Car stereo speaker wiring

[rockyfeller]

I've wired many things but I must admit I don't have the most technically correct knowledge. In a speaker system for instance that puts out 50 watts per channel, It's perfectly acceptable to plug in 4 speakers that can handle 50 watts RMS at 4 ohms....Now instead if I wanted to wire a set of 30 watt speakers in parallel with a set of 20 watt speakers into the front channels, what would happen? I believe that speaker impedence comes down to 2ohms??? Is this bad for the amplifier? I believe only some amps can handle a low impedence like that. In another words, what is the safe way to tap more speakers into a channel? If the amp puts out 50 watts per channel, and I wire in 2 speakers to one of those channels, is each speaker getting 25 watts? What about 2 50 watt speakers wired into a channel giving out 50 watts? I have wired/tapped speakers like this before, without any problems, but my present system is expensive enough to be cautious. I don't want to blow anything and want everything wired sound and my amp to last for a long time.

[Incantation]

i do know that if you wire them in parallel your ohmage will drop to 2.. and that will be bad for the amp if it's not powerful enough to run it.. so be careful. i do know that if you run the channel into a crossover, and then have two speakers run off that you will be ok as far as the amp is concerned.. maybe go that way?

what kind of set up are you running?

[jpkasper]

If you wire speakers in parallel, make sure your amp can handle a 2 ohm load. At 2 ohms the power output of your amp should nearly double, buy may become unstable. The wattage of the speaker really is not a factor. This is merely a rating of how much amp power they will handle.

Paul Kasparian
'94 530iT

[rockyfeller]

There are external amps that I know can handle a 2ohm load, or even down to 1ohm stable....But I am talking about the internal amp of the car stereo though that puts out 50x4 at 4 ohms. Is there a way to wire more than 4 speakers to a system designed for only 4? Like I have said, I've done this before without much consequence (I once had a 10 speaker system with a 4channel output on my old system) but I'd rather not be so ignorant this time and know if it's bad for the amp and how/why. I wouldn't realize the difference, but I feel that the system ran a bit "hotter" than it should, but I never blew anything, even though I played it loud. I realize there are crossover systems that are available, but are they necessary? The pros that wire those 6, 8 or 10 speaker systems I realize are using multiple amps as they add extra channels, but are they all using crossovers? Is that how they do it? Is there a way to wire them serial or something, or with a type of component that can keep the impedence at the original 4ohms and also allowing speakers to share that 50 watts equally? Am I making sense?

[Javier]

electronic books say:

A crossover split he signal over the frequency range, actually, it’s designed to keep a constant burden over the whole audible frequency spectrum, but the power for each frequency range is directed to its corresponding speaker. (for example, High, Medium, Low, in the front of the car). As far as I know, BMW amplifier for 10 speaker systems has internal crossover to feed, straight from the amplifier, each speaker.

Wonder why would you like to have more than one speaker per channel, if it is because you are using high, medium, and low range separated speakers, then, you shouldn’t wire them in parallel/series, as low range signal will interfere with the high range in the twitter, and the system will have poor sound, then you will NEED a crossover to separate them.

If it is just because you need sound in multiple different points, and you are to be using full range speakers, you can wire identical speakers in parallel or series, remembering that paralleling two will half the impedance, paralleling three will make it one third, an so on; also in series, the impedance will be added, so you will have twice, three times and so on. This is valid only if the speakers are identical, also they will share the total power available in equal parts.

There are 8 ohm speakers available, problem may be to fit them in the car, also, you can have 4 x 4 ohm speakers in two series of two, then paralleled, one fourth of the power each, this way you will have 4 ohm for the group. This is not very good for multiple way speakers with internal crosovers.

Must of the amplifiers are suitable for an impedance range, Let’s say 2 to 4 ohms, for the sake of the amplifier, you shouldn’t connect lower than minimum recommended impedance, for the sake of the power output and sound quality, you shouldn’t go higher.

Yes you can match impedances with an audio transformer, square root of 2 to 1 ratio will match 2:1 the impedance, but this is not the way to go.

