How to address unwanted distortions (english)

Some users may experience clipping and noise artefacts after updating. While some distortions are inherent to the simulation (and also to be found on a real Hammond organ, like AO28 triode distortions and power amp overdrive), sometimes an old parameter settings or a too aggressive tapering may lead to unwanted distortions. Here is a short manual to locate and defeat these, valid for HX3.5 as well as HX3.6 boards.

Locate Distortion/Noise Source

Locating the distortion source is crucial. There are several places where clipping may occur in the simulation, as internal audio processing is limited to 16 bit due to FPGA constraints:

• Busbar accumulators
• Matching transformer
• AO28 preamp
• Tube power amp
• Speaker crossover
• Speaker simulation

Finding the distortion source is handled from top to bottom. Play a handfull of notes known to be critical. Repeat your tests always with the same notes played. Set Rotary and Tube Amp (Tabs #1136/#1137) to Bypass and Volume Pots AO28 Tube Age #1089 to 0, so they won't affect your sound. If reducing a parameter mentioned does not reduce clipping, leave it where it was. Do not change parameters randomly, as this will limit the organ's dynamic range as well as (intended) tube amp overdrive.

Distortions still occur when Rotary and Tube Amp set to Bypass

This means that clipping occurs in the organ itself (first three points).

• Reduce AO28 Trim Cap Swell #1088.
• Reduce manual/pedal/percussion levels, parameters #1082 to #1085.

If reducing these does not help, a too aggressive tapering may lead to busbar accumulator overflow. Update the taperings to latest version or create new taperings with a lower scaling value (Defaults tab in HX3 Tapering Designer).

Distortions only occur when Rotary and Tube Amp are active

The purpose of a tube amp overdrive is to produce distortions, so we will miss out this point here. However, clipping may occur in the speaker crossover and rotary simulation. In this case, try the following:

• Reduce Rotary Inits, Input Level #2104.
• Reduce Rotary Inits, Horn Level #2105 and Rotor Level #2106, especially when clipping depends on speaker position.