KHE Audio | ACS 4x2 MK-II

4x2 Switching System for Guitar Amplifiers, Speaker Cabinets and Load Boxes
with Attenuator Insert Loop, Dual-Cab Mode, MIDI Control, Link Mode and Rack Mounting Brackets

>>> USER MANUAL (pdf) <<<

UPDATES MK-II VERSION

• Including Rack Mounting Brackets

• Added the Attenuator Insert Loop

• Added the Linking Functionality

• Improved Safety Functions & Features

The KHE ACS is the most advanced guitar amp switcher on the market:

FEATURES ACS 4x2 MK-II

• Amp and Cab Switching – Switch between 4 amps and 2 cabs or load boxes at the push of a button. One amp active at the time, with up to two speaker cabs or loads. No need to put your tube amps into standby or stop playing! Share pedals like Boosts, Overdrives, Distortion and and such in front of all amps

• Attenuator Insert Loop - Share s single attenuator with all amps and cabs. The attenuator loop must be activated in the ACS System Menu (more info here)

• Dual-Cab Mode - Activate and play two speaker cabinets or load boxes in parallel at the same time (more info here)

• Midi Remote Control - Remotely control your amp collection by a MIDI Footswitch or controller (see some examples here)

• Front & Rear Guitar Input, Tuner Output, Ground Lift

• Compatibility: Works with tube & solid-state amps, speaker cabinets & load boxes, heads & combos

ACS SAFETY FEATURES

• No Load active? No Amp! The digital logic ensures that no amp can be activated unless a load is activated. Invalid combinations are impossible, making operation “foolproof” and protecting against user errors.

• Cabinet Detection: Speaker cabinet outputs are constantly supervised. Unused cab jacks are automatically excluded and locked from switching, so amps can never be connected to an inactive cabinet.

• Input Muting: Unused amps are muted at the input, ensuring no signal can reach the power amp accidentally.

• Dummy Load Resistors: All unused amps are connected to dummy load resistors to prevent from a no-load scenario. The dummy resistors are universal type and work with all 4/8/16 Ω amps.

• NEW: Dummy Resistor Supervision & Acoustic Alarm Buzzer: The ACS continuously monitors the internal dummy load resistors for overload conditions, which can result from incorrect use, cable faults or mix-ups, or amplifier malfunctions. If an overload is detected, the ACS enters an error state and activates a loud piezo buzzer to alert the user and shows the affected amp by a blinking amp light. Power-off the amps immediately and check the wiring / setup. More info about it in the “Safety Warnings” Section of this user manual.

• Voltage & System Monitoring: The ACS continuously monitors the DC input voltage. If the voltage goes out of range, the ACS enters a safe error state and blinks the CTRL light orange. Relay driver chips and hardware are continuously supervised too to prevent latch-up. In case of any fault, the relay power supply is safely cut off.

ACS HIGHLIGHTS

• Safe Amp Switching: The ACS provides safe and reliable amp/cab switching. It automatically manages the correct order for amp and cabinet activation, allowing instant switching with a single push—no need to deactivate other amps first or worry about the switching order. The ACS supervises all operations, applying a clever switching logic to prevent unsafe operation. See all ACS safety features and functions below.

• No Sound Coloration: The ACS is as transparent and true to the sound as it gets. No signal-loss, no change in dynamics or tone, no coloration or added noise.

• No Ground Loops or Hum: The KHE ACS is a fully isolated design. It does not tie all the amp grounds together, like some other amp switchers do. Everything is nicely isolated, without any ground loops or hum.

• Relay Signal Switching: All signal switching is performed via high-quality relays, digitally controlled by a microcontroller (the toggle switches don’t switch any audio signals). A relay matrix switches between amplifiers and load devices up to 150 W RMS.

• Silent Switching: A special soft-mute circuit removes any clicks and pops during the switching. Switching between amps or loads is quieter than most amp channel changes, and the signal path remains completely transparent without added noise or coloration.

• Full MIDI Control: The ACS can be safely controlled by any MIDI footswitch or Stream Deck.

• High-Quality Construction: Built in Switzerland, the ACS uses premium components: 2mm PCB with NEUTRIK jacks, OMRON relays, high-quality toggle switches, all housed in a robust 19" 1u rack enclosure made of steel.

• Made in Switzerland, built by Markus @ KHE Audio: All KHE products are built like a tank and are tested for 24 hours. Get world-class customer support directly from Markus, the designer of the ACS and CEO of KHE Audio (it’s just a one-man operation). Thank you for supporting my small business and for trusting my switchers. Email me at info@khe-audioelectronics.com

PRODUCT PHOTOS

High-resolution images will be added soon.

CONNECTION DIAGRAMS

SPECIFICATIONS ACS 4x2

Model: KHE ACS 4x2 MK-II
Type: Guitar Amplifier / Speaker Cab Selector (programmable Relay Switcher)
Amp Switching: 4x (mono, one amp active at the time)
Cab / Load Switching: 2x (two cabs can be active at the time)
Dummy Load Resistors: YES
Dual-Cab Mode: YES (must be activated in the system menu)
Attenuator Insert Loop: YES (must be activated in the system menu)
Linking / MIDI / Tuner: YES
Ground Lift: YES

Weight: 2.0kg (Steel Enclosure)
Dimensions: 24cm x 20cm x 5cm
Rack Mounting: Including mounting brackets for rack mounting
DC Power: +15V DC, 15W max.
Power Supply: Included, works world-wide (90-240V 50/60Hz), 3-pin AC mains connector. Only use the original KHE power adapter.

Switching Element: Relays, digitally controlled by MCU with advanced safety functions
Guitar Input Impedance: 2.2MOhm
Guitar Output Impedance: < 1kOhm
Guitar Input Type: active buffered
Amp / Load Impedance: universal, 1:1 pass-thru
Maximum Amp Power: 150W RMS
Frequency Range: 20Hz-100kHz +/- 0.1dB
Switching Time: 2 - 15mS

Warranty: 5 Years
Made In: Switzerland by KHE Audio Electronics

IMPORTANT NOTES

• No amp can be activated if no load is activated!

• No stereo amp switching - mono only!

• No bi-amping - only one amp active at the time!

• No cables included (instrument, speaker or midi)

• No built-in load box for silent recording (external load required)

• No remote foot controller included

SHIPPING & DELIVERY

• Payment: Credit Card or PayPal in CHF (Swiss Francs). For Bank Transfer (IBAN), send us a message.

• Stock units are usually shipped within one working day

• Shipping from Switzerland (non-EU)

• Price excluding VAT. Import charges may apply for the customer on import.

• Worldwide shipping (check the shipping costs during checkout)

• Shipping Delivery Time: USA 2-5 days, EU 5-8 days (UPS Express or UPS Standard)

• The shipment is fully covered by insurance. If it's lost or damaged, you'll get a new switcher!

Any questions about the switcher? Not sure which switcher to choose? Send us a message if you have any questions!

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