Quick help, please! Using factory wiring to speakers

[jjski78 10+ year member]

No good installer would ever run speaker wires from the amp to the factory wiring. All they are is plain old lazy. That wiring is too small for an amplified set of components. I would demand that they re-do the wiring and run it straight to the speakers. And when they do, make sure they don't do something stupid like drill another hole in your door for the wiring. Make sure it's run through the door molex, otherwise you're begging for a leak. Just my .02, but the way I see it is if you're paying for install, they better do it right, or do it free.

 

[StuartV 10+ year member]

Thanks for all the replies, guys. Let me try to address a few of them:

KaeZoo, where do you get the 100W -> 5 amps numbers? Got a link to a reference or anything? My own math went something like this: amp is fused for 25 amps per channel. I'll assume it's setup to only normally peak around 20 amps and the 25 amp fuses give 5 amps per side of safety margin. I'll *assume* it's a Class AB amp and has 50% efficiency. In which case, each output channel should peak at 10 amps. Am I figuring something incorrectly here?

 

[StuartV 10+ year member]

The real issue at this point is going to be my assertion that running new wire is something that I would reasonably expect for this kind of install, even though I didn't explicity spell it out for them.

They gave me a quote for the install and, in my mind, this type of install would be assumed by any competent professional installer to include running new wire all the way to the speakers. In which case, I would expect them to do that within the cost of the original quote. Otherwise, they would rightly expect me to pay extra for that, beyond the install fee they originally quoted me.

And so, that is why I am trying to establish if there's any professional standards that apply to this wiring that I can point to in my argument that they should run the new wire within the price of the original quote.

 

[StuartV 10+ year member]

So, speaking of all that, what effort should this install take?

Here's what I brought them:

'06 F350 SuperCab

Alpine IVA-W200 HU already installed and working

XM module already installed and working

PAC steering wheel remote interface module already installed and working

PAC video bypass module already installed and working

iPod interface cable already installed and working

Alpine PXA-H701 NIB (New In box) to be installed behind the back bench seat

Alpine KCA-100BT Bluetooth module NIB to be installed (mic in the overhead computer and control module on dash)

JL Audio Stealthbox sub NIB (replaces bottom portion of front bench seat center console) to be installed

Rainbow Germaniums NIB to be installed, woofers in front doors, tweeters in A-pillars

3 Carver amplifiers, 2 NIB, 1 used, to be installed behind the back bench seat

They provided 0-gauge power and ground wires, power distribution blocks, Stinger RCA cables, speaker wire and remote turn-on wire, an AI-Net cable, and Dynamat. Basically everything else needed to install the stuff I provided.

They quoted me a flat $400 for all the parts, including Dynamat, a flat $200 to install the Dynamat in the two front doors (on the inner and outer skins), and then $50 per hour labor for everything else. They estimated approx. 6 hours labor to do the rest, with the understanding that it could be less or it could be more.

At this point, they've already had the truck for 2 full days and today is their 3rd day with it. I'm afraid they're going to come back when they're done and want to charge me for 20 hours of labor on top of the $600 I already paid them to cover the parts and Dynamat install.

That seems totally off the chart unreasonable to me, but I've never done such a big install myself, so maybe I'm wrong. What do y'all think?

 

[StuartV 10+ year member]

dude i live closeby i woulda helped ya install them and run NEW wires...

Hey man, thanks for that. I took it to Auto Audiophiles on N. Monroe here in Tally and I felt like I just didn't have the time to do it myself, plus they had a guy there that supposedly worked on top-level SQ cars, so I figured they would do a better job than me, even if I did do it myself. Now I'm in for a pound....

 

[KaeZoo 10+ year member]

Thanks for all the replies, guys. Let me try to address a few of them:
KaeZoo, where do you get the 100W -> 5 amps numbers? Got a link to a reference or anything? My own math went something like this: amp is fused for 25 amps per channel. I'll assume it's setup to only normally peak around 20 amps and the 25 amp fuses give 5 amps per side of safety margin. I'll *assume* it's a Class AB amp and has 50% efficiency. In which case, each output channel should peak at 10 amps. Am I figuring something incorrectly here?

