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7. Application Tips
The Descratcher and the Denoiser are easy-to-use audio restoration tools based on extremely
efficient signal processing algorithms. In most cases you will automatically achieve good
results. To get the maximum, especially when working with heavily damaged audio material,
there are some practical rules:
1. Use a stereo record player if you restore old mono vinyl or shellac records and process
both channels individually before merging again to mono. This improves the signal-to-
noise ratio by at least 3dB (actually a factor of two) when compared to the descratching
procedure applied to pure mono files.
2. transfer recordings to be restored directly to .WAV file without using any processing device
like a limiter or compressor prior to the descratching procedure.
3. If the audio material to be restored contains very strong clicks, you may allow some
clipping while transferring to the digital domain. We recommend you make a few versions
recorded with different input gain and compare the results after the descratching process.
4. Do not exaggerate with the declick and decrackle parameters to avoid artefacts. When
working on heavily disturbed material, use a good acoustical compromise between the
level of remaining disturbances and artefacts introduced to the output signal. Be
indulgent if you have hopelessly damaged material; nobody can restore original data from
nothing.
5. Very strong changing noise level and noise characteristic may be problematic. In such
cases professional mastering engineers try to cut the original piece in parts and treat them
individually with different de-noising parameters. Later the denoised pieces are joined
together.
6. Do not exaggerate the parameters threshold and reduction to avoid artefacts in the form of
singing or robot-like sounds (time aliasing). Begin with a moderate adjustment by setting
the noise profile to just above the background noise level (approx. 10 dB) and gradually
increasing the reduction parameter. Finally try to recursively find the best relation between
these two parameters.
7. If you are working on heavily disturbed material, find a good acoustical compromise
between the level of remaining noise and artefacts introduced to the output signal. Be
indulgent if you have hopelessly noisy material. Nobody can restore the original signal
without having enough original information.
8. It helps sometimes to apply the denoising process two or more times consecutively with a
moderate parameter setting rather than one pass with an extreme setup.
9. A recommended tool that significantly helps to adjust the Denoiser parameters is the
Analyzer. It allows for following the denoising process, especially the influence of the
noise profile and parameters.
Algorithmix® Sound Laundry™ TerraTec Edition (English)
9
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