal for driving long interconnect cables to remotely located power amplifiers.

The unit is available in Classic and Deluxe specification. Deluxe builds on the Classic's specification with a superior chrome and gold finish, with extra outputs to facilitate bi-amping systems, and a neon power monitor light.

*Discounting occasional random premature failure of valves.

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