RedSeven Amplification AMP CENTRAL User manual

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AMP CENTRAL
Reactive load – I.R. Loader
Version 2.1
Aug 2023

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How NOT to use AMP CENTRAL
Amp Central is a load device who takes the output of your tube based amplifier and transforms this
energy by dissipating it into heat.
Since NO volume is perceived, you might be tempted to turn your amplifier’s master volume to a very
high, almost ear-killer and dangerous level, which is not recommended for various reasons.

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First of all, by having such a behavior, life of your power tubes will be incredibly reduced, and we all
know they aren’t 'cheap' nowadays.
Second point, you’ll send too much signal into Amp Central, for no benefit. A fan, inside the unit is
placed to protect load section from overheating and it will automatically turn on as soon it will feel
the need to.
Last but not least, most modern amplifiers are fine-tuned to NOT push power amp stage very hard.
99.9% of the time, gain comes from preamp section, there’s no practical, sound-wise or “I have the
biggest dick ever” reason to fully open master volume on your 100W amplifier. It’s simply a wrong
habit.
While Amp Central is safely rated up to 100W, we do recommend to use your amplifier at the same
volume as you would use with a regular cabinet, or just a bit more perhaps.
Keeping care of your gear will result in a better sonic performance and a way longer life.
WHAT’S NEW AFTER S/N 22056 (mid May 2022)
Amp Central still the same exact product but after mid May 2022 (starting from serial number 22057)
and for all future units, we introduced few different features which are mostly minor update. Here’s
the complete list:
•
24volt (negative center) power supply (now included with A.C.).
Every unit, now on, will
required a total of 24 volts to be powered (before, 9 to 12 volts). This leads to couple
advantages: increased overall headroom and ability to incorporate a real audiophile grade
headphone amplifier.
While the convenience of having 9 to 12v supply was the ease of sourcing a proper power
supply real quick, headroom was not enough to drive low impedance headphones with
enough volume. Now you have the best of both worlds, an included 24v power supply AND a
superior quality HP integrated amplifier.
•
FLAT/CUT switch.
Some guys love how A.C. sounds, other asked for a more “hi-fi” type tone.
We managed to have best of both words also here. First, this switch works ONLY on IR filtered
MAIN outputs (both XLR and jack outputs), and it DOES NOT WORK on Line Ouput. In FLAT
position, you have the most possible flat sound from DAC to main outs. In CUT position you
have a gentle lowpass filter set around 10KHz, which was the standard sound of A.C. on units
previous to s/n 22057, what we called the “analog feel” filter.
•
MAIN OUTPUT JACKS are now fully balanced.
On unit’s back panel there’s couple XLR outs,
along another two 6,3mm jacks, wired in parallel to XLR. Starting from s/n 22057, jacks are fully
balanced, where until s/n 22056 they were unbalanced.

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INTRODUCTION
What is AMP CENTRAL?
Amp Central is our answer for modern guitarist who still love to use any tube based amplifier in live or
studio situation, even where silent stage is required.
Amp Central, as the name suggested is a hub to connect your amplifier to the outside world, without
the need of a real cabinet or any volume at all.
THE CONCEPT
Since few years, digital systems became very popular in guitar amplifier market, replacing real amps in
most of “inconvenient” gig where a proper stage volume was not possible, or for example, during
practice sessions at late night.
What we found is missing in the world right now between other various choices is what we call a “total
experience” of a real amp-speaker interaction. What me mean, is, simulations/profiles could work in
some situation in term of pure sound, but how about the feeling under your fingers?
It’s the same as you were playing your amp thru a real cabinet? Of course, no.
What could we do to improve the experience of a “fake” or profiled amplifier, played with headphones,
which in most cases yields bad results?
Well, we came up with a solution and we brought a couple of different technologies into the game,
one very old and one not so old, respectively called
Dummy Load
(in our case a Reactive Load) and
the
Impulse Response
technology.
It’s a known fact your tube based amplifier needs to have a cabinet wired to the output jack when
used, or at least a proper load, the potential penalty could be the reduction of output transformer’s
life, or worst, its total fault.
With this in mind, we built the very first stage of Amp Central, by creating a proper dummy load, or
better, a Reactive/Resistive Load, to mimic the best approximation of a real cabinet. We've gone fully
analog with best available components, something audiophile experts will appreciate. Audophile
capacitors, custom made inductors, superior ceramic resistor, just to name a few..no digital processing
or equalization is applied up there, we do believe your amplifier needs a proper analog load to sound
and feel at its best.
Where do we go from there? Amp is now safe and running, while no sound will come out of it. At this
point we decided to embrace digital world, with Impulse Responses* technology.
With Amp Central we wanted to offer the best of both worlds, by offering the possibility of playing
your favorite amplifiers and not a simulation/profile, with some Impulse Response of your favorite
cabinets.
This will be YOUR and not someone else's sound. Your own amp(s) and possibly your own cab’s I.R.
*An Impulse Response is in layman's terms an equalization, or a “snapshot” of your favorite mic’ed
cabinet, to be applied to the raw sound coming out of your loaded amplifier. Return act as the complete
sound (amp + cabinet + mic) as you should hear from your studio monitors, or headphones.

