N-audio 8X7 User manual

N-AUDIO AMPLIFIER CABINET SWITCHER
MODELS 8X7 AND 4X4
USER MANUAL

Introduction
The main function of N-audio 8X7 and 4X4 systems is to switch between amplifiers and cabinets
quickly without routing cables manually. It is a quick routing system that can handle up to 8 (4)
amplifiers, an external power attenuator, and up to 7 (4) speaker cabinets. It is a good choice
when you have a few amplifiers and cabinets and want to make a quick comparison between
them, or just choose your favorite guitar tone. Also, this system works great for studios or guitar
shops where a lot of equipment has to be tested or routed quickly.
The unit works with any amplifier including tube amplifiers, solid-state amplifiers, and bridged
mono amplifiers. There are a lot of hardware and software logic built-in protections to keep your
amplifiers safe. The whole signal path contains relays only to give a pure tone. There is no active
electronics except for the tuner out. Special circuit implementation is used to reduce pops when
switching. There are no dead spots when switching between the amplifiers or the cabinets giving
perfect work on stage or studio recording.
Controls and connectors
1. A guitar input jack is input from your guitar or pedalboard.
2. The MUTE/MIDI learn button has two main functions:
- Mutes the whole system by turning off all enabled devices.
- Acts as MIDI learn for adding the current preset to a MIDI preset.
3. The amplifier buttons correspond to each amplifier connected to the device.
Pressing a button routes the signal from the guitar through each selected amplifier.
4. The power attenuator button enables an external power attenuator.
5. The cabinet buttons send signals to cabinets.
6. The power button turns on the device.
Back panel
1. A universal IEC mains input.
2. Outputs to cabinets.
3. Send/return connectors for an external power attenuator.
4. Inputs from the speaker outputs from your amplifiers where normally you plug your cabinet.
5. MIDI IN and MIDI OUT connectors. MIDI out works as MIDI thru.
6. Outputs to connect the inputs of the amplifiers where normally you plug your guitar.
7. Guitar in input is a master input, and it disables the front input if used.
8. Tuner out output for an external tuner. This buffered output works all the time.
Getting started
The whole system uses a lot of cables. Ensure that you have the right cables for your needs:
- All signal cables between the “to amplifiers inputs” and the input of your amplifier where
normally you connect your guitar, the inputs, and the tuner output must be guitar shielded cables.
Those cables are usually used when you connect the guitar to the amplifier.
- All cables between “from amplifiers speaker outputs”, power attenuator send and return, and
“outputs to cabinets” must be proper speaker high current cables. Use quality 2×1.5mm2 or
2×2,5mm2 cables.
- The mains power cord is a standard IEC type. Use the provided cord.
Front panel

Connecting the whole system
Connecting the amplifiers
Each amplifier must be connected with two cables:
1. Connect a guitar shielded cable between the input of the amplifier where you normally plug
your guitar and the “to amplifiers inputs” jack.
2. Connect a speaker cable between the cabinet jack on the back of your amplifier where
normally the external cabinet is connected and the “from amplifiers speaker output” jack.
The jacks numbers on the back correspond to the amplifier button number on the front. Each
amplifier must be connected between the same numbers on the back! The cables from the first
amplifier go to the first “to amplifiers inputs” and the first ”from amplifiers speaker outputs”. Do the
same procedure for all other amplifiers.
NEVER CONNECT ONE AMPLIFIER TO DIFFERENT JACK NUMBERS ON THE BACK!!!
Pay attention when connecting the amplifiers! For best performance try to separate the input
cables from the output cables having some distance between them if possible.
Connecting a guitar combo
1. Connect a guitar shielded cable between the input of the combo where you normally plug
your guitar and the “to amplifiers inputs” jack.
Note: to enable playing through a guitar combo, the internal protections have to be bypassed.
This could be done by enabeling one of the connected cabinet or the power attenuator.
Connecting an attenuator
The switching system supports an external attenuator if needed, connected to the speaker signal
path.
1. Connect the amplifier input from the attenuator to the “to input /send/” jack
2. Connect the speaker output from the attenuator to the “from output /return/” jack.
Use only speaker cables!
Connecting the cabinets
Connect the “to cabinets” and the input jack of the cabinets with speaker cables.
There are power-on and power-off sequences that have to be used to prevent damaging your
amplifiers.
Power-on sequence
1. Connect the whole setup with proper cables
2. Turn on the N-audio system
3. Turn on all amplifiers with a reduced master volume.
4. Try all amplifiers and cabinets before increasing the master volme pots.
Power-off sequence
1. Turn off all amplifiers
2. Turn off the N-audio system
AMP 1
To the guitar input
From the speaker
output on back
To input
From
output
Cabinets
To tuner
AMP 2 To the
guitar input
From the speaker
output on back
GUITAR CABLES
SPEAKER CABLES
321
MIDI controller
MIDI cable
Guitar
Combo

