AB_LM (AB Loudness Match)
AB_LM is a gain control which enables level matched and sample accurate AB comparison of FX chains.
We at TBProAudio found us very often in mixing or mastering situations where we need to quickly identify the contribution of a certain plugin (FX) or even a complex FX chain to the sound.
Most DAWs can easily enable/disable (AB) single plug-in or even whole FX chains, but in most case there is an audible loudness difference between both cases. In order to compare the impact of a plugin chain objectively the loudness of the incoming signal should match with the loudness of outgoing signal.
Comparing the plugin effect at equal loudness levels avoids the "louder is better" - pitfall.
Mode & Link Channel
Sets the mode of the plugin, either Sender or Receiver and the link channel for the communication. Sender is placed before the plugin(s) which should be AB level matched, Receiver is inserted after. Use the "L"-button (auto) to quickly set next highest (free) sender/receiver channel. In addition AB_LM makes suggestions for channel auto link, which may work depending on DAW/plug-in type.
Some plug-in add latency to the plugin chain. For a sample-exact AB loudness comparison audio streams need to be synchronized. This can be done automatically (just press PDC button and wait 1-2 seconds) or manually by entering the latency value (in samples).
This meter shows the current and maximum loudness of the audio stream just before the plugin(s). Many plug-in work best at a certain loudness level (e.g. -18 dBFS)
This meter shows the loudness difference of pre and post-FX signal. The match button lets you set the additional post-FX gain (match mode "manual") based on current loudness difference. Match mode "Auto" does this automatically.
AB-LM lets you match the loudness either manually, or automatically. The match gain is added after FX chain. If "inverse" is enabled match gain is added before FX chain. The mode "Gain Stage" works differently: The additional FX drive gain is just removed from the audio stream right after the FX chain for "pure" gain staging purposes.
AB_LM provides 4 snapshot slots to store and recall settings for FX drive and Post-FX gain. So you can test your plugin chain with different gain levels, all loudness matched.
This parameter adjusts the additional pre-FX gain.
This button lets you seamless switch between pre and pre-FX audio signal.
This meter shows how close the loudness of the incoming signal is matched with a certain reference level. Many engineers work with loudness calibrated audio systems.
- match pre and post-FX loudness
- match pre-FX loudness with reference level
- 3 loudness match modes: manual, auto and gain stage
- FX chain drive
- up to 256 sender/receiver pairs including auto channel select
- automatic latency measurement/compensation
- 5 measurement modes: RMS Sum, RMS Avg, EBU R 128 SL, EBU R 128 ML, VU
- adjustable RMS measurement window
- bypass AB_LM
- 4 snapshot slots
- very CPU friendly
- large and easy to use GUI
Demo version versus Registered version
In demo mode (without registering) the plugin mutes audio every 90 seconds for a short period. This could be circumvented by clicking on the "AB_LM" logo within 90 seconds.
Please download AB_LM here.
- Windows XP or newer
- Mac OS X 10.5 or newer
- Win: 32/64 Bit VST, 32/64 Bit VST3, 32 Bit RTAS, 32/64 Bit AAX
- OS X: 32/64 Bit VST, 32/64 Bit VST3, 32/64 Bit AU, 32 Bit RTAS, 32/64 Bit AAX
- Tested with: Cockos Reaper, Steinberg Cubase/Nuendo/Wavelab 6/7/8, FL Studio 12.x, PT10/12
Please order AB_LM registration key here.
ReferencesTop Mix Tip: Using Reference Tracks - Warren Huart: Produce Like A Pro
- GainStaging: remove PreGain during AB off
- DSP code optimizations
- Gain staging fix: add. PreFXGain compensated
- VU Metering
Fixed PDC bug
Small bug fixes for issues which could cause incorrect measurement after a while
RMS modes changed: RMS->RMS sum, RMS+3->RMS avg
Fixed Pre FX max readout
EBU filter denormal fix
Auto link channel:
works optimal in pairs
new plug in instance: even instance_count => sender, odd instance_count => receiver, next free channel is chosen (does not work for AAX/RTAS)
copy track with linked pairs: sender/receiver pair is re-linked (does not work for AU and AAX/RTAS)
copy plug in: next free channel is chosen
(Attention: Please remove all instances of AB_LM before installing V1.3.0 (incompatible parameter set))
Added auto channel select
Link channels extended to 256
RMS/EBU measurement bug fixed
(Attention: Please remove all instances of AB_LM before installing V1.2.0 (incompatible parameter set))
Adds Measurement Modes EBUR128 ML (400ms) and EBUR128 SL (3000ms)
Small GUI fixes
Inverse gain match switch
Link channels extended to 32
Fixed crackle in auto gain mode during startup
Demo "Stutter" fix