Koch TwinTone II OPERATING INSTRUCTIONS

TWINTONE II

OPERATING INSTRUCTIONS

BEDIENUNGSANLEITUNG

GEBRUIKSAANWIJZING

 2005 Koch Guitar Electronics

GB

DE

NL

EC DECLARATION OF CONFORMITY

We, Koch Guitar Electronics, Neonweg 27, 3812 RG Amersfoort, The Netherlands, declare
under our sole responsibility that the product:

TWINTONE II Guitar Amplifier

to which this declaration relates is in conformity with the following harmonized standards:

* EN 50081-1 (1991) Electromagnetic compatibility. Generic emission standard.

Part 1 : residential, commercial and light industry;

* EN 50082-1 (1991) Electromagnetic compatibility. General immunity standard.

Part 1 : residential, domestic and light industrial environment;

* EN 60065-1 (1993) Household electronic apparatus.

Part 7 : Heating under normal operating conditions;

* EN 60335-1 (1988) Safety of household and similar electrical appliances.

Part 1 : general requirements.

following the provisions of Council Directive 98/336/EEC on the approximation of the laws
of the Member States relating to electromagnetic compatibility and the provisions of
Council Directive 73/23/EEC on the approximation of the laws of the Member States
relating to low voltage and electrical safety.

Amersfoort, 01 March 2005

Dolf Koch

Front panel

OD+

Normal

OD

Clean

Bright Clean

Inputs

Channels

Clean Channel

-5 +5-5 +5-5 +5010

Bass Bass

Mid Mid

Tre ble Tre bleVolumeVolume

0

Gain

10

010010

Overdrive Channel

Presence

-5 +5 -5 +5 -5 +5

Power

Standby

Twintone II

14

3

56 8 9

Back panel

100

100 Watts, 50/60Hz

Fuse: 100/120V - T3.15A

~

115 230

220/240V - T1.6A

VAC

HT

Fuse

T500mA

Footswitch

Rhythm
Volume

o-o

0

Volume

0

Reverb

(FX Mix)

Effects Loop

To FX-in

10

Serial

1 4 5 6 8 9 10 11 1223 7

From FX-out

Parallel

7

Power Soak: 50W, 8

If Main speaker jack is unplugged

Amp’s output connects to

the internal Power Soak

Extension

Main

Speaker Outputs

W

W

8

W

4

Signal is derived from

amp’s (speaker) output

and voiced for 1x12“

reproduction

Recor-

Head-

ding

phones

102

CAUTION

RISKOF ELECTRIC SHOCK

!

DONOT OPEN

* Disconnect Power Supply before changing Fuse
* No User Serviceable Parts inside
* Refer Servicing to Qualified Personnel only

Serial #

Designed & Handcrafted by:

KOCH GUITAR ELECTRONICS
Amersfoort, The Netherlands

E N G L I S H

Thank you for choosing the TWINTONE II from KOCH. You now own a "state-of-the-art" all-tube guitar amplifier of the highest quality.
The TWINTONE II has been designed and built by people who - from their own experience as musicians - take guitar sound and quality
very seriously. That is why this product was designed and built with the utmost care in order to meet all professional standards. Our
goal was not only to design an amp which sounds fantastic and is easy to operate, but also to build it in such a way that it will serve you
loyally for many years to come.
Please take your time to read this manual carefully before you switch on the TWINTONE II and also please fill in the warranty card and
mail it. Thanks and lots of succes with your new TWINTONE II !

CAUTION:
* BEFORE PUTTING INTO OPERA-

TION READ THESE OPERATING
INSTRUCTIONS CAREFULLY.

* NO USER SERVICEABLE PARTS

INSIDE.

* REFER SERVICING TO

QUALIFIED SERVICE
PERSONNEL ONLY.

FRONT PANEL FUNCTIONS

[1] INPUTS

NORMAL - Input for standard instruments, e.g. guitars with single­coil pickups.

BRIGHT CLEAN - Input for high-output instruments, e.g. guitars
with humbucker pickups. This input has 6dB gain reduction to
prevent overload of the input stage and a filter which compensates
guitar cable losses by boosting the high frequencies as of 3Khz.
(Due to their higher coil impedance, humbucker pick-ups suffer
more from cable losses than single-coils, which may result in lack
of sparkle in the clean sound)

NOTE: The BRIGHT CLEAN input only changes the CLEAN
channel but does not affect the OD and the OD+ channels.

