NP1136 Peak Limiter In the form of an open source plugin for the JesuSonic platform:

plugin download: http://forum.cockos.com/showthread.php?t=27764

Summary: The NP1136 is DSP plugin designed to mimic some of the functionality of modern hardware sound sculpting tools such as the UREI 1176LN and the Elysia mpressor. The plugin is provided in the open source form of a JesuSonic code and released under the GNU General Public License.

author:

Lubomir I. Ivanov /Technical University of Varna/

website: email:

http://neolit123.blogspot.com [email protected]

NP1136 Documentation - Page 1

Explained The NP1136 uses a variety of features to extend the possibilities of signal manipulation in the digital domain. It can be categorized as a peak limiter, compressor and also as a tone corrector. Adjustable compressor threshold The compressor threshold goes from 0dB to -40dB. Adjustable ratio Ratio values are from 1:1 to 20:1. Adjustable attack The attack of the compressor can be set either very fast - 3µs or slower - up to 150ms. Adjustable release The compressor release can be set within these boundaries: 20ms - 1500ms. Program dependant mode (PD Mode) / "British Mode" When the compression ratio is set to 20:1 the compressor enters PD mode, where the attack, release and ratio change depending of the detector signal material. For sharper transients in the signal the attack and release increase and for duller dynamics the values decrease. The ratio on the other hand, decrease for the transients and increase for the post transients, while remaining in these ranges 12:1 - 20:1. Due to these dynamic changes in attack, release and ratio, the total harmonic distortion (THD) will increase in PD mode, this will also add a certain overdrive tone and also "pump" to the processed signal. When the PD mode is on, a letter [B] will light up on the interface. Detector stage High-Pass filter The compressor envelopes can be calculated from a detector signal which is first processed trough a highpass filter. The high-pass filter is engaged only when set to values above 20Hz. A 12dB per octave Butterworth filter is used here to ensure minimal ripple at the cutoff frequency. The control can be used to minimize the gain reduction from lower frequency transients. This can produce additional pumping effects. Range is 20Hz .20kHz. Gain Reduction Limiter (GR Limit) A GR limiter can be engaged so that the gain reduction is hard-limited to a certain value. GR Limit control is only activated when the control is set to values above -40dB. This can be used to decrease the amount of unwanted pumping for certain types of input material. Tilt EQ (Niveau Filter): The NP1136 also provides a tonal control in the form of a Tilt EQ roughly modeled after the "Niveau" Filter. It has only two controls: Boost/Cut and a center frequency. While boosting or cutting volume with a shelving filter above the center frequency, it does the opposite with the range below the center frequency. This can produce very quick changes on the spectrum. Positive values give high-shelf boost / low-shelf cut and negative values give low-shelf boost / high-shelf cut. Range is 20Hz - 20kHz, -6dB : +6dB. Parallel Processing The "Mix" control mixes the output of the unit (wet) with the input signal (dry). Range for "wet" is 0% - 100%. Mono or Stereo processing Mono will drastically reduce CPU usage. Compressor Linked Stereo Mode (Detector Mode) With mode detector signal, the unit utilizes less CPU power as it only calculates one envelope. Hard clipper On the output stage of the unit there is a "Hard clip" switch that limits the output to -0.02 dBFS.

NP1136 Documentation - Page 2

Sidechaining Sidechaining is possible when engaged from the "Detector Input" control. Uses channels 2-3. Indication: Gain Reduction meter An accurate GR meter that shows gain reduction values down to -18dB. The meter attack/release is linked to the compressor settings. Indication: Gain Reduction limiter When the GR limiter is set above -18dB a small block will be positioned over the GR meter. Indication: Detector HP frequency - DHP The frequency of the HP filter is shown in the lower left corner of the interface. Units are hertz. Indication: Tilt filter frequency - TLT The center frequency of the Tilt filter is shown in the lower right corner of the interface. Units are hertz. Indication: "British" mode When the "British" mode is activated a brown letter "B" will light up. Indication: Attack time - A Attack time is shown on the interface as A: time, where units are microseconds Indication: Release time - R Release time is shown on the interface as R: time, where units are milliseconds.

