I have an MX5 NC 3.5 with the Bose amplifier and I was going to change the radio to an Alpine iLX-705D, I have bought the DAB antenna and the Mazda MX-5 2009 - 2015 Double Single Din Stereo Stalk Bose Amplified Fitting Kit containing the Fascia, and Steering Wheel Interface loom from dynamic sounds and I was going to get that fitted soon.
However, the Bose amplifier has decided to develop a fault where random noise spikes come out from the speakers.
It happens often when the radio is on, but it happens less often when the radio is turned off. This leads me to suspect is the amplifier.
I am now in a predicament as the amplifier is probably toast.
From looking around in the MX5 forum, I saw that there is the possibility to get that repaired in the UK
However has anyone gone the other way and replaced the bose amplifier with something else (better newer/smaller)?
I don’t mind spending the money and upgrade the amplifier with something else as long as its not too difficult to replace it (i would prefer plug and play solution). Not sure what needs to happen with the speakers as they are the Bose 2 ohm ones and the normal standard is I believe 4 ohm? do we need to add a 2 ohm resistor to all speakers? is there a replacement kit for the speakers as well?
I had the same happen to me, also looked at getting an upgrade / alternative. I came to the conclusion that I’d have to rip out the existing wiring speakers etc etc and just got the amp repaired by the specialist you have linked. It is the simplest option plus I was already happy with the existing Bose system enough that I didn’t want to put in extra money time and effort.
The main issue is that the Bose system has strange wiring from the amp.
The left and right door speakers are two channels.
The dash speaker is one channel
The two rear speakers are wired together and use one channel.
However - the head unit puts out 4 normal channels of pre-amp and the amp itself decides where to sent the power.
If you wanted to replace the bose amp with a regular 4 channel amp - it would mean re-wiring the car to use the door speakers as fronts and then re-wiring the rear speakers to accept two channels of feed.
its all doable - it would just need time and cabling.
I took out the middle console and the rear speaker panel before when I fitted the roll bar so its not much of an issue to redo the rear speakers and add a separate channel for the other speaker.
Would I need to add a 2 ohm resistor to all speakers?
Most amplifiers aren’t fussy provided the load isn’t too small.
However, putting a 2 Ohm in series with the speaker to raise the load impedance seen by a replacement amp will wreck the frequency response because speakers are a very peculiar load, very non-resistive!
TBH - if you are only using the door speakers ( rears & dash removed ) - It would be quite easy to stick a 2 channel amp in. ( many car amps are 2 ohm capable )
The pre-amp feeds are already in the loom ( just need phono plugs adding to the amp end.)
The wires to the door speakers are already in ( just need removing from the connector at the amp end and connecting to the new amp )
