* The Amp Doctor | The Amp Doctor
 

Upgrades

Component Upgrades

Virtually all amplifiers are built to a budget, and meeting the budget means that the components used need to literally fit the bill. Better quality and uprated parts can often be cost effectively installed when the amplifier is being serviced and if combined with bias upgrades can yield a significant improvement in performance and sound quality. As amplifiers vary so much between brands and even by build date, upgrades are quoted on a case by case basis once they have been inspected. Again you are under no obligation to proceed with any recommended work.

BIAS

We offer many upgrades, however the first is always setting the bias correctly, as this is one of the most important upgrades that can be made to an audio amplifier. Biasing is needed to ensure a smooth handover between the positive and the negative halves of the signal waveform. If this isn’t done correctly, then other modifications will make little improvement to the sound. Due to the time and skill needed to set this optimally, most amplifiers have the bias set too low, as this ensures reliability; unfortunately this is at the cost of sound quality. These pictures show the signal waveform and the distortion element contributed by the amplifier.

Unmodified

In this picture, we are testing an amplifier straight out of the box, that has a pretty good specification (on paper at least).

unmodified_amp

The analyser, however, shows a distinctly jagged distortion waveform caused by the bias being set too low. These sharp edges contain a lot of high order harmonics, which are not found naturally in the music so they appear discordant and unpleasant to our ears. They will be audible and will give a thin and edgy character to the sound, and low level detail such as ambiance will be muted.

Modified – Correctly Biased Amp

This picture shows the same amplifier with the same signal, but now with the bias set correctly .

correctly_biased_amp

Note how the sharp edges have gone from the distortion trace and how the distortion figure is now a third of what it was. More importantly, the small amount of distortion that remains is benign as it is made up of low order harmonics, which are naturally present in music. With the correctly set bias the amplifier will sound full, and much more natural and detailed.   Please feel free to contact us to discuss how we can improved the quality and performance of your equipment.