Signal flow chart Input L

Mixer

C6

Output L

Clipper C8

Input R

Mixer

SC L SC R

G

C7

C5

DHP C2

C3

PD mode algorithm

Envelope

copy

Output R

CV

Tilt Filter

Output stage

GRL C8

C1

C1

average

CV

DHP discard

Clipper

G

average

C7

C6

C2

C3

PD mode algorithm

Envelope

GRL

copy

discard

C5

Tilt Filter

GR stage Detector section

Tone correction stage

Conditions and markings: C1 - Detector Mono / Stereo C2 - Detector High-pass enabled C3 - Program dependant mode enabled C5 - Tilt filter enabled C6 - Hard clipper enabled C7 - Sidechain enabled C8 - Input Signal Mono / Stereo GRL - Control voltage L / R trough GR limiter G - Makeup gain

NP1136 Documentation - Page 3

Program dependent mode

Ratio Attack Release

Parameter beheviour in PD mode

Note: Chart values are nominal

In PD mode, the attack, release and ratio become linked to the amplitude of the detector signal. Initially the attack and release are decreased from their maximum values, then for transient their values quickly rise. The opposite happens for the ratio - at transients the ratio gets a decrease from the initial 20:1 value, then at posttransiens it quickly rises back to 20:1. Minimum ratio value is 12:1. All three parameters are interpolated in realtime, so that the distortion from the curves is reduced to minimum, still a subtle overdrive tone is acheived. Also all parameters are limited so that no unwanted values are assigned.

"Tilt" filter - Low Boost

0dB to -6dB of "Low Boost" at 639Hz. The top end turns to minimum at -6dB (low-pass filter).

NP1136 Documentation - Page 4

"Tilt" filter - High Boost

0dB to +6dB of "High Boost" at 639Hz. The bottom end turns to minimum at +6dB (high-pass filter).

Examples NY compression Set slow attack, fast release time, low threshold and high ratio. Set mix amount to 10-20%. Fat drums Set fast attack, medium release, ratio to 8:1, lower the threshold to get 6-9dB of gain reduction. Drums snap Set medium attack, fast release, ratio to 4:1, lower the threshold to get 6-9dB of compression. Sidechain compression Enabled sidechain from the Detector input. Input desired signal to compressor at channel 2-3 (instead of 0-1) For example if you wish to sidechain a mix buss with the kick drum, route the kick drum to channels 2-3 of the compressor. This way every time the kick is triggered gain reduction will be applied to the whole mix buss. Heavy compression Fast attack and release settings, high ratio, low threshold. Apply a lot of makeup gain. Fat dynamics Set the ratio to 20:1 (PD mode). Set fast attack, medium release. Other settings to taste. Tone compression Fast attack and release settings, medium ratio values, lower the threshold. Set the Tilt filter to extreme settings for example +6dB for high tone. Apply makeup gain and lower the mix amount to taste. Compressed snare To compress only the snare in a drum track. Set the detector high-pass to 200Hz, set fast attack, medium release, ratio to 4:1, lower the threshold.

NP1136 Documentation - Page 5

TERMS OF USE: NO WARRANTY IS GRANTED. THIS PLUG-IN IS PROVIDED ON AN "AS IS" BASIS, WITHOUT WARRANTY OF ANY KIND. NO LIABILITY IS GRANTED, INCLUDING, BUT NOT LIMITED TO, ANY DIRECT OR INDIRECT, SPECIAL, INCIDENTAL OR CONSEQUENTIAL DAMAGE ARISING OUT OF THE USE OR INABILITY TO USE THIS PLUG-IN, COMPUTER FAILTURE OF MALFUNCTION INCLUDED. THE USE OF THE SOURCE CODE, EITHER PARTIALLY OR IN TOTAL, IS ONLY GRANTED, IF USED IN THE SENSE OF THE AUTHOR'S INTENTION, AND USED WITH ACKNOWLEDGEMENT OF THE AUTHOR. FURTHERMORE IS THIS PLUG-IN A THIRD PARTY CONTRIBUTION, EVEN IF INCLUDED IN REAPER(TM), COCKOS INCORPORATED OR ITS AFFILIATES HAVE NOTHING TO DO WITH IT. LAST BUT NOT LEAST, BY USING THIS PLUG-IN YOU RELINQUISH YOUR CLAIM TO SUE IT'S AUTHOR, AS WELL AS THE CLAIM TO ENTRUST SOMEBODY ELSE WITH DOING SO. Released under GPL: .

All brand and model names are trademarks of their respective owners.

NP1136 Documentation - Page 6