Tech Support



+ How do I wire my speakers in 2 Ohm configuration for my MS-AM702 Zone Amp? (Parallel Configuration)

To wire 2 x 4 Ohm speakers in parallel to present a 2 Ohm load to the MS-AM702 amplifier per channel, simply follow the below diagram showing the Positive terminals from each speaker connected to each other and the same with the Negative terminals. When this is done, simply connect the Positive and Negative wires from the closest speaker to the stereo.




+ A simple guide to the Ohms Law.


+ What are the benefits of Class-D amplifiers on my vessel ?

The simple answer is that with a Class-D amplifier you get higher output power (more Watts) and reduced current draw (play your music for longer periods). To give you a comparison between Class-AB and Class-D, the normal output of a standard head unit ( class AB) is, say, 40-50 Watts peak per channel. The Fusion 600 Series head units (MS-CD/IP/AV600 Class-D) have a rating of 70 Watts per channel, and due to their efficiency, consume less power per Watt of output. In essence, this means that you can go louder for longer. The other major benefit is that the Class-D amplifier in the 500 and 600 series is 2 Ohm stable (stereo). What this means is that you can connect 2 x 4 Ohm speakers per channel in parallel wiring configuration. This produces more power but is divided between the 2 speakers, eg. at 4 Ohms per channel, output is 26 Watts RMS and at 2 Ohms it is 43 Watts RMS, so divided by two is 21.5 Watts RMS per speaker.

The theoretical efficiency of Class-AB is about 75% with a real efficiency between 50%-70%; the theoretical efficiency of Class-D is about 100% with a real efficiency of more than 85%. The Fusion Class-D Marine Zone amp MS-AM702 is a perfect example of a compact high output solution for the boating enthusiast that loves their music loud.

+ Why does my mono block or single channel amplifier have 4 speaker terminals?

Some mono block (single channel) amplifiers have 4 speaker output terminals, as shown below. These are internally linked with positive together and negative together, to make connection to multi coil subwoofers easier when configured in parallel. You can connect each coil directly to the terminals (one per side) rather than at the subwoofer. 




+ What size inline fuse should I use for the power cable to my amplifier?

The inline fuse should be fitted as close to the battery as possible with the rating (amperage) the same or higher than the total on-board fusing of your amplifier. This fuse is to protect the power cable from grounding and potentially starting a fire. 

+ What is the best way to match my speakers/subwoofer to an amplifier?

My speakers are 300 Watts “Max” and 90 Watts “Rated Power”. What size amplifier do I need to drive them to achieve the best performance? 

When you are choosing an amplifier to drive speakers or a Subwoofer, you should use the “RMS” per channel ratings (amplifier) and the “Rated Power” (speaker/subwoofer) as the reference for your choice. Always define which ratings you are comparing and try and get them as close as you can.                                                                                                   

Max/Peak” Power Rating

The “MAX/PEAK” power rating of a speaker is the amount of power that the speaker can handle in short bursts or peaks without causing permanent damage to the voice coil. If this rating is exceeded constantly, you will risk burning the voice coil.

 “Rated Power” Power Rating

The “Rated Power” rating of the speaker is generally considered to be the nominal constant power that the speaker will handle continuously without causing damage.

Therefore if your speakers are rated at 90 Watts (rated power) you should drive them with an amplifier that is capable of supplying 90 Watts RMS per channel or as close to that as possible. That is not to say that an amplifier capable of a higher output cannot be used if the amplifier settings are managed responsibly, remembering the potential to overdrive your speakers exists. This rule also applies to using an amplifier that is under driving your speakers. Constantly driving a distorted signal from an overdriven source to your speakers can cause damage to the voice coils.

+ How do I bridge my amplifier ?

Bridge mode is commonly used to get more output power from amplifiers by combining two single channel outputs into one output. This can only be done safely if you know the minimum load (Ohms) permissible when bridged. This is more common when driving subwoofers that have dual voice coils, or when you have multiple subwoofers. First check the installation manual or look at the speaker terminal block on the amplifier, as they normally have a diagram showing the bridged connections.

Below is an example of a 4 channel amp speaker connection terminal block. As shown, bridging is achieved by connecting the positive terminal from the left channel and the negative terminal of the right channel to the corresponding terminals on the subwoofer coil or coils depending on configuration. There are a number of different configurations depending on the load applied to the amplifier - see subwoofer coil configuration.  It all depends on whether you have a  4 Ohm, 2 Ohm or 1 Ohm stable amplifier (mono). An example of the different power ratings for a four channel amplifier is below.



100 Watts RMS x 4 @ 4 Ohms
200 Watts RMS x 2 Bridged @ 2 Ohms

These are examples only to give you an idea how this works. This also applies for  2 channel amplifiers and depends on whether they are Class-AB or Class-D amplifiers, as the 1 Ohm rating applies to Class-D amplifiers in general.

Install Tips & Guides

+ My amplifier's protection light Is on.

If the protection LED is illuminated, this indicates that the amplifier is in protection mode due to a fault condition. There are numerous causes for this which may mean the Amplifier will need to be inspected and diagnosed by a technician. It may also be a speaker or subwoofer causing the fault condition.
To eliminate this as a possible cause, disconnect the speakers or subwoofer from the output of the amplifier. If the amplifier still goes into protection mode with nothing connected to the 'out' terminals, this indicates a fault with the amplifier.

