Rivera Knucklehead Reverb KR 100 T User manual

Knucklehead Reverb 1.0 p 1
OWNERS MANUAL
Version 1.0
December, 2001

Knucklehead Reverb 1.0 p 2
Introduction
Your Rivera Amp Is An Important Part Of Your Sound
Your sound is your signature, your mark, your voice. An amp only deserves to have
your guitar plugged into it if it can deliver the tone you want—and, of course, the
dependability you need. It's as simple as that. And it's exactly why you bought your
RIVERA amp. For that, we thank you, and we're confident that you'll enjoy your amp for
years to come.
Many factors go into creating a great amp—experience, an understanding of what
guitarists want, and a lot of hard work. You'll notice that tone isn't on any parts list.
Roadworthiness isn't, either. And there's no law saying that an amp must sound good
or be well-made. But we dedicate ourselves to making the best-sounding, most reliable
amplifiers anywhere. That's why we use only the highest-quality components,
regardless of price. Such features as metal jacks, ultra-strong dadoed cabinet
construction, and highest-quality electronic components are part of our uncompromising
approach. They're chosen for their precision, strength, and ability to withstand the
rigors of years of use—and occasional abuse—on the stage and in the studio. No
compromises are made because cutting any corners—no matter how small—means
settling for second best. This is the premise and promise by which we make amps.
This requires dedication to you, the guitarist, and a belief that an amp is more than a
collection of parts. It's part of your sound.
Please fill in the following information for future reference:
Model Name: Knucklehead Reverb 55 or 100
Model Number: KR 55T, KR 100 T
Serial Number:
Dealer's Name:
Dealer's Address:
Date of Purchase:
Rivera Research & Development Corporation
13310 Ralston Ave.
Sylmar, CA 91342 USA
Ph: [phone]
Fax: [phone]
Email: [email protected]
Web: http://www.rivera.com

Knucklehead Reverb 1.0 p 3
Packing Information
Unpacking
Before you plug in, inspect your Knucklehead Reverb amp for any damage. Your amp
was inspected and sound-tested before shipment, but transportation can sometimes be
tough. Check that the Head Master MIDI Controller and power cord have been shipped
with the amp. If parts are missing, or if any damage has occurred, contact your dealer.
Packing Materials
We designed the original box and packing materials to protect your amp during
shipment. Save them. If you ever need to send your amp to us or to anyone else, the
original box and packing materials will ensure safe transit.
Safety
Throughout this manual, the lightning flash with an arrowhead symbol
within a triangle is intended to alert you to the presence of un-insulated
"dangerous voltages" within the product's enclosure that may be of
sufficient magnitude to constitute a risk of electric shock to persons.
Warning: There are no user-serviceable parts inside of this amplifier.
Warning: To avoid the risk of shock or fire, do not expose this amplifier to moisture. Do
not remove the chassis from its cabinet, or remove metal covers from chassis parts.
Removing the chassis from its cabinet exposes extremely dangerous high voltages.
There are no user-serviceable parts inside. Hazardous voltages are present inside the
chassis. Refer all servicing to qualified personnel.
The exclamation point within a triangle is intended to alert the user to
the presence of important operating and maintenance (servicing)
instructions in the literature that accompanies the product.
Caution: To avoid a fire hazard, always replace the fuses with the same type and
rating.
Caution: Always replace the line cord (mains supply) with the proper type.
Caution: Always turn off the amplifier before making or unplugging any speaker
connections.
Always transport your amplifier securely, preferably in a suitable flight case or packing
carton. Before operating your amplifier, be sure the speakers used are properly
connected. For countries where 220 to 240 volts AC is encountered, make sure that

Knucklehead Reverb 1.0 p 4
you have the correct power cord. Our 230-volt export unit can be used with any of
these voltages. For the United Kingdom, South Africa, Australia, and New Zealand, we
build a special 250V version able to handle higher Mains voltages. For Japan 100 VAC
models, all instructions for the 115 VAC models apply.
In the event that you have questions, comments, or suggestions, please contact us at:
Rivera Research & Development Corporation
13310 Ralston Ave.
Sylmar, CA 91342 USA
pH: [phone]
Fax: [phone]
Email: [email protected]
Web: http://www.rivera.com
No Time To Read The Manual?
At Least Read This Part Now!
Before you plug in:
Take a quick look inside the back of your amp. Make sure of the following:
The tubes are securely seated in their sockets.
A speaker cord is plugged into the Speaker 1 output (this jack must always be used
first) and the input jack on a speaker cabinet with a minimum impedance of 4 ohms.
The impedance selector is set to match the cabinet's impedance.
The power cord is plugged in.
Now look at the front to make sure:
The Volume and Master controls are set at low levels ('2' is a good starting point).
The Power switch is off (the lower half is pushed in).
The Standby switch is set to standby mode (the lower half is pushed in).
Plug in!
Now plug the amp into the wall, plug your guitar into either input jack, and set your
controls to one of the Quick Start settings outlined here. Then turn on the Power
switch. Wait for about a minute for the tubes to warm up. Turn on the Standby switch.
Now it's time to rock.
After you've played with your Knucklehead Reverb for a while, check out the rest of the
manual for some good tips on getting the most out of your amp.

