Hafler DH-200 Instructions For, THE HAFLER DH-222 AMPLIFIER BRIDGING KIT, FOR THE DH-220, LM056

INSTRUCTIONS FOR

THE HAFLER DH-222AMPLIFIER BRIDGING KIT

FOR THE DH-220

The DH-222 may be installed in a Hafler DH-220 power amplifier to enable easy conversion to a high power monophonic amplifier, bridging the two conventional chan- nels to a single floating output which can deliver in excess of 400 watts into an 8 ohm load. Its rated power output is 350 watts across the audio band.

When switched to monophonic operation (UP), signal input should be provided to the LEFT input jack only, and the output should be connected only to the two center BED ( +) terminals. No connection of the load is to be made to the black output terminals. Because of the floating output, neither side of the load may be grounded. Thus it is unlikely that stereo speaker switching boxes, or headphone adapters may be used, as these often have a common ground between the left and right chan- nels.

The speaker fuses may be replaced with higher values than the 2-5 ampere range suggested for stereo operation, if de- sired, depending on the degree of protection for the speaker which is intended. The graph shows the nominal sustained power output limit of a 7 ampere standard fuse, which is the maximum recommended value. Smaller values will provide more protection for the speakers; larger ratings are at the user’s risk.

Both speaker fuses should be the same value. If one speaker

fuse blows in mono operation, both should be replaced, for it is likely that the second has been weakened. For equivalent load impedance, each speaker fuse provides the same power output protection as in stereo operation.

With the internal conversion switch DOWN, the amplifier functions as a conventional stereo amplifier, with normal input and output connections. The minimum recommended load impedance, which is limited only by thermal factors (abil- ity of the heat sinks to dissipate high energy levels), is 6 ohms in mono; the usual 3 ohms in stereo. The amplifier circuit can safely accommodate lower impedance loads, of course.

The conversion, which takes less than an hour, involves only changes to the input wiring, and installation of the switch with its mounting bracket and one resistor. These instructions assume familiarity with the usual kit building descriptions, and reminders. For more details in this regard, see the con- struction section of your DH-220 amplifier manual. You must be certain you have made a good solder connection wherever one is called for, not only to the wire you have attached, but to any others already connected to that point. The notation ( S) indicates a soldered connection; (S-2) denotes that there are two wires to be soldered. Use only 60/40 rosin core solder. Be careful not to let the soldering iron touch adjacent components on the circuit board: excessive heat could change their opera- tion, with the possibility of damage to the amplifier.

KIT PARTS LIST

Switch, DPDT	sz114
Mounting bracket	MS183
Indexing washer	HW123
Lockwasher	HW122
Nut, switch mounting	HK125
Nut, 6-32 KEP	HK112
Screw, machine, 6-32	HA116
Resistor, 3000 ohms	FLzo17
Wire, red, 22 gauge
Wire, green, 22 gauge
Wire, black, 22 gauge

	I
1	I	I	I
	6	12	16

RESISTIVE LOAD IMPEDANCE - n

LIMITED WARRANTY

The parts in the DH-222 are guaranteed against defects for one year from the date of purchase. Installation in a DH-220 amplifier is the owner’s responsibility. In the event of difficulty with the completed unit, charges for service, if any, will be in accordance with the warranty provisions for the amplifier, if it was purchased as a kit. If it was purchased as a factory assembled unit, there is the further stipulation that faults incurred as a result of improper installation of the DH-222 are the owner’s responsibility, but in other respects the original warranty applies. This warranty gives you specific legal rights. You may also have other rights which vary from state to state.

5910 CRESCENT BOULEVARD, PENNSAUKEN, NJ 08109.609/662-6355

LM056