Ceriatone Overtone Special User manual

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Ceriatone
Overtone
Special
S&M Edition
50W and 100W amplifiers

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User’s Manual
Thank you for the purchase of your Ceriatone Overtone Special guitar amplifier!
Here, we hope to explain how best to use your new amp.
Table of Contents
1) About the S&M Overtone Special………………………………………..…………………………………………page 2
2) Quick setup……………………………………………………………………………………………………………page 3
3) Front Panel controls………………………………………………………………………………………………….page 4
4) Rear Panel controls…………………………………………………………………………………………………..page 7
5) Tube compliment and external bias jacks and adjustment………………………………………………………page 10
6) Frequently Asked Questions………………………………………………………………………………………...page 14
1) About the Overtone Special S&M Edition 100W and 50W amplifiers
The release of our Overtone series of amplifiers has been overwhelmingly popular, and the support of customers such as you
has instigated the release of currently 8 different versions within the series. In addition, we have released the Klein-ulator and
C-lator effects loop interfaces specifically for use with our Overtone amplifiers. We have been pleased to provide many players
access to our unique take on these legendary amplifiers.
This particular incarnation of the OTS amplifiers, the S&M edition, is the result of our direct collaboration with international
guitarists Sami Marttila and Marin Debelic. They both enjoyed their OTS amplifiers, but yearned for a slightly brighter overdrive
tone that had extended upper harmonic content and the ability to add even more sparkle to their clean tones. We delivered,
and the result is a non-HRM, high plate OTS amplifier with a slightly more stinging, coarse overdrive tone, and a more
traditional clean tone.

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While our work could not have been possible without the gracious information shared over the last decade in the public domain,
we hope you appreciate our modifications, component selection, and construction techniques. Most of all, we hope the OTS
becomes an integral part of your tone equation to exhilarate your playing and music.
Rock on!
-Nik Azam
2) QUICK SETUP (for instant gratification)
1) Plug your guitar using a 1/4” instrument cable into the NOR input on the lower left of the front panel
2) Plug a suitable power cable from the OTS’s rear panel MAINS cable inlet to your wall power receptacle
3) Plug the OTS into your speaker cabinet using 1/4” speaker cable
4) Set the IMPEDENCE selector to the match the impedance of your speaker cabinet
5) Plug the footswitch cable into the FOOT PEDAL jack on the rear panel of the amplifier
6) Set the OD and PAB switches on the rear panel in the PEDAL position
7) Set all rotary controls on the front panel to 12:00 (clock face)
8) Turn POWER AMP MASTER control to about 9:00 (clock face)

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9) Set front panel BRIGHT and MID BOOST switches in the down position
10)Set front panel ROCK / JAZZ switch in the up position (ROCK)
11)Set rear panel MAINS switch in the ON position (with adjacent switch to STANDBY) for 30 seconds to allow tube
filaments to warm up
12)Set rear panel OPERATE / STANDBY switch to OPERATE
13)ROCK!!!!!!
3) FRONT PANEL CONTROLS
On the front panel of the S&M Overtone Special, you can see thirteen items of interest.
From left to right:
1) INPUT ¼” instrument jacks (FET and NOR)
2) VOLUME control
3) BRIGHT two-way toggle switch
4) MID BOOST two-way toggle switch
5) ROCK / JAZZ two-way toggle switch
6) TREBLE control

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7) MIDDLE control
8) BASS control
9) LEVEL (OVERDRIVE) control
10)RATIO (OVERDRIVE) control
11)MASTER (POWER AMP) control
12)PRESENCE (POWER AMP) control
13)INDICATOR LED
INPUT jacks provide two tonal options. First, FET routes your signal through a high-input impedance, low-output impedance
JFET gain stage before hitting the first triode tube stage. Originally, the FET input was designed for piezo pickups without an
onboard preamplifier. Since then, it has provided players a unique option for fine-tuning their tone. Second, NOR is a typical,
1megaohm input impedance as seen on most guitar amplifiers. In most circumstances, NOR will provide the best results in
clean and overdrive modes.
VOLUME adjusts the signal strength coming out of the tonestack, and going into the second tube stage. Think of this as a gain
control primarily for your clean channel, but note it will impact the overdrive mode as well.
BRIGHT is a high-frequency boost that can be used to add sparkle to your tone in both clean and overdrive modes. This high
frequency boost is more prominent as VOLUME is turned down. With the toggle switch in the UP position, BRIGHT is on. In
the DOWN position, BRIGHT is off.
MID BOOST is a midrange-frequency boost. You can use this to add fatness to your clean or overdrive tones, or even make
single coil guitars sound thicker and less scooped. We particularly like MID BOOST with the overdrive mode. With the toggle
switch in the UP position, MID BOOST is on. In the DOWN position, MID BOOST is off.
ROCK / JAZZ adjusts the overall frequency response and voicing of the amplifier. ROCK has a fatter midrange and a deeper,
spongier bottom end. You might find ROCK more familiar territory. JAZZ tightens up the bottom end and adjusts the contour of

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the midrange, giving the amplifier more of a hi-fi response. Experiment with both, as great sounds rest in each. With the toggle
switch in the UP position, ROCK is on. In the DOWN position, JAZZ is on.
TREBLE adjusts the high frequency response for both clean and overdrive modes. At near-maximum settings, you may also
notice an increase in gain.
MIDRANGE adjusts the mid frequency response for both clean and overdrive modes.
BASS adjusts low frequencies in your amplifier for both clean and overdrive modes.
LEVEL (OVERDRIVE) adjusts the amount of gain, and in turn distortion in the overdrive mode.
RATIO (OVERDRIVE) serves a sort of volume control for the overdrive channel. However, just like this version of the original
amplifier, there are not individual master volume controls for the clean and overdrive channels. Instead, the RATIO control
serves to balance out the volume of the overdrive channel with the clean channel.
MASTER (POWER AMP) sets the overall volume of your amplifier.
PRESENCE (POWER AMP) adjusts the high frequency response of the power amplifier using negative feedback. Use this
control to add sparkle and clarity to your tone.
INDICATOR will illuminate when the OTS is powered by turning the rear panel MAINS toggle switch to the ON position. If
INDICATOR does not turn on, check your power cable connections, and then the 2A slow-blow fuse on the rear of the unit.

