Pro-EQ
linuxDSP has a proven reputation for producing high quality plugins in LV2, linuxVST and JACK formats for linux audio workstations such as Ardour. The Pro series plugins continue the development of this DSP technology, inspired by classic analogue designs.
Our DSP development benefits from many years of experience from design engineers who have worked for some of the worlds top pro-audio companies such as SSL, and also from feedback provided by professional recording engineers.
Are all EQs created equal?
All EQs have their own 'sound' and this is just as true in the digital domain as it is in the classic analogue designs. The sound of an EQ is a complex mixture of the parameter ranges and the filter technologies employed in the design. The linuxDSP Pro-EQ takes professional quality processing, and combines it with analogue design experience to produce a very musical sounding EQ that enhances the channel processing in any Digital Audio Workstation.
Efficient CPU usage
Efficient CPU usage (and almost zero CPU load when bypassed) means that the EQ can be a standard addition to each channel's processing in a DAW.
Interpolated Controls
Control interpolation is an important aspect of the filter design which is often overlooked. Parameter changes initiated either by the user via the GUI, or by the host DAW via automation, need to be smoothed in order to prevent abrupt changes in the filter parameters which could cause noise, thumps, clicks or pops. The linuxDSP Pro-EQ uses a two stage interpolation process to accomplish this, which allows accurate coefficient generation for the filters, without the need to resort to CPU intensive calculations.
Soft Bypass Switching
Just as it is important in analogue designs to ensure that switching the EQ in or out of the signal path does not cause any clicks or thumps in the audio, the same is true in digital processing. The linuxDSP Pro-EQ combines almost zero CPU load when the EQ is bypassed with smooth switching between the bypassed and processed signal paths.
Denormal Processing
In an EQ which uses floating point processing throughout, as is the case with the Pro-EQ, it is necessary to ensure that so-called 'Denormal' numbers are efficiently processed. 'Denormal' numbers are typically very small floating point values which fall outside the range of 'normal numbers' that can be represented in standard floating point form within the CPU. Therefore it is necessary for the CPU to switch to a different method of processing in order to handle them, and this can require more processing cycles. If Denormal numbers are not handled correctly by the DSP algorithms in a plugin (especially in recursive processes such as used in some filters), this can rapidly result in excessively high CPU usage, typically manifesting itself during periods of audio silence.
Technical Specification
| Internal Processing Resolution: | 32Bit Floating Point. | |
| Frequency Response (Hz): | 0 to Fs/2 - EQ bypassed or set flat - where Fs is the sample rate. | |
| Filter Types: | High and Low shelving + swept mid-range parametric. | |
| Filter Boost / Cut: | Up to 20dB, all bands. | |
| Filter Frequencies: | LF Shelf: | 100 - 200Hz |
| HF Shelf: | 4KHz - 8KHz | |
| Mid: | 200Hz - 4KHz | |
| Filter Bandwidth: | Mid: | 0.5 - 2.0 Octaves. |
Download
Visit the download page to download the Pro-EQ, together with the Pro-Dynamics and Gate plugins. The plugins will run in demo mode, allowing free evaluation with your linux distribution / host DAW application, and come with a comprehensive manual and installation instructions.