[Silverbmw328]

I've just purchased the Apline retro fit kit for the front which I haven’t fitted yet but I had a play tonight and could believe how crap the rear parcel shelf speakers are when on full fade.

I know most say ignore them but I thought as I'm doing it anyway I'd replace them. I've found a few 4" on eBay but can't make up my mind on what to get.

PS : Not amping them.

Help ?

Focal IC100
http://www.ebay.co.uk/itm/2808843430...84.m1438.l2649

INFINITY REF 4032 (2 ohms)
http://www.ebay.co.uk/itm/1607879872...84.m1438.l2649

HERTZ ECX100.4
http://www.ebay.co.uk/itm/1607137730...84.m1438.l2649

Hertz DCX 100
http://www.ebay.co.uk/itm/Hertz-DCX-...item3f17612970

Ground Zero Hydrogen
http://www.ebay.co.uk/itm/Ground-Zer...item27c5904ddd

Rockford Fosgate Punch P142
http://www.ebay.co.uk/itm/Rockford-F...item5894194836

Pioneer TS-E1002i
http://www.ebay.co.uk/itm/Pioneer-TS...item27bc2b5be2

[makkan00]

Good research.
Well rears are hi-passed so the sound will always be crapy, unless you get it coded to hi-fi.
After coding, it is slightly better, but not great.
I will go for pioneer, Focal or infinity.
Not sure about other brands.

[parapaul]

My 2p:

As the rears aren't amped, they're really only for a bit of fill. Power handling is relatively unimportant because the power output of the HU is only a few watts per channel.

Ignore the ebay ads and go straight to the CAD website, compare the sensitivity of each set of speakers. They're all good brands, find the set with the highest sensitivity and go for them.

It's all about signal:noise ratio - you want to get the maximum output per watt of input power.

HTH

If I get bored at work later and have the time I'll do it for you

[Silverbmw328]

Many thanks

[gIzzE]

Completely pointless to upgrade them, you have a bandpassed signal going to them, it is not the speakers that are limiting what you hear, it is the signal.

[mob17]

If you really want to, just get Vibe Slicks. They are cheap but decent.

[Silverbmw328]

Originally Posted by parapaul

My 2p:

As the rears aren't amped, they're really only for a bit of fill. Power handling is relatively unimportant because the power output of the HU is only a few watts per channel.

Ignore the ebay ads and go straight to the CAD website, compare the sensitivity of each set of speakers. They're all good brands, find the set with the highest sensitivity and go for them.

It's all about signal:noise ratio - you want to get the maximum output per watt of input power.

HTH

If I get bored at work later and have the time I'll do it for you

Been looking at most 4" speakers sit around a sensitivity bewteen 85 - 95 db and an input of 30w - 90w rms . Don't really know what I'm looking for to be honest.

[parapaul]

Power handling is mostly irrelevant, the HU only outputs about 10-15W per channel so even 30W speakers will be more than capable.

Sensitivity is logarithmic - ie a 2x increase in sensitivity equates to a 10x increase in output. The difference between an 85dB and 95dB speaker will be easily noticeable - which ones are 95dB?

[makkan00]

Originally Posted by parapaul

Power handling is mostly irrelevant, the HU only outputs about 10-15W per channel so even 30W speakers will be more than capable.

Sensitivity is logarithmic - ie a 2x increase in sensitivity equates to a 10x increase in output. The difference between an 85dB and 95dB speaker will be easily noticeable - which ones are 95dB?

None is 95dB

Top three, most sensitive out of OP list are

Infinity 4032: 92dB but 2 ohms
Focal Intengration: 90.3dB
Hertz DCX 100; 90dB

Others are less sensitive.

HTH.

[gIzzE]

A decent install will rip the rears out anyway.

Fir the Alpine kit first and see what you think.

[parapaul]

I'd be happy with either Focal or Hertz but I can't help but think it's a waste of money for the OP either way.

[gIzzE]

Complete waste of money.

[mob17]

Im upgrading my rears soon, but this is because of level matching issues with MS-8 calibration. The following is assuming you want your non amped rears to keep up with your amped front stage, i.e same volume.

Be aware that you should compare the same types of sensitivity ratings. The OEM base spec rear mids are rated at 87db/1W/1M and 90db/2.83v/1M. If you want your rears to be 3db louder you have to double the wattage. This is for every 3db increase.

Think of it this way. If you replace your rears with 4 ohm speakers that are 6db more efficient, so rated 93db/1W/1M (and 96/2.83v/1M), then this will be the SAME volume as your OEM base rears fed with 4 times the wattage.

If you still want to replace your rears and do it right then this is what you should do. Find out what the Alpine mids are rated at. For this example say they are rated at 90db/1W/1M. Using a SPL calculator, such as http://myhometheater.homestead.com/splcalculator.html this is a volume of 113.3db SPL at the listening position (using 80w and 2 feet distance). So then you need to work out what sensitivity rating of your new speakers should be to get the same SPL at the listening position. Say the watts from the HU is 20. Using the same calculator you will need a speaker rated at 96db/1W/1M, so 6db higher. This follows the earlier rule, for every 3db increase you have to double the power.

This was just an example. I used 2 feet as the distance for fronts and rears. If you want to do this find out the exact output wattage to the rears and sensitivity ratings of the Alpibe mids.

[AlanYoro35i]

doesn't his alpine kit comes with amp? can he not split the rear speaker channel to the shelf speakers? ofcourse this isn't pro and infact you're halving the signal but isn't it better than running it thur the headunit? i guess the op does not hope for a award winning but a simple improvement with less hassle?

[gIzzE]

The amp is 4 channel, it uses channels 1 and 2 to drive the front mids and tweeters and channels 3 and 4 to drive the subs under the seats.