Knucklehead Reverb 1.0 p 5
Quick Start Settings
If you're looking for a good starting point, try these settings. Remember that every
guitar and speaker cabinet sounds different, so try both inputs, and adjust the Focus
and Presence to suit your taste. These diagrams include settings for the Subwoofer. If
the Sub is NOT used, set the SUB LEVEL to 1 and PUSH it in.
Paul Jr's Settings – Use High Gain Input
BOOST
PUSH PUSH PULL
PULL
BOOST SCOOP
MASTER 2
MASTER 3
HI-PASS
POWER AMPLIFIER
PRESENCE FOCUS
SUB LEVEL
TREBLE MIDDLE
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PUSH PUSH PUSH PUSH PULL PULL PULL
BOOST
PULLED
PULLED
PUSHED PUSHED
MIDDLE
TREBLE
GAIN
NOTCH
BRIGHT
CONTOUR CHANNEL 1
MASTER BASS
CHANNEL 3 CHANNEL 2
BASS GAIN GAIN
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Web Guy Craig's Settings – Use Low Gain Input
BOOST
PUSH PUSH PULL
PULL
BOOST SCOOP
MASTER 2
MASTER 3
HI-PASS
POWER AMPLIFIER
PRESENCE FOCUS
SUB LEVEL
TREBLE MIDDLE
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PUSH PUSH PUSH PUSH PULL PULL PULL
BOOST
MIDDLE
TREBLE
PULLED
PULLED
PULLED
PUSHED
PUSHED PUSHED
GAIN
NOTCH
BRIGHT
CONTOUR CHANNEL 1
MASTER BASS
CHANNEL 3 CHANNEL 2
BASS GAIN GAIN
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Knucklehead Reverb 1.0 p 6
Clean Deluxe – Use Low Gain Input
PUSH PUSH
PULL PULL PULL
BOOST
PULLED
PULLED PULLED
PULLED
MIDDLE
TREBLE
GAIN
NOTCH
BRIGHT
CONTOUR CHANNEL 1
MASTER BASS
1
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PULL
HI-PASS
POWER AMPLIFIER
PRESENCE FOCUS
SUB LEVEL
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Austin Blues – Use High Gain Input
PUSH PUSH
PULL PULL PULL
BOOST
MIDDLE
TREBLE
GAIN
NOTCH
BRIGHT
CONTOUR CHANNEL 1
MASTER BASS
1
2
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PULL
HI-PASS
PULLED PUSHED
POWER AMPLIFIER
PRESENCE FOCUS
SUB LEVEL
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80's Scoop – Use High Gain Input
PUSH PULL PUSH
PULL
BOOST SCOOP CHANNEL 2
MASTER 2
HI-PASS
POWER AMPLIFIER
PRESENCE FOCUS
SUB LEVEL
TREBLE MIDDLE BASS GAIN
1
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PULLED PUSHED
Fast Aggressive – Use High Gain Input
BOOST
PUSH PULL PUSH
PULL
SCOOP CHANNEL 3
MASTER 3
HI-PASS
POWER AMPLIFIER
PRESENCE FOCUS
SUB LEVEL
TREBLE MIDDLE BASS GAIN
1
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PULLED PUSHED

Knucklehead Reverb 1.0 p 7
New Metal Crunch – Use High Gain Input
BOOST
PUSH PULL PUSH
PULL
SCOOP CHANNEL 3
MASTER 3
HI-PASS
POWER AMPLIFIER
PRESENCE FOCUS
SUB LEVEL
TREBLE MIDDLE BASS GAIN
1
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PULLED
Lead – Use High Gain Input
BOOST
PUSHED
PULLED
PUSH PULL PUSH
PULL
SCOOP CHANNEL 3
MASTER 3
HI-PASS
POWER AMPLIFIER
PRESENCE FOCUS
SUB LEVEL
TREBLE MIDDLE BASS GAIN
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Front Panel
BOOST
CH.1
PUSH PUSH PULL PUSH PUSH PUSH PUSH
PULL PULL PULL
PUSH
PULL
BOOST SCOOP
BOOST
MIDDLE
TREBLE
GAIN
NOTCH
BRIGHT
CONTOUR CHANNEL 1
INPUTS
HIGH
GAIN
LOW
GAIN
MASTER BASS
CHANNEL 3 CHANNEL 3
MASTER 2
MASTER 3
HI-PASS
POWER AMPLIFIER
PRESENCE
POWER
STANDBY
HANDCRAFTED BY
SYLMAR, CALIFORNIA USA
RIVERA RESEARCH & DEVELOPMENT
FOCUS
REVERB REVERB
CH.2/3
SUB LEVEL
TREBLE MIDDLE BASS GAIN GAIN
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High Gain input
This is a high-sensitivity input. If your guitar has hot pickups, then plugging into it
makes it easy to overdrive the preamp section, creating harmonic distortion. Guitars
equipped with low-output pickups seem hotter than usual when plugged into this input.
Low Gain input
This is a low-sensitivity input. Guitars plugged into it have more headroom before
distortion sets in (meaning that you can crank up a channel's volume a little louder
before you experience Preamp distortion). This is a good choice for a clean overall
sound, and is especially well-suited to active pickups or guitars equipped with preamps.
Channel 1
Channel 1 is extremely flexible, with a flavor that brings to mind the great classic
American tones and textures. You can get some pretty impressive blues overdrive
distortion out of Channel 1, and as a rhythm channel it brings out every subtlety of your
playing. The range of tones can be anywhere from sparkling-clean to perfect for bluesy
rhythm—the kind of sound that has an attitude and gets meaner as you pick harder.

