Hafler VRM 15SCE, User Manual

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MEHSA
(Maximum Efficiency HeatSink Application) MEHSA is a proprietary process that yields up to 5 times
better heat transfer than traditional FET mounting techniques using the exact same components. A
multi-layer insulated metal substrate operating with minimal thermal resistance spreads heat both
downward and outward to quickly dissipate heat from each device across the heatsink. This process
combined with our DSM technology and MOSFET devices allows us to squeeze more watts per cubic
inch from every output device as well as provide consistent thermal stability.

The Result: Better reliability through faster heat dissipation.

Trans•ana
Trans•ana (TRANSconductance Active Nodal Amplifier) is a circuit that allows the audio signal to pass
through the amplifier at low voltage. The signal is directly level-shifted to the fixed high voltage rails
via a pair of driver transistors. Signal linearity is assured by an active node formed by the driver transis-
tors at ultrasonic frequencies. This allows amplifier performance similar to Trans•nova which is highly
stable and linear while utilizing the advantages of a non-floating power supply.

The Result: An extended frequency band width accurately supplied to the output stages of the 
amplifier. 

MOSFET Devices
HAFLER is one of the few manufacturers in the sound community to utilize MOSFET devices in the
amplifier output stage.  MOSFET (Metal Oxide Semiconductor Field Effect Transistor) devices offer sev-
eral important inherent advantages over older bi-polar designs.  These advantages include: thermal sta-
bility, fast switching speed, ultra low output impedance and wide bandwidth linearity.  In addition,
MOSFETs operate very similarly to vacuum tubes in that they are more linear than bipolar transistors.
However, MOSFETs can deliver the midrange clarity without the limitations of transient response and
high frequency phase shifting normally associated with tube 
operation.

The Result: Thermal stability, fast switching speed, ultra low output impedance and wide bandwidth
linearity. 

Heat Monster:

High output MOSFET device

Solder

Copper heat spreader

Dielectric layer

Base Layer - aluminum

Thermal grease

Heat sink

Screw, no pressure on component!

Multiple heat paths

PC Board

Clamp Bar

Heat generating component

(typically a power MOSFET or

bipolar semiconductor)

Thermal grease

Mica

Thermal grease

Heat sink

Screw

Heat path

PC Board

The MEHSA Way

The Old Way

Technical Design Features