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LOGIC SCHEMATIC
TUBE
AMPLIFIER
Speaker
output
AMP CENTRAL LOGIC SCHEME
REACTIVE/
RESISTIVE
LOAD
THRU OUTPUT
(to connect a
guitar cabinet)
1 2
1When a guitar cabinet is connected to THRU output, internal load is automatically bypassed. 2When a guitar cabinet is used, you need to match amp’s output impedance with cabinet ‘s impedance. 3 Loop FX is placed after IR loader, you will not hear any fx patched here into your guitar cabinet.
LINE OUT
&
Line out level
IR
LOADER
USB
LOOP
FX 3
SEND RETURN
XLR &
1/4’’ JACK OUTPUTS
NOTE: A.C. internal load is rated at 8 ohm/100W
RedSeven Amplication - July 2022

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FIRST USAGE
We think it’s better to start slow and to understand the workings of the Amp Central before diving
in and trying the unit.
What you need to know to proceed in the safest way, is to consider the Amp Central as a normal guitar
cabinet.
AMP CENTRAL HAS AN INTERNAL LOAD
RATED UP TO 100W @ 8 OHM.
USE THE 8 ohm tap OUTPUT OF YOUR
AMPLIFIER TO CONNECT IT TO AMP
CENTRAL.
Hit standby switch of your amplifier ONLY AFTER PLUGGING A CABLE FROM THE OUTPUT
OF YOUR AMPLIFIER TO “FROM AMP OUT” of Amp Central.
!!!! Do not attempt to connect your amplifier to Amp Central in other "fancy" ways, your amp’s life is
important! We are not responsible for any improper usage that could potentially lead to damage !!!!

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FRONT PANEL
(left to right)
• VIRTUAL CABINET SELECTOR: chose one of the sixteen preloaded I.R.'s.
• BANK/CAB: for the convenience of memory, the sixteen cabinets are divided in four files with
four I.R.'s in each file. Toggle between them by turning the VIRTUAL CABINET ENCODER left or
right.
• INPUT LEVEL: attenuation level of the output of your amplifier. This should be used in
conjunction with the analog LED METERS and DAC CLIP meter. The goal is to reach a proper
signal without any clipping. Turn it up until CLIP led starts to blink at the higher dynamics of
your clean channel and then kick it back just a little.
• HEADPHONE LEVEL: this pot controls the output volume of your headphones. Everything
coming into the Amp Central both from your amplifier or LINE IN will be affected by this
control, using the headphones output.

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• RESISTEVE/REACTIVE SWITCH: chose between a pure resistive load or a completely reactive
one.
• FLAT/CUT SWITCH: control over XLR/JACK of high frequencies. Flat, is unprocessed sound, cut,
is a gentle slope around 10KHz. This filter do not apply to line output, but only at I.R. output
• HEADPHONES OUTPUT: connect your headphones here.
• AUX INPUT: connect to your PC, soundcard or whatever line level signal you want to hear
through every output of the Amp Central.

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BACK PANEL
(from left to right)
• LOOP FX: Stereo fx loop placed between the I.R. and the final outputs. Connect your favorite
outboard effevts like delays, reverbs, etc. here.
• TO SPEAKER: this is the "through" jack for if you want to use a real cabinet. When the TO
SPEAKER output is used, the internal load is bypassed, the amplifier will see only the real
connected cabinet as the load. Be sure to match the impedance of the amplifier with your
cabinet
• LINE OUT: the line level signal coming from the reactive load, without the I.R. processing
applied.
• LINE OUT LEVEL: the volume control of the line out.
• FROM AMP OUT: this is where you must connect the output of your amplifier.
• MIDI INPUT/THRU: Midi input and thru ports for midi connection. Switch between the I.R. by
sending Midi CC's to the Amp Central.
• MAIN OUTPUT (XLR and jacks output): main output from Amp Central. Both set of outputs are
fully balanced and the only difference between the two are format.
A balanced signal is a stronger and less prone to noise signal, but if you want to use a standard
mono instrument cable, you just need to plug into jack outs, A.C. will work in unbalanced
mode too.
• USB: connect to your PC/MAC for uploading your own favorite I.R.'s.