First use
Initially when you first power on the device it is in a muted state and performs an LED sequential
test. Each cabinet button has a dual-color LED on top. The green LEDs indicate where you have
a connected cabinet. You can enable only cabinets with connected cables on the back. All others
can't be selected.
1. Choose a cabinet by pressing its button. A red LED shows the active cabinet.
2. Enable the attenuator. Skip this step if not used.
3. Select an amplifier.
As a rule of thumb, always try the whole system with reduced master volume to prevent mistakes
while routing the entire system. If you can hear a signal, then you can increase the volume.
During the playing, any of the possible cabinets, the attenuator, or any of the amplifiers can be
selected by the front panel buttons or via MIDI. When the Mute switch is pressed, you have to
start from the beginning by selecting a cabinet.
Extra features
Using more than one cabinet in parallel
The unit can drive up to 3 cabinets in parallel simultaneously. Adding an extra cabinet is simple:
while holding a button for the first cabinet, press another cabinet button. While holding two
cabinet buttons, press the third one. Exit this mode by pressing any of the allowed cabinet
buttons.
WARNING: Adding cabinets reduce the output impedance. Two 8 Ohm cabinets are visible by
the amplifier as a 4 Ohm speaker. To use this mode, it is highly recommended to use 16 Ohm
cabinets. Using more than one 4 Ohm cabinets with a solid-state amplifier may damage it!
Silent recording via an external power attenuator
In normal operation, the N-audio switcher won't turn on an amplifier and the attenuator until a
cabinet is selected. This extra feature is used when you want to take a signal from the line out
without driving a cabinet. To enable this mode, press and hold the power attenuator button. Its
LED will start flashing. When it stays on, it turns the attenuator on. Now the system allows
enabling an amplifier without a cabinet. Exit this mode by pressing MUTE or POWER ATT.
WARNING: Use this mode only when you have a power attenuator connected to the system!
Press
and hold
Press to enable
second cabinet
Press
and hold
Press to enable
third cabinet
Press and hold until stops flashingand stays on
Enable the desired amplifier

Hardware and software protections
To protect the amplifiers the N-audio system has integrated hardware and software protections:
- Each cabinet jack has a sense circuit for detecting connected plugs. Only cabinets with
connected plugs to the back (a green LED lights) can be turned on.
- When the system works and a plug is removed from a selected cabinet, it turns into mute state.
- When a MIDI command is sent to the unit and there is a missing cabinet to the MIDI preset, it
turns into mute state.
- Each amplifier has a grounded input and a resistive load connected to the output when not in
use.
- The whole system has a resistive load connected before the attenuator input to protect against
cable routing mistakes.
- Each amplifier is completely galvanically isolated, allowing the use of any amplifier including
bridged mono amplifiers. This also reduces the ground loop noise.
MIDI implementation
The N-audio system can be controlled by any MIDI controller. The MIDI controller and the unit
must use the same MIDI channel. MIDI channel 1 is default. When a MIDI command is sent to the
N-audio system the MIDI LED flashes. This is a good way to test the MIDI connection between
the devices. The unit has a MIDI out connector. It acts as a MIDI thru, sending the same MIDI
commands received from the MIDI in.
Selecting a MIDI channel
1. Power off the N-audio system.
2. While holding the MUTE button, power on the unit. The MIDI and the MUTE LEDs start
flashing sequentially.
3. Release MUTE button. A red LED shows the last selected MIDI channel.
4. Press one of the red buttons. Each of them responds to a specific MIDI channel. See below.
5. The selected MIDI channel flashes, then the sequential LED test pass.
6. Done.
The N-audio 8X7 switcher supports all 16 MIDI channels, while the N-audio 4X4 switcher
supports 1, 2, 5, 6, 9, 12, 13, 15, and 16 MIDI channels.
MIDI programming
1. Connect a MIDI cable between the MIDI Out of the MIDI controller to the MIDI In of the
N-audio system.
2. Enable the desired devices from the front buttons to add them to a specific preset.
3. Press and hold the MUTE/MIDI learn button until the MIDI LED starts flashing.
4. Send a MIDI command from the MIDI controller. The MIDI LED will stop flashing.
5. Done!
If you want to cancel the procedure, press the MIDI button while MIDI led flashes.
Note: If a MIDI preset is sent to the unit and one or more cabinets from the preset are
missing, their LEDs flash and the unit goes to MUTE.
Ch.1 Ch.2 Ch.3 Ch.4 Ch.5 Ch.6 Ch.7 Ch.8 Ch.9 Ch.10 Ch.11 Ch.12 Ch.13 Ch.14 Ch.15 Ch.16
MIDI channels
Ch.1 Ch.2 Ch.5 Ch.6 Ch.9 Ch.12 Ch.13 Ch.15 Ch.16
MIDI channels