[2] CHANNELS SWITCH: Selects the Clean, the OD (OverDrive)

or the OD+ channel if the Footswitch is not connected.

[3] VOLUME: Controls the volume level of the Clean channel.

WARNING:
* TO REDUCE THE RISKS OF ELECTRICAL

SHOCK, DO NOT REMOVE THE COVER.

* TO REDUCE THE RISK OF FIRE OR

SHOCK HAZARD, DO NOT EXPOSE

AMPLIFIER TO RAIN OR MOISTURE.
* THIS APPARATUS MUST BE EARTHED.
* TUBES ARE HOT.

DO NOT TOUCH DURING OPERATION.

[8] BASS, MID & TREBLE: Classic post-distortion passive tone

controls for the Overdrive channel.
[9] STANDBY SWITCH: Allows the TWINTONE II to be placed in
Standby (green LED off) or Active (green LED on) mode. In
Standby mode the tubes remain hot, but the amplifier is not
operational.
The green LED monitors the internal HT power supply for the
tubes. If the amp is switched from the Active to the Standby mode,
the green LED slowly dims indicating that the HT power supply
slowly loses power. The TWINTONE II remains (partly) operational
until the LED is completely off.

[10] POWER SWITCH: Turns AC power On (red LED on) and Off
(red LED off). When the switch is Off the amplifier is completely
shut down.

NOTE: When switching the amplifier ON, leave Standby switch [9]
in “Off” position for 5-10 seconds thus allowing the tubes to heat up
before switching to the Active mode. When switching the amplifier
OFF, first select Standby [9] mode and allow green LED to dim
completely before switching Power off.

[4] BASS, MID & TREBLE: Classic passive tone controls for the
Clean channel.

[5] GAIN: This ‘Dual-Gain’ is a very powerful feature combining
Drive (OD) and Gain Boost (OD+) in one knob. It has been
achieved by controling the amount of amplification in the Overdrive
Channel preamp, in one stage of the OD channel and in two
stages simultaneously of the OD+ channel. Thus garanteeing a
well dimensioned boost when switching from OD to OD+ in every
position of the Gain knob.
Cleaner sound is achieved at lower settings (2 to 4), at middle
settings (4 to 6) medium overdrive occurs which will produce more
sustain and a subtle distortion. At high settings (4-10) mega
overdrive occurs, adding loads of sustain and compression.
Accurate pre and post shaping circuitry prevent the low end from
getting muddy even at the highest Gain settings in the OD+
channel.

NOTE: High GAIN settings in the OD+ channel may cause
squealing and/or excessive hum and noise, due to
microphonic guitar pick-ups and insufficient screening of
guitar-circuitry.

[6] VOLUME: Controls the volume level of the OD and the OD+

channels.

[7] PRESENCE: Controls the amount of boost in the upper mid
frequency range of the Overdrive channel.

REAR PANEL FUNCTIONS

[1] A.C. POWER:

INPUT - Power cord input. The amp is equipped with a worldwide
power supply. Inside the amp a mains selector switch can be set
on one of three voltages, 100, 115 or 230. Either of these voltages
will work worldwide with minor power differences. The amp will
work on either 50 or 60 hertz. After resetting the internal mains
selector switch make sure fuses are replaced with printed

ratings on rear of amp.

FUSE - Both fuse and spare fuse are located on the sled of the
fuseholder. Fuse sled can be removed with a screwdriver. If the
fuse should fail, it must be replaced with the same type and

value in order to avoid damage to the amp and to prevent
voiding the warranty.

If the amp repeatedly blows fuses, check for a bad power tube. If
tube-failure is not the cause, the amp should be taken to a
qualified service center for repair.

WARNING: Only a qualified technician should attempt an
input voltage change. Personel injury or equipment damage
may occur if done incorrectly.

WARNING: The fuse should be replaced or the voltage should
be reset only when the power cord has been disconnected
from its power source.

[2] HT FUSE: This fuse protects the power supply in case of tube
failure. If it blows, check for a bad power tube. If tube-failure is not