The following is the process in which i built a custom stereo for my 1967 Citroen Ami6.
Because of modifications to the car by previous owners i was able to take some liberties in the installation but i wanted the install to be largely unobtrusive on the overall appearance of the car. I have a long history of installing absurd stereos in places they don't necessarily belong but this was the first time i was attempting to hide the majority of the install. I decided that if possible i wanted to avoid running a head unit all together since there is nothing more out of place in a vintage car than a modern digital head unit with flashing lights and a whacky EQ visualization.
A long time ago i knew a lot more about what I'm doing, i understood amps, ohms, watts, etc. and the fine details of putting a system together. Not so much anymore, mostly i just do things the way i remember and guess when i don't. This whole system might seem a little hacked together and to some of you it might even seem flat out wrong. It was all an experiment and i am very happy with the results.
Please use this information as proof of concept only, i am not educated enough on what I've done to say with absolute certainty that you won't electrocute yourself, burn down your car or otherwise cause serious harm or damage your body or property.
Also please feel free to tell me why I should have been killed or maimed during my own installation process if you notice any glaring errors.
Step 1: What are we working with
A vintage French Car.
As you may note, this car has a somewhat unique aesthetic and you might agree it shouldn't be disturbed with various modern components.
One of the attached images is from a french magazine in which the car was featured, unfortunately this is the only image i have showing the state of the door cards when i received them. The drivers side card had already been cut for a speaker and all four door cards were extremely warped and the vinyl was peeling and delaminating.
I knew i could rebuild the doorcards but someone had already cut one of them up so it would never be near original again, this was the impetus behind the project. A doorcard with a hole for a speaker needs a speaker!!!
So now i knew i was willing to put front speakers in and i didn't want a head unit.
I took some measurements around the rest of the car and decided i could get some shallow components in the front door and a set of 4x10"s under the backseat in a custom box along with a 10" sub and amp behind the backseat.
I just needed to find the right shallow sub, either an under-seat box or something meant for behind the seat of a pickup truck.
But first lets figure out if ditching the head unit is feasible.