Intruder User's Manual Aiken Amplification, Inc. 1225 Montague Avenue Greenwood, SC, 29649 Tel: 864-993-8383 http://www.aikenamps.
Contents Getting Started.....................................................................................................3 Front Panel Controls and Switches...................................................................5 Rear Panel Controls and Switches....................................................................7 Tube layout and replacement.............................................................................9 Biasing....................................................................
Getting Started Congratulations on purchasing your new Aiken Intruder amplifier! The Intruder is an all-tube amplifier, available in 18,30, or 50 watt versions. This amplifier is truly touch-sensitive, going from clean to crunch to singing leads by just adjusting the volume control on the guitar. to provide a wide range of tones from any guitar, using single-coil or humbucking pickups.
Solid 16-gauge steel chassis, zinc-plated, yellow chromate conversion coated for durability, corrosion-resistance and appearance. Front and rear faceplates are gold anodized aluminum for durability and a classic appearance. All hand-wired, “military style” turret-board construction, using chassis-mounted tube sockets for ease of maintenance and reliability. Built to last.
Front Panel Controls and Switches Input jack: Plug your guitar in here and you are ready to rock! Plexi/Ali switch: This switch configures the preamp section to match either the warmer early "plexi/Bassman" style preamp circuits or the later and brighter "aluminum panel" circuits. For full-volume output stage distortion/crunch tones, the plexi/ali switch is usually best put in the "ali" position, as this cuts some of the low end and adds a bit more gain and midrange boost on the second stage.
Presence: The presence control adjusts the high frequency equalization in the output stage. It acts similar to a Vox-style “cut” control, but only for very high frequencies. It is voiced specifically to take the “hair” off distortion tones to tame a bright or “buzzy” sounding speaker. When full up, the cut is essentially out of circuit. It is best used as a final tonal adjustment to add or remove “bite” from the distortion tone.
Rear Panel Controls and Switches AC Mains: Plug the supplied IEC mains cord into this outlet to provide power to the amplifier. Mains Fuse: 18W amplifiers: operation. 2A slo-blo for 100V/120V operation, 1A slo-blo for 200V-240V 30W/50W amplifiers: 3A slo-blo for 100V/120V operation, 1½ A slo-blo for 200V-240V operation. AC Mains voltage selector: Set this switch to the appropriate position to match the mains voltage in the country in which you are using the amplifier.
do NOT, under any circumstance, use guitar cable to connect the amplifier to a speaker cabinet. Doing so may cause damage to the amplifier. Effects Loop: This is a 1/4" TRS (tip/ring/sleeve) insert style jack. The nominal 0dBu level allows use of line-level (pro) effects for lowest noise levels. The TRS insert jack allows use of a single TRS cable to connect the effects, instead of the two 1/4" cables normally required for an effects loop.
Tube layout and replacement The Intruder uses four ECC83/12AX7 tubes and two 6BQ5/EL84 output tubes (or two EL34 tubes in the 30W or 50W version). The preamp tube function is as follows, starting at the side closest to the input jack: preamp 1 (ECC83/12AX7), preamp 2/cathode follower (ECC83/12AX7), effects loop driver/receiver (ECC83/12AX7), and phase inverter(ECC83/12AX7). The chassis top view layout is shown in the diagram above. The preamp tubes are housed in removable "bayonet" metal shields.
Output power reduction by using 6V6 tubes (30W models only): It is possible to reduce the power of the 30W Intruder to around 18W to 20W by changing the two EL34 output tubes to 6V6 tubes. The amplifier will need to be rebiased before using, to insure the tubes are running at a safe idle current . In order to familiarize yourself with the biasing procedure, you should read the next section on biasing before making this change.
Biasing Biasing is very easy, and doesn't require removing the chassis from the cabinet. You simply use a voltmeter (any inexpensive digital multimeter will do), set it for the smallest DC voltage range (typically 200mV). Then: (1) Unplug any guitar cords going into the input jack. Turn the two volume controls all the way down (other control positions don’t matter). Unscrew the lock nut on the bias pot on the rear panel, and turn the bias control all the way down (counterclockwise).
result in failure of the tubes, possibly damaging screen grid resistors or other amplifier components. The HT fuse should prevent any major damage to output or power transformers, or other expensive components. IntruderMKIIManual.doc 06/17/13 Copyright 2004-2011, Aiken Amplification, Inc.
Speakers Changing speakers is like getting a whole new amp. Every model sounds completely different, some sounding quite good and some amazingly bad. The amplifier is particularly suited for use with Celestion loudspeakers, which give the characteristic "British" sound this amplifier is designed to create. Celestion Greenbacks have less volume and a dip in the mids, which makes them nice and smooth.
Troubleshooting Pilot lamp not lit: Is the amplifier plugged into a functional outlet of the appropriate voltage? Is the mains fuse blown? If so, replace with the appropriately rated fuse. If the fuse again blows, the amplifier may have a shorted output tube or blown rectifier diodes. Replace the tubes and fuse, and power the amplifier up again. If the fuse still blows, the amplifier will need to be serviced.
Humming or buzzing noise: Unplug the guitar cord from the input and unplug any cable used for jumpering the two inputs. If the buzzing stops, try replacing the cord. Be sure to use only guitar cables, not unshielded speaker cables! If in doubt, unscrew the connector and look to see if there is a shield around the center connector. Some smaller speaker cables are easily mistaken for guitar cables. Fluorescent lights and light dimmers can be a source of hum/buzz, as can computer monitors.
"Ticking" noise: Some tubes tend to exhibit a low-level "ticking" noise right after the amplifier is taken off standby. The noise stops after a second or two, when the tube has had a chance to stabilize, and is not indicative of a problem.
Specifications Output Power: 18W for the 2-EL84 model, 30W for the 30W 2-EL34 model, and 50W for the 50W 2-EL34 model at onset of clipping into resistive load at rated impedance. Input Impedance: 1Megohm Input sensitivity: 10mV for output clipping, all volume/tone controls fully up, ali mode. Tube complement: Four ECC83/12AX7 two EL84 (18W model), or two EL34 (30W or 50W models).
