Hughes & Kettner Red Box "Cabinetulator" guitar speaker direct box


Last Update 12-09-2017

The Hughes & Kettner Red Box is a direct box with filter circuitry designed to emulate the sound of a guitar speaker cabinet, hence its "Cabinetulator" moniker.  To date there were at least five different versions.  I used to own the Red Box MKII which I sold to the guitar player in a band I was in.  Later when I revived my recording hobby I also revived playing the guitar, so in the interest of avoiding the hassles of micing a speaker cabinet (and keeping the peace with the neighbors) I acquired a Red Box again, this time the "MK III" version.  The only difference is that it includes a switch to select between the emulation of a 4x12 cabinet or a combo cabinet.  I have no experience with the other versions.

The Red Box can accept line outputs or speaker outputs, but if you opt for the latter:
  1. If your guitar amp has a tube power stage, you MUST use a speaker or passive load in the THRU jack.  A tube power amp MUST have a load connected or you will damage your amp.
  2. You must make your connections BEFORE you turn the amp on.  Otherwise you will damage the Red Box and H&K assumes no responsibility for this user error.
The Red Box does a fine job of emulating the sound of a guitar speaker cabinet.  The 4x12 setting sure sounds like a Marshall cabinet, and the Combo setting does sound like an open back cabinet associated with combo amps.  The box can be powered from battery, from AC adapter, or phantom power if your console is equipped.  Going direct into a recording system offers the maximum flexibility for processing that isn't possible with a guitar rig.  My guitar amp has a line output; I briefly tried that into the "line in" of the Red Box.  It doesn't sound right because the line output of guitar amps take the signal before the power amp stage, which is where half the tone is developed.  This is where the "speaker in" is valuable, and you can insert the Red Box between the amp and the speaker cabinet (just be sure you heed warning #2 above!).

If you wish to play guitar without the crushing volume that introduces new neighbors (and law authorities), you can omit the speaker cabinet and run the balanced output into a mixer and practice with headphones (be cautious of headphone volume so you don't damage your ears).  However if your guitar amp has a tube power stage, it absolutely positively MUST have a load connected to it or you will damage the amp ($$$ output transformers will go POOF).  In place of the speaker, you need a passive resistor that equals the output impedance of the amplifier and has a power rating higher than the amp.  A power resistor is not a small component and since the terminals are exposed you must take precautions that they are never shorted or you will damage your amp.  These things get hot so keep them away from flammable materials (definitely DON'T leave it on carpeting).  Highly recommended that these be installed in a suitable box to isolate them (don't forget the vents so the heat can escape!).  Stay away from carbon power resistors as they are a fire hazard as they approach their maximum power rating.

At least four guitar player friends have tried my Red Box and they were happy enough with what they heard that they all acquired one of their own.  One of them said the Red Box gave him the best guitar tone he ever got on a recording.