Knucklehead Reverb 1.0 p 8
Gain (with channel-select Push-Switch)
The Gain knob regulates the Preamp's volume and works with the Master to set the
level and distortion amount. A simple rule of thumb is, the higher the Gain is set, the
more distortion you get.
Treble (with Pull Bright switch)
This Treble control is similar in operation to the one on Channel 2/3. In addition, it has a
built-in Pull Bright switch. When pulled out, it adds bright highlights to the tone. As the
Gain control is increased past about '5', the bright switch's effectiveness will be
decreased.
Middle (with Pull Notch switch)
The midrange circuit has a slight notch in the frequency spectrum at about 550 Hz, and
turning the knob alters the depth of that notch. Its Pull Notch switch shifts the frequency
center of that notch down to about 250 Hz. (For reference, most 1950s tweed amps as
well as many British amps have their notch centered at 550 Hz, while classic
"blackface" American amps have theirs centered at 250 Hz.). Experiment with this,
especially if you're looking for a uniquely expressive rhythm texture.
Bass (with Pull Contour switch)
The "chunk" and support that form the backbone of your tone come from this control.
Pulling the Bass control out will engage a special "Contour" circuit thereby enhancing
bottom end, especially useful with thin sounding guitars where more bottom end is
required for a great comping tone. Also, when using a singled coil guitar for a jazz or
bebop tone, this control will add the needed fatness to the lower strings.
Master (with Push Boost switch)
Channel 1 has a special EQ circuit that works in conjunction with the distortion circuit to
sweeten the tone. Therefore, the Master knob's effect goes beyond loudness control.
Try it with different Gain and Middle settings to adjust the amount of "singing" and "grit".
The Boost, activated by pushing the Master knob, is a sweet-sounding boost
characterized by a more subtle effect on the harmonics than Channel 2's Boost control
while adding sustain. The Ch.1 Boost helps to drive the power amp, and the best
description of its influence over the tone is that it thickens it.
Channel 2
All three channels are voiced differently, and Channel 2 is definitely geared toward
creating impressive and massive crunch and lead tones (think of it as a great "British"
tone). Grit, grunge, dirt—whatever you're looking for in the distortion department is
here, from sweet and singing to hard-driving to maximum sustain. Note: Like the
controls on all classic amps, the Treble, Middle, and Bass interact, creating smooth,
musical tone changes. All three controls operate with even response throughout their
ranges. This amp has so much potential gain and sustain, you should not assume that
the Gain controls should be set on a typical '10' to start with. You might try 3-5 as a
starting point. This is also applies to Channel 3.

