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Technologies for Pure Sound


Audiophile Inventory have perfect sound as first priority of work.

Our audio technologies specially optimized for listening. What is it?



Human ear has audio range of perceptions 20 to 20 KHz. Many people have upper frequency boundary below 20 kHz.

We often witness the debate: do we hear above 20 kHz in HD record? But testing our hearing with sine oscillator show real value of high listening frequency.

Audio equipment bring in non-liear distortions for playing sound. Some harmonics appear in audio output of device.

Harmonics is sine oscillations with different levels and frequencies burned by input signal. No input signal - no harmonics.

Some harmonics (burned by non-audible frequencies above 20 kHz) appear into audible range. We listen it as whistle and/or noise.

AuI ConverteR 48x44 supress these whistle and noise.


Frequency filtration of audio signal uses into sample rate conversion algorithm. In digital audio used two types of filters:

- linear phase filter;

- minimal phase filter.

Linear phase filter generate unwanted oscillations (ringing) at output (output file of sample rate converter) before passing of input signal to output.

Other words we listen noise (burned by input signal) before we listen the signal.

Linear phase filter has equal passing time delays for different frequencies. It is suitable for listening drums, guitars and other instruments.

Minimal phase filter don't generate unwanted pre-oscillations. But minimal phase filter has non-linear phase responce.


Comparing linear and minimum phase SRC filters

No Pre-Ringing (minimal phase filter) vs. Traditional Pre-Ringing (linear phase) filter

Click picture for enlarge

For minimal phase filter Audiophile Invetory picks phase responces by criterion of listening quality (minimization of audible distortions).

According to some experts minimal phase filter has more natural sound than linear phase filter.



Below described features of digital signal processing technologies

      used into audio converter AuI ConverteR 48x44.


AlphaC Technology

Sampling rate and bit-depth conversion technology.


1) Extremal minimisation of artefacts.

2) Linear phase conversion

3) No Pre-Ringing conversion (minimum phase filter without output artefacts preceding begining of sound)

4) Supressing ultrasound intermodulations for HD records (read more about reasons ultrasound intermodulations...)

5) Simple user control (minimum settings). Already all settings tuned for perfect sound.

6) 64-bit (double precision float) mathematic calculations.




AlphaD technology

Advanced dithering technology based for suppressing non-linear distortions of quantisation errors (signal level errors) due bit-depth conversion.


1) Pure sounding for Hi-Res (24-bit and more) from 16-bit conversion

2) Pure sounding for 16-bit from Hi-Res (24-bit and more) conversion

3) User control dithering depth for minimizing of noise level.

4) 64-bit (double precision float) mathematic calculations.



Last News

Where is the Limit of Audio Quality?

I read many endless discussions about audio equipment: cables, lossless vs. lossy, compression algorithms, jitter, ultrasound, playback files from different places of hard disk, power conditioners, etc.

I suppose, reason of the discussions is small perceived sound difference, that is not obvious for everybody, or no difference.

It is the end of high-end?

Below I want to discuss: can we get sound improvement, obvious for almost everyone, in future audio equipment?

New AuI ConverteR 48x44 v.6.4.7. ISO's Album Catalog Number

Released new studio audio converter AuI ConverteR 48x44 v. 6.4.7 CD ripper, ISO, DFF, DSF, WAV, FLAC, AIFF, ALAC. Album catalog number is extracted from ISO and stored into metadata of converted files.

How to Convert with Downmix 5.1 to stereo


Music stuff conversion with downmix 5.1 to stereo used to playback multichannel audio files at stereo systems.

At portable audio players and mobile phones stereo headphones are used to music listening. Conversion 5.1 records to stereo allow to reduce music file size to place at limited space of disk drive of portable audio player or other device.


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