[muffking]

I'm buying an amp tomorrow to power the 6 speaker base stereo system in my F31.
Which size speakers should I opt for the front doors. 4"with adaptor rings or can a 5.25" be made to fit?

[JimmyDee]

5.25" won't fit, without cutting the door.

There are a number of 4" options... just depends how much you want to spend.

[muffking]

I don't really want to go too expensive as I don't know how much I will be able to improve on the base setup.

Amp will be a 5 channel Alpine MRV-V500. 4x 40W and 250W for subs.

[Billfitz]

Originally Posted by muffking

I don't really want to go too expensive as I don't know how much I will be able to improve on the base setup.

Probably not much, if at all. I don't know if the drivers in the base setup are the same as those for the hi-fi, but my measurements of the hi-fi driver Theile-Small specs and response show them to be quite capable. I won't spend a dime on replacement drivers that aren't proven upgrades. OTOH you don't have tweeters. Adding them all around would be a decided improvement.

[muffking]

Originally Posted by Billfitz

OTOH you don't have tweeters. Adding them all around would be a decided improvement.

No tweeters in the base setup, just mid range in the doors and subs under the seats.
Will coaxial speakers be up to the job?

[Billfitz]

Co-axials are great... if your ears are located on your knees.

Otherwise you want separate tweeters, as those can be placed closer to head level where they need to be. There are threads here that show how to add them.

[JimmyDee]

Originally Posted by muffking

No tweeters in the base setup, just mid range in the doors and subs under the seats.

WTF?
There's no tweeters in the base system?

[muffking]

Originally Posted by Billfitz

Co-axials are great... if your ears are located on your knees.

Fair point.
The only options I can think of to add aftermarket tweeters are-
Drill a new position them in the doors (probably would mean drilling a hole in the door too).
Drill a hole in the blank A-pillar door trims (cheap solution, but wouldn't look factory).
Buy the A-pillar door trims with the Harmon Kardon tweeter locations (expensive, but factory look).

If there are cheap A-pillar trim replacements then I would rather go for them.

Originally Posted by JimmyDee

WTF?
There's no tweeters in the base system?

Yep, all you get is 2 mids in the front doors, 2 mids in the rear doors and 2 subs under the seats ran from the front channels. The idea is that I separate the subs from the front channels to create a 6 channel setup and bridge the subs to mono and run a 5 channel amp.
Once I know how that sounds on the standard speakers I can then look at upgrading the speakers.

Essentially this is why I posted as I don't think that the door speakers will be up to the job, especially with no tweeters.

[Billfitz]

Originally Posted by muffking

Drill a hole in the blank A-pillar door trims (cheap solution, but wouldn't look factory).

That might work, it depends on the tweeter trim. With these, for instance, I can see it working well:
https://www.amazon.com/gp/product/B0...?ie=UTF8&psc=1

I put these in my rear doors, so I can vouch for them looking OEM there.

Essentially this is why I posted as I don't think that the door speakers will be up to the job

An assumption based on advertising for 'upgrades' no doubt. As I said before, I don't know what your base system uses for drivers, but I do know that the hi-fi drivers are high quality.

[Hammer Werke]

^you don't even need the harmon A-pillar trims....the regular Hifi package has tweets in the A-pillar trims too.

[Billfitz]

He doesn't have the hi-fi package.

[muffking]

True, but it has opened up my eyes to the possibility of buying non HK pillar trims if they're cheaper. That's something for me to look for on ebay perhaps.

[muffking]

In the mean time I came back from the car audio shop after having a long discussion with the staff about my options. I was swayed to a better amp (a 5-channel Kenwood X801-5) and will try it out on the stock speakers.

Problem is that he suggested running it in stereo from the front channels as he believes that the rear channels are not full range. If this is this the case wouldn't I lose the beeping from my parking sensors if I don't the rear channels from the headunit?

[Hammer Werke]

Originally Posted by Billfitz

He doesn't have the hi-fi package.

I know but I meant he could look for them as well....might be cheaper than the HK ones.

[BEM-S4]

Bavsound will sell you the trims with their tweeter upgrades. That might be a good place to start.

[muffking]

Got the amp in today and wow, what a difference.
I'm no expert in sound quality, it's loud, but the quality tails off when you drive the stock speakers hard. I may well be looking in to replacements, but for now it's a million percent better.

One thing though, the amp does get very hot. I assume it would shut down if this became a problem?

[Billfitz]

It should have thermal protection circuitry to shut it down if it gets too hot.

[muffking]

Thanks. I think my earth may have been bad as I made the earth connection better and it seems to run cooler now.