Knucklehead Reverb 1.0 p 9
Gain (with channel-select Push-Switch)
Although it's labeled "Gain," this control does a lot more than determine how loud
Channel 2 is. It regulates the Preamp's volume and works with the Master to set the
level and distortion amount. A simple rule of thumb is, the higher the Gain is set, the
more distortion you get. The push switch selects which channel is active. Its circuitry is
designed so that you don't hear a loud pop or click when the channel is changed.
Bass
The "chunk" and support that form the backbone of your tone come from this control.
Its effect on your overall sound will be different at high and low volumes due to the
speaker's characteristics and how much distortion you use. The bass EQ curve has
been specially tailored to complement the maximum bass response of the RIVERA
Knucklehead 412-Cab (T/B) speaker enclosures.
Middle (with scoop Pull-Switch)
The midrange circuit provides the "meat" that fills out your sound. Two notch
frequencies are available-550Hz (when pushed in), and 750 Hz (when pulled out).
Notch is the hinge point of the Bass and Treble controls. Think of it as a valley between
two mountains on a graph. Turning the knob alters the depth of that notch, letting you
dramatically change the overall voicing of your tone. Vintage Tweed and Plexi British is
typically at 550 Hz. Modern lead sounds are often EQ’d in the studio to 750 Hz dip.
Adjust to your taste.
Treble
Whether you're looking for edge, slash, or just a little shimmer, this knob's for you. Like
the Bass control, the apparent effect of the Treble changes with the loudness and
distortion you dial in.
Master (with Push Boost switch)
Think of the Master as a sort of governor that sets the maximum loudness for the
channel. Also, think of it as the second half of what the Gain knob does. With the Gain
turned down and the Master up, there's less distortion than if you crank up the Gain and
set the Master lower. The Master control comes after all distortion and tone-shaping on
Channel 2, so its level doesn't have a bearing on your basic tone. When you push the
Boost switch on Channel 2, it adds a whole range of harmonics, and not just gain. This
is easy to hear by playing a power chord and comparing its sound with the switch
pushed in and pulled out. With the switch activated, the tone blooms, going from fat to
ferocious.
Channel 3
Channel 3 shares the EQ with Channel 2, but is a different texture of distortion and gain.
A extra section of a Preamp Tube is switched into the circuit for Channel 3. Identical in
controls, EQ, and features, it's difference lies in it's internal circuitry and distortion
textures. Different music can at time require a different fabric of harmonics and
textures. Many players have said that the tone is more greasy and more hard-core.
Like Channel 2, all of the descriptions of the features and the instructions for their usage
apply. Because of the extra tube stages involved in the circuits, the attack and
compression response also differs from Channel 2. Just try it and you will hear.

Knucklehead Reverb 1.0 p 10
Sub Level Output (with high pass Pull-Switch)
This control is a RIVERA exclusive feature. This control varies the output level of the
Sub Woofer output circuitry the feeds a full range low source impedance signal to Sub
Woofer Output jack (see rear panel features) to an external Powered Sub, like our Sub
1 or Sub 2 powered Sub Woofer cabinets. It also can be used as an Auxiliary Send to a
Mixer, Recorder, PA System, and a sub-Woofer system that utilizes it’s own electronic
crossover and separate power amp, like our Rivera LB-212 Sub Cab and a Rivera TBR-
5, 320W Power Amp (requires a separate non-Rivera made electronic crossover). This
signal is dry, meaning any signal present in the effects loop return, will not be in the
signal stream from this jack. The internal power amp of the Knucklehead Reverb is
normally a full range signal, with all of the frequencies of the amplifier powering the
Speaker Output jacks. When the Sub Level control is pulled, a high pass filter
frequency dividing network is activated, with the internal power amp only reproducing
the frequencies higher than the frequencies that the Sub 1 or Sub 2 powered Sub-
Woofers are optimized for. This gives you an increase in dynamic range and definition
of the normal speakers connected to the Knucklehead Reverb. This is because they no
longer have to handle the fatiguing low frequency energy. This switch was provided for
players to have a choice in tones, or to be able to use the Knucklehead Reverb without
a subwoofer speaker system.
Focus
This control is another RIVERA exclusive that actually lets you change the speaker's
response characteristics, from tight to loose. The effect can give closed-back cabinets
a sound more akin to an open one, and vice-versa, plus you can "custom blend" the
amount of hardness your final sound has. This function is independent of the use of the
Sub Woofer Output, and even with the Sub Level control pulled, it will continue to affect
the Knucklehead Reverb speaker output damping.
Presence
The Presence control is incorporated as a vital part of the power amp section. Think of
it as a final brightness control after all the EQ, distortion and effects.
Standby
By turning the Power on and the Standby off (the down position, labeled with a '0'), you
can warm up the amplifier before applying full voltage to the Preamp and power output
tubes. This prolongs tube life. Using the Standby switch when you're taking a break
also helps to extend the tubes' life, plus it keeps the amp constantly at the ready. Just
flip the Standby switch to the up ('I') position, and you're ready to play.
Power
This is your main power switch. The on position is indicated by the light being
illuminated. The off position is marked by the "0" on the switch. Before turning the amp
on, always check that a speaker is connected and that the power cord is firmly plugged
into the amp and the outlet.

