User manual HALCRO LOGIC DM78

[. . . ] 1 Contents Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 Important Safety Information. . . . . . . . . . . . . . . . . . . 3 Symbols . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 Wiring to the loudspeaker terminals to Class 2 wiring (US wiring regulations) . . . . . . . 6 Output Current Limiting . . . . . . . . . . . . . . . . . . . . . . . . . . 16 Output transistor protection. . . . . . . . . . . . . . . . . . . . . . 17 Unusual output conditions. . . . . . . . . . . . . . . . . . . . . . . . . 18 Power supply output current limiting . . . . . . . 18 Internal power supply protection. . . . . . . . . . . . . . 18 Mains transient overload protection . . . . . . . . 18 Input overload protection . . . . . . . . . . . . . . . . . . . . . . . . . . 18 Amplifier inter-stage protection . . . . . . . . . . . . . . . . 18 dm78 Specifications. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19 dm88 Specifications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21 Care and Maintenance. . . . . . . . . . . . . . . . . . . . . . . . . . [. . . ] Earth loop generated mains hum and ripple, or high frequency interference should not be a problem unless the source equipment is poorly designed. Sources with current-mode outputs are rare and are most likely to have an RCA output socket. The advantages of this source are that: Input styles Balanced voltage input Required output source impedance Low impedance. Very high impedance; "infinite. " Earth loop generated mains hum and ripple are minimized, and cable, plug and socket generated interference is minimized (from poor connections which may be affected by sound vibration for example). The unbalanced input is quite satisfactory so long as earth loop generated mains hum and ripple are not a problem. The minimal path input will result in the most pure sound; unless as above, earth loop generated mains hum and ripple is a problem. The input sockets may have active sources simultaneously connected to them. The selector switch selects the input to be amplified. Input socket XLR Input impedance 100 kohms + 100 kohms Unbalanced voltage input Minimal path voltage input Current-mode input RCA 100 kohms RCA 660 ohms RCA 60 ohms 14 Operation All or some of the input sockets may have active sources simultaneously connected to them. o Once the external cables are connected to the unit, ensure the master ON/OFF switch is in the OFF position. The master ON/OFF switch is on the base of the lower compartment, near the mains socket on the unit. You will have to kneel on the floor at the back of the unit to access the switch. In this mode a small current is drawn from the mains supply, but the unit will not drive the loudspeakers. The mode switch is a small pressure switch accessed when standing at the front of the unit. When the amplifier has been switched to ON, the LEDs on the front and rear will glow green. It is recommended that the unit be switched to Standby when not in use. It is safer to turn the mains power off when not using the dm78 or dm88 monoblock amplifiers for extended periods. However the amplifier may be left on in the Standby mode for periods between active use. If you wish to turn the mains power off, the amplifier has a minimal warm up period. 15 Electronic Protection and Reliability Electronic protection circuitry and amplifier reliability, alas, is an area sadly neglected by many high-end audio amplifier designers. · all Halcro integrated circuits are at least "industrial grade" rather than the usual "commercial grade" Industrial grade components are rated at least from ­40ºC to +85ºC whereas commercial grade components are only rated from 0 to 70ºC. In addition, the electronic specifications of industrial grade components are superior to commercial grade. Considering that most amplifiers run at significantly elevated temperatures, it can be seen from the table below that the Halcro high temperature rated capacitors are highly advantageous compared to the standard 85ºC rated devices. Components Our components are selected not only for performance but reliability as well, for example: · all Halcro electrolytic capacitors are rated at a minimum of 105ºC instead of the usual 85ºC rating The operational life of electrolytic capacitors is severely shortened at temperatures near the maximum temperature rating. This is shown in the table below. Electrolytic capacitor temperature rating 85ºC (most commonly used) 105ºC (used in Halcro amplifiers) Mean lifetime at 40ºC 50, 000 hours 180, 000 hours Mean lifetime at 85ºC 2, 000 hours 8, 000 hours Mean lifetime at 105ºC 0 hours 2, 000 hours Typical data from a highly respected manufacturer 16 Output Current Limiting In terms of maximum available output current, there are basically three amplifier type options: · · an amplifier with a reasonable limit placed on the maximum available output current an amplifier with no limit placed on the maximum available output current, which will either blow a fuse or self destruct if excessive current is drawn, for example through a dead short an amplifier with a very high limit placed on the maximum available output current, but designed not to blow a fuse if this very high current is drawn types above), highly overload sounds may be overload sound may loudspeaker overloads suffers voltage overload. [. . . ] Check for a signal from the preamplifier (with headphones if available). Check for a signal from the audio source (with headphones if available). Try a different audio source. If none of the above rectifies the problem please contact your dealer. 26 Service and Warranty Information Overview All Halcro products are designed and built to world-class standards of quality, reliability, and performance. Since so much care has gone into our products, we are able to offer a strong warranty that protects your investment in Halcro products for years to come. [. . . ]