KHE + Fryette Power Station

This guide explains to how to use the Fryette Power Station (PS-2A, PS-100) in combination with the KHE Amp / Cab Switcher. Make sure to read this guide and all product manuals in great detail before hooking things up. If incorrectly connected or used, the equipment may be damaged. Better be safe than sorry!

Table Of Contents:

• Overview

• Wiring & Setup

• Basic KHE + PS Operation

• Safety Notes

• Power Station FX-Loop Operation

• Using the PS FX-Loop in 4-CM

• Using the Power Station as a Power Amp (Fryette Cyclops, external preamps)

• Troubleshooting & FAQ

Overview

The Fryette PS is an active-type attenuator: Instead of using a simple passive attenuation pad like most traditional attenuators, the PS uses a reactive load box in combination with a tube power amp (mono). Between the load box section and the power amp section, it has a line-level fx-loop, which enables to use effect pedals post-amp, even if the amp doesn't have a real fx-loop.

The Power Station is best connected to the ACS Attenuator Insert Loop. All functions of the PS can be used as normal with the ACS amp switcher:

• Use the PS as a global power attenuator with all amps and speaker cabs (or power booster).

• Use the PS fx-loop to share effect pedals like Delay, Reverb, EQ with all amps (post-amp loop).

• Use it as a load box in for silent recording.

• Use it as a power amp for preamps and modelers.

• Use the line out with an audio interface for recording and IR processing, or as a dry amp-line-out for a w/d/w setup.

The KHE and the Power Station are a perfect match (we love our PS-2A)!

Wiring & Setup

The Power Station is best connected to the ACS Attenuator Insert Loop. This is a serial insert point between the amp outputs and the speaker cabs. By default, the KHE’s Attenuator Insert Loop is deactivated. If not activated, the attenuator won’t work correctly.

Important: Before connecting the PS to the KHE, make sure the KHE and all amps and cabs are all working correctly. It’s crucial to be methodical during the setup. Start with the most basic KHE setup possible (only amps+cabs, no pedalboard or attenuator) and add things step by step. Same for the PS fx-loop: Get the basic PS/KHE setup running first, and only add the fx-loop if things are working correctly.

1. Connect the PS AMP IN jack to the white KHE S-LINE SEND, using a speaker cable. This sends the activated amp speaker output signal to the input of the PS’s reactive load box.
   

2. Connect the PS SPEAKER OUT - TOP JACK to the white KHE S-LINE RETURN jack, using a speaker cable. This sends the PS’s speaker output signal back into the KHE cabinet switching section. Do not connect or use the bottom speaker jack at all. For the Impedance Switch settings, see all details further down below.
   

3. Power-On the KHE. Do not power-on the amps or PS yet and set the PS bypass switch to OPERATE. Turn the master volume of the PS and amps down.
   

4. Activate the KHE Attenuator Loop in the System Menu after connecting it. If not activated, the attenuator won’t work correctly. See this link: How to activate the KHE Attenuator Insert Loop
   

5. Activate a Speaker Cab on the KHE to provide a load for the PS output (it’s a tube amp).
   

6. Power-On the PS and the Amp Heads and let them warm-up for 2 minutes .
   

7. Activate an Amp on the KHE and slowly increase the volume of the amp and the PS and test everything in detail.

8. The system is now ready to use.

Impedance Setting

• Set the PS Amplifier Impedance switch to match the impedance of the amp heads.

• Set the PS Speaker Impedance switch to match the impedance of the speaker cabinets.

• If the PS is set to ON and OPERATE, it will isolate the amp heads form the speaker cabs by it’s reactive load box and power amp. The amps can be safely set to a different impedance than the cabs.

• If the PS is set to OFF or BYPASS, the PS will connect the amp head to the speaker cab. Ideally, the speaker impedance should match the amp head impedance.

• Do not use the second bottom speaker output jack at all.

• Learn more: KHE Impedance Guide

Ground Lift Switch

In case of hum or high-pitched noise issues, experiment with the ground lift switch setting. See the section below for more troubleshooting information.

Alternative Wiring Variants

• Single Cab or Load Box: If the PS is only used with a single cab, or as a load box with its internal load and no speaker attached, connect it to a red KHE CABINET jack. For the KHE ACS 4x2, this wiring is the only connection variant.

• KHE ASX / CSX: Connect the ASX CAB MAIN to the PS Amp Input. Connect the PS Speaker Output to the CSX Speaker Input. Use speaker cables. See more information in the ASX CSX user manual.

