Help with 3-way setup in a roadster

deni2s said:

I understand the roadster config itself is not the best for SQ, but that's exactly the reason why I want high quality components - to get the best possible sound without customizing car.

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Unfortunately that's not really how reference tier sound works.  It's mostly location/aiming of the drivers and proper deadening and maybe 10% what drivers you use (provided you're not using complete gutter brands).

I've been running 3 way in my Jeep for ages and use a 6.5" midbass in the factory door location and 6.5" mid + tweeter in the kick.   I'm using Q-form kickpanels.  They probably do not make them for less common cars, but they're a good buy if you can get them.  Otherwise you could perhaps find someone to build you some custom kicks from fiberglass or if you're up for a challenge try to build your own.  Kickpanels are great locations for sound staging since they give you a more equal distance between speakers and your ears AND it keeps all the mids and highs on each side close enough together that you avoid a lot of phasing issues around your crossover points.

That all said you have gobs of processing power in that head unit and can probably brute force past a lot of issues with just that.

That in mind, why even buy a "3 way set" when you can just shop around Madisound or Parts Express and buy separate components?  You don't need the passive crossover and you don't need drivers that'll be matched to have the same sensitivity.     If you want convenience of one brand package stick with the better brands and just stay out of the entry level lines and you'll be fine.   Focal is solid and I've been impressed with the sound of the JL Audio 3 way sets.   Not sure if JBL makes a 3 way set but I'm a big Harmon fan and I've always had great results with their lineup.

Do not think that premium priced speakers are a shortcut to good sound.  Care in deadening and prep of the locations and good placement will make or break you.  Oh, and you definitely want a subwoofer, where you put it isn't terribly important (though some testing may reveal some locations/aiming work better than others), and for your purposes a small sub in a sealed box would probably work great.  Don't over think or over complicate that.  

Good luck and post some pictures of your build when you get there.

The issue you will have with putting midbass in the rear is that it is directional so it will sound like it is behind which is not good for staging and imaging. If you are set on going 3 way all the drivers will have to be mounted in the front door/dash/ pillar.

deni2s said:

Well, the sound deadening is already done pretty well in that car by previous audio installers (it was a 2 way setup on older Pioneer headunit and 2 A/B class amps with capacitor). Also subwoofer sealed box with JL w10v2 inside already done by them is quite fine.

About different distances between ear and speakers - I hope p99rs headunit will cover that with time alignment.

If you compare Jeep and z3 sizes, you might get an idea why kickers is really not much of an option - there is just not much space in small 2 seater car. I am not even sure if I could find space for 6.5 speaker, it might be that 5"1/4 is the biggest I can fit.

I agree that I don't need any crossovers, but I still would like to know which speakers would be the best. I want to place lows in rear speaker positions probably for the same reason why you are telling that subwoofer location is not so important - probably lows location is more important than subwoofer location, but still less important that mids and highs.

Decided to go to 3 way setup, just because I bought that p99rs headunit - I like the design of it and it looks like very serious unit, so decided to put it to full potential. So question still stands - would my 3-way config with not so optimal speaker location described in first post still sound better than similar 2-way config or not? And can someone recommend the best speakers for 3 way config (preferably with small dimensions)?

P.S. Talking about Harman - these cars had Harman Kardon sound system as option from factory, but it actually quite ******, and everybody is upgrading that.

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Really a good 3 way system would use 6.5" woofer, 3" or 4" midrange, and tweeter.  I use 6.5" midrange just because that's what the kicks fit, I've used 4" mid and also 4X8" planar mid before and been very happy.

You definitely won't be disappointed with that Pioneer head unit.  They're top quality and very powerful as far as processing power.

As to putting midbass behind you, not so hot.  The big issue is what our ears are designed for.   80hz and down is very non directional  and not really getting into things that will want to be localized in front of you (the human voice in particular).   You can't make something behind you sound like it's coming from in front of you period and the higher the frequency the more directional it will be.

Consider also the distance between each speaker.   TO find the wavelength divide the speed of sound by the frequency..... For example,  at 80hz you divide 1125 by 80 for 14 foot wavelength.   The half wave is really where you get into trouble, so pretty much if your subwoofer is <7 feet from the mids you're not in big trouble as far as cancellation at crossover points.  Obviously closer is still better, but you get the point.   Now try the same thing at 400hz which may be more in the neighborhood where your midbass is crossing into the midrange and you have 2.8 feet.   This tells us that ideally you'll want your midbass and midrange less than 16" apart to avoid possible cancellation.  Tweeters should be within an inch or two of the midrange for best results and that's why you'll notice tweeter is often put further from the listener than the mid (in kicks or A-pillar pods) so that the voice coils (magnets) are equal distant between all speakers and your ears.

Now the midbass can be a bit away from the mid and tweet and work out fine but these are things that you'll have to fight by trying to run things out of phase or otherwise brute force later, but possibly not with as good results as just keeping everything in one place coming out the gate.

IMO if the midbass behind you is the only option I'd rather go with a stout set 2 way components that can live up front.  You might could get away with 5 1/4" up front with what you're doing I suspect you could run the sub up to 100 or 120hz without too much issue pulling the sound behind you.

By Harmon, I meant Harmon International Group, JBL/Crown/Infinity products.   Stock sound system is stock sound system.  They're "good" for what they are, but it's likely they're built around some severe limitations imposed by the auto manufacturers.