Icon Audio LA 5 TX Pre Amplifier


A very special transformer based pre-amplifier

Transformers sound best!

Well made audio transformers can provide perfect coupling in a hi fi system. Free from the “mechanical” sound of solid state and the deficiencies of output capacitors, they can make reproduction more vibrant and focussed.

The heart of the LA5tx are two very special line level output transformers, developed “in house” over several years to give what we think is the best sound balance.

Something for nothing?

This can be done with a “passive” transformer, but the results will vary depending upon the source impedance of the previous stage. If it is not “strong” enough poor matching will be obtained. In electronics you cannot get something for nothing! The LA5tx single 6SN7 valve “buffers” the input source, this way the LA5tx always presents a constant high impedance load, so the “strength” of the previous stage is irrelevant. The “strong” output of the 6SN7 then drives our transformer to give either a perfect “balanced” output as well as a phono RCA.

The very low 250Ω output impedance of the LA5tx is then strong enough to drive virtually any length or type of interconnect cable without loss or damage to the precious signal.

So we feel that this is a better solution than just using a transformer alone.

A high end pre amplifier must have the best power supply. The LA5tx has two chokes in double Pi configuration for well conditioned power giving superb smoothing for velvety inky black silence. The GZ34 rectifier valve has a more fluid sound than silicon diodes making a surprising difference.

The LA5tx is designed for the very best transistor and valve power amplifiers where musical purity is required rather than starkness.

The audio valve we use is the 6SN7 double triode. This 1940 vintage valve has all the best characteristics for the job, and its larger size means long life and good stability. Also the sound is more musical as we feel these have a more fluid sound. You can experiment with both vintage and modern types.

Specifications and Features

• • Icon Audio custom output transformers
• All hand wired point to point
• ALPs Blue motorised volume pot.
• Stepped attenuator option
• All Triode simple design
• 2x 6SN7 valves
• GZ34 Valve rectifier (also 274B/5AR4)
• Double Choke HT supply
• DC heater supply
• Signal to noise level -90db#
• Freq response 20Hz-15kHz +0 -0.5db
• Freq response 13Hz-20kHz +0 -1db
• Freq response 7Hz-28kHz +0 -3db
• THD typically less than 0.18% (0.5v output)
• Gain 3x, 7db
• Max output level 20v for 6.66v input
• Low output impedance of 250Ω
• Suitable for power amps 100mv-2v sensitivity
• High quality 2w metal film, & wire-wound resistors
• Solen/SCR audio capacitors (Jensen option)
• Silver PTFE audio cable
• Gold plated Input terminals
• Four line inputs
• Record loop
• 220/240volts 75watts
• Comprehensive manual supplied
• C E compliant
• 34.5cmW, 32D, 19.5H (with 274B), or 17H with GZ34 18kg with packing
(Specifications subject to change)

Various valve and capacitor upgrades are available, contact us for more information.


A simple low gain pre-amplifier that buffers the input and provides the transformer with optimum drive to achieve the full potential from our unique output transformers.