Knucklehead Reverb 1.0 p 11
Rear Panel
RETURNSEND
SEND
LEVEL
CAUTION: NO USER SERVICEABLE PARTS INSIDE.
REFER SERVICINGTO QUALIFIED PERSONNEL.
Z OUT
560 ΩZ OUT
560 ΩZ OUT
560 ΩTOTAL
MIN. Z 4 Ω
Z IN
250K Ω
RETURN
LEVEL IMPEDANCE
SELECTOR
SPEAKER 2
HIGH
LOW
SERIAL NUMBER
CAUTION: CHASSIS SURFACE HOT.
POWER CLASS
VINTAGE / MODERN
MODEL KNUCKLEHEAD REVERB
TO REDUCETHE RISK OF ELECTRIC
SHOCK, DO NOT REMOVECHASSIS
RIVERA RESEARCH & DEVELOPMENT CORP. SYLMAR, CA,USA 91342
100W. RMS
SPEAKER JACKS
IN PARALLEL
SPEAKER 1
USE FIRST
H.T.
FUSE
OUTPUT
POWER
MAINS
FUSE
MAINS INPUT
115V 60Hz INPUT
POWER
440 WATTS
Patents
Applied for.
1A 250V
SLO-BLO
4A-250V
SLO-BLO
REPLACE FUSEWITH SAME
TYPE AND RATING.
RECORDING
OUTPUT
SUB OUTPUT
LOOP BLEND
PUSH LOOP
EFFECTS LOOP
MIDI
CHAN
SELECT
MIDI
OUT/THRU MIDI IN RIVERA MIDI PEDAL ONLY
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CAUTION
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16
F
U
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S
E
MIDI Connectors
CAUTION: NO USER SERVICEABLE PARTS INSIDE.
REFER SERVICINGTO QUALIFIED PERSONNEL.
MIDI
CHAN
SELECT
MIDI
OUT/THRU MIDI IN RIVERA MIDI PEDAL ONLY
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MIDI THRU
Standard MIDI thru, passes data from the MIDI IN to additional MIDI gear.
MIDI IN
Standard MIDI input. Use this to connect any standard MIDI controller.
Special Combo MIDI In And DC Power Out
This connector is labeled "RIVERA MIDI PEDAL ONLY"
On earlier versions of the Knucklehead, this connector is labeled "FTSWITCH FS-9
ONLY". (The original name for the Head Master was the FS-9). The function is exactly
the same, only the label is different.
In addition to being a standard MIDI IN, this connector ALSO provides DC power to the
Head Master.
Even though the MIDI connector has 5 pins, only 3 of them are used. The other two are
undefined by the MIDI specification and unused by most MIDI gear. The Knucklehead,
and all future Rivera MIDI enabled amps, provides DC power on these pins.
Warning: This connector should ONLY be used to connect the Head
Master or other Rivera MIDI pedal. There is no agreement among
manufacturers on the use of these two pins. Some manufacturers also
use them to provide power, but it may be a different voltage or polarity.
If you plug a cable from the special Combo connector into another
device, and that device ALSO uses these pins , BOTH devices may be damaged!

Knucklehead Reverb 1.0 p 12
Midi Cables For The Special Combo Connector
Even though the MIDI specification only defines three pins, most manufacturers of MIDI
cables provide all five wires. This means that most normal MIDI cables will work
correctly in the special connector. However, if you find a MIDI cable that only has 3
wires, it will not work.
A Few Thoughts On Non-Standard Connectors
When we designed the Head Master, we faced a difficult decision. We wanted to supply
power to the pedal from the amplifier using one cable for both power and MIDI. We then
had two choices - Use a standard MIDI connector in a non-standard way, or use a non-
MIDI connector.
If we had used a non-MIDI connector, the unit would have been more foolproof. The
special combo MIDI and Power connector could ONLY be connected using the special
cable. There would be no way to hook it up incorrectly.
But then we thought about the poor guy on the road, far from a well-stocked music
store. If his special cable failed, he would be out of luck. We decided to use a standard
MIDI connector and cable in a non-standard way because it is very easy to find a
replacement.
Of course, the downside of this decision is that it is possible to connect our non-
standard connector to a standard MIDI connector. If the MIDI device only uses the three
standard pins, there will be no problem. However, some manufacturers have also used
the two extra pins for their own special non-MIDI functions. We believed that if we
warned the users to hook up the cables according to the instructions, they would accept
this tradeoff.
The Two Midi Inputs Are Not A Midi Merger!
The Knucklehead has two MIDI inputs - one regular MIDI IN and a special Combo MIDI
IN and DC Power Out.
The special Combo connector is used with the Rivera Head Master.
The standard MIDI IN is used with other MIDI controllers.
WARNING: DO NOT USE BOTH INPUTS AT THE SAME TIME!
The Knucklehead DOES NOT contain a MIDI MERGE function!

