3rd dash speaker handling?

[essmaker]

Happy Thursday!!

I am putting in a new radio while my dash is apart.

I have the two door speakers and the dash speaker (no rear speakers for now).

How have others handled the 3rd speaker? Just wiring it as one of the rear? As one of the front?

The new radio I am installing has the options for two front and two rear, just to be clear.

[ratdude747]

Generally, unless you have another device to use it with (CB, HAM, GMRS, etc.), the center location is a no-go. I tried some crazy way to use it in a hybrid stereo-mono setup, but all I managed to do was fry a vintage Sharp aftermarket headunit.

Just use a pair of good speakers in the door. If you want more, behind the seats is the way to go.

[Gary Lewis]

I like to make a "center channel" by using the positive from one channel and negative from the other to power the center speaker.  I'm running that combo in the shop and it works very well.

Basically what it does is to put only things that are in both channels in the center channel.  Anything in just the left or just the right will stay there, but anything that is in both channels shows up in the center.

[Ifitaintbroke]

I have a speaker for my cb but don't feel like pulling the dash (again) to put it in. I think for the radio that rear speakers would be a better investment, time and money-wise.

[ratdude747]

That's exactly what I did with the Sharp radio (which had a setup where each R/L side was a + and - rail with a floating center for F/R balance). Never could get the balance right... once I finally had the correct (in theory) 16 ohm speaker installed (to account for the double voltage on the center speaker), it worked OK until I had a channel fry. Don't know if running 4/8 ohm center speakers earlier caused the later failure or if it just didn't like things being connected between L and R, but I saw enough to know not to try it again. Not to mention that head unit was quiet... the unit I currently have (a custom autosound lookalike unit) does better but is still a bit junk. Seems "dual knob" headunits are hard to find that are "good" (and aside from the lookalike "modern" units, none have the line-in I like to have).

[Gary Lewis]

Bummer!  I'd forgotten that, Larry.  I guess back in my day the systems didn't care, but today that's not a safe way to wire it.

Given that I'd go with a dual voice coil speaker.  Each side is wired to its own coil but the cone moves most when both sides have the same information.  That way you won't hurt the head unit but will get a bit of center channel.

[essmaker]

Thanks for all the inputs. I think I will just not connect it and if my hearing gets worse, I'll install some rear speakers. 😀

[BigBrother-84]

Guys, I don’t understand why connecting the center that way won’t work:
• Center speaker to RFront
• Driver’s door to LRear
• Passenger’s door to RRear

This could enable full control on dash speaker loudness.
And why leaving LFront empty could cause a problem?

[Gary Lewis]

Jeff - I'm not sure what "that way" you mean.

The way you laid out will work, but with only RF to the center speaker you'll have an out of balance sound.

The way I initially advocated, with the RF + and LF - to the center speaker, and then RF to the RF speaker and LF to the LF speaker gives a center channel and balance.  But for some reason it may have contributed to blowing Larry's head unit, so let's not do that.

The last way I suggested, of using a dual voice coil speaker in the center channel and connecting the LF to one coil and RF to the other coil would not blow any head unit.  And if you then connect the LR to the RF speaker and RR to the RF speaker you'd have an easy way to select how much center channel you have.  Full front would be all center, full rear would be no center.

[BigBrother-84]

Gary Lewis wrote

Jeff - I'm not sure what "that way" you mean.

Gary, I was referring to the initial question:

essmaker wrote

How have others handled the 3rd speaker? Just wiring it as one of the rear? As one of the front?

I find this is a simple way to go, no complicated add-ons.
I understand that the dash speaker will rely on some balance to the Right  (if wired as one of the Right speakers), but at the time there is some sound to the Right, you still have control on how much the center dash will have, playing with the fader button.

Lazy Mechanic speaking here.