Speakers - again

[Vagrant No2]

Right , I have repaired the split speaker cone and all sounds good so far .
Next 2 questions for the audio experts is
1) an amp with 2 inputs and 4 outputs , can this have 2 different pairs of watt speakers on the outputs .
2) can more then 2 pairs of speakers be put on the same output , if so do they have to be the same watt .

I have the possibility of a 8 speaker set up , the front pair with no amp , and 3 pairs of speakers in the back off the amp with different watts ?

[nero279]

It depends a lot upon the amp,

How I understand it is that....

(i am not a qualified audio installer, or auto electrician or anything, so please use your own, or someone else's, discernment before blindly following what i say. Most of what i learn't has been from the internet, my experience, and other people telling me i have done things wrong)

Car systems normally run at 4ohms resistance.

Speakers normally have a 4 ohm impedance and amps are designed to run best with a 4 ohm load. Automotive systems that is, home stereo's and PA systems i believe are normally 8 ohms.

However some amps are also 1, 2, or 8 ohm stable. That is they will cope with either a 1,2,4, or 8 ohm load. 1 ohm stable amps are normally high end, single channel, digital monoblock bass amps, so probably not what we're looking at in this situation. Some mid-range, multi-channel amps are 2 ohm stable, many more are 8 ohm stable. Probably closer to what we're talking about. The thing with these amps is that although they claim to be 'stable', they are essentially still designed to work best with a 4 ohm load, ie) still running a single speaker or a combination of speakers wired in such a way that they give 4 ohm resistance.

To wire a combination of 4 ohm speakers to total a 4 ohm resistance you would, i think, need a minimum of four speakers on each channel, in doing this the current draw would be greatly increased and therefore the amp probably couldn't cope anyway. So we're again back to one speaker on each channel again.

Still with me??

Therefore an amp that is only 4 ohm stable and will only run one speaker on each channel effectively.

An 8 ohm stable amp could be used to run two 4 ohm speakers on each channel. By wiring two speakers in series the total resistance would be 8 ohms, the signal quality would be affected by running at 8 ohms but probably not too badly, ie) the speakers would still sound ok to the ear, but if you were to actually analyse the sound quality somehow it would show up. You still have to remember though that despite your amp claiming to be 8 ohm stable, you are effectively doubling the load on it, and therefore doubling the work the amp has to do, so probably halving it's life expectancy. Provided it's not going to be blasted at high volume regularly this would probably still be ok.

A 2 ohm stable amp could run a pair of speakers wired in parallel, and in my opinion this would be the way to go. By wiring two 4 ohm speakers in parrallel, the overall resistance across the circuit is 2 ohms. The signal quality is not as badly affected, and amps are often run at two ohms to run subwoofers etc.

You really could go on for hours about different general solutions about this kind of thing, let us know what you've actually got.

What amps, what speakers etc. and i'll explain what i would do or do a wiring diagram and then others can post their comments.

[Vagrant No2]

Believe it or not, I did understand wot you wrote. . Need to check amp ohms for rating .

[nero279]

Let's hope someone else did and can confirm this is right, i'm pretty sure on ti though. I've got a mate who does stereo installs, and alarms professionally so if you want us to run anything past him i can, i'll be seing him on sunday.

[andy_enuff]

To make it more confussing, the power output of the amp will be determined by the load which is attached, for instance the amp i am currently installing is 1000Watts at 4ohm, 1750Watts at 2 ohm and 2500Watts at 1ohm. Usual rule is that there is half the power for double the resistance.

You will need to check what output the amp is not just in Watts PEAK but also Watts RMS. Your speakers and amp should normally roughly match RMS wise, however the speakers can usually take a little more in the peak periods but not constantly.

Depending on the type of amplifier that you have you may well be able to attach all the speakers following the rules nero279 mentioned. If you want to connect speakers of different power ratings you will need to consider that they will both receive the some amount of power each if wired in parallel (and they are the same resistane) and different powers if they are different resistance (connected in parallel) OH lord, I'm glad I only have.... the possibility of 14 speakers in my car! It's gonna be a long weekend!

VagrantNo2 if you would like me to have a look at a plan for your system, give me a PM with all the speaker resistances (impedances) and the make/model of the amp and any specifications you have. If you are anywhere close to me you could pop over, plenty of chance to fix it up here if you wish.

[MattF]

Firstly, lowest rated speaker needs to have a wattage rating
higher than the maximum output you intend to run at. You
need the true RMS rating, not PMPO, as PMPO appears to be,
(from past experience), a random number manufacturers
pick to make things sound better than they are. If I remember
correctly, PMPO ratings are usually defined by manufacturers
running a speaker for several minutes at a certain power
before it fries. They then use some calculation to exaggerate
figures. RMS, however, is a true rating of what the speaker
can happily, (and truly), handle for an extended duration of
time. In other words, ignore PMPO ratings.

Secondly, you can wire in any combination of series and
parallel to keep the impedance, (not resistance), within the
rated spec of the amp. Weird configs will cock it up to some
degree, but not enough to cause problems. If you can measure
a resistance across the final connections that is around the
impedance you require, you'll be fairly close. However, don't
expect perfection of sound. There will be some output power
variation per speaker.

