JonW

As most people know ive fitted Infity 6.02CS to my Dynamtted and foamed doors and use a Sony headunit rated at 4x40w with the rear std Scoob speakers disconnected. Now I know the Infinitys are 90w and the passive XOvers take lots of power but Im not hugely happy with the sound levels. I can almost play the HU at full volume with no distortion (expect when tracks are quite bassy and then it distorts but you can easily feel it by touching the doors by that point!) and whilst its 'loud' its not really 'loud enough' (!) to combat the road noise...

Have to say its a huge improvement over the standard kit tho... sound is clearer and we now have treble, which can be quite cutting on occasion...

So what to do... fit better rears and connect up or an amp or just uprate the cable... or dare I ay it, all...?

J.

SecretAgentMan

U need a decent amp and a sub in the boot mate.

My small, and very modest setup is very loud if needed.

Pioneer DEH-P7000R headunit.
MDS (Swedish make) amp with 4x50 <B>real</B> W @4ohm.
MDS 10" sub in a 20 l sealed box.
JBL GT 602 something front components.

Forget rear speakers, they'll only mess up your soundstage.



/J

Adam M

You have done the right thing by disconnecting the rears if you are trying to achieve "car hifi". If volume is more important to you than stereo imaging, then upgrade and reconnect the rears. they will produce better bass too as the boot is better for this than the door panels.

Volume is not just determined by power rating. the important thing is the efficiency, or sensitivity of the speakers. Low efficiency speakers are not necessarily bad, they just require a lot of driving. I dont know specifically but I would guess the infinities are low efficiency, so the best thnig to do is drive them harder with an amp.

I seem to remember someone selling two phoenix gold amps for £500 earlier this week needing a quick sale.
Ask if he will split them and offer £150 for the zx250. It will do wonders for the sound. Very capable amp and looks great too. This should give you some more volume, but will not be as effective as replpacing the rears.

It is your choice.

I personally dont bother with in car hifi anymore. As a younger an, I would buy the amp. but the cheaper option is to reconnect and listen.

If you have to spend money then the amp is going to be the better option to achieving a better sound. It also gives mmoe controlled bass etc.

never beieve the claims of 4 by 40 watts, that is quoted at pathetic distortion levels and isnt the rms value.

A truly capable 40 wrms amp is much bigger than teh thing in the back of a head unit.

rockin'Ru

Cheers again Jon.Like I said before,those Infinity's will impress you much more with an amp.Your hu is putting out 40x4 MAX,so you're only giving them MAYBE 20 watts rms.I have a Pioneer P7000R hu like SecretAgentMan,and it has a true MOSFET amp in it,45x4 max,but it's nothing like a good quality outboard amp.
If you can find a good amp that puts out around 100x2 rms,you'll be plenty happy.
As for the rear speakers,IMO,hook them up to the hu's rear channels and listen.I don't agree with people that say all rear fill is bad.That is a choice to be made by the listener.And to truly re-create a concert affect in your car,you need the echo of the rear wall of the stadium.It's always there but you don't really notice it compaired to the front.My hu has an FIE feature(front imaging enhancer)that cuts the fqz response of the rear channels down to 250hz.No highs at all,just low midrange on down.You can do the same with your set up with a pair of "choke coils" on the + wires of the rear speakers.10 minute upgrade.
Again,this is YOUR system and you should set it up the way YOU like it.Experiment a little.If you don't like the rears working,disconnect them again.
Oh,and the Infinity's spl rating is 89db's.That means it takes more power to achieve the same loudness as a speaker with a rating of say,96 db's and a little power.You just gotta feed'em.

john banks

I have the cheaper Infinity 605CS and if I had heard them amped, I would not have bothered with a sub... the bass really is that good if you kick them hard ie &gt;100WRMS. May wish to try?

JonW

Ta for all your help guys, looks like amping is the way to go. I agree that the Infinitys are very bassy such that the Sub is not high on my priorities at the moment. Ive done a bit of digging and have got my installer to do the same so amp and new cable is on the cards.

Rockin, tell me more about these chokes re costs and how to fit as they 'sound' quite useful at getting more bass (if I need it) by using these and a slight upgrade from the std scoob rears.


Cheers for all your help people, Jon.

john banks

I think the dude is talking about 1st order passive low pass filters - i.e sticking a coil of wire in of a specific inductance to filter out the high frequencies. Every octave (doubling in freqency) the signal will be progressively cut by 6dB (ie about 75% loss of power) compared with the coil not being present. This would allow you to use meaty rear speakers but kill the treble to them therefore keeping the impression of sound in front of you. A more neanderthal method would be to disconnect the tweeter from the rear speakers - this is very easy. I tried this and noticed very little difference and put it back again. However, I guarantee fireworks if you fit rear speakers yourself - it is a royal pain in the ***. Even if I had no sub, and then 4 amp channels to play with I would put all the juice to the front Infinity comps.

See here for more:

rockin'Ru

John,you didn't truly eliminate the higher fqz's.A 6x9 speaker is capable of a very wide range of sound.Just by disconecting the tweeter does little for the tone control of the woofer as it is fed a full range signal still.And will generate lots of distortion trying to do everything alone.The tweeters "buffer" this effect.
Jon,the coil does just what John said,it filters out the high fqz's and only alows low fqz's to pass,but at a certain power loss.
Remember when you installed the xovers for your Infinity comps;inside the xover there was a small coil of copper wire?That's a choke coil and that's what it does.
I have a bunch of books on this stuff from high school somwhere and you can make your own for little or nothing.But as far as buying them,they're only a few dollars each.They're nothing more than a piece of copper wire wrapped around a "core" (either iron or just air),and the number of winds and the gauge of the wire together determine the cut-off fqz.