Alternative to Bose Power Amps with Plug & Play

Hello, everybody.

for eight years now I am proud owner of a V8 with Bose sound system.
From the beginning the relationship with this sound system was, well let's say a little strained.
When I bought the car, only the front power stages still worked - well, they gave at least some noises that reminded of music.
With a lot of patience and spit I went to work to repair my sound system. Many power amplifiers can be done quite well by renewing all MOSFETs and everything wa Elko - if the ICs on the board are still ok. If all "weak" components are renewed, then you have to worry again for a few years.
In the meantime, the power amplifiers are already available individually at the friendly shop.
Considering the way AUDI and BOSE went with the Class-D in the 1980s, the word is still revolutionary. I'm pulling my hat from the performance that was done at that time. When I first took a look at a Bose level, I didn't want to trust my eyes - where is the heat sink? Isn't that supposed to be that ridiculous tin? Yes, it should.
EIne of these power amplifiers delivers almost 70 watts of sine on a Bose loudspeaker with a 1-Ohm impedance!
Personally, I think Class-D is a great thing. With an efficiency of almost 90% and already in the lower to middle line range is quite ingenious. Every Class AB full bridge end stage with its just under 50% in the middle line area can get quite warm. If a power amplifier pumps 11 watts of heat into the heatsink at 13 watts of music line and a class D power amplifier only 1.6 watts, then you wonder if Class-AB should be an abbreviation for any heating element.
Uuups, I've drifted a little off the subject...
What has always bothered me personally with the V8 Bose system was the impression as if the basses are dominant, the middles so strongly dampened and the heights - there are any?
A look at the frequency response of the V8 Bose power amplifiers reveals why this is the case. The depths show high altitude, the middles are strongly dampened...
Since I had no desire to build commercial power amplifiers into my trunk or screw them to the back bench, the idea arose to develop a class-D power amplifier, which is identical in size to the V8 power amplifiers and you only have to replace the boards.
The main problem with this was, however, that there were almost no Class-D chipsets for this - until the beginning of this year.

I once added some pictures.

Here are some data of the final stage:
Frequency response: 6Hz - 22KHz
Reinforcement: 26 dB
Power: ~72W @ 1 Ohm (Sinus), 36W @ 2 Ohm (Sinus), 20W @ 1 Ohm (Sinus)

Have installed the power amplifiers in my V8 for a few weeks in the course of a conversion of the Navi from RNS-D to RNS-E. At the same time I replaced the rear speakers of Bose with Infinity Reference 9623i. The plastic housing of the rear LS has to be worked because the infinity has a thicker magnet and is higher. There are certainly other and also better LS than this, but Infinity is besides JBL one of the few manufacturers that produce LS with 2 Ohm impedance (2.65 Ohm to be exact).
Why is this important? Quite simply: The power is calculated from the square of the voltage divided by the impedance. A speaker with 1 ohm impdance generates a factor of four higher power at the same voltage as a speaker with 4 ohm impdance.

I left the front speakers original. Since there are now Laustprecher with 1 Ohm impedance installed in the front and 2,65 Ohm in the rear, I have made an appropriate adjustment on the front side of the amplifiers so that I do not have to use the fader.

The RNA-E is a partial active system, i.e. it has four preamplifier outputs and two that can be connected directly to speakers. I knew from the first hearing test that I wouldn't need it. The Infinity Reference at the rear and the Bose speakers at the front harmonize so well that the front LS can no longer improve the sound image in my opinion.

In the next few days, I'll stop by the Legans. There is a voluntary one, who sometimes tests the power stages on an original radio and can be missionaryed :-)

Many greetings
Maadin