STAX SRM-T8000 Electrostatic Headphone Amplifier

Description:

Key features

• Electrostatic headphone amplifier
• High sound quality
• Coupling capacitor-free configuration from input to output
• Frequency response：1～115kHz per channel
• High-quality parts
• Fully balanced from input to output

What is it?

Every Stax ‘earspeaker’ is an electrostatic design. Every electrostatic needs a specialist, dedicated high-voltage amplifier (Stax calls it an ‘energiser’). Stax makes more top-end earspeakers than it does energisers, so there’s call for a really top-notch energiser from the brand to match the SR-009 and the new SR-009s. The SRM-T8000 is that energiser.

Two years in the making, the hybrid SRM-T8000 is the first of what Stax classes as a new ‘T’ series energiser. Instead of relying on a combination of FET input stage running in Class A and valve output stage using 6FQ7 valves, the T8000 features a pair of 6922 double-triodes in the input stage and a solid-state output stage. This form of hybrid amplifier circuit is commonplace in traditional two-channel amplifiers, but has been harder to utilise in Stax energisers because of the high impedance of an electrostatic transducer.

SRM-T8000 is Stax’s latest flagship electrostatic headphone amplifier utilizing hybrid technology. It employs two 6922 in the input stage, driving a Class-A solid-state output stage. The vacuum tubes isolated in a separate section made of vibration-proof damper and shield cover to eliminate vibration and noise. The high-capacity large toroidal transformers and selected high-quality parts allow the highest refinement in sound.

The big ‘first’ for the SRM-T8000 – which goes some way to explain the reason why this energiser is roughly twice the width of its counterparts – is its use of a large-capacity toroidal transformer, mounted on a non-magnetic aluminium chassis. It has both balanced and single ended inputs – balanced sounds best.

The SRM-T8000 is the best energiser Stax has ever made, and if resolution and imaging are your audio ‘triggers’, then this is also the best energiser you can get for a Stax. Especially if you have one of the better Stax earspeaker systems, like the SR-009.

How does it work?

Low-noise, well-established 6922 dual triode tube adopted for high sound quality. The noise level is extremely low and, by just that much, the particle of low-level sound usually buried in noise comes up to the surface. Then even the usual level sound clears up to improve sound quality such as transparency. It seems as if the glass which superficially looks transparent has been cleaned anew. The whole circuit forms a hybrid one using class-A semiconductor output stage with large current emitter follower. The result is very low noise, live and smooth musical sound as well as excellent spatial description.

Balanced inputs realizing true tone quality of balanced transmission. Coupling capacitor-free configuration from input to output. The vacuum tube of the first stage is mounted on an independent board in order to eliminate vibration and external noise. Further, noises have been excluded thoroughly by vibration-proof damper and vacuum tube shield cover used also for a hard disk etc. The first large-sized toroidal transformer in the history of STAX driver unit has been adopted to attain low noise and low leakage flux. This also enables the reproduction of high-speed and live sound over the entire frequency region. The chassis is made of non-magnetic aluminum instead of conventional iron. Thus the factor of cloudy tone quality has been eliminated and the weight has become lighter at the same time. Four pairs of inputs are equipped. (Notes: LINE4 is an optional circuit board slot for future purpose. As for now, release is not yet determined.)

LINE1, LINE2 or LINE3 inputs of the SRM-T8000 can bypass the incorporated volume controller, enabling it to connect to source equipments with volume controller or to an external attenuator. That is, the unit can be used as an exclusive power amplifier with no volume controller.

What’s in the box?

• STAX SRM-T8000
• Warranty