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• DC IN: (prior to s/n 22057 9 to 12V @250mA), from s/n 22057, 24V negative center and at least
with a current output of 300mA.
INPUT SECTION and CALIBRATION ( !!! VERY IMPORTANT – READ THIS AT LEAST COUPLE TIMES!!! )
The very first thing we recommend to do when you start using Amp Central is to set the proper input
level in order to achieve the best signal to noise ratio possibile without any clipping.
To make this happen, we highly suggest to use the most dynamic sound at your disposal, which
usually happens to be your clean channel, or at least the most clean sound you have at your disposal.
The very first big suggestion is to keep your amp’s volume
COMPARABLE
as you were using a real
cabinet. Do not try to push both preamp and master volume higher, just because you don’t hear any
sound or just too little volume from yours monitors. That’s a step we will cover later.
If you don’t remember how much loud you’re in the real world (with real cabinets), please, wire a cab
very quick and make a test. Then don’t move preamp/master volumes.
Once you reached your desired clean-ish sound, you can follow these few steps:
• Connect your amp’s output to Amp Central and hit standby switch;
• Start with INPUT LEVEL of Amp Central at 0;
• Increase Amp Central’s INPUT LEVEL, while heavily strumming your guitar on your clean
channel, until LED METER starts to blink. There’s three LEDs, indicating 0dB, +6dB and CLIP. The
goal is to have your maximum dynamic level by having +6dB led blinking. You don’t want to
hear more volume incoming at this point, since you will likely experience some very
unpleasant clipping.
What to do with crunch or distorted sounds? By nature, a distorted sound is WAY more compressed,
so audio peaks are already smaller than a much cleaner sound, at the same SPL.
If you follow this procedure step by step using the cleanest sound at your disposal, without
experiencing any clipping, you will have absolutely no problem with your dirty sounds. You still hear
clipping when you hit strings very hard? Turn INPUT volume on A.C. a little back again.
What to do if I have all my sounds set without any clipping but I don’t have enough volume out
of my speakers?
Amp Central is a substitute for your guitar cabinet and microphone . You still need a microphone
preamplifier, or that knob with “GAIN” written on your audio interface. Raise it up. You also still have
your “MONITOR VOLUME”, always on your audio interface or “VOLUME” knob on your amplifier/active
speakers. Raise it up. Those are all the places where you need to look for more output volumes if you
feel you need more. Even from your DAW’s channel/master volumes.
Do not look for output volume on A.C., while you have only control on input volume.

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REACTIVE LOAD SECTION
Amp Central is supported by a
100W RMS / 8 ohm
reactive/resistive load.
This means you can plug amps rated up to 100W RMS of total output. We choose the best
inductors/capacitors/resistors in the market (audiophile quality), to ensure unsurpassed audio quality.
You need to connect your amp’s output into “ FROM AMP OUTPUT ” jack in order to use the Load
section of Amp Central.
“TO SPEAKER” is where you want to connect your cabinet, in case you wanted to use one, but of course
it’s not mandatory. When a cabinet is used, internal Reactive Load will be fully bypassed, and the
amplifier will only see the cabinet as its load. Be sure to use a power cable and not an instrumental
cable to connect a speaker cabinet with amp central.
WHAT IMPEDANCE DO I NEED TO SET MY AMPLIFIER IF I USE A CABINET ALONG WITH A.C.?
In case you wanted to use a cabinet WITH Amp Central, A.C.’s internal load will be automatically
bypassed and you need to match cabinet load to amp load. Amp Central impedance, in this case, is
out of the picture.
LINE OUTPUT
Line output is reduced in amplitude signal from amp’s speaker output.
Line out level on back panel allow you to set line out volume, and it’s total independent from INPUT
knob. Line out is also fully isolated thru an isolation transformer, in order to avoid ground loops of any
kind, by using main outs (filtered by I.R.) and line out at same time.
IMPULSE RESPONSE SECTION
Amp Central will only read “.WAV”, MONO, 24bit, 48kHz type I.R.'s.
Please, before writing or ask, be sure to check your IR 100% respect these requests.
Any other attempt to load I.R.'s with different fratures than this, will simply not be recognized and
sound will not processed. You can place only one I.R. in each of the sixteen available files when you
connect the Amp Central to your PC/MAC, and you have to delete previous one. Please read USB
chapter on the next pages for more information on this process.
Amp Central will cut the length of any I.R. to the total length of 20ms, which is the maximum ability of
the internal DSP's calculations.
If you do some basic math, those 20ms will guarantee you a full frequency spectrum response,
including the super low frequencies, even at 40-50hz.
There’s extreme cases where extra long I.R. (i.e. 4-500ms) are not recognized, even if 48/24 and MONO.
Try to cut them around 100ms, A.C. will do the rest of the job for you.