Knucklehead Reverb 1.0 p 13
The Midi Channel Selector Switch
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The Knucklehead uses a rotary switch to select the MIDI channel. It is a high quality
switch, and is much easier to use than the DIP switches used by some manufacturers.
Unfortunately, it is numbered in a way that can create confusion.
As shown on the diagram, the switch is numbered from 0-15.
Most MIDI devices define the MIDI channels as 1-16
So, it is necessary to add 1 to the number on the switch to get the MIDI channel
SWITCH POSITION 5 = MIDI CHANNEL 6
So, why is the switch labeled wrong?
In the world of electronics and programming, it is not labeled wrong.
It selects one of 16 four digit binary numbers, 0-15 is 0000-1111 in binary.
It is labeled correctly for what it does.
Internally, MIDI gear uses channels 0-15.
Long ago, MIDI manufacturers decided that musicians would be uncomfortable.
with channel zero, so they decided to add a 1 to the actual value.
Counting From Zero
As you may or may not know, computer programmers start counting from zero instead
of one.
Most people would count a list of items like this:
One, two, three, I have three items.
A programmer would do the same if he was counting the items, but if he was using
numbers as names he would name the first item "item number zero," the second would
be called "item number one" and the third "item number two." Programmers call this
process enumerating the items.
Why do programmers do this?
Here is an example:
If you are standing in front of your house, how far do you have to walk to get to your
neighbor? You have to walk ONE house unit away.

Knucklehead Reverb 1.0 p 14
How far do you have to walk to get to your OWN house? Since you are already standing
in front of your house, you have to walk ZERO house units away.
Zero is the starting point, you move from zero some number of units.
Programmers frequently deal with lists of things. The same logic applies to these lists. If
you are looking at the first item in a list, how far do you have to move to look at the
second? You have to move ONE unit.
How far do you have to move to look at the first item? Since you are already looking at
it, you move ZERO.
Another way of looking at it is to ask the question, "How many single digit numbers are
there?" There are 10. They are: 0, 1, 2, 3, 4, 5, 6, 7, 8 and 9. You don't get to the
number 10 until you add another digit. Programmers can't afford to be wasteful, they
use ALL of the digits, especially zero.
This is also the root of the controversy over the year 2000. If you start counting at zero,
2000 is the millennium.
MIDI is a computer communication protocol, and internally, it starts from zero.
MIDI Channels are actually numbered 0-15 and Program Changes are numbered 0-
127.
But, since most people are not comfortable counting from zero, MOST MIDI instruments
add an extra one and define MIDI Channels 1-16 and Program Changes 1-128. NOT
ALL MIDI instruments do this!
We debated long and hard over which philosophy to adopt. In the end we chose to
follow the de-facto standard and number from one. We believed that this decision would
result in less confusion and fewer problems.
One problem we could not avoid was the numbering of the Knucklehead MIDI Channel
Selector switch. The manufacturer of the switch numbered it from 0-15. These are in
fact the actual numbers the switch uses. We had no control over the labeling.
The unfortunate result of this mismatch is that you have to set the Knucklehead MIDI
Channel Selector Switch to 0 to select MIDI Channel 1.
Series-Parallel Effects Loop
Of course, you can use pedals and rack-mounted effects between your guitar and the
amp. In fact, that's where most wah-wahs, compressor-sustainers, distortion stomp
boxes and other pedals sound exceptionally good. However, rack signal processors are
often best suited to being placed after the Preamp's tone-shaping circuitry. Your
Knucklehead Reverb's Effects Loop is designed to give you the best match between the
amp and the processor by allowing you to set the level of the signal going to the effect,
as well as the one coming back. Therefore, you can tailor your amp/effects levels for
best signal-to-noise ratio and the amount of effects signal you want to blend in.
Note: The Effects Loop send can also be used to route a signal to a guitar tuner,
recording mixer, another guitar amplifiers effects loop return, etc.

Knucklehead Reverb 1.0 p 15
The Effects Loop comes after the Preamp section. In addition, it's low-impedance
circuitry lets you drive everything from the simplest stomp-box effect to the most
sophisticated pro signal processor with excellent results. It's also fully buffered,
meaning that it can drive long cords and line-level gear and mixing consoles. (Because
the signal is electrically unbalanced, you can use an unbalanced-to-balanced output
transformer to connect to equipment requiring a balanced input.) By having a Blend
control, you can adjust your effects devices for 100% wet signal, then adjust the Blend
control for the desired amount of effects. This "Parallel" feature allows the least amount
of amplifier signal deterioration potentially caused by the effects signal chain. If the
Blend controls is set for 100% Loop, the loop can now be considered "Serial".
Before you connect a signal processor to your amp, either turn the amp off or to
standby. Use high-quality shielded cords between the amp and processor. Never use
a speaker cord.
Setting Effects Loop levels
1. After you connect the amp's Send and Return with the signal processor's input and
output, set the amp's Send Level and Return Level between 1 and 2, and the Blend
control on 10.
2. Plug in your guitar, turn the signal processor on, and then turn on the amp (or flip the
standby switch). Turn on the Effects Loop by pressing the Blend control.
3. Set the amp's Effects Loop Send Level and the signal processor's input level so that
you don't overload the processor. Keep your ears open for unwanted distortion from
the signal processor (you'll know it by its crackly, unmusical sound). Whack a few
chords on your guitar to check that your settings are correct.
4. Now turn up the Effects Loop Return knob until the proper volume and overdrive are
dialed in. You'll probably have to experiment with the signal processor's output level
until you get the best sound and lowest amount of noise. Adjust the Blend control
for the desired amount of effect.
5. Make sure that you consider the straight/effects blend at the signal processor, since
all of your Knucklehead Reverb Preamp's signal is passed through the Effects Loop
in series mode (Blend at 10 or 100%-Serial). You may use an effects-only output to
return from the processor to the amp, utilizing the Blend control for 0-100% wet
signal. You may also use the "mix" output, if the unit has one, adjusting the mix on
the effects processor to suit your taste. Note: If delay sounds such as slap echo,
reverb, and repeat delay will be your primary choice of effects, usually a 100% wet
mix from the effects should be used.
6. The Effects Loop Send is configured so that it is always active, so you can use it as
a variable output. Note that if you use the Send to drive slave amps, etc., and have
nothing plugged into the Return jack, the signal still passes from the Preamp to the
power amp even when the Effects Loop is bypassed.

