Component speaker wiring

MrT · October 5, 2017, 13:35

Hello forum
I'm struggling to find definitive instructions on search engines or the forum. I would like to wire 2 way component speakers with crossovers (HPF for woofer and tweeter) to a 2ch amp and bridge a sub-woofer over the same 2ch amp with LPF crossover. Does this make sense or do I need to sketch up the wiring? Amp is plenty powerful enough, all speakers matched 4ohms etc. I will need to build the LPF crossover for the sub based on the wiring advice I am asking for.

Can anybody help please? No, I don't want to bug a bigger amp, or second amp etc. As we know, space is a premium and I want to economically optimise the audio of the car. I could leave the sub and use high quality component speakers but I already have the speakers from old projects and can't afford high end speakers. So I'm working with what I have, just unsure how to wire it.

Thanks in advance.

shnazzle · October 5, 2017, 14:07

I knew I had this, but I don't remember when I drew it or for what car, but I remember it was the product of discussions with someone who did know what they were talking about.

I guess ignore the two rear speakers and add in another filter?

shnazzle · October 5, 2017, 14:14

Universally, front left speaker is
Pos: white
Neg: white/black

And front right :
Pos: grey
Neg: grey/black

Hext007 · October 5, 2017, 16:33

Schnazzle, that's using the head unit as the power for the fronts, not what he asked to do.

shnazzle · October 5, 2017, 16:42

Fair enough. Thought it might help

Essex2Visuvesi · October 5, 2017, 17:38

I'm not sure what you want to do is possible with a single 2CH amplifier

The theory would be this:-
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But I'm not sure you can do it without damage

Hext007 · October 5, 2017, 17:48

Not sure about that as you are bridging the amp and running it as two channels as well, not sure if it would damage the amp? safest way would be to do as per shnazzles diagram, does the amp have a single channel output with low pass filter? If not you need a filter for the sub. I would try the door speakers off of the head unit first, sub from the amp, you may be surprised at the results.

vx220 · October 5, 2017, 18:31

Old Rockford Fosgate amplifiers used to be able to do this, and I assume some others of the era (90s). Search "tri-mode" amps. You could take a + from one side and a - from the other for the sub. Not sure any modern amps do it now...
I know you said it wasn't what you wanted to do, but I bought a tiny Class d Pioneer four channel amp that can do just what you're after for £90, small enough to hide under the seat, powerful enough to run a pair of components and a sub, only uses tiny power cable. A larger, class ab amp could probably be had for £60/70?

vx220 · October 5, 2017, 18:37

Pretty much any of these will do it, as a four channel bridged to three

m https://www.caraudiocentre.co.uk/catego ... ageItem=12 m

vx220 · October 5, 2017, 18:40

I use this

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m https://youtu.be/qhwlBlw3164 m

MrT · October 6, 2017, 11:55

Thanks folks.
To clarify, the Amp only sees a load at each terminal. It is the electronics calculations of load and the crossover design that I need guidance on. If/How this load will impact the Amp and whether an amp can be bridged and not at the same time. The Amp I have is bridgeable and can run 1ch but I don't know about running both 1 & 2ch simultaneously.

Shnazzle
Thanks, I specified however specifically how I wish to wire the speakers. The head unit, ALL head units, are only ~10-15w RMS and insufficient to drive decent speakers alone. Therefore I want the power of an Amp to deliver some power from the speakers or they will never be sufficiently driven to perform. Running too low power to the speakers will potentially give worse performance not better in certain circumstances.

E2V
That is exactly what I described, thanks. As I say above, it is the electronics understanding and calculations that I am not able to determine myself.

Can anybody else advise please?

s12vea · October 6, 2017, 13:29

The Rockford amps back in the 90s could do the above but I would say now the modern stuff wouldn't. I would use the comp speakers you already have soundproof the doors and use your amp. Or you can use the headunit to power your fronts and the amp for the sub.

vx220 · October 6, 2017, 18:22

Quote from: "s12vea"The Rockford amps back in the 90s could do the above but I would say now the modern stuff wouldn't. I would use the comp speakers you already have soundproof the doors and use your amp. Or you can use the headunit to power your fronts and the amp for the sub.

It used to be a cheap "cheat" for audio competition. Amps are so cheap now, that it's not really a thing anymore...
You'll get a much better, more adjustable result from a four channel bridged down to a three

s12vea · October 6, 2017, 20:19

Quote from: "vx220"
Quote from: "s12vea"The Rockford amps back in the 90s could do the above but I would say now the modern stuff wouldn't. I would use the comp speakers you already have soundproof the doors and use your amp. Or you can use the headunit to power your fronts and the amp for the sub.

It used to be a cheap "cheat" for audio competition. Amps are so cheap now, that it's not really a thing anymore...
You'll get a much better, more adjustable result from a four channel bridged down to a three

I agree, and thankfully amps are much smaller and lighter now

JoeCool · October 6, 2017, 20:37

Yes, you can do this. It's called 'tri-mode' operation. It used to be very common practice.

You wire the stereo components as normal, then you wire the sub to the -ve of the left channel, and the +ve of the right channel, effectively bridging the output for the sub.

It looks like this:

There are a number of subtleties to it: your amp has to be capable of being wired that way. Your sub cannot be too low impedance (because it effectively bridges the amp, so a 2 ohm sub would show a 1 ohm load to the amp, which is close enough to short circuit to set most cheaper amps on fire). And you need to use passive low pass crossovers to filter the signal for the sub.

If you can give specs of amp and sub, I can check it'll work ok with the kit you have.

Personally, in these cars, I'd just put a bit of effort into mounting a good set of 6.5"components, which can drop surprisingly low when mounted with a bit of thought.

But your plan is sound, it just needs careful checking to ensure there is no equipment damage.

MrT · October 16, 2017, 22:17

Hi JoeCool

Thanks.

cheers

Tyler

MrT · October 17, 2017, 12:10

Hello folks

Further to discussion, I finally got a reply from the manufacturer, Sony. My head unit is a WX-GT90BT FYI.

The front rear channels of either side are not bridgeable. The rear channels can be used in "Sub woofer direct" mode to drive a single sub through the LPF but ONLY on one channel, still with a peak of only 52w. These must NOT be bridged either.

So as we all already knew, head unit amps are meek and feeble and not suited to high output or high power bass tones. A Stand alone amp is the only way.

Also, upgrading the door speakers is only marginally beneficial with a headunit alone and mustn't be overrate for the headunit. Very difficult considering they all start at about 45w RMS and the headunit is only 10-15w RMS...

But onwards. Looks like a bigger amp is best. My audio is going to have more power than my ICE at this rate...

cheers

Tyler