Daimler Bluetooth Radio

In my last entry, I replaced the speakers in my Daimler.  I now had four working speakers.  It was actually sounding pretty decent through the old Pioneer.  I still needed to replace it.  The CD eject mechanism didn’t really work properly, and it looked terrible in the dash.

Replacing the radio wasn’t so simple.   The Daimler Double-Six Vanden Plas came as standard with a Radiomobile 8 Track.  However, this is an older style type radio that uses a smaller opening and the radio is held in place through the shafts for the knobs.

When I purchased the car a while back, I purchased a Radiomobile 8 Track from the UK that had been converted to Bluetooth.  Generally I prefer original radios in my car, but the Radiomobile is AM only, and I don’t own any 8 track cartridges.   I figured this would be a good option to make the car look the part, but be able to play music from my phone.

When the Pioneer was fitted, the opening in the dash was enlarged to DIN size.  This involved cutting the metal backing plate as well as the finishing plate that sits in front it.  Last year when I was in the UK, I bought a second hand finishing plate, and a new backing plate.  The Backing plate wasn’t quite the right part number – It was for other Series 1 XJ models that were optioned with the regular Radiomobile.   From the pictures it looked very close.

My first attempt was a fail.  My workshop manual was only for the Series 2 cars, and it didn’t describe how to remove the trim.  Being sensitive about breaking it, I ordered the correct Series 1 manual.  Shockingly a brand new one was cheaper than a dog eared second hand copy.   The trim removal wasn’t difficult, but there was a specific order to it.    Since the old radio was a DIN, it came out before the trim.

As well as the radio, this panel covers the HVAC controls.  They were all intact, but two of the vacuum fittings were broken.   That may be a factor in time when I attempt to get the A/C working.   One was for the heat, and one was for the recirculation.   The V12 makes so much heat, that I don’t really need the actual heater to work in this car.

With the bracket out of the car, the most time consuming part of this was getting the radio to fit. I realized what the difference between the two part numbers is. The Radiomobile 108 ST is a physically narrower radio. I had to use a dremel to carefully cut material from the new bracket. This was mostly from the sides, but a little at the top, and even a little where the shafts go through to allow the radio to sit lower and line up with the face plate.   I also had to transfer over all the hardware from the old backing plate to the new one.  This was primarily the little fittings to allow the silders to go on, and the heater control levers.

I also had to do the same thing, transferring over the decals from the old faceplate to the new one.

From there I created a wiring harness for the radio – to connect the speakers and to add in bluetooth charging. Not much good playing music from my phone if the battery runs out.

I did a test connection before putting it back into the dash. It sounded absolutely terrible. Even at moderate volume, it distorted like crazy. I figured I had done something wrong, so set about eliminating possible issues. First was power supply to the radio. I used a power probe to check voltage to the radio and ground. I then applied 12v directly to the radio from the battery, and the distortion was the same.

Next thing to eliminate was Bluetooth. The way the radio worked is that a small bluetooth box connected to a headphone jack that went into the radio. I used a lightening to headphone adaptor to plug my phone directly into the the phone, bypassing bluetooth. Still distorted.

Final thing was speakers. The radio has two channels, apparently 50W each. I assume that is peak, not RMS. For my setup I had two speakers connected to each channel. I tried a few different combinations. First one speaker per channel. Then just one speaker total. I used a few combinations, e.g. front left and rear right. Distorted every time.

Being perplexed, I messaged the seller of the radio for any advice. It is out of warranty, but I hoped he would have a few tips. He was good enough to reply and asked to see the specs of my speakers, which I sent him. His view was that my speakers were undersized, and that they should be at least 50W RMS.

That left me perplexed. Most classic cars have tiny speakers, so finding a 50W RMS speaker in 4″ seems unobtanium. If that scenario was correct, I would have expected it to distort only at high volumes. He offered to bench test it for me, if I sent it back, which was kind of him to do. Given the cost of shipping, I wanted to do more tests myself.

The final test before finishing up for the day was to use a different radio.  I figured a pinstripe Becker would be a good test.  A Becker Europa II has two 7W channels, so if it could play the speakers then anything should.

I took out a Becker Europa II from my Becker collection and ran a simple test, one speaker.   It sounded really good.   That gave me a good avenue for further testing.