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4) REAR PANEL CONTROLS
On the rear panel of the S&M Overtone Special, you can see eleven items of interest.
1) MAINS IEC cable inlet
2) 3 AMP / 2 AMP slow-blow fuse
3) MAINS power two-way toggle switch
4) OPERATE / STANDBY two-way toggle switch
5) SPEAKER OUTPUT ¼” speaker jacks
6) IMPEDANCE three-way rotary selector
7) EFFECTS LOOP RETURN ¼” instrument jack
8) EFFECTS LOOP SEND ¼” instrument jack
9) OVERDRIVE two-way toggle switch
10)PREAMP BOOST two-way toggle switch
11)FOOT PEDAL 5-pin DIN female jack

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MAINS IEC cable inlet –plug a suitable IEC power cable into this inlet to power your amplifier
3 AMP / 2 AMP slow-blow fuse –used to protect your amplifier from voltage spikes or excessive current draw. Replace only
when necessary. 3A is used for amplifiers used with a 120VAC country supply, and 2A is used with 240VAC.
MAINS two-way toggle switch powers the OTS on and off. With the toggle switch in the UP position, the OTS is ON. In the
DOWN position, the OTS is OFF.
OPERATE / STANDBY applies high voltage to the vacuum tube anodes (and screen grids) during use of the OTS. To ensure
long tube life, first power the unit on with the toggle switch in STANDBY position for approximately 30 seconds. Then switch to
OPERATE to use the OTS. With the toggle switch in the UP position, the OTS is in OPERATE mode. In the DOWN position,
the OTS is in STANDBY mode.
SPEAKER OUTPUT ¼” speaker cable jacks. Use a ¼” speaker cable to connect your speaker cabinet to the amplifier using
these jacks. If you use one speaker cabinet, use the jack labeled MAIN. If you want to run two cabinets in parallel, connect the
second cabinet to the amplifier using the jack labeled EXTENSION.
NOTE –never turn your amplifier to OPERATE mode without connecting the amplifier to a speaker cabinet or suitable dummy
load! Failing to do so may damage your amplifier!
IMPEDANCE three-way rotary selector. Set this selector to the position that matches the impedance of your speaker cabinet.
NOTE –if you are using two speaker cabinets in parallel (ex –two 16 Ohm cabinets), set the impedance selector to half that of
a single cabinet (in this case, 8 Ohms).
EFFECTS LOOP RETURN ¼” instrument jack can be used to directly interface the power amp of the OTS, thereby bypassing
the preamp and using the amplifier as a power amplifier. Conversely, this is usually used as the RETURN of the effects loop.
Plug the output of your effects unit, or interface device (ex –C-lator, Klein-ulator) into this jack using ¼” instrument cable. The
effects loop in the OTS amplifiers are all passive, like the originals.

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EFFECTS LOOP SEND ¼” instrument jack can be used to directly interface the preamp of the OTS, thereby bypassing the
power amplifier and using the OTS as a preamp. Conversely, this is usually used as the SEND of the effects loop. Plug the
input of your effects unit, or interface device (ex –C-lator, Klein-ulator) into this jack using ¼” instrument cable. The effects
loop in the OTS amplifiers are all passive, like the originals.
OVERDRIVE two-way toggle switch manually switches between clean and overdrive channels. If you are using the foot pedal,
set this in the PEDAL position. If you are not using the included foot pedal, the toggle switch in the PEDAL position switches
the OTS to OVERDRIVE mode. In the MANUAL position, the OTS is in CLEAN mode.
PREAMP BOOST (aka –“PAB”) two-way toggle switch manually switches between boosted and normal configurations. In this
series of OTS amplifiers, the PAB accentuates midrange frequencies and attenuates low frequencies, making it great for cutting
through during a solo. Engaged, you will also notice an increase in gain and distortion characteristics. If you are using the foot
pedal, set this in the PEDAL position. If you are not using the included foot pedal, the toggle switch in the MANUAL position
switches the OTS to PREAMP BOOST mode. In the PEDAL position, the OTS is in normal mode.
NOTE –if the FOOT PEDAL is plugged in, but the PAB and/or OVERDRIVE toggles are in MANUAL, the foot pedal LED
indicators will still light up but functions will not be switched. For the FOOT PEDAL to function, PAB and OVERDRIVE rear
panel toggles MUST be in PEDAL.
FOOT PEDAL 5-pin DIN female jack is used to connect the foot pedal to the amplifier. Use the foot pedal to control the
OVERDRIVE and PREAMP BOOST modes. Red LED indicates OVERDRIVE, and Green LED indicates PREAMP BOOST.

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5) TUBE COMPLIMENT AND EXTERNAL BIAS JACKS AND ADJUSTMENT
50W Overtone Special 100W Overtone Special
From left to right:
V1 –12AX7/ECC83 (clean and overdrive stages 1 and 2)
V2 –12AX7/ECC83 (overdrive stages 3 and 4)
V3 –12AX7/ECC83 (phase inverter for power amplifier)
V4 –6L6GC
V5 –6L6GC
V6 –6L6GC (100W version only)
V7 –6L6GC (100W version only)
NOTE the HT fuse, which protects the circuitry from excessive current draw, in the lower right corner. Use 1A Fast Blow only.