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VIRTUAL CABINETS (I.R.)
You have sixteen different Impulse Responses at your disposal to choose from. Impulse Response
section comes pre-loaded with original RedSeven Pro Cab series 4x12 I.R.'s, but of course you can
upload your personal favorites, by connecting Amp Central to your PC/MAC through the back panel’s
USB port. Please read the USB chapter on next page for more information on how to do.
HEADPHONES AND AUX INPUT
To maximize the experience with Amp Central, we decide to add a comprehensive input/output
section for monitoring. AUX IN is intended for your backing track/click track or whatever line level
source you want to hear through headphones output, along with the sound of your amplifier.
Volume control for your source, it on the source itself.
This is a great feature to improve your skills at late night for example, without connecting Amp Central
and your amplifier to any audio interface. Just put your phone output into Amp Central, and open
YouTube to play along with your favorite tunes!
Everything coming out from H.P. output will be affect by H.P. LEVEL pot. This is a “master volume” for
your headphones.
NOTE: since s/n 22057 (mid May 2022 – 24v powered units) we added an audiophile grade headphone
amplifier, to be able to drive virtually any HP on the planet. Before serial 22057 (on units powered at
9-12v) you may need an external HP amplifier in order to properly drive low impedance headphone.
NOTE: You could use the headphone output at gigs to send a copy of your guitar sound to your
personal IEM mix, in order to have total control of your personal volume. Most of personal IEM system
let you to have two inputs: your instrument (that should be carried by Amp Central) and the band,
usually carried by FOH or stage mix personnel.
LOOP FX
An effects loop is usually placed between your amp’s preamp and power amp, and it’s the place where
you usually want to insert your time-based effects. Older amps (like vintage Fender or Marshall for
example) don’t have one. We also took care of this.
We decided to place a stereo FX loop inside AMP CENTRAL to let you insert your favorite external
effects in the audio chain. FX loop is placed between IR LOADER section and A.C.’s main outputs, this
means you’re sending the already I.R. processed signal to your external effects.
To the most experts out there but also according to us, this is the best place to insert your effects,
especially time based one. Why?
If you think at a traditional setup, with a standard loop fx between pre and power amp, and a standard
guitar cabinet, your time based effect placed into amp’s loop fx are heavly band passed and equalized
by guitar speakers themselves, who are notorious to be way far from flat, in terms of frequencies
spectrum.
By placing those time based effects AFTER speakers (in this case after I.R.), they will processed a full
48Khz audio signal, which is way superior from a normal guitar speaker frequencies response.

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The result is a superior natual sound, an overall 3D sounding environment, especially if listened in
stereo. This is the next step in listening your effects. Stereo is the way to go.
NOTE
: While SEND section is stereo, only one I.R. can be loaded at a time, for both left and right outs.
SENDS will simply make a buffered copy for your right and left effect inputs, to be returned to stereo
RETURNS.
So, what is the advantage of sending the signal in stereo instead of using only one mono send and
then a stereo return?
Well, there are no advantages at all for a mono input device, besides the facts that some effects want
to see a stereo input signal to help make their algorithms work in the best way.
If you have a MONO input external device, use LEFT send to send a MONO signal.
If you want to use a MONO external device and only one jack/XLR out, use LEFT side first.
USB and HOW TO CONNECT THE AMP CENTRAL TO PC/MAC
You must connect Amp Central to your PC/MAC with a USB cable, to upload new I.R.'s by following
the next steps:
• Power off Amp Central by unplugging power connector on rear panel
• Connect a USB cable into AMP CENTRAL first and then your PC/MAC after.
• Amp Central will automatically be recognized as an external device (like your memory stick or
hard drive for example) with “AMPCENTRAL” name;
• Double click on it, and you’ll see folders with names from 0 to 3. By clicking on each folder,
you’ll find four more folders, each one with an I.R. inside. This means a total of 16 files/folders
are available, divided into four banks with four cabinets in each bank.
•
UPDATE: From unit with s/n 23037 and higher, bank are numbered from 1 to 4 and not 0
to 3. It does not change anything in practical life, but if can be confusing.

