Ashdown Engineering CTM-200-RACK Valve 3u Rack Bass Head User Manual
- June 3, 2024
- Ashdown Engineering
Table of Contents
Valve 3u Rack Bass Head
User Manual
CTM-200-RACK
CTM-200-RACK Valve 3u Rack Bass Head
THANK YOU
Thank you for purchasing your Ashdown Engineering Amplifier and welcome to the
family! We really think you’ve made the right choice and know that this
amplifier will give you years of great tone and service. It is a machine
though and needs to be looked after, please read through this user manual
which will help you get the most out of your new Amp and keep it running as
long as some of our happiest and very famous customers.
REGISTER ONLINE
Please register this product online so we can make sure we give you years of customer support through our friendly in-house service center. Here is where you need to visit to register your product: http://www.ashdownmusic.com/pages /register-your-product
INTRODUCTION
Built to be gigged the CTM-200R rack head is housed in a 2mm mild steel chassis with spot welded supports fabricated in Essex, England, hand-finished and powder coated in black before being fitted with its beautifully engineered heavy-duty circuit boards which support the valve compliment of four KT-88 power tubes as well as the array of pre-amp valves consisting of 2 x ECC-832 2 x ECC-82 1 x ECC-99.
FRONT PANEL FACILITIES
INPUTS – There are two instrument inputs marked LOW and HIGH. The LOW input is high sensitivity and also high impedance to suit the output from PASSIVE (Low Output) basses – The HIGH input is low sensitivity and lower impedance to suit the output from ACTIVE (High Output) basses. Plugging an active (High Output) bass into the LOW input will overload the input, creating a fatter, warmer, and more distorted sound. Experiment by plugging your bass into either input to achieve the desired sound.
EFFECTS SEND AND RETURN – These 1/4” jack sockets should be used to
connect to an external effects device or pedal board. The EFFECTS SEND output
should
connect to the INPUT of the effects unit, and the output of the effects unit
should be connected to the EFFECTS RETURN input.
EQ CONTROLS – Use the MIDDLE, BASS and TREBLE controls to effect the
overall tone of the sound. The MID SHIFT switch causes the MIDDLE control to
operate on higher frequencies in the up position, and lower frequencies in the
down position. The BASS SHIFT switch causes the BASS control to operate on
deeper frequencies in the up position, and less deep frequencies in the down
position. The BRIGHT switch adds an overall brightness to the sound when in
the up position.
(Note: The BRIGHT switch is not effective when the GAIN control is set to
full).
GAIN – This controls the level of the signal sent to the MASTER section.
To achieve a cleaner sound, turn the GAIN control down and the MASTER up. To
achieve a richer,
more distorted sound, turn the GAIN control up and the MASTER down.
MASTER – This controls the overall output of the amplifier.
MUTE – In the up position, this switch mutes the out put of the amplifier
(useful for tuning, etc.).
PRE/POST – This switch determines whether the signal from the DI OUTPUT
(see Rear Panel Facilities) is taken before/PRE the EQ section (down position)
or after/POST (up position).
VU METER – The VU meter provides a visual indication of the output level
of the amplifier. It also acts as a bias meter, please see the following page
for more details.
REAR PANEL FACILITIES
DI OUTPUT – This 1/4” stereo jack socket is used to connect the amplifier
to a low impedance, balanced input on a PA system or recording mixer. The
signal can be taken PRE or POST EQ (see above), ie with or without the tone
shaping added by the EQ section of the amplifier.
LINE INPUT – This 1/4” jack socket is used to connect the output of line level
devices such as samplers and sound modules.
SPEAKER OUTPUTS – There are dedicated Speakon connectors for 2, 4 and 8! load
speaker cabinet configurations. It is important that the correct output or
outputs are
used to match the impedance load of your cabinets. Please refer to the
diagrams later in this manual.
OFF/PREHEAT – Use this switch to pre-heat the valves, bringing them up to
the correct operating temperature before performing.
STANDBY/FULL – No signal is sent to the speakers when this switch is in
the STANDBY position. Switch to FULL when you are ready to perform.
THE VU METER
The VU meter fitted to the CTM is a dual function meter detailed as follows:
By using the push button selector switch marked “AUDIO / BIAS” the functions
are accessed in the following manner:
1/ “AUDIO” – In audio mode the meter is set to read the audio output of each
of the six power tubes and each can be measured by utilising the rotary
selector switch on the front panel. Whilst playing this is the normal mode of
operation of the meter and the reading obtained will be a direct indication of
the power being produced by each output tube, the meter is calibrated so that
when the needle reaches the start of the red section the power tube being
measured will be producing maximum clean volume.
The switch can be rotated to select any of the power tubes and its relative
output will be indicated on the meter, note that when performing this test you
will need to play at equal volume for each test.
2/ “BIAS” – In this mode the meter will glow RED.
To check the bias of the output tubes proceed as follows: Run the amplifier
for at least 10 mins to allow the output tubes to fully heat up with the
amplifier set to mute. Standby on. Select.. Tube 1 and with an insulated
jewelers screwdriver gently adjust the trimmer situated on the rear panel. The
reading to aim for is the needle just at the start of the red ie 0db. Note
that although each tube can be adjusted individually it is possible to get
tubes that cannot be adjusted to the correct reading, these can still be used
providing the
reading is not in the red, a lower reading is acceptable and will note impact
audibly on the power output or sound quality of the amplifier.
Please also note that the trimmers are 25 turn types to make adjustment easy,
This type of adjuster has no end stop so if you reach a point where the
adjuster will not give any more adjustment then the output tube will have to
be replaced if the reading is to high ie in the RED.
Repeat this for each of the four output tubes in turn.
RETURN THE METER TO “audio” MODE AFTER BIASING. DO NOT RUN THE AMPLIFIER IN
BIAS MODE WHILST PLAYING.
Note there is a protection fuse fitted to each of the output tubes and if no
reading is obtained on the meter this fuse will have failed. The protection
fuses are situated next to the output they are protecting the correct rating
is 315Ma quick blow, in the event of a blown fuse they MUST be replaced with
fuses of the correct rating and type.
A continually blowing fuse would indicate either an incorrectly biased output
tube or a defective output tube.
VALVE COMPLIMENT:
SPECIFICATIONS:
Inputs
High Input
Low Input
Effects Return
Line Input| Impedance – 3.9M ohms
Impedance – 10k ohms
Impedance – 22k ohms
Impedance – 22k ohms| Input range 150mv to 20v p – p
Input range 300mv to 40v p – p
Input level 0dbu nominal
Input range 300mV
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Outputs
Effects Send
D.I.Output
Speaker Outputs
Frequency Response
Headphone Output| Impedance – 22k ohms
420 ohms balanced
Minimum Impedance – 4 ohms
-3db at 22hz and 25khz
3.5mm Jack output @ 320hms| Level 0dbu nominal
pre ground lift Level -20dbu nominal
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Equalisation
Bass
Middle
Treble
Shape
Signal to Noise
Distortion
Output Power| +/- 15db @ 100hz
+/- 15db @ 660hz
+/- 15db @ 7khz shelving
+ 8db @ 50hz + 10db @ 10khz
Better than 80db (E.Q. Flat)
Less than 0.5% Thd
200watts into 4 ohms
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