K4 - 300w, 12 inch / 2x4.5 inch / 2x2.5 inchThe K4 is an advanced, extremely versatile stereo keyboard amplifier that delivers a wide spectrum of tones. More importantly, it has the ability to sound right with a minimum amount of tweaking.
The K4 consists of three separate, built-in amplifiers, for true stereo operation with a mono-summed woofer. A 200-watt Low Frequency amplifier drives a 12-inch, 200-watt woofer, while a pair of 50 watt amps drive the left and right channels, delivering the mid and high frequencies through a set of 4.5-inch, 30-watt midrange drivers and a pair of 20-watt 2.5-inch compression drivers with horns.
One unique feature of the K4 is how Channel 1 utilizes a pair of 12AX7 tubes, one for each channel, left and right. These preamp tubes supply warmth and smooth out the harsh harmonic overtones often associated with many modern Digital keyboards. It also excels at maintaining the warmth and character of vintage synthesizers and organs where it isn't always practical to use the much larger powered speaker cabinets they are typically associated with.
There is also a select switch to toggle between using either the tube or a Solid-State signal path, bypassing the tube on the input altogether, for those times when the cleanest signal path possible is preferred. Channel one also features a foot switchable Tube Overdrive control, for those who like to add a small amount of grit to their playing. Depending on the level, a small amount of warmth right up to full grit can be had from the Tube Overdrive. Natural tube compression is a very desired tone as the subtle dynamics can't be properly emulated by most of today's digital workstations. Use this feature to add some grit to an otherwise sterile keyboard tone to make it a truly vintage, tube-based one. A single button latching footswitch, like our AFS-1 can be used to engage the Lead/Overdrive feature. If a footswitch is connected, it will disable the front panel switch. Additional tonal control can be had thanks to the three band EQ and 5 position (Bypass, Studio, Live, Piano, Organ) selectable voicing presets.
Like Channel One, Channel Two also features its' own Gain control as well as a 3 band EQ. Available inputs include a stereo pair of balanced 1/4-inch TRS inputs and a single XLR, for mono only operation.
Channel Three utilizes an independent Gain control to set the levels for the stereo pair of balanced 1/4-inch TRS inputs and stereo pair of RCA inputs. All three channels feature their own input clip LED's for simple monitoring of input levels from the darkest of stages and a single Master Volume and Power Switch let you be heard when you want to.
Channel 4 inputs and Gain control can be found on the rear panel. The possibilities are endless with it. Use it to bring in an external click track or drum monitor mix, or get a microphone feed from the FOH or monitor console. The two inputs can even be used for monitoring two different sources if desired. The signal goes directly into the power amplifier, so it bypasses the Master Volume and Line Outs entirely.
A Master Volume control is located on the front panel along with the Power switch and LED.
Front panel controls for Channel 1 include:
- Two parallel pairs of balanced 1/4-inch TRS inputs for mono or stereo operation
- Gain, Bass, Mid, Treble controls with a boost/cut of 15db
- A five position voicing selector (Bypass, Studio, Live, Piano, Organ)
- Tube/Solid State input switch
- Lead Level control
- Overdrive Trim control
- Lead Bypass switch
- Input clip LED
Front panel controls for Channel 2 include:
- Parallel pair of balanced XLR (mono only) and stereo balanced 1/4-inch TRS inputs for mono or stereo operation
- Gain, Bass, Mid, Treble controls
- Input clip LED
Front panel controls for Channel 3 include:
- Gain control
- Parallel pair of unbalanced RCA and stereo balanced 1/4-inch TRS inputs for mono or stereo operation
- Input clip LED
Channel 4 Monitor
Channel 4 has been added as an extra channel for monitoring purposes, the signal does not mix in with the Main stereo bus and thus the Line Out is not affected by it. The input has it own level control. The left and right inputs can even be used as two separate monitoring sources and the signal goes directly into the amplifiers, bypassing the master volume entirely.
Rear panel controls for Channel 4 include:
- Gain control
- Stereo balanced 1/4-inch TRS inputs for mono or stereo operation
Subwoofer out is provided via a TRS 1/4-inch jack. This mono signal features no filtering, so it can be used to feed a powered sub, remote powered speakers or any other device requiring a mono-summed Full range signal.
Balanced Stereo XLR Line Outs
These are used to connect directly to a mixing console, or for direct recording. The Line Out jacks are Pre-Master control, turning the Master control up or down will not have any affect on the level of the Line Out jacks.
The ground lift switch is located beside the XLR jacks. It lifts the balanced Line out ground (Pin 1) when pushed in.
When used in conjunction with any single button latching footswitch, like our AFS-1, the Tube Overdrive mode can be activated or deactivated remotely at will.
Two 3-inch fans cool the K4, The fans, normally operate at a low speed, the speed increases depending on how hard the amplifier is working. The air intake vent is located at the top of the cabinet and the exhaust vents are located at the front and back of amplifier.
Caution: The top vent must be kept clear in order for the air to enter into the amplifiers. The rear and front vents are used to allow the warm air out of the unit.
Head Phone Jack
A 1/4-inch headphone jack is provided on the rear panel as well. When the jack is used, it mutes the signal that comes out of the amplifier, with the exception of the monitor channel 4.