Transcript
CORNELL AMPLIFICATION
OWNERS MANUAL
Custom 80
MUSICAL EQUIPMENT DESIGN & DEVELOPMENT Unit 13 Rosshill Industrial Park,Southend-on-sea, Essex. SS2 5PZ England Telephone/Fax : (01702) 610964
INDEX 1.
INTRODUCTION CONSTRUCTION & DESIGN
2.
TECHNICAL DESIGN Pre-amp and outputstage
4. CONTROLS
5.
THE SPECIFICATIONS
6.
BLOCK DIAGRAM
Please read all instructions before operating unit! if you require any further information regarding the Custom 80 amplifier or other CORNELL products , please do not hesitate in contacting us.
D.C. Developments CORNELL EQUIPMENT DESIGN & DEVELOPMENT Unit 13 Rosshill Industrial Park, Southend-on-sea, Essex. SS2 5PZ England Telephone: (01702) 610964
INTRODUCTION Thank you for choosing a Cornell custom 80 amplifier. Your amplifier employs valve technology. It is hand built to Ministry Of Defence (MOD) standards. Only top quality components are used so that you enjoy years of trouble free use.
Please take time to read this manual, to ensure that you get the best from your custom 80 amplifier.
CONSTRUCTION & DESIGN Virtually all modern amplifiers are built, using printed circuit boards, which means conductor tracks that connect components together, often run very close to one another. When this happens, a small capacitance is produced. The result of which is a substantial loss in both high frequency response and harmonic richness. The Cornell custom 80, is designed to avoid this by having specific point to point wiring. Components in the custom 80 are mounted onto a specially designed panel, and then connected, using heat resistant wire and finally sealed using a conformal coating to prevent noise and reduction of component life, caused by moisture penetration. The chrome-plated steel chassis hold specially designed, interleaved, transformers, wound on impregnated paper bobbins to minimize the gap between iron core and windings. The design ensures a very close reproduction of the full harmonic spectrum of your guitar’s pick-ups.
TECHNICAL DESIGN The Pre-amplifier The custom 80 is designed to be simple in use, and yet produce the wide range of sounds that the musician of today expects from a professional amplifier. The ‘BASS’ and ‘TREBLE’ controls work over the entire frequency range of your guitar, allowing for increased amounts of low and high frequency adjustment.
The Output Stage. Part of the output transformer of the custom 80 is a small independent winding that picks up the signal being produced in the final stage of the amplification process. As the winding is in the output transformer itself, it will exactly reproduce, the speakers signal. This output is used to feed the line output , reproducing the sound of your guitar as accurately as possible. These output are ‘off-ground’ ensuring that no earth loop can be produced, when they are connected to a mixer or power amp.
The custom 80 amplifier output stage is Class AB1, This means that the grids of the output valves are controlled by a negative voltage. This is known as the bias voltage. The method used in biasing greatly affects the tone of the amplifier. Should the bias be set to high - cross-over distortion occurs and is constantly present in the sound of the amplifier, creating a ‘fuzzy’ tone. If set to low, then the valves might start to ‘glow red’. This will considerably reduce their life and result in expensive replacement. It is recommended that a Qualified engineer re-bias the output valves when changed.
Tube Replacement Tube life varies depending upon playing style and application. Power tubes have a much shorter life than pre-amp tubes which can last for years. To maintain the optimum performance of your amplifier, the tubes should only be replaced with the same type tubes as specified below. Your Custom 80 amplifier has 7 valves three pre-amp valves 12AX7 or ECC83, and four power valves 6L6.
Warning When changing tubes, ALWAYS unplug the amplifier and remember that the TUBES ARE HOT! wait for the tubes to cool or replace tubes when amplifier has not been used for several hours.
THE CONTROLS 1.
INPUT Hi & Lo. High impedance input connections for instruments Input Hi provides 6db more gain than the Lo input.
2.
VOLUME. Adjusts the overall volume of the amplifier.
3.
BASS. Adjusts the amount of low frequency boost.
4.
TREBLE. Adjusts the amount of high frequency boost.
5.
MAINS. When illuminated the valve heaters are on and there is power to the amplifier.
6.
STANDBY. Connects power to the valves for operation, use standby mode for breaks in usage,
7.
OUTPUT. OUTPUT LOW position operates the power of the amplifier to 1/4 of its output. OUTPUT HIGH position returns the amplifier to its full output.
8.
LINE OUTPUT The 3 pin mail socket on the base of the chassis next to the output valves is a 600 ohm line output for use with a Mixer or power amplifier. Pin 2 anc 3 are live and pin 1 is chassis earth.
9
OUTPUT SWITCH The switch at the base of the chassis next to the line output is a impedance switch, this switch should be pointing inward for normal use 8 ohms internal speakers and should be switched to point outward for use with an 8 ohms extension cabinet totaling 4 ohms.
10
Mains Fuse The fuse holder contains the mains fuse to the amplifier and protects the amplifier from electrical faults.
Replace a failed fuse only with the same type and rating. Do not operate the mains switch without a 30 second delay between operations. There is an internal thermistor to reduce mains surges. The Thermistor works by introducing a resistance in the circuit when switched on. Within a few seconds the thermistor is heated and the resistance is reduced. It then takes a few seconds to cool and retain its initial resistance.
THE SPECIFICATIONS POWER.............................................. 230 Volt AC 50hz 120 Watts 115 Volt AC
60hz 120 Watts
FUSE .................................................F2 Amp 240v Slo-blow for the 230v Model F4 Amp 120v Slo-Blow for the 115v Model INPUT IMPEDANCE.................. HI 2.2 Meg Ohm. LO 136k Ohm.
CONTROLS...................................... Volume, Bass, Treble . ............................................................... (Reverb optional extra).
LINE OUTPUT ...……………… Coil tapped trom output transformer. ............................................................... 600ohms at 0.25 Watt.
OUTPUT........................................... 80/20 Watt R.M.S SPEAKER......................................... 2X Tone Tubby 16 ohm ............................................................... with 8 to 4 Impedance selector.
CABINET.......................................... Ply wood-shell and baffel. Leather handle. SIZE.................................................... Height 20in 510mm 21in-535 with foot Width 26in 660mm Depth 10in 260mm WEIGHT........................................... 74 Lbs 34 Kgs.
OPTIONAL ON REQUEST....... Speaker, Colours, Modifications.
WARNING: To prevent damage, fire or shock hazard, do not expose this unit to rain or moisture. No user serviceable parts inside, refer servicing to qualified personnel only.
This unit must be Earth grounded, use correct mains cord.
Custom 80
BLOCK DIAGRAM
INPUTS
Hi TONE CONTROLS
Lo BASS
VOLUME
TREBLE
Output Transformer Speaker Outputs
Output Switch
8 4
2 Line Output
1 3
Power Transformer connections Only to be altered by Qualified personnel
Mains Switch
1
A B C
Fuse
Thermister
2
F
115 Va/c Mains Connect 1 to A&D Blue/Red Connect 2 to C&F Black & Brown B&E Yellow/Orange no connection
HT
BLACK
Bias
ORANGE
E
BLUE
240 Va/c Mains
YELLOW
RED
D
Connect 1 to A Blue Connect 2 to F Brown Join C & D Black/Red B & E no connection
BLUE
Heater BROWN
100Va/c Mains Connect 1 to A&D Blue/Red Connect 2 to B&E Yellow and Orange C&F Black/Brown no connection
