How To Do a Sample-Accurate Test To Compare the Relab LX480 To The Lexicon 480L
The LX480 Dual-Engine Reverb is the only plug-in available that is a truly faithful re-creation of the original with full dual-engine capability and added modern functionality to bring this classic reverb into the 21st century.
The LX480 not only sets a new standard for quality and accuracy in plugin-based hardware re-creations. We believe this is the most accurate and versatile emulation ever created of this legendary reverb.
And in this article, we're going to show you how to properly do a sample-accurate test to compare the LX480 with its closest hardware counterpart, the Lexicon 480L.
Performing The Relab LX480 and the Lexicon 480L Comparison Test
To ensure that you are getting a sample-accurate recreation of the original sound, it is important to follow the proper steps in the testing process.
With this article, we'll walk you through how to do a sample-accurate test to compare the Relab LX480 to the Lexicon 480L. By following these steps, you can be sure that you are getting an accurate comparison of these two units.
The first step in doing a sample-accurate test is to ensure that the firmware for your Lexicon Hardware is the final version (v4. 10)
On the LX480 plug-in, double check that the emulation settings in the config tab are all turned on (18-bit, Saturation, RH bug, Mod Truncation)
Next, ensure that each unit is set to digital in and out (I/O). You’ll need the Lexicon LF10 Digital Audio Format Converter or the AES I/O daughter board, as the initial release of the 480L did not have a digital out. Using the analog in/outs is a source of potential errors, because it requires the use of AD/DA converters, plus any other possibilities of further coloration (like a console etc). Plus in analog, it is incredibly difficult to accurately set the input and output levels using the potentiometers behind the front panel (you have to open the front panel to get access to the analog potentiometers), not to mention the tolerance of the analog pots. They would have to be set to the exact same spot as our hardware was set. So for the most accurate test - it must be digital to digital.
Once both the 480L and the LX480 are set to digital in and out, make sure that it is connected to your interface and verify the signal is being sent to and returned from the hardware correctly. Also make sure that your dual-engine configuration is set to single engine mode. Often many users of the original hardware would default to split-mono mode.
Next, you need to choose the exact same original factory preset that uses an algorithm that is free of any modulation or randomization. A good choice for this would be a preset using the Hall or Plate/Room algorithm.
You also need to set the DCO parameter to 0. The DCO parameter in the original hardware uses a buffer to calculate the envelope of the sound, so there is no guarantee that the buffer is filled at exactly the same time between the hardware and software. This can potentially cause a mismatch of values between the hardware and the software - at a setting of 0, this buffer is not used.
Create two stereo aux tracks in your DAW of choice.
Next, you will want to insert the LX480 on one track and the 480L on the other track.
Make sure that both the hardware and the DAW are running at the same sample rates. We recommend setting both to a sample rate of 48kHz.
Once both the hardware and plug-in are set up properly in your DAW, you can begin playing back audio through them, make sure that the same signal and level is sent to both. Impulses are a great choice of test signal and are easily time aligned. You may also want to experiment with using source material that contains a wide range of frequencies and levels. (We’ve included the impulse we used for our test below)
Look at the rendered Waveforms and make sure that they are time aligned to account for any potential latency.
Use a spectrum analyzer or similar tool in your DAW to compare the output of the two units and look for any differences in frequency response. Or you can zoom in on the waveforms to see accuracy in the reverb tail decay or time domain.
Additionally, with all modulation and noise turned off, once they are time aligned, you can also perform a null test.
Below are some pictures of this same testing procedure being done by our QA team. As you can see the output is identical both in the frequency domain (top image) and the time domain (bottom image). This is for the preset Medium Hall
Getting accurate results when comparing the Relab LX480 to the Lexicon 480L is easy, as long as you follow these simple steps.
So go ahead and give it a try for yourself. Happy testing!
Comparison Test Impulse File For Your Convenience
Here's the impulse we use for the above test in case you needed it.