Tweater,Midrange,Midbase + a Sub!

ijwalla · 03-03-2007, 07:44 AM

Hi guys, what do you think? Below is my stock speaker setup, one which for the moment I am to leave as is... Only thing new for the moment is my AMP (Sony Xplod XM-504Z) & SUB (Sony Xplod XS-L122P5)

Front
2x Tweeter 8ohm
2x Midrange 8ohm
2x Midbass 8ohm

Back
2x Tweeter 4ohm
2x Midrange 8ohm

Trunk
1x Sub 4ohm

Here is the amp setup I think will work best:

My question is which and how many cabin speakers (front or back) can I hook up to the amp? Tho the amp highlights 1 pair of speakers, can I hook up both back and front tweaters or is there an impedance issue considering this?

Thanks...

durwood · 03-03-2007, 08:02 AM

Yes you could hook up both front a back speakers as long as you have passive crossovers on the front and rear sets of speakers separating frequencies for the tweeter, midrange, and midbass. With passive crossovers, your amp will effectively see 4 ohms at each channel.

ijwalla · 03-03-2007, 08:36 AM

Quote: Originally Posted by durwood

Yes you could hook up both front a back speakers as long as you have passive crossovers on the front and rear sets of speakers separating frequencies for the tweeter, midrange, and midbass. With passive crossovers, your amp will effectively see 4 ohms at each channel.

Thanks, for your reply, as you can tell I dont know much about this.
Where would I buy a passive crossover device?

From my understanding, it is bad to have lower ohm speakers than the stated minimum for the amp (4 ohms on mine), something about impedance matching. Having a highter ohm speaker is ok, lower ohms speaker is bad, right? Or is it the other way around?

I was thinking, I could use the 2 front Tweeters @ 8ohms plus the 2 back midrange speakers @ 8 ohms.

My reason for this is if I use a tweeter + midrange + sub, I have most of the audio frequencies covered... right?

durwood · 03-03-2007, 08:58 AM

Quote: Originally Posted by ijwalla

Thanks, for your reply, as you can tell I dont know much about this.
Where would I buy a passive crossover device?

Usually the crossovers are designed specifically for the speakers, but since I am assuming these are stock speakres, you have no idea what the specs are let alone any idea on how to design the crossovers.

I am a big fan of www.partsexpress.com
For your rear speakers you need a 2-way. See here.
for your fronts you need a 3-way. See here.

Another option is to look around on ebay and buy a pair of component speakers and use the crossovers from those instead. Plus then you have soem backup speakers if your stock ones can't handle the power.

Quote:

From my understanding, it is bad to have lower ohm speakers than the stated minimum for the amp (4 ohms on mine), something about impedance matching. Having a highter ohm speaker is ok, lower ohms speaker is bad, right? Or is it the other way around?

You do not want to go lower than what your amp is rated for. 4 ohms is typical, most car audio amps will allow 2 ohms in stereo mode but it increases heat and distortion because your amp has to work harder. Look at it like this, the closer you get to 0 ohms (a piece of wire), that is like a dead short across your amp.

Quote:

I was thinking, I could use the 2 front Tweeters @ 8ohms plus the 2 back midrange speakers @ 8 ohms.

That would sound weird to only have your front tweeters playing and your rear midranges playing.

The passive crossovers help to keep your amp seeing 8 ohms from each of your front and rear speakers by separating the frequencies going to each speaker. THen when you connect your front speaker in parallel with your rear speakers on your amp 8 and 8 ohms now becomes 4 ohms. (See Ohm's law)

Just be careful if you are using your stock speakers. They might not be able to handle the power output from your amp. Go easy when adjusting the gains on the amp.

ijwalla · 03-03-2007, 09:17 AM

I apreciate your reply.

Just to clarify, which sets of speakers (of the ones I have in my cabin) were you refering I should use, ofcorse including my sub in the trunk...

Front
2x Tweeter 8ohm
2x Midrange 8ohm
2x Midbass 8ohm

Back
2x Tweeter 4ohm
2x Midrange 8ohm

durwood · 03-03-2007, 09:34 AM

You can use all of them. That's what I am trying to tell you.

I suggest doing a little bit of research because I would be here all day explaining.

Things to search for
Passive crossover
2-way passive crossover
3-way passive crossover

Wikipedia or even google will give you tons of results. I was looking for a good diagram but this all I found at the moment.

http://www.trueaudio.com/st_xov_1.htm

durwood · 03-03-2007, 09:40 AM

Here's another diagram I drew up quickly.

XC-C30 · 03-03-2007, 10:10 AM

He'll get a 2Ohm load, that way.... I hope the amp can handle that.... Also he won't be able to tune the volue of front and rear separatly....

durwood · 03-03-2007, 10:50 AM

Not if they are 8 ohm speakers, he gets 4 ohms. EIther way the Sony amp SHOULD be able to handle it.

Good point I forgot to mention, you will not be able to control front and rear separately.

XC-C30 · 03-03-2007, 11:11 AM

Clearly I(m missing something

.... Good thing I'm building an active system

durwood · 03-03-2007, 11:14 AM

In a passive system, the impedance is = to the imdeance of the drivers (8 ohms in this case). He does have a 4 ohm tweeter, but it's more dependent on the woofers rather than the tweeters.

Active Filtering

XC-C30 · 03-03-2007, 11:33 AM

Oh, so that's were I missed out. I thought it counted up.... So I came to a load of 2.666 for the frontstage, and 4Ohm for the rear, which would give 1.5Ohm load, probably narrowed down to 2Ohm due to the resistance of the filter....

scott_fx · 03-03-2007, 12:46 PM

ic, as long as the drivers aren't playing the same frequency the final imp. load will be 8 ohms (same as the drivers)

BUT.... if the x-overs are designed for a 4 ohms speaker the x-over points will be altered if he's using an 8 ohm speaker and vise versa.

I think the op will be a lot better off spending the money on a predesigned component speaker package rather then trying to make your own. I'm probably way more into audio then he is and I wouldn't tackle this project.... I wouldn't even tackle a 3-way active project (going 2-way for my first go around)

XC-C30 · 03-03-2007, 12:48 PM

yeah, I'm going 2-way active first too, before tackling a 3-way project.

learning everyday

ijwalla · 03-03-2007, 03:04 PM

Quote: Originally Posted by scott_fx

I'm probably way more into audio then this he is and I wouldn't tackle this project.... I wouldn't even tackle a 3-way active project (going 2-way for my first go around)

Oh man, I was gona follow the approach durwood had drawn out for me, especially with those nicely drawn out diagrams of his.

But I think scott_fx may have brought me back to my senses, I really dont know much about this stuff.

So... to make things a little easier on myself, how would a boom box sound?

Ah well, whats the difference between durwood suggestion, and a 2-way / 3-way active project you guys are working on?

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