Installing an EQ?

[tr10av 10+ year member]

I've got a EQ I took out of an old Dodge Ram before we sent it to the scrap yard. I guess its a stock EQ, not really sure but its all pretty self explanatory as far as wiring goes except for on the input wires (power, ground, +/- L and R speakers) there are 2 extra wires which are for "left speaker common" and "right speaker common" and on the output side there is just +/- L and R.

So basically what are those common wires for? I'll take a pic of the EQ in the morning to see if that helps anyone figure it out.

Click to read more...

 

[tr10av 10+ year member]

bump for pics

Actually tried hooking it up today but couldn't get any sound to come out. I plugged in the input lines into the amp and the output lines into the speakers. Also I couldn't determine which input wire was for + and which was for -. I tried both ways but no luck.

Anyone got any ideas

 

[bubbagumper6 5,000+ posts]

the common is the negative for that side. I believe they refer to it as common because both of the speakers attach to it.

 

[drpeeb 10+ year member]

First, I'd try excluding the amp and all the speakers but one first until you get some audio out of that one speaker.

Second, in your first post you say "... except for on the input wires (power, ground, +/- L and R speakers) ..." but then you say "there are 2 extra wires which are for "left speaker common" and "right speaker common" and on the output side there is just +/- L and R." ... That's backwards from what your picture shows.

Might you need to just take another look?

Finally, another possibility: Maybe the EQ needs low level RCA inputs, and you're feeding it high-level speaker signals? I think you'd still get some audio, though.

 

[tr10av 10+ year member]

Alright just for clarification for me and everyone else this is exactly how I hooked everything up:

(Input side)

Red wire: Connected straight to the battery (for testing purposes)

Black: Connected to wear amps are grounded to

All other wires from input to the appropriate speakers

(output side)

Connected to amp with no luck

Oh crap think i switched up the input and outputs. The input should be connected to amp and output to speakers duh. That was stupid. But if I got it I right now I connect everything on the input side to the amp, power, and ground and everything on the output side to the speakers.

But how do I wire to the speakers? The EQ has 6 wires that need to go to 4. If the common is the ground where do the other 2 wires go? Thanks

 

[bubbagumper6 5,000+ posts]

The eq has outputs for 4 speakers...which would have been 8 wires, but the left side shares a common wire, and the right side shares a common wire...

 

[tr10av 10+ year member]

The eq has outputs for 4 speakers...which would have been 8 wires, but the left side shares a common wire, and the right side shares a common wire...

Gotcha that makes sense. Thanks for all the help. I'm gonna go outside and see if I can get this working. Does that input impedance of 100 ohms and output impedance of 4 to 8 ohms matter at all in the way I hook it up?

I'm running a 2 channel amp @ 4ohms each channel.

 

[bubbagumper6 5,000+ posts]

You know, now that I think about it, that EQ is probably not meant to see the kind of power that amp will put out...it may fry.

 

[drpeeb 10+ year member]

Head Unit's outputs go to the EQ's inputs (browns & grays)

The EQ's outputs go to the amp's inputs.

I think the EQ should go in ahead of the amp, not behind it.

 

[bubbagumper6 5,000+ posts]

Head Unit's outputs go to the EQ's inputs (browns & grays)
The EQ's outputs go to the amp's inputs.

I think the EQ should go in ahead of the amp, not behind it.

Yes it should, but the EQ probably has speaker level outputs, not RCA outputs...so unless his amp has a high level input, he'll need a LOC.

But seriously that would be way too much work for little reward. You'd be better off just spending a little money on a decent aftermarket EQ. Stock equipment is rarely worth running...

 

[tr10av 10+ year member]

Yea I know theres a possibility it will fry but its just a leftover from an old scrap truck so I don't really care. Just want to try it out and see if it works.

And I can't hook it up before the amp. It has to go in after because there are no RCA ouputs or inputs.

 

[drpeeb 10+ year member]

Yea I know theres a possibility it will fry but its just a leftover from an old scrap truck so I don't really care. Just want to try it out and see if it works.
And I can't hook it up before the amp. It has to go in after because there are no RCA ouputs or inputs.

Then proceed ... with a fire extinguisher! //content.invisioncic.com/y282845/emoticons/laugh.gif.48439b2acf2cfca21620f01e7f77d1e4.gif

Kidding ... this all doesn't seem worth it to me, though.

 

[bubbagumper6 5,000+ posts]

Most likely all it's going to do is waste your time...and possibly introduce noise into the signal

 

[tr10av 10+ year member]

I mean really its only like 30 minutes worth of work. And I've got tons of time on my hand to mess around. And if it works I've got more control over my music and if not whatever no harm done.