SLAM! stands for Stereo Limiter and Micpre and SLAM! is a pretty accurate description of what this beast will do (if you want it to) to most VU meters. Manley's design team put a switch in to drop its internal VU meters 3 & 6dB to keep the needles from bending. It will get your tracks LOUD and it will get them LOUD fast (hence that exclamation mark).
When it comes to classic audio gear, especially classic limiters, many engineers still go misty eyed at the thought of LA2s, 1176s, 2264s and others. Part of the design brief for the SLAM! team came from posing a question What if those sounds could be achieved in one stereo tube unit?
SLAM! is the aggregation of classic limiters like LA2s, 1176s, 2264s and others in one unit. Manley combined their favorite Electro-Optical circuit with a very fast FET based brick-wall limiter reminiscent of some of the old classics. They added a sidechain filter which can remove low frequencies, making it more useful for a variety of tasks, while retaining an easy, it just works quality that has made it a favorite for recording vocals in many studios. The FET-based limiter has different desirable characteristics that both optimise the signal for digital recording, due to the brick-wall capability, and let you dial in just how clean crunchy punchy loud and proud you want it.
The SLAM! Mastering Version offers a step beyond the original SLAM!, with no mic preamps, dedicated mode switches for the ELOP and FET limiters and additional ELOP limiting ratios and FET limiter modes. The ELOP® limiter has 5 ratios, which may put it into the compressor / limiter category. You'll find the lower ratios better suited to complex mixes. The FET limiter has 5 modes (50%, NORM, LP Lim, BOTH and CLIP). The output level knop is placed before the FET-Limiter so you can set the peak-stop threshold and adjust the incoming level.
All pots are replaced with rotary switches for detented resets and easier calibration. The unit has two bypass functiona. A true hard-wire bypass and a Limiter bypass with the tubes and transformers still active. There are dedicated unbalanced transformerless inputs and a switch on the back of the unit selects XLR or 1/4” jack inputs.
The SLAM! is designed primarily as an old school text book limiter and as such the Output Level knob is not after the final FET limiter. The idea is to More fun is to be had adjusting the Input and Output Level controls than the Thresholds, which can often just be thought of as set and forget especially if the FET Attack time tends to live in one setting. The Output level is not a gain make-up control typical of a compressor but consider it as another Input level before the FET and after the ELOP...