Javier

[rockyfeller]

Hmm interesting...especially about parallel mixed with series wiring with a 4x4 arrangement. Javier, you seem to be a wiring guru for the E34, thanks! See here's the thing....I have bypassed the internal BMW amp so I can utilize the high output of the internal 50 watt per channel amp of my aftermarket Pioneer head unit. What I have done is wired new 6 1/2 Kenwood Excelon speakers into the front kick panels. The Kenwwoods, as most aftermarket speakers do, have built-in crossovers for itself. I wanted to retain the dash midranges and the A-pillar tweeters. Since these factory speakers originally relied on the factory amp/crossover network, this left the disconnected factory speakers susceptible to full range power. I wired in small custom-made inline crossovers for the factory midrange/tweeters (I did the same for the rear tweeters) and then I just wired all these speakers in parallel with the Kenwoods. The Kenwoods can handle up to 120 watts. I've done all this so I could fill in the sound (instead of a boring 4-speaker system) and utilized all the remaining factory speakers while having high-power, super-clean sound on my aftermarket deck that can play mp3s, has DSP/EQ and can drive an external amp for 12" subs. I've been running this set-up for over 1yr with no problems. I figure this is giving a low-impedence load for the amp....but nothing bad has happened yet...like I said I have done this on other systems too....but I'd rather know the right way to do this on a serious system I'd plan to build and not fry because of my wiring ignorance. Am I taking a risk for something to blow?

[Javier]

If I understand, you have now a 10 speakers system, 3 on each front channel, 2 on each rear channel, as your aftermarket unit does not have internal crossovers to split the output range over the speakers, you did install some for each original BMW speaker, as your new speakers did have their own crossover (Low pass filter I guess). Did you also install Kenwoods speakers in the rear channels, as you told, you did install crossovers only for the rear tweeters.

When you split range for the speakers using crossovers, speakers are not paralleled, the impedance do not get lowered. As long as crossovers are properly set and do not overlap significantly every thing should work fine.

Javier

[jplacson]

OK, I didn't want to start a new thread... but I want to replace the stock wiring (previous owner spliced too many times ... dunno why, so now my wiring has electrical tape all over these hand twisted connections.) and I'd like to know how easy is it to snake new wirings from the front kick panels to the trunk/boot? Where does the original stock wiring pass? I don't wanna go and rip out any carpeting unless necessary, so I'd like to know where you guys pass your front wires. Thanks! :)

[Javier]

no need to rip out any carpeting, just some side kick, rear seats, and pillars trimming disassembling.

Javier

[rockyfeller]

Yes I have Kenwood Excelon 5 1/4" in the rear too (wish I could go bigger as they don't sound too great; I wanted 6x9s but anything bigger than 5 1/4" would have been a difficult butcher job)....The crossovers are not some complicated professional type. It's more like a custom-made resistor that is inline that someone designed for me. The speakers sound just as they were with the factory system and don't strain at all with the additional power of the new deck. So you say as long as the speakers have their own crossovers they don't get paralleled? So theoretically I can add 2 sets of Kenwood 5 1/4" speakers (not that I would, I'm just asking) to the rear channel with no problems becasue each speaker has it's own built in crossover system? How is it that the resistance stays consistant at 4ohms? Is it because the crossover acts as a resistor? I know in the case of a subwoofer, which dosen't have a crossovers, the impedence is an issue as to how many subs are being wired to what kind of amp...So what I can understand here is that I'm safe with what I've done, thanks for the help.

[Javier]

in the rear, as they are in the same frequency range. The impedance of the speakers system for this frequency range will be one half (yes they are in parallel). The crossover makes the impedance for the intended speaker infinitum (open circuit), for all frequencies out of its intended range, that is the reason that the amplifier only sees on speaker for each frequency, but if both speakers are in the same range, the amplifier will see them both.

Here are a couple links on Crossover design, just for fun.

