SLAM! stands for "Stereo Limiter And Micpre" and it pretty much describes what it will do to most VU meters. We had to put a switch on this limiter to drop its internal VU meters down 3 & 6dB to keep the poor little needles from bending– it'll get LOUD fast (hence the exclamation mark). And on top of being an amazing pair of (actually four) Limiters, and Class A tube mic preamps, it also has masters degrees in DI, AtoD and DtoA, VU and PPM but that was too much for an acronym.

When it comes to classic gear, especially classic limiters, we can all agree numbers like LA2s, 1176s, 2264s, and others come to mind. What if all those sounds were to be found in one stereo tube unit. Interested? We combined our favorite Electro-Optical circuit (ELOP®) with a damn fast FET based brick-wall limiter reminiscent of some cool classics. And we added a sidechain filter that can remove low frequencies that makes it more useful for a variety of tasks, while retaining that easy, "it just works" quality that has made it a favorite for vocals everywhere. The FET-based limiter has different desirable characteristics that both optimize the signal for digital recording, due to the brick-wall capability, and let you dial in how clean or crunchy, or punchy, and how loud and proud you want it.

DIFFERENCES

First off: no microphone preamps. You mastering engineers certainly don't need those. The mic pre and input select switch are removed and the switches become dedicated "mode" switches one each for the ELOP and the FET limiters.

1) The ELOP limiter gets more Ratios - 10:1, 5:1, 3:1, 2:1 and something new called AutoHF which starts off as a 1.5:1 ratio and increases gradually to 10:1 for highs. This is something like a de-esser, and of course can work with the ELOP SC toggle at 200Hz for even more effect.

2) The FET limiters get new modes that are 50%, NORM, LP Lim, BOTH, and CLIP. 

The "50%" setting mixes in the straight signal to the limited signal which is often difficult to do in a mastering environment and because the FET sidechain 'reads' off the output, the amount of gain reduction doubles. It resembles halving the FET ratio but is cleaner due to the mix.

The "LP Lim" setting only comes into play for hot signals and reduces the depth of gain reduction for high freqs. This translates to - hot signals + moderate gain reduction = brighter, more present signal, less distortion, more balls. This mode allows more high frequencies to pass through without being limited.

Finally, the "BOTH" setting on the FET limiter engages both the "LP Limit" and the "CLIP" functions at the same time. This might be appropriate for metal and projects demanding intense volume. The "BOTH" mode is designed for situations where extreme processing and loudness is required but where attack, brightness and aggressiveness needs to be preserved or enhanced.

3) The LEFT blue erstwhile-"limit" button becomes a master stereo LIMIT bypass switch here in the Mastering Version. When it is not engaged, it becomes a true hard-wire bypass (This was not possible on the mic preamp regular version obviously).

4) The Right blue button becomes the DAC select switch (stereo).

5) The what-was-the-Phantom toggle on the back of the unit becomes the Unbalanced 1/4" jack input select in this new mastering version.

More than that, we really like the way it works and sounds and we generally prefer it to the non-mastering version for stereo tracks. There is a lot less fiddling involved to maintain L/R balances and the new modes are subtle but fun. It is easy to make just about anything sound better.