GBMINI stereo – Tweeter screw ups found

Back from visiting Tweeter again today.
Incredibly the installer discovered that he had crossed the feeds to two of the four speakers, so that half the sound was out of phase which is a guaranteed way to destroy the bass! I cannot believe that he made such a basic mistake and did not catch it. It appears that there was just about zero testing of the system after the install was complete.

Unfortunately I still have an engine noise through the speakers – a whistle related to engine revs, loudest around 2500-3000rpm. With the head unit volume at zero, the noise remains (it is present even when the cables from the head unit to the amp are disconnected).
Tweeter were unable to eliminate the noise. They say they contacted Boston Acoustics who claim no knowledge of similar problems.
So I am currently stuck with noise from perhaps a bad installation or perhaps a bad amp; and no-one is doing anything to fix it. I feel some strong letters coming on …

I have had some incredible advice from “Tacotim” which has helped me to understand how the “System Q” (tone) adjustment controls in the head unit work to control the sound.
Now that I have properly wired speakers, I am getting reasonable sound levels – hard to say if it is actually an improvement over the Harmon Kardon designed factory system in the car previously … I hope to be able to compare my car with a stock HK equipped car over the next few weeks (must be time for another visit to MINI Peabody.

My impression of the Harmon Kardon equipped MINI has gone up dramatically in the last week – now that it is no longer in my car. I would recommend the system to people who want amazing clarity in their car, but don’t need super loud volume and don’t mind the front sound stage setup.
Currently the $550 HK upgrade compares very variably with the $1500+ spent on my car.