Knucklehead Reverb 1.0 p 16
Sub Woofer Output Jack
This jack is primarily designed to drive a powered subwoofer. The signal produced at
this jack has all of the EQ from the preamp, but NO effects. Its level is controlled by the
SUB LEVEL control on the front panel. It is NOT low-pass filtered! It provides the Full-
Frequency signal to the subwoofer, the subwoofer must handle any low-pass filtering.
This is not a speaker output, so never connect it to a speaker jack and always use a
shielded cable when connecting it to an external power source.
Recording Output
The RECORDING OUTPUT is primarily designed to connect the amp to a Mixer or
Recorder. The Recording Out is equalized and calibrated internally, so every bit of tone
from your Preamp, and effects (if used) is sent from this jack. Although the recorder or
mixer doesn't receive the tone that comes from the speaker or the power amp section, it
does receive all of the signal from every other stage of the Preamp, and for live-
performance recording it does an excellent job of isolating your guitar sound. By
switching the Standby switch “Off”, you will be able to utilize the entire Preamp section,
including the Recording Output. This means of course that when the Standby if “Off”,
there will be no sound coming from the Speaker Outputs. This is perfect for silent
recording, or when multiple s are used and you only want one or two of them to power
speaker cabinets.
Warning:Do not connect the Recording Out to speakers or
headphones. For further information, refer to the hookup
diagrams for proper connection.
Driving Other Amplifiers
Although there is no specific SLAVE AMPLIFIER OUTPUT, There are several choices
available for driving another amplifier as a slave.
If you are not using an effect in the Effects Loop, you can use the EFFECTS SEND, it
provides a signal from the Preamp Post-EQ and Post-Reverb.
If you are not using a subwoofer, you can use SUB OUTPUT. It is the same as the
Effects Send, except it is controlled by a different knob.
If you want the second amp to have Effects, use the RECORDING OUT. It is Post-EQ,
Post-Effects and Post-Reverb. Its level is fixed.
Impedance Selector
Set the Impedance Selector to match the impedance load of your cabinets. Here's how:
4-ohm setting = One 4-ohm cabinet or two 8-ohm cabinets (one plugged into each
speaker output).
8-ohm setting = One 8-ohm cabinet or two 16-ohm cabinets (one plugged into each
speaker output).
16-ohm setting = One 16-ohm cabinet plugged into the Speaker 1 jack

Knucklehead Reverb 1.0 p 17
Warning: The Knucklehead is designed and rated to drive loads of 4
ohms and greater. If you use a speaker combination whose impedance
is between 2 and 4 ohms, the amplifier may overheat.
UNDER NO CIRCUMSTANCES ever use a load lower that 2 ohms!.
Warning: Loads that are not matched properly may harm your amp. If
you aren't sure if your speaker load is correct, contact your RIVERA
dealer, or call RIVERA Customer Service. If unequal speaker cabinets
loads, i.e. a 4 ohm cabinet and an 8 ohm cabinet are used together,
unequal amounts of power may be distributed to these cabinets.
Speaker outputs
A speaker must always be connected to your amp. The amp is designed to deliver
at least 55 or 100 watts to a 4-16 ohm speaker load (with the Impedance selector
appropriately set to match the given load). If it has to drive speaker loads lower than 2
ohms, its output transformer or other components could be damaged. You can use 8-
or 16-ohm extension cabinets, either alone or in pairs (one into each speaker output). A
2-ohm speaker cabinet alone or a pair of 4-ohm extension speaker cabinets together
can be used, however, it is not an optimum match, and the Impedance Selector Switch
must be set at it's lowest setting, 4 ohms. The only time you may run the amp without a
speaker connected is if you have a proper "dummy" impedance load box plugged into
the speaker output, or of the Standby Switch is in the down or Off position. Using a
dummy load protects the output transformer, but prolonged use shortens the life of the
amp's output tubes. Always use a heavy-gauge speaker cord. The larger the diameter
of the wire, the lesser of power to be lost. A shielded guitar cord can't handle the power
that your amp provides, and therefore won't sound right—plus it may actually harm your
amp. Refer to the connection diagrams for further information.
Warning: Never use a speaker output to connect directly to the input of
a mixer, a tape recorder, a slave amp, or headphones. For further
information, refer to the hook-up diagrams for proper connection with
extension speaker cabinets.
Vintage-Modern switch
Switching amongst the two settings will produce a change of output power as well as
harmonic balance. In Modern mode, the output power amplifier operates in "Pentode"
and will sound the cleanest, have the most headroom, and sound bright, with odd
harmonics (i.e., 1,3,5,7, etc.) more noticeable. Vintage mode brings the output tubes to
work in "Triode" mode, halving the power selected by the High-Low power switch, and
lowering the odd harmonics while raising the even (2,4,6,8, etc.) resulting in a sweeter,
darker tone.

