Lab.gruppen fp 6400 Guida Utente

long-term current draw. Read more about the AFS limiter under “Protection” on page 

Technical Note on our website 

: AFS limiting and power consumption. 

It is more useful to state the current draw in different loads and output power levels. These figures can 
be found on the specification sheet. The current draw is measured in Ampere rms. This figure 
corresponds to the minimum value of the mains fuse needed. 
We recommend you to design the power distribution at least for the current at 1/8 power, and for 1/3 
power for heavy-duty demands like discotheques, etc. 
Second, the maximum expected average current under worst case program material, which is 1/3 of full 
power according to the FTC standard. At this level the music will be in the state of constant clip and is 
therefore the highest power level one can obtain without completely obliterating the program. 
Last, the "regular operating power" as defined by the safety standard IEC 65/ANSI/UL 6500 and used 
by a majority of safety agencies. The regular operating power is measured by using pink noise, and with 
an average output power equal to 1/8 of full power. The one eighth of the total power is as loud as you 
can play music while making some attempt to avoid obvious clipping. It also corresponds to a headroom 
of 9dB, which is very low for regular audio program.  

e calculated as in the following example: 

 4 ohms load on an amplifier 

tts, and 

to the chart above is then 1975 watts. This chart shows the active 

he heat power produced is the difference between the power consumption and output power: 

roduced in watts, in kcal per hour, and also in BTU per hour. 

he efficiency can also be calculated, it being the output-power divided by the input-power:  

Power*

AFS activated

1/3 Power

1/8 Power

Idle

[W]

[W]

**

***

fP 6400

8 ohms

2x

1300

1300

1230

575

105

4 ohms

2x

2300

1450

1975

900

105

2 ohms

2x

3200

1850

2950

1290

105

* = Will be reduced by AFS limiter.

** = Average power with music as program source. The amplifier driven to clip level.

*** = Regular music power with 9dB headroom, IEC standard power rating.

MAINS INPUT POWER

MAX OUTPUT POWER

The heat power can b
We consider a headroom of at least 5dB (1/3 of full power) and a
producing 2300 watts per channel. The 1/3 power per channel is accordingly 2300 / 3 = 767 wa
total output 2 x 767 = 1534 watts. 
The power consumption according 
power consumption of the amplifier with different loads and power levels.  
 
T
1975 - 1534 = 441 watts per amplifier. 
The chart below shows the heat power p
 

1/3 Power* 1/8 Power** 1/3 Power* 1/8 Power** 1/3 Power* 1/8 Power**

[W]

[W]

kcal / h

kcal / h

BTU / h

BTU / h

fP 6400

8 ohms

363

250

310

220

1240

850

4 ohms

442

325

380

280

1510

1110

2 ohms

817

490

700

420

2790

1670

* = Average power with music as program source. The amplifier driven to clip level.

** = Regular music power with 9dB headroom, IEC standard power rating.

HEAT POWER

T
1533 watts / 1975 watts= 78%.