Basic KHE + PS Operation

Power Station Power & Bypass Switch

• With PS power OFF, the PS is in full bypass. No attenuator or power amp is active. The bypass switch setting is ignored. The amp head output is hard-wired to the speaker cabinet at the PS output 1 and the internal load box is disconnected. If the PS speaker out 1 is not connected, the internal load box will be active (switching jack).

• With PS power ON and OPERATE, the PS functions as an active attenuator or load box with power amp. The amp head is connected to the PS internal load box + power amp. The amp heads are isolated from the speaker cabs so to speak. If the PS speaker out 1 is not connected, the internal load box will be active (switching jack).

• With PS power ON and BYPASS, the attenuator is bypassed: The amp head output is hard-wired to the speaker cabinet at the PS output. See the section below for more information about the attenuator bypass operation. If the PS speaker out 1 is not connected, the internal load box will be active (switching jack).

Attenuator Operation

To use the PS as an attenuator, set the PS power switch to ON and OPERATE. Make sure to have a cabinet active on the KHE and the Attenuator Loop activated. Use the PS VOLUME knob to set the master output volume of the rig. Use the KHE’s amp and cab switches to freely choose any amp or cab at the push of a switch (no need to stop playing, the KHE takes care of the switching and muting).

Silent Operation (Load Box Mode)

To use the PS as a load box in silent mode, set the PS power switch to ON and OPERATE and turn the VOLUME all the way down. The PS AC power must be on. To use it as a load box without AC power, disconnect the PS SPEAKER OUT cable on the PS side so the internal load box is active (switching jack, do not unplug KHE S-Line Return). No PS AC power reduces the PS load rating by 50%. On the KHE, a cabinet must always be activated, but it won’t receive any signal from the power amp. Alternatively, if the PS is exclusively used as a load box with no speaker cabs at all, it is best connected to the KHE’s Cabinet Switching Outputs (red CAB jacks).

Attenuator Bypass

The PS Bypass Switch can be used to remove the PS from the signal chain completely. Simply set the switch to BYPASS. The internal load and power amp get disconnected and the amp head is hard-wired to the activated speaker cab. When shutting the system down, always set it back to OPERATE. Warning: Do not operate this switch under signal. Always deactivate the amp on the KHE first before putting the PS into bypass or operate mode. Note: The KHE itself can not bypass the attenuator. Deactivating the KHE Attenuator Loop does not bypass the the attenuator. Learn more: ACS Attenuator Loop Guide

Device Position in the Room

In some situations, being close to the attenuator or load box with the guitar can result in a high-pitched squealing noise. This happens due to the strong magnetic field generated by the inductors and transformers of the attenuator or load box, causing feedback with the guitar pickups. Try physically separating them and avoid standing too close to the device with your guitar. You can find additional information in this Video by Fryette Amplification and in this Blog Post by Two Notes Audio on the topic. Make sure to provide proper cooling airflow for the attenuator or load box.

Line In Jack

This jack enables to connect a line-level preamp source to the power amplifier section of the PS, to use it as a power amp instead of an attenuator. Using the Line In jack deactivates the signal from the amp head and the load box section (the amp head is still safely loaded). The PS fx-loop is after the line in. Any connected effects will be active when using the line in. If the PS is set to bypass, the line in and power amp section is deactivated. This jack is an unbalanced 1/4” TS connection. Use shielded instrument cables. This jack can be used for some advanced KHE switching setups. See more info below.

Line Out Jack and XLR

This jack enables to send a dry amp line-level feed into other line devices. It is a dry output and does not have any speaker simulation or IR processing. It can be connected to an audio interface to add an IR or speaker simulation (use XLR out). Or it can be used in wet/dry/wet setups to send the dry amp signal to the input of the effects unit. This line out is pre-fx-loop: Any connected effects will NOT be active with the line out. The line out can be used in both attenuator- and load box mode. Both the line out 1/4” jack and the XLR have the same signal present. XLR is balanced and transformer isolated. 1/4” line out is unbalanced TS and not isolated (use instrument cables). In complex setups it’s usually recommended to use the isolated XLR out for ground isolation. The line level control adjust both output levels. This jack can be used for some advanced KHE switching setups. Learn more: Advanced Active Attenuator Setups and KHE + Wet/Dry/Wet (coming soon)

Safety Information

Always have a Speaker Cab or Load activated on the KHE

To provide a safe load for the PS tube power amp, always have one speaker cabinet activated on the KHE. The KHE’s Recall Mode enables to automatically activated the last active cab on the next power-up. The new KHE Cab-Safe Mode modifies the KHE safety logic so it never let’s you deactivate the speaker cab at all (starting Feb’24).

