Hafler DH-500

BENCH TESTED AND LISTENED TO BY HOLLYWOOD SOUND. 
FOUND TO BE PERFORMING FLAWLESSLY.
MINOR SCRATCHES ON THE SURFACE & therefore condition listed as 5/10.  See photos.

INTRODUCTION [FROM THE MANUAL]:::  The Hafler DH-500 is a two channel audio power
amplifier designed to the very highest performance standards. It is available as a kit, or factory assembled. Its
power rating of 255 watts per channel is very conservative,
and it can deliver appreciably higher powers into impedances below the rated 8 ohms. You must be very cautious
in the application of this amplifier, as its output capability
is more than most speakers can safely tolerate. We urge
you to read the “Operation” section of this manual so your
speakers will be reasonably protected. The best protection
is still common sense in choosing program levels which
your speakers can tolerate. The DH-500 combines power MOSFET technology
with a uniquely simple and effective circuit which reduces
all types of distortion at all power outputs, over the entire
audio spectrum, to levels where the finest test equipment
has great difficulty in measuring it. The DH-500 sets a new
high in reliability and resistance to abusive operating conditions at such high powers. This is one of the direct benefits of the power MOSFET’s ability to current limit under
abnormal conditions.
Where the conventional bipolar transistor must be protected by special circuits from entering “thermal runaway” when it gets hot due to heavy signals, tending to get
even hotter, the MOSFET self-corrects to reduce the current, and thus the heat under the same conditions. You
thus gain the dual advantages of simpler circuitry and the
elimination of one of the chief causes for distorted signals
imposed on the music-the sound of the actuation of complex protective circuits. The speed-measured as the slew rate-of the DH-500
delivers unmatched transient linearity, revealing the most
delicate nuances of the music. In refining the basic Hafler
MOSFET circuit the overall open loop gain was reduced
by using more local feedback in the input stage. This required less compensation to stabilize the circuit, with the
result that it was faster overall. With the built in bandwidth
limitation at the input, all other stages are free of any transient overload. The fully complementary, symmetrical push-pull circuit
is direct coupled throughout (except at the input). It uses
all silicon discrete devices in a format which is directly related to the acclaimed Hafler preamplifier circuit. With its
unconditional stability into virtually any load, and its
enormous power capability, the result is complete freedom
from listening fatigue. The longer you listen to this remarkable amplifier, the more certain you will be that you
could not have made a better choice. While modest in cost, through the elimination of frills
and gadgetry, the quality is evident not only in the sound,
but in the conservatively rated components. The oversized power transformer, the conservative operating levels
of the MOSFETs, the computer-grade electrolytics totalling 40,000 microfarads, the enclosed relay, the use of film
capacitors in signal circuits-all are evidence of the design
efforts to achieve exceptional reliability simultaneo’usly
with state of the art sonics and specifications. So rugged is
the DH-500 that it can deliver over 20 amperes into a short
circuit!
For those with special power needs, the DH-500 can be
adapted to monophonic operation, delivering in excess of
800 watts into 8 ohms, by installing the DH-502 input
bridging kit.
Those who have chosen to build this amplifier from the
kit will find the assembly instructions assume no technical
ability other than how to make a good solder connection.
Even that has been described for those who are new to the
fun of kit building. Through pre-assembly and testing of
the complete signal module, the performance of the kit has
already been assured, for assembly involves little more
than interconnection of the power supply and control elements. You can look forward to just a few hours of construction fun, to hear the finest audio amplifier yet produced.

Power Rating: Less than 0.025% total harmonic distortion at any power level up to 255
watts continuous average power per channel into 8 ohms at any frequency between
20 Hz and 20 kHz with both channels driven.
IM Distortion (SMPTE): Less than 0.007% from 1 watt to 255 watts into 8 ohms
Typical THD at 255 watts into 8 ohms: 1 kHz-0.002%; 10 kHz-0.007%
Frequency Response into 8 ohms: -3 dB, 0.5 Hz to 120 kHz at 1 watt
kO.5 dB, 5 Hz to 40 kHz at 255 watts
Typical Channel Separation at 1 kHz: 60 dB
Signal to Noise Ratio: Exceeds 100 dB referred to 255 watts into 8 ohms, unweighted
Exceeds 90 dB referred to 1 watt into 8 ohms, A weighting
Input Impedance: 47,000 ohms
Input Sensitivity: 2.35 volts for 255 watts into 8 ohms; 0.145 volts for 1 watt
Damping Factor: 200 to 1 kHz into 8 ohms; 60 to 10 kHz into 8 ohms
Rise Time: 10 kHz, 80 volts p/p square wave, 10% to 90%: 2.5 us.
Slew Rate: 1 kHz, 120 volts p/p square wave: 45 V/us.
Semiconductor Complement: 27 transistors, 12 power Mosfets, 33 diodes, 8 zener diodes,
one integrated circuit, one diode bridge.
Power Consumption: 240 VA quiescent; 1200 VA @ rated power into 8 ohms, 2 channels
Size: 7-l/4” high, 19” wide, 13” deep including handles
Net Weight: 45 lbs.
Shipping Weight: 49 lbs.

SEE PHOTO OF ADDITIONAL AUDIO EQUIPMENT FOR SALE 

NOTE: BUYER PAYS SHIPPING AND  2.9% PAYPAL FEE  
ITEM HAS BEEN INSPECTED BY HOLLYWOOD SOUND

SOLD AS IS - NO RETURNS ACCEPTED        

HAVE QUESTIONS??? WE'RE HAPPY TO ANSWER THEM.  
SHOOT US A MESSAGE AND WE'LL ANSWER YOU PROMPTLY.  
HAPPY SHOPPING! - THE SAVITZ MUSIC FAMILY