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Let’s take a look this chart to visualize it in a very simple way:
BANK 1
CABINET 1
CABINET 2
CABINET 3
CABINET 4
BANK 2
CABINET 1
CABINET 2
CABINET 3
CABINET 4
BANK 3
CABINET 1
CABINET 2
CABINET 3
CABINET 4
BANK 4
CABINET 1
CABINET 2
CABINET 3
CABINET 4
To substitute an I.R., you simply can delete the existing one, and drag and drop or copy/paste new
one in the folder.
Remember: only one I.R. can be place into a cabinet folder. You cannot place two or more in a folder,
in that case Amp Central will not process the incoming signal.
Once you've uploaded your selection of I.R.'s, you need to eject mounted AMPCENTRAL device from
your PC/MAC as you normally would do with any another external devices, by simply clicking the
EJECT button.
FILE TYPES
AMP CENTRAL can only read 48Khz, 24bit, MONO I.R .'s
Any other attempts to upload other I.R.'s will result in no sound. We highly suggest to make a copy
of the AMPCENTRAL folders before you copy/past or substitute I.R.'s.
TIP: we experienced some know issues with very long I.R. (4-500ms).
If you do some basic math, those 20ms will guarantee you a full frequency spectrum response,
including the super low frequencies, even at 40-50hz.
There’s extreme cases where extra long I.R. (i.e. 4-500ms) are not recognized, ore better, supported by
A.C., even if 48/24 and MONO. Try to cut them around 100ms, A.C. will do the rest of the job for you.

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OUTPUTS
On the back of Amp Central there are two sets of outputs: XLR and 6.3mm jacks.
- Until s/n 22056 6.3mm jacks were unbalanced, while XLR were fully balanced;
- From unit 22057 and on, both set of outputs are fully balanced, with the only difference in form
factor, out of ease of connection. You can still connect an unbalanced instrument jack to one
or both jack outputs and run the unit with an unbalanced signal.
There’s no global output volume since the INPUT knob will act as the one and only volume for the
entire system.
Both jack and XLR outputs are separated from the line out thru an isolation transformer. You can for
example use XLR for live monitoring and record line out (to have any IR applied in a second time),
everything thru your audio interface at same time, without any ground loop or wired noise.
MIDI
Amp Central has a MIDI IN and MIDI THRU port, to remotely select any of 16 available I.R..
The first operation, is to select desired midi channel on Amp Central.
A.C. is shipped with default midi channel #1 as the default.
To change it you need to:
• press “Virtual Cabinet” knob for three seconds until BANK/CABINET leds blinks and immediately
release it;
• select your desired midi channel, by following next page’s instructions and by moving “Virtual
Cabinet” knob to left or right;
• press “Virtual Cabinet” knob again to store desired midi channel.

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MIDI CHANNEL LIST:
MIDI CHANNEL
BANK
CABINET
1
0
0
2
0
1
3
0
2
4
0
3
5
1
0
6
1
1
7
1
2
8
1
3
9
2
0
10
2
1
11
2
2
12
2
3
13
3
0
14
3
1
15
3
2
16
3
3
Following is Control Change list, you have one CC for each I.R.
Please remember, to select an I.R. on desired CC, you need to send a value equal or greater than value
64 for that desired Control Change:
Control Change
BANK
CABINET
100
0
0
101
0
1
102
0
2
103
0
3
104
1
0
105
1
1
106
1
2
107
1
3
108
2
0
109
2
1
110
2
2
111
2
3
112
3
0
113
3
1
114
3
2
115
3
3

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TROUBLESHOOTING
• Amp Central IS NOT TURNING ON
Check the voltage AND polarity first. You need a 24volts / negative center power supply.
Check the power cord; sometimes it could be loose and incapable of making good contact
with power socket. Try to replace it.
• The Amp Central IS TURNING ON BUT WITH NO SOUND
Check if your amp’s standby is off. Make sure your guitar’s volume is on 10. Be sure to have
correctly plugged in every single cable. Turn off mute from your mixer/soundcard/recording
device. Check incoming signal from A.C. led meter first, then check output signal with a led
meter from your daw/mixer.
For any problems you can contact a qualified tech at:[email protected]
We will reply to you as soon as possibile.
WARRANTY DESCLAMER
Please, do not try to open this device, in any case. For any problem contact your seller or write to us.
Any inexpert person should not even think of doing anything inside of this unit. RedSeven
Amplification offer a standard two year not transferable warranty for any component (except to wear
subjects).
By removing top piece or by making any modification to original state, you will violate the standard
warranty and RedSeven Amplification will not be responsible for any damage to people, things or
animals.
Revision 2.1
August 2023
!