Factory defaults
If you want to delete all programmed MIDI presets from the unit, follow this procedure:
1. Power off the unit.
2. While holding the MUTE button, power on the unit. The MIDI and the MUTE LEDs start
flashing sequentially.
3. Release MUTE button.
4. MIDI LED flashes and the sequential LED test passes.
5. Done. All MIDI presets are deleted.
Factory defaults procedure deletes only the user presets keeping the latest saved MIDI channel.
A few words about the impedance and restrictions
There is a lot written about impedance mismatch using tube amplifiers. You can find many topics,
videos and information on what is possible and what is not. Here are a few quick tips and
limitations about the impedance and the impedance mismatch based on the type of the amplifier.
Solid-state amplifiers
Most solid-state amplifiers work with any impedance between 4 and 16 Ohm. Usually, they have
a minimum listed impedance. Try to keep away from it. Increasing the impedance will reduce the
power. Usually, it is good to use 4 or 8 Ohm cabinets. Keep in mind when using more than one
cabinet simultaneously! This will reduce the impedance. When using more than one cabinet it is
highly recommended to use 16 Ohm cabinets. The bridged mono amplifiers and some of the
modern class D amplifiers can work with impedance down to 2 Ohm, but this is not common for all
other class AB amplifiers. Read the amplifier manual for its specs. The only rule using solid-state
amplifiers is to keep the impedance above or at least at 4 Ohm.
Tube amplifiers
The tube amplifiers have output transformers that match the output impedance of the power
tubes to the impedance of the connected speaker. Most of the tube amplifiers have an impedance
selector on the back giving the flexibility to use any cabinet with a different impedance. It is good
to match the impedance of the cabinets with the impedance of the amplifiers. Using mismatched
impedance won't blow your amplifier, but it will change slightly the tone. If you want to use an
amplifier and a cabinet with mismatched impedance, try to keep the ratio between the impedance
with just one step: 4 and 8 Ohm or 8 and 16 Ohm. Avoid using a 4 Ohm amplifier to a 16 Ohm
cabinet or a 16 Ohm amplifier to a 4 Ohm cabinet. It is possible to use 4 Ohm amplifier for 8 Ohm
cabinet or 8 Ohm amplifier for 16 Ohm cabinet. Keep in mind the impedance when using more
than one cabinet! In this case, it is good to use 16 Ohm cabinets and 8 Ohm amplifiers. When
some impedance mismatch is used, reduce the master level by 20-30% from its maximum for
safety. The table below shows different mismatched impedance restrictions:
Amplifier impedance Speaker impedance
4Ω8Ω16Ω
Acceptable
Perfect Not good
4Ω
4Ω8Ω16Ω
Acceptable Perfect
Not good
8Ω
16Ω
4Ω8Ω16Ω
Acceptable
Perfect
Acceptable

What is in the box
The N-audio 8X7 and 4X4 switchers comes with a mains IEC cable and user manual. The 4x4
unit has optional 1U mounting brackets sold separately.
Technical specifications
Dimensions: 8X7 system: 19" 1U rack unit W:48.2cm, H:4.5cm D:13cm
4X4 system: W:30cm, H:4.5cm, D:13cm
Available brackets for 19" 1U rack installation
Weight: 8X7 system: 2kg
4X4 system: 1.3kg
Mains power supply: Universal mains power supply 90-260VAC
Power consumption: Max 10W @ 110VAC, Max 5W @ 230VAC
Input impedance: 10 Meg. No active buffers though the signal path
Tuner output impedance: 10 kOhm