Always activate the KHE Attenuator Insert Loop

The Attenuator Loop is deactivated by default. If deactivated the attenuator won’t work correctly. Always activate the Attenuator Loop in the KHE System Menu. The KHE can not bypass the attenuator.

Never operate the PS Bypass Switch under Signal

To prevent dangerous no-load moments for the amp head, always deactivate the amp on the KHE before operating the PS Bypass switch, so the amps are safely loaded.

Cabling Safety

Make sure to wire and connect the system correctly. Always power-off all amps and attenuators during cabling changes. Use quality cables and make sure the plugs are fully inserted into the jacks. Do not leave the rig unattended. If you leave the room, set all amps AC power switch to standby! Better be safe than sorry. Learn more: ACS Cable Guide

Speaker Out TWO (PS-2A only)

Do not connect or use output two (bottom jack). Always use output one (top jack). Only one output can be connected to the KHE. The PS-100 instead has TRS remote switching jack for channel select and fx-loop bypass labeled Footswitch Jack.

Power Station + Transistor Amps

Quote Fryette PS user manual: “The Power Station is not intended for use with solid state amplifiers that use current feedback and an un-grounded output. Using the power station with such product may cause oscillation and potential damage to the amplifier. The Power Station is not intended for the use with Class-D or PWM amplifiers.” Comment KHE: This is also true if the PS is set to bypass or off.

Load + Switching Power Rating

The Fryette Power Station reactive load box is rated for 200W RMS @ 4/16ohm or 150W RMS @ 8ohm. If the PS AC power is off, its’ power rating is reduced by 50%. The KHE has a maximum power switching rating of 150W. Learn more: KHE Maximum Amp Power Rating

Power-On Sequence

All amps + KHE + PS power off (set to OPERATE) > KHE power on > KHE activate CAB > PS power on > Amp Heads on with standby for 2 minutes > KHE activate AMP > Ready to rock!

Power-Off Sequence

Deactivate KHE Amp (leave Cab activated) > Amps power off > PS power off (set to OPERATE) > KHE power off > Good Night!

Power Station FX-Loop Operation

The PS fx-loop can be used as a master-fx-loop for all amps on the KHE. It enables to easily share post-amp effects like Delay, Reverb, EQ or a Noise Gate with all amps with only two cables. With the PS-2A, the fx-loop is always active (no bypass function). With the PS-100, it can be bypassed by an external footswitch. The PS fx-loop is a serial mono loop for line- or instrument level and operates post-amp, after the preamp section of the activated amp, similar to a traditional amp fx-loop.

FX-Loop Wiring

1. Connect the PS FX-SEND to the input of the pedal board by a shielded instrument cable (TS).

2. Connect the PS FX-RETURN to the output of the pedal board by a shielded instrument cable.

3. Set the PS fx-level switch to HI for line-level effects or to LO for instrument-level effects (pedals).

4. Connect any pedals such as Overdrive or Boosts in front of the KHE guitar input.

Pedal Board Power

Use isolated DC power for each pedal section. Do not use daisy-chain adapter cables between the pre- and post section. Keep the grounds of each section isolated all the time. If using a single PSU with multiple DC outputs, make sure the outputs are 100% isolated. Many cheap PSUs are not or have grouped outputs. Otherwise a ground loop may happen (hum & squealing noise). Also experiment with the Ground Lift switches and check which setting gives the best results. See the section below for troubleshooting tips.

KHE FX-Loop vs. Power Station FX-Loop

One common question is whether to use the KHE fx-loop switching or the PS fx-loop. The answer is simple: It depends.

• If you plan to always use the Power Station as an attenuator and like how it sounds, there's no reason not to use its fx-loop. It only needs two cables, making it easy to use. It even adds an fx-loop to amps that don't have one. It’s very convenient. However, if you set the PS to bypass, the fx-loop will also be inactive.

• On the other hand, if you only want the PS for the fx-loop and don't really need the attenuator function, I suggest the KHE fx-loop switching instead. A load box + power amp will always slightly change the sound compared to the true amp + cab interaction. Not necessarily better or worse, but different. For the most authentic amp sound, use the real amp fx-loop with the KHE fx-loop switching (without any attenuator at all). Also, the KHE fx-loop is active all the time, whether or not the PS is in bypass.

Using the PS FX-Loop in 4-CM

4-Cable Method with the Power Station FX-Loop

It is possible to use the PS fx-loop in 4-CM, for example with multi-effects units, Noise Gates or with pedal switching systems. Also it is possible to use modern amp modelers as a 4-CM effects units, such as the Neural DSP Quad Cortex, Fractal Axe Fx, Boss GT-1000 or similar. Used like this, the device will only work as a effects processor (usually no amp- or cab modelling). With these devices, a clean grounding is crucial. Sometimes these devices can create a ground loop which requires to be solved with a signal isolation box (with transformer).

