The rowing world has seen a high rate of failure with speakers in coxed boats recently.  Coxmate investigates and has found the cause, and a solution.

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Coxmate loudspeaker for rowing boats.

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The rowing world has seen a high rate of failure with speakers in coxed boats recently. We have identified the cause as being an increase in amplifier power put out by the NK CoxBox Mini and CoxBox Plus. The old metal cased CoxBoxes had a maximum voltage (pk to pk) of around 10V. The current Mini and Plus are up around 24V. This equates to approximately a sixfold increase in power.

The maximum power into an 8 ohm speaker (as used in rowing boats) with old units was around 1.5 watts. However it has now increased to around 9 watts. Given that NK and Coxmate speakers have a 2 or 3 watt rating, it is not surprising we are seeing high failure rates.  Whilst having powerful amplifiers will improve audio quality – provided speakers are capable of handling extra power, overpowering speakers will cause distortion and ultimately failure.

To address this imbalance Coxmate has upgraded its speakers to 6 watt maximum power and increased impedance to 12 ohms (8 ohm ones will also be available). This means even at maximum volume the amplifiers will not exceed the speaker’s power rating.

The new speakers use a 3 inch cone (increased from 2.5 inches), which improves both efficiency and sound quality. The 12 ohm impedance also enables 4 speakers to be safely used with NK amplifiers (4 speakers at 12 ohms puts less stress on amplifier than 3 speakers at 8 ohms).

The new speakers have been optimally designed for use in boats:

• Use rare earth metal magnets to minimises weight – it is less than half the weight of an NK speaker.
• The diaphragm has no wires penetrating it – less chance of corrosio
• Includes a Microvent – allows air but not water to pass through. This ensures pressure inside speaker remains the same as ambient when temperature changes.  If pressure builds up in speaker it will force the diaphragm out of position and create sound distortion.
• Velcro fitting for ease of installation. (Screw lugs are also provided)

Upgrade your Coxmate speakers at no charge (12 mths old)

Understanding that there are many speakers in existence which are vulnerable to being destroyed, we are offering the following upgrade service:

Speakers less than 12 months old: We will replace the speaker on your SP, Mod-D or Mod-C at no charge, excepting freight. This will be an exchange service.

Speakers over 12 months old: For £15 (inc VAT) per speaker plus freight we will replace the speaker on your SP,Mod-D or Mod-C . This will be an exchange service. The new speakers will be returned with a 12 month warranty.

Contact Rowperfect UK if you bought your speakers from us.

For customers in Australia, contact peterhodson@coxmate.com.au where the charge is AU$25 (inc GST) and the arrangement is identical.