DH-222 Installation Instructions

10Disconnect AC power from the amplifier, and remove all con- necting cables. Wait 5 minutes to allow capacitors to discharge before proceeding with disassembly.

2cl Remove all 8 screws between the fins of each amplifier module so that the cover may be removed, and the modules tilted out- wards for easier access.

30Unsolder the pair of twisted wires connected to holes 1 and 2 at the top of the right channel PC-19 circuit board. The right channel is the one nearest the power switch. This pair must also be unsoldered from the right input socket on the back panel, because it will be more convenient to use lighter gauge wiring.

40Prepare a 6%” red wire, and a 61/2" black wire. Start with the black wire 1/2"”longer than the red wire, and twist them together uniformly throughout their length. At the end where the black wire projects, connect it to the short lug of the right input sock- et. (S-2). Be sure the existing wire to the adjacent ground lug is properly connected. Connect the corresponding end of the red wire to the long lug of the input socket. (S). Place this pair off to the right edge.

50Prepare a 5%” red wire, and a 5%” black wire. With the ends

even, twist these together and connect ,the red wire to hole #l at the top of the right channel PC-19 circuit board. (S) Connect the black wire to hole #2. (S).

60Prepare a 20”green wire. Cut a 20” black wire, but remove the insulation from only one end. Starting with the bare end of the black wire 1/2”longer than the green wire, twist these together. At the far end, where the black insulation has not been re- moved, the black wire will not be connected, but instead will be secured by wrapping it in a tight circle around the green wire a short distance from the bare green end. It is very important that no bare wire be visible from the black insulation. The single green wire is to be connected near the center of the lefi circuit board to the hole designated “B”, located just below the bias adjustment potentiometer. t S). It must be securely sol- dered, but be careful that you do not damage adjacent compo- nents.

70Making sure that no wires are pinched between the module and the chassis in the process, reinstall the left module to the chassis with 4 sheet metal screws.

80Select the switch and its 2 nuts, lockwasher and indexing flat washer, and the switch mounting bracket. Install one nut all

the way onto the switch collar, and follow it with the indexing washer with its lugprojecting towards the handle lever. Mount the switch on the bracket so that the lever points in the direc- tion of the bracket flange, and the indexing lug engages the locating hole in the bracket. Secure it with the lockwasher and the second nut.

90 Select the two machine screws and nuts, and install the switch bracket between the two transistors at the rear of the right module, so that the switch lever points towards the fins.

100 Select the 3000 ohm resistor and trim its leads to 1/2" Connect it between switch lugs #4 and #5. Solder only lug #5.

11 0 Select the red and black pair from the right input socket and connect the black wire to switch lug #3. Do not solder this con- nection yet. Connect the red wire to switch lug #1. (S).

12cl Select the red and black pair from the right channel circuit board holes 1 and 2. Connect the black wire to switch lug #3. (S-2). Connect the red wire to lug #2. (S).

13Cl Select the green and black pair and separate the wires for about 1%“. Connect the green wire to right circuit board hole “A”. (S). Connect the black wire to hole “E”. (S). Hole “A” is located in line with the switch about 11/2” from the rear edge of the board. “E” is located 1/2” below hole 2, near the top of the board.

I4 Cl Place the green and black pair towards the rear of the module, and down past the midline of the switch. Where it passes lug #5, approximately 41/2"”from the end of the wires, cut only the green wire. Strip each end 1/4" Connect the short green section to switch lug #4. (S-2): Connect the longer green wire from the left board to switch lug #6. (S).

I5 Be careful no wires are pinched as you reinstall the right mod- ule to the chassis with 4 screws. Place the long green and black pair under the rear lip of the chassis. The pairs to the top eyelets on each board, and to the connections in the center of the board should be kept at least 1/2" off the board, where they are clear of the components. Make sure the unconnected black wire end near the left circuit board cannot touch any compo- nents.

16The switch lever should be placed in the upper position for monophonic operation. In the lower switch position, the amplifier functions as a conventional stereo amplifier. Rein- stall the amplifier cover with the remaining 8 screws.

DH-200 specifications

The Hafler DH-200 is a well-regarded power amplifier that has earned a dedicated following among audio enthusiasts since its release in the early 1980s. Known for its excellent performance and reliability, the DH-200 has become a staple in many home audio systems.

One of the key features of the DH-200 is its high power output, delivering 100 watts per channel into 8 ohms and 200 watts into 4 ohms. This robust power handling capability makes it suitable for driving a wide range of speakers, from compact bookshelf models to larger floor-standing designs. The amplifier's low distortion and high current output ensure that it can reproduce dynamic and intricate musical passages with clarity and precision.

The DH-200 utilizes a unique circuit topology that incorporates a high-performance, complementary push-pull output stage. This design minimizes crossover distortion while providing excellent linearity and frequency response. The frequency response extends from 20 Hz to 20 kHz, matching the full range of human hearing and allowing for a natural reproduction of both low and high frequencies.

Another notable technology in the DH-200 is its use of a toroidal transformer, which contributes to the amplifier's efficiency and low noise operation. Toroidal transformers are known for their compact size, reduced electromagnetic interference, and improved power supply regulation, which translates into cleaner audio performance.

In terms of build quality, the Hafler DH-200 features a rugged chassis and a minimalist front panel design. The amplifier is a two-channel unit, with individual volume controls for each channel, allowing for precise adjustments. The rear panel is equipped with standard RCA input connections and binding posts for speaker outputs, making it compatible with most audio sources and speaker systems.

The DH-200 is also praised for its thermal management, featuring multiple heat sinks to dissipate heat effectively during extended use. This design helps to ensure long-term reliability, even under demanding listening conditions.

In conclusion, the Hafler DH-200 is a power amplifier that stands out for its exceptional sound quality, powerful performance, and robust build. Its combination of advanced technologies, such as a complementary push-pull output stage and toroidal transformer, make it an enduring choice for audiophiles seeking a reliable and high-performing amplifier for their home audio systems. Whether for casual listening or critical listening sessions, the DH-200 has proven to be a versatile and gratifying component in any audio setup.