Tech Support

- Technical support from FUSION Electronics

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. Then connect the Positive and Negitive wires from the closest speaker to the Stereo.

 

 

A simple guide to the Ohms Law.

What are the benefits of D Class Amplifiers in my vessel ?

The simple answer to this question is higher output power  (more Watts) and reduced current draw (play your music for longer periods). To give you a comparison between Class AB and D class, 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   D Class) have a rating of 70 Watts per channel and due to their  efficiency consume less power per Watt of output. In essence you can go louder for longer.  The other major benefit is that the D Class amp in the 500 and 600 series is that it's 2 Ohm stable (stereo).What this means is that you can conect 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 ouput 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% as well 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 D Class  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 Positive together and Negative together, this is to make connection to multi coil Subwoofers easier when you configure 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 and 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 amp     
    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 amp
     capable of a higher output cannot be used if the amplifier settings are
     managed responsibly realising 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 channels output 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.

This 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  are as follows.

 

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  class AB or  D class amps as the 1 Ohm rating applies to D class amps in general.