Knucklehead Reverb 1.0 p 18
Power Output switch
Between the use of the High Power/Low Power positions in combination with the use of
the Vintage-Modern Switch, 4 different output voltages can be accessed:
100 Watt Versions
Power Output Modern Vintage
High 100W 50W
Low 25W 12W
55 Watt Versions
Power Output Modern Vintage
High 55W 30W
Low 12W 8W
The actual high voltages as well as the bias voltage is changed when switching
between High and Low Power setting. The amp may be on, but does not play or feed
signal at the moment that you switch. A thumping noise can be heard through the
speakers and this is normal.
HT Fuse
The power amplifier circuit has its own fuse for protecting the output section from short
circuits and transient current peaks that exceed the normal current draw. These
conditions are usually caused by a bad tube. When a short circuit or transient peak
causes the fuse to blow, the output tubes should be checked and replaced, if
necessary.
For 100VAC and 115VAC 55 versions, the HT Fuse is:
1/2 Amp, 250 Volt Slo-Blo type (3AG, or MDL).
For the 100 versions, the HT Fuse is
1 Amp, 250 Volt Slo-Blo type (3AG, or MDL).
For 230/250 VAC 55 versions, the HT Fuse is:
T 1A (time-delay, 5mm x 20mm size).
For 100 Versions, the HT Fuse is:
T 500 Ma (time-delay, 5mm x 20mm size).
Note: Repeated blowing of the HT fuse is a clear indicator of a defective
output tube. Always use the correct fuse value when replacing the HT
Fuse.

Knucklehead Reverb 1.0 p 19
Mains Fuse
This AC line fuse protects your amplifier from damage due to shorts, momentary
surges, and defective power tubes. In the event of a fuse failure, always replace it with
the same type of fuse.
For 100VAC 55 versions, the Mains Fuse is:
3 Amp, 250 Volt Slo-Blo type (size 3AG, or MDL).
For 100 versions, the Mains Fuse is:
5 Amp, 250 Volt Slo-Blo type (size 3AG, or MDL).
For 115VAC 55 versions, the Mains Fuse is:
3 Amp, 250 Volt Slo-Blo type (size 3AG, or MDL).
For 100 versions, the Mains Fuse is:
4 amp, 250 Volt Slo-Blo type (size 3AG, or MDL).
For 230/250VAC 55 versions, the Mains Fuse is:
T 1.6A (time-delay, 5mm x 20mm size).
For the 100 Versions, the Mains Fuse is:
T 2A (time-delay, 5mm x 20mm size).
Warning: If the Mains Fuse or the HT Fuse repeatedly blows, refer your
amp to your local RIVERA dealer or contact us at [phone] for
further service assistance.
Note: Always turn the amp off and wait about five minutes before
replacing a fuse. This allows the parts to cool and high voltages to
dissipate.

Knucklehead Reverb 1.0 p 20
Mains Input
Your Knucklehead Reverb has a detachable power cord that connects to the chassis
AC connector labeled Mains Input. Always use this cord and, in the event that the
power cord requires replacement, replace it with the same type of power cord. Consult
your RIVERA dealer for further information. Be sure to use a grounded electrical mains
power supply socket whenever possible. These outlets have a grounding pin in addition
to the normal line and neutral pin. The power cord supplied with your Knucklehead
Reverb has a 3-pin plug. Do not cut off or damage the ground pin. If the available
electrical outlet is of the older 2-pin type, use a suitable ground-lift adapter.
The U.S.A., Canada, and Japan share a common CSA/UL-style cord. Most of Europe
and Scandinavia utilize a Euro plug and have a SEMKO/VDE-style cord. Australia uses
a different type of plug, as does England, and South Africa as well.
Note: Avoid using long power extension cords. Long cords have
sufficient resistance to electrical current that the voltage arriving at your
amp can be significantly reduced. This can have a bad effect on your
tone.