Noise Gates in the FX-Loop

When using a noise gate with key input, such as the Fortin Zuul, you may have to use a quality signal splitter with transformer isolation for the key input source. Keep the grounds of each section isolated all the time. Otherwise a ground loop may happen (hum & squealing noise).

Using the PS as a Power Amp

The Line In jack can be utilized to use the Power Station as a power amp for preamps or amp modelers. Using the Line In jack deactivates the load box / amp head signal (switching jack). The Line In is in front of the fx-loop so any connected effect pedals will be active with the preamp too. It is not possible to use the Line In and the amp head + load box at the same time, only one function can be used.

The input of the preamp is connected to a KHE amp channel (black Amp In jack). The output of the preamp is connected to the Power Station Line In jack. If the preamp is not in use, the PS Line In cable has to be manually unplugged so the load box + amp heads are active again.

When using pedals or modelers in 4CM, a clean grounding is crucial. Sometimes some isolation boxes are required to remove ground loops.

Update May ‘24: Fryette released the Fryette Cyclops, which is a routing device that allows to seamlessly integrate & switch external preamps with the Power Station, to use the PS as a power amp for the preamps. How to use it with an amp switcher:

Troubleshooting & FAQ

No sound at all / Attenuator isn’t working correctly

• Check if the Attenuator Loop is activated in the KHE System Menu.
  Maybe it got deactivated because it not connected during power-up (safety feature)?

• Make sure an amp + cab is activated on the KHE

• Double check wiring, it’s easy to mix things up.

• Make sure cables are fully inserted & functional.

• Downsize system to only amps+cabs with no attenuator or pedals.

• Make sure the devices are being operated correctly.

Hum Noise or High-Pitched Squealing Feedback Noise

• Is the KHE Attenuator Loop activated? Double-check everything above.

• Check if the Ground Lift & FX-Loop Level switch has any positive effect.

• Dynamic Noise: Does the noise change your position in the room? Does it get worse if you move closer to the attenuator or load box? If the noise disappears when turning the guitar volume down, then the noise is most-likely caused by magnetic interference with the (reactive) load device and the guitar pickups. You are standing too close to the device. Move your guitar around to learn how it reacts. Try moving the attenuator or load box a little further away or lower gain and volume as a last resort.

• Static Noise: If the noise is still present, even with the guitar volume turned all the way down and not changing with your position in the room, the noise is most-likely caused by a ground loop somewhere. First, check the PS fx-loop and the pedals. Make sure to use isolated 9V power for the fx-loop to avoid ground loop. Don’t use daisy-chain power adapter cables. Temporary remove the pedals to isolate the problem. If using a noise gate with key input such as the Fortin Zuul, use a splitter with transformer isolation for the key input to avoid ground loop. Keep the pre- and post pedal section ground isolated all the time. Experiment with the PS and KHE Ground Lift Switch setting. Make sure to have an amp activated on the KHE.

Sound or noise coming from inside amp/attenuator/load box

• Sound of broken speaker inside the amp: When an amp or load box is pushed hard, it can cause weird noise and sound which kinda sounds like a small broken speaker, coming from inside of the amp or transformers. Fear not! This is normal. The vibrations from the transformer laminations and inductors can create strange distorted sounds, but there's nothing to worry about.

• High-pitched squeal coming from inside the amp: Immediately power everything off (PS, KHE, Amps) and verify the correct wiring of the amp. Make sure the cables are fully inserted and in good working shape.

Can I use fx-loop without attenuator or in bypass?

Nope, it’s not possible to use the fx-loop in standalone. It is part of the full system: Load Box > FX-Loop > Poweramp

Learn more: KHE Troubleshooting Guide and ACS Attenuator Loop Guide

Links:

• Fryette PS-2A Website + User Manual

• Fryette PS-100 Website + User Manual

• Power Station Block Diagram

• Power Station Ground Loop Flow Chart

• Power Station Model Comparison Chart 2019

Return Home: KHE ACS Help Center

Disclaimer: All product names, trademarks, and logos used in this guide belong to their respective owners. This guide is purely informational and does not suggest endorsement, sponsorship, or affiliation with the mentioned companies. While great efforts have been made to ensure accuracy, actual compatibility of our product with third-party products may vary, and we do not guarantee their performance or functionality. ALWAYS READ AND STUDY THE USER MANUALS OF THE INVOLVED PRODUCTS. Users are advised to thoroughly test and validate any combinations, and we disclaim responsibility for any issues that may arise. If you have any feedback to help improving this guide, please let us know.