[Vagrant No2]

I still follow this ! I must be getting cleverer as I get older .
Thanks so far , this is helping me decide wot to do .

[AndyLala]

Lets complicate it further then...

Impedance is one thing... and your prime consideration when wiring amplifiers up. Next consideration is excursion limits on the drive units, and positioning of those drive units within the body space. Any speakers playing the same frequency information should deliver the sound to the listeners ears at the same time. Any sound travelling through the mount and subsequent body work should be minimised or eliminated. This is where the 'more speakers - less clear sound' comments comes from.

Encouraging the wave front from all the drivers to arrive co-incidentally at the listeners ears... will deliver dividends (this is how some of the SPL guys designed their systems for a while...). Consider passively crossing over the drive units to encourage that. You can also have a Google search for Zobel networks to control the impedance of certain drive units, with notch filters to control others. Any passive filter on the speaker system will also add impedance to the load, and so need to be considered.

How about sharing what you are trying to do, and what with. Perhaps someone has already tried it...

[Vagrant No2]

Lets complicate it further then...

Impedance is one thing... and your prime consideration when wiring amplifiers up. Next consideration is excursion limits on the drive units, and positioning of those drive units within the body space. Any speakers playing the same frequency information should deliver the sound to the listeners ears at the same time. Any sound travelling through the mount and subsequent body work should be minimised or eliminated. This is where the 'more speakers - less clear sound' comments comes from.

Encouraging the wave front from all the drivers to arrive co-incidentally at the listeners ears... will deliver dividends (this is how some of the SPL guys designed their systems for a while...). Consider passively crossing over the drive units to encourage that. You can also have a Google search for Zobel networks to control the impedance of certain drive units, with notch filters to control others. Any passive filter on the speaker system will also add impedance to the load, and so need to be considered.

How about sharing what you are trying to do, and what with. Perhaps someone has already tried it...

OK Andy , I just want to wire in some 1/2 decent sounds to my old Runner . The interior is far less plush as a 2nd gen so very little or no soundproofing/ deadening material to help rattling trim .
I have a 6 disc player and a radio/cassette head unit . Also have a 200w 4 channel amp with choice of 4 channel high input or 4 channel low input , also switchable 2 channel input but out of 4 channel. Head unit only has 2 channel low out put and 4 channel high out put .
I have 6 reasonable speakers to use ranging from 160w to 330w all 4 ohm .
I also have the 2 little in dash speakers which , although 70w Pioneer , are not much cope due to the mounting etc .

Oh dinners ready will add more later

[AndyLala]

Sorry Rick, didn't mean to go off the deep end...?

[Vagrant No2]

Mmmmmm , yummy kidneys and bacon and onions with mash spuds .

Well back to thread ...
So how could I wire this lot up so I can control the level from each pair of speakers ? Do I use both the outputs from head unit ie low out put into low input 2 channel 4 channel out on the amp, and 4 channel high out put from head unit or will it all go BANG ?

[AndyLala]

First thing...

Lets recap...

Head unit... pre outs (4 high outputs, and 2 low outputs...) and amplified outputs... How many channels?

Number of options...

Initial question, is how do you like to listen to your music...?

What is the model of amp... and do you have a manual for it...?
What I am trying to find out is, what can the amp do....?

I would run a four channel amp (if thats all you have got amp wise)....

two channels for the front speakers (full range), and two channels for a sub or pair of subs (or just midbass's) ie. disconnect the tweeters on the rear.

Run your rear speakers with the head unit outputs... and you can fade front to rear to just add a bit of ambience to the sound stage. ie. turn the rear up until you can just hear it, then back it off a notch.

That way, the rear midbass speakers re-enforce the front speakers... with non-directional mid-bass (well less directional). If you can get the rear speakers boxed off (ala 2nd gen...) you should get some serious welly out of them.

Shouldn't sound half bad then...

Others may disagree, but I have used this method with a few vehicles to some success...

[AndyLala]

I would always prefer a sub in the equation... but I was only ever happy with my own sub enclosures... something with a bit or articulation... ie. more than your usual one note samba... each to their own...

I just like to feel it all the way down to 19hz....

[AndyLala]

I keep toying with the idea of doing a system in my Toy.... don't want to have to strip the interior again... prefer to spend as much time driving as possible.

USD Audio waveguides... 2 x BC3's, backed up by some rather nice Audio Control processors, and 2 x USD Audio 8" Pro Mid-basses... (2 sealed, and 1 aperiodic)... all run by an 800w four-channel Kicker competition amp...

With an optional 12" solobaric on a d-class 1200w Kicker amp... just in case some chavs want to try it on...

[Vagrant No2]

First thing...

Lets recap...

Head unit... pre outs (4 high outputs, and 2 low outputs...) and amplified outputs... How many channels?
4 high output and 2 low outputs , no idea about amplified outputs and channels

Number of options...

Initial question, is how do you like to listen to your music...?

Loudish with reasonable but clear bass

What is the model of amp... and do you have a manual for it...?
What I am trying to find out is, what can the amp do....?

Cheap amp from Wembley market , never fitted in any vehicle from new , no known make , but I got an instalation manual !