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

http://sound.westhost.com/lr-passive.htm

Javier

[rockyfeller]

snaking wires in some areas are really tough but others are easy. Behind the dash, things are stuffy! It took me 2 hrs just to snake RCA cables for my subwoofers from my headunit downwards towards the console/bottom of the dash. The rest of the path should be easy. I have a snaking tool which really helps, I'd highly recommend it. It's a cheap, long, flexible, metal grabber thingy normally used to grab small lost items from obscure places. Even so be prepared to sweat and bust a few knuckles....unless you intend to disassemble EVERYTHING. Instead of butchering wires there are harness available to prevent a mess like you have. It depends how you want to wire though. I wanted to bypass my factory amp; but it still needed it's power supply so it could supply FM reception. Inevitably some wires had to be butchered. My hope is 1 day when I sell the car, I can put everything back as it was without anyone noticing anything.

[jplacson]

Well, from an ETK that I saw... most of you seem to have the HI-FI setup...where there is a factory cross-over in the trunk...where all the speaker wires meet. That would've been ideal in my case.

Mine came with the STEREO setup... no amp or crossover in the trunk...and all the wires meet in the HU area.

Problem is, when I got the car, it was setup...but in a really bad way... components were decent (mid-level JBLs and Bostons... a good RF sub, Alpine amp, and Soundstream amp for the sub) ... but everything (and I mean everything) was just mounted wrong. Sub-box is horrible... no calculations for internal space... no baffles... tuned wrong... cables were spliced from the original wiring to feed both amps. One factory speaker cable was replaced with a higher gauge mid-way with 3 cuts and hand-twisted together with some electrical tape...etc..etc... you get the pic.

Basically, I want to rewire the thing clean. The line-outs from the HU to the amp and sub are fine. So it's just the speakers I wanna re-do. I want straight wires from the front kicks and dash, straight to the trunk amp/crossovers. That's all. My main concern is actually the dash speakers... where the wires go from there... and where do they pop out... anyway, I will look for that snaking tool thing. I already busted a few knuckles trying to get the kick panels out. I'm wearing gloves next time!!! hahahaha

[rockyfeller]

I guess you have the older setup. The newer setup is a 10-speaker overly complicated system (truly as overengineered as the rest of the car). I wouldn't exactly call it an advantage since the sound output can only be descibed as decent. To make music sound really good, you have to go aftermarket. Our systems are not exactly aftermarket friendly. There were many times I tried to avoid butchering the wires, but I couldn't help it. There are limitations when putting together a system in an E34....For instance you said the box for your subs was just wrong for the subs. I want to install 2 Infinity 12" Kappa Perfect subs and I need exact dimensions/construction to make them sound their best. Our trunks are large enough to handle a box needed for the subs but heres the magic question: Will it actually fit into the OPENING of the trunk? I learned my lesson long ago on my old car. I had a box perfectly custom made as per my specs and I made allowance for the internal volume of the trunk, but when it came time to actually put it in.....It wouldn't fit through the opening!!! I had to have the entire box disassembled and rebuilt. I don't know if I want to bother with the custom install again....It was such a pain! We are limited by using a box no higher than 15" high/deep though with width, you can go as much as 36". For a bandpass box I need a 11" port and 6' cubic volume using 1" thick wood. When it comes to readymade boxes (which I am almost forced to go with this time) that will fit the opening, you will end up with a box too small for specs...The ports are too short, the internal volume is too small and the wood thickness will be minimal at 3/4" and the bass will be too dampened. Some of you will ask...isn't 1 sub enough? Well logically yes....but I like my music loud so I'm being a little unreasonable. To really go perfectly with specs, the best platform is an SUV where you have plenty of space to work with.

[jplacson]

Ewww... but you'd be driving a boat... it would at least handle like one anyway! :lol:

I never liked the whole SUV thing... even the X5/3... If you wanna go off-road... get a real truck. If you hardly leave asphalt... stick to a car... handles better... drives better... feels better.

Anyway... back to the sounds. Well, I'm happy with one sub. I'm not a hip-hop kinda guy, so the bass is just right from my single 12" RFosgate. According to their site, I just need a basic 19Wx14Hx12D box. I'm sticking with a sealed enclosure since the ported ones sound too 'pimpin'.

Well, if all I gotta do is stuff the wiring under the side panels... then I'm off to buy some audio cables/wires tomorrow :)