+ Power cable voltage drop table

When running a power cable for amplifiers, it is wise to calculate what the voltage drop will be, especially if you are using long runs. The below table will help you to calculate the correct size cable you require. 




+ Amplifier gain control adjustment (input sensitivity)

The gain or level pot is not a volume knob; it is used to match the relative output level (voltage) of your source unit to the input circuit of your amplifier. The gain control determines how far you have to increase the volume on your source unit for the amplifier to reach full power. If you have your gain set too low, your amplifier will not be able to reach full power, which could allow the source unit to clip which in turn will result in a distorted signal being delivered to your speakers. This is especially relevant with low voltage sources (lower than 2.5 Volts - typically OEM units). If the gain is set too high with higher voltage sources (2.5 Volts or higher), the amplifier will be able to reach full power at a lower volume control setting from the source unit. This will allow the amplifier to be driven into clipping. The gain settings should generally be set lower, meaning a higher setting on the volume control of the source, to minimize amplifier clipping.

Guide to Setting Gain Control

 If you do not have the correct equipment (oscilloscope)  this may help        
 you to set your gain:

1. Once you have installed the system power it down.

2. Adjust the amplifier gain to the minimum.

3. Power up the system and adjust the volume control of your source unit

   to about 3/4 of the way up.

4. Slowly increase the gain control until it reaches the maximum level you 

   are comfortable with, or until it starts to clip, and then reduce the level

   until you are happy that you will not damage your speakers or subwoofer.

+ General amplifier installation guide

Before any wiring and installation is performed, FUSION recommends you first plan the complete installation. Look at wiring routing, amplifier location and fitment. Please re-check the installation at completion.

Appropriate mounting is very important for the prolonged life expectancy of any amplifier. Select a location that allows enough space for sufficient airflow to be maintainable, and a location that provides protection from moisture. Keep in mind that an amplifier should never be mounted upside down. Upside down mounting will compromise heat dissipation through the heat sink and could engage the thermal protection circuit.
Excessive heat will shorten your amplifiers life. To maximize heat dissipation, be sure to leave at least 2.5 inches of clearance around the amplifier. If space is of the essence and the amplifier must be mounted in an enclosed or restricted area, a small 3 inch fan should be used in correspondence with a duct so the heat can flow past the heat sink.

WARNING: Do not mount any amplifier on a subwoofer enclosure as extended exposure to vibration may cause malfunction of the amplifier.

1: Ensure the vehicle 12 volt lead is removed from the battery before any equipment is connected.
2: Investigate the vehicles gas tanks, brake lines and electrical wiring locations before you begin installation.
3: Attach the product securely to the vehicle to prevent damage in the event of an accident.
4: Ensure all wiring is protected to avoid damage or pinching of the cables.

Make sure before any connection is made to the amplifier or source unit that you turn the audio system off. Failure to do so could result in either the stock system or your new FUSION product being damaged. FUSION will not warranty damaged amplifiers due to incorrect installation.
When wiring FUSION amplifiers, ensure that the wires are away from sharp objects, and that rubber grommets and insulated bungs are used when wiring through door jams and any other steel panels.

Note: Ensure the audio system is off during the installation of FUSION products. Once the installation is complete FUSION recommends that you turn the volume of the source unit up slowly to avoid damaging the speakers. Please recheck the complete installation prior to turning the audio system on.

Always ensure that the ground connection point is a clean, bare metal connection. It is a good idea to apply silicone over the bolt and connection to prevent the formation of rust. If the amplifier is powered on without an earth connection or a poor connection, this will cause damage to the amplifier and/or head unit as it will try to find an earth via the least path of resistance, which could be through the RCA connectors back to the head unit . This will burn the earth track on the head unit or it may go through the chassis of the amp to the floor of the car. This is traceable by a technician to verify the cause of the damage.


+ General amplifier trouble-shooting

My Amplifier isn’t working.

- Check to see which, if any, LED indicator is on.

-       If neither indicator is on, first check your inline fuse in the power cable near the battery. (If blown, replace with the same rated fuse.)
-       Ensure the earth/ground and power connections on the terminal block of the amplifier are clean and tight.
-       Ensure your remote wire has a good connection at the amplifier and head unit/source.   
-       Check the amplifier fuses. If blown, replace with the same rated fuse, but if they fail again you may have a problem in your amplifier circuit. Do not replace with a higher rated fuse as this could result in major damage.
-       If the problem persists please consult your authorized dealer at your place of purchase.

Protection LED On
-      If the red protection LED is on it may be that the amp has gone into thermal protection (overheating).
-      Let the amp cool down for 15-30 minutes and try again.
-      If the amp still goes into protection, it could be the result of a speaker/sub problem. To check this, disconnect the speaker/sub from the amp and turn the amp on. If the power indicator comes on and stays on, that would indicate that you have a problem with your speaker/sub.
-      If the protection LED comes on you may have an internal problem with your amp.
-      There could be a fault that needs professional diagnosing and servicing.
-      If the problem persists please consult the authorized dealer at your place of purchase.
 Power LED On With No Sound
-      This can indicate that the amp is not receiving a signal from the head unit/source, so check your RCA cables and settings.
-      Check the wiring connections on the output of your amp and the subwoofer.
-      You may have a problem with the output circuit of your amplifier.
-      If the problem persists please consult the authorized dealer at your place of purchase.

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