Hafler DH-200 power amplifier

Both ears and instruments attest to the excellent quality of the DH-200 power amplifier. It has both superior test specifications and the listening quality to satisfy the most critical listeners, including those for whom price is not a limitation.

The DH-200 follows in the path of the widely acclaimed DH-101 preamplifier which has had highly laudatory reviews and wide spread consumer acceptance. Like the preamplifier this 100 watt per channel amplifier is available either in easy-to-assemble kit form or factory assembled. Either way it is a highly reliable piece of equipment which can satisfy the most hyper-critical listener, including the audiophile with the most difficult loudspeaker load. And, in kit form the DH-200 provides a significant cost saving for a pleasant few hours of assembly time, using factory pre-assembled and tested audio modules.

Two completely assembled and fully tested amplifier modules comprise all of the kit's active circuitry, leaving just a handful of parts for the builder to complete the mechanical assembly and power supply wiring. This makes your job simpler and faster, and assures that your finished kit will easily meet all of its specs, and provide the ultimate in listening pleasure.

The DH-200 employs a unique circuit configuration using all discrete transistors, operating the very latest output devices, power MOSFET's in a conservative array. The result is that the benefits of Class A output stages are obtained - such as high speed, minimal crossover distortion, and decreasing distortion at lower signal levels - without the disadvantages of high cost, high heat, low efficiency and thermal instability that are a part of conventional Class A operation. Like the Hafler preamplifier, this power amplifier has a completely symmetrical, mirror-image complementary push-pull circuit from input to output.

Exceptionally low distortion is apparent on reading the specifications, but such figures cannot detail the unit's true capabilities. The significance of achieving orders of magnitude reduction in Total Harmonic Distortion and Intermodulation DIstortion lies in the correlative elimination of other distortion products. The footnote at the end discusses this in detail.

 

The DH-200's characteristics of vanishing distortion at lower signal levels, and minimal indication of any forms of transient distortion, such as slew induced distortion, as observed at all power levels of square waves, tone bursts and pulse tests, will , we are confident, maintain its superiority as new standards and tests become applicable.

T.H.D. and Intermodulation Distortion (both SMPTE and CCIR measurements) are below the threshold of the finest test equipment - from one-tenth of a watt to beyond 70 watts. Measured with the Sound Technology Model 1701A analyzer, typical mid-band distortion at full power into 8 ohms averages 0,0015%

Another limiting factor in correlating sound quality to measured performance is that conventional amplifiers may measure well on the standard resistive test loads, but exhibit distortion when confronted by the complex reactive loads of the loudspeaker and its crossover network. The Hafler DH-200 has the power reserves to handle mismatched loads (it can deliver 150 watts into 4 ohms, and 100 watts into 2 ohms), but more important, it can handle the back - EMF from the loudspeaker cone without generating interfacing distortion components.

With no need for special protective circuits which may compromise sonic performance, the self-protective design of the DH-200 output stage prevents the thermal runaway which is a threat to other designs.

For applications requiring extraordinary power, the DH-200 may also be bridged to convert it to 300 watt (at 8 ohms) monophonic amplifier, with similar distortion specifications. As a modestly priced, versatile "no frills" design, operating premium quality components conservatively for extended life, this new Hafler amplifier is the audio perfectionist's answer to state of the art. Performance at affordable prices.

 

Specifications

Power Rating:  less than 0,02% T.H.D. at any power level up to 100 watts continuous average power per channel into 8 Ω  at any frequency between 20 Hz and 20 kHz with both channels driven.

Intermodulation DIstortion (SMPTE): less than 0,005% from 1 watt to 100 watt into 8 Ω

Typical Total Harmonic Distortion at 100 wats into 8 Ω :

1 kHz :  0,0015%

10 kHz :  0,005%

20 kh :  0,012%

Frequency Response (into 8 Ω ):

-3db, 1 Hz to 100 kHz at 1 watt

±0,5 dB, 10 Hz to 40 kHz at 100 watts

Typical Channel Separation:

20 Hz :  66 dB

1 kHz :  66 dB

20 kHz :  60 dB

Signal-to-Noise Ratio (Unweighted): better than 100 dB at 100 watts into 8 Ω

Input Impedance:  22,000 Ω

Input Sensitivity:  1,5 volts rms for 100 watts into 8 Ω

Damping Factor:

150 to 1 kHz into 8 Ω

50 to 10 kHz into 8 Ω

Rise Time:  10 kHz, 60 volts peak to peak square wave, 10% to 90% :  2,5 µs

Slew rate:  10 kHz, 60 volts peak to peak square wave :  25 V/µs

Semiconductors:  26 Transistors; 8 Power MOSFETs; 24 Diodes; 4 Zener Diodes; 1 Diode Bridge

Power Consumption:  Quiescent 100 VA, 100 watts into 8 Ω  ; 370 VA

Dimensions (W x H x D): 16" x 5-1/8" x 10-1/2"

Weight: 26 lbs net