Ramsey Electronics UAM4, Manual

UAM4

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spacers and the 4 mounting holes on the corners, try mounting the board 
to a piece of aluminum or some other metal and see if the problem is 
solved.  You can also use the 2 holes located between the output screw 
terminals and U1 to mount to a metal plate.  These are closer to U1 and 
will dissipate the heat faster.  You may need to adjust the threshold once 
the heat sink is installed.  Remember to use metal spacers and the 
absolute lowest setting of the threshold necessary. 

NEAT-TO-KNOW INFORMATION: Determining Speaker Phase 

A speaker is an electromechanical device that converts electrical impulses to 
sound waves.  This is done with a magnet and a coil of wire.  When an 
electrical current is passed through a wire, a magnetic field is produced.  If the 
wire is made into a coil and attached to, for example, a piece of paper, and a 
magnet is placed inside the coil, we have the components of a speaker.  
When a changing electrical current (like an audio signal from the UAM4, for 
instance) is applied to the coil a changing magnetic field is produced in the coil 
which interacts with the magnetic field of the magnet and the coil moves, thus 
moving the paper.  Moving the paper causes the air around it to move at the 
rate of the applied signal and sound is produced.  The paper is the cone of the 
speaker, and the coil is called the voice coil.  Current in one direction will 
cause the cone to move in one direction and the opposite direction when the 
current is reversed. 
 
To determine which way the cone moves with a given current polarity applied 
you will need a battery such as a ‘AA’ cell and a resistor with a value of 10 to 
100 ohms.  You will also need to be able to see the cone of your speaker.  
Using clip leads connect one to one lead of the resistor and the other to a 
terminal of the speaker.  Connect the other lead to the other speaker terminal.  
The resistor value is not critical but is necessary to prevent allowing too much 
current to flow in the voice coil and damaging it.  Now the fun begins! 
 
Connect the clip lead with out the resistor to the ‘-‘ terminal of the battery and 
then connect the free lead of the resistor to the ‘+’ lead of the battery while 
watching the cone.  If the cone moves toward the front of the speaker, mark 
the speaker terminal with the resistor with a ‘+’.  If it moves the other way 
mark the terminal attached to the battery ‘-‘as “+’. 
 
Repeat this same procedure on the other speaker.  When you connect the 
speakers, simply connect the marked lead of each speaker to the ‘+’ terminal 
of the desired channel, (left or right), output terminals and the other to the 
corresponding ’-’ terminal and you will have a properly connected set of 
speakers!  It really doesn’t matter which lead you mark on the speaker, since 
as long as you mark both speakers the same way they will be in phase. 
 
What if you can’t see the speaker cone, don’t have a battery or resistor or are