My math is simpler yet:

Ohm's law for finding current when you know the power and resistance:

(I=current, P=power, R=resistance, E=voltage)

I=Sqrt(P/R)

I=Sqrt(100/4)

I=Sqrt(25)

I=5

Note that amplifiers increase the output voltage. You can't compare input current to output current because the input voltage is limited to 12-14 volts. But the voltage at the speaker outputs can be higher, which means the current can be lower to reach a given power rating (P=IE).

 

[StuartV 10+ year member]

KaeZoo, I gotcha. Thanks for 'splainin'.

Now I see where our difference comes from. You're basing your calculation on the RMS power. I am concerned with the peak current through the speaker wires. If I estimate the peak power at 300W per channel (they're 100W RMS per channel), then, using your math, I still get just under 9 amps per speaker wire.

Basically, the same as the other way I calculated it. And I get the same conclusion: 20 - 24 awg factory speaker is too thin for good SQ results (and safety) in this application.

 

[mach999 10+ year member]

The real issue at this point is going to be my assertion that running new wire is something that I would reasonably expect for this kind of install, even though I didn't explicity spell it out for them.

The fact that you are putting in Rainbows with an amp automatically would justify running new wires, IMO. If you were to buy some cheap $60 coaxials and were planning on running them off the factory HU then the factory wiring would be fine. Honestly I think you should be allowed to kick the installer squa in the nuts.

 

[StuartV 10+ year member]

Heh. //content.invisioncic.com/y282845/emoticons/smile.gif.1ebc41e1811405b213edfc4622c41e27.gif I agree!

But, I will trade the opportunity to roshambo the installer for simply not having to pay any extra (beyond the original quote) to have the wiring done right.

 

[timm24 10+ year member]

stick with the rms value. KaeZoo is correct with 5 amps per speaker.

 

[StuartV 10+ year member]

Okay, that's fine. The number is really not the primary question. It is just one piece of information to consider in trying to answer the real question, which is:

If I bring the above parts to an installer and he quotes me 6 - 8 hours labor to install them, is it reasonable to expect that that would include running new speaker wire into the doors or not? It wasn't explicitly discussed, so if I say "that should have been included in your estimate without having to be explicitly discussed", am I off base or not?

I mean, you don't discuss it, but you reasonably assume that they're not going to run the power wire for the amps into the factory wiring harness power wire that goes to the head unit, right? So, where do you draw the line? To me, with these components, I just assumed that, like the amp power wire, the speakers would also not run through the factory wiring harness. But, is my expectation justified enough to insist that the installer not charge me extra, beyond his quote, to do the wiring that way?

I kind of feel like I've been bent over. I think if we had discussed it ahead of time, they would have said "yes, doing it that way is factored into the estimate." But, because we didn't discuss it, they took the lazy way out and are now going to try to make me pay extra to do it right.

 

[JohnnyChuttz 10+ year member]

It would only take an extra 10 min. tops to continue running wire from the spot where they cut the wire at the deck on into the doors.

In the shop I work at: comps and amp = new wire to the doors or kickpanel or whereever.

 

[crow 10+ year member]

To be honest, the charge for running the wires should be pretty minimal, especially if you are already paying for the midrange install and the dynamat install. I would understand if they added it to the hourly fee, but a well equipped and experienced shop should have no problem running wires from an amp to a door. I'd rather do that than screw around with the factory wires anyway.

To me the main problem is that when they had the dash apart and you requested they run the wiring direct they ignored your request. You had to find out for yourself they didn't do the work which I think is pretty shady on their part.

Did you buy the Rainbow's from this shop?

 

[StuartV 10+ year member]

Nope, I bought the Rainbows from 6spdcoupe here on this forum.