[T3] FW: radio in

[Dennis Stiefel]

Typical speakers are 8 Ohms. If you put 2 in parallel, you've reduced the
resistance to 4 Ohms. Three in parallel will put it at 2.666 Ohms. So the
current you're asking from the radio has gone from, for example, 1 A to 3 A.
In the electronics world, that's a big difference.

If you put the 2 rear speakers in series, they now measure 16 Ohms, so
putting that in parallel with the front speaker now asks the radio to drive
5.333 Ohms. So the current in the same example will now go from 1 A to ~1.3
A. That's not such a big deal.  

The current you actually ask the radio to provide depends on how far up you
crank the volume, so if you keep things moderate, you can get away with a
lot.  

Some of your posts seem to imply that this is a stereo, which is unusual for
a Sapphire from our era. If that's the case, consider wiring the rear
speakers as L & R, and then combine the ground returns from them into one
conductor and pass that thru the dash speaker. This creates a "center
channel" which might work nicely, but note that you can't do this unless the
2 channels have a common ground. Keith can probably tell you if this will
work on the radio he fixed up for you. Be careful. If you do this wrong,
you'll damage the radio.

--
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Jim Adney, jadney at vwtype3.org
Madison, Wisconsin, USA
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Yes I understand what you are saying about the ohms of the speakers and
changing that in a parallel circlet as opposed to a series.  It's just been
a long time since I've dealt with a car stereo that just has a place for two
speakers but what you say make sense I guess I just worded that last email
all wrong.  I struggle sometimes with communicating through text like an
email as I am more of an auditory learner. That's why I done so many video
blogs on you tube during the restoration of her.  Any who yes this is one of
those rare birds in the Sapphire world that dose have FM stereo. That's why
I really wanted to make this work.  It's a Sapphire 16 (I think) and from
what I heard they only made a few in 72.  If you look in the photo I had
with the first email in this thread you can see at the right side of the
dial display there is a light lit up indicating a strong FM stereo signal.
After you mention it I do remember as a teen seeing speakers wired up this
way on car radios back when mono or stereo with only 2 places to hook up a
speaker were more common.  I can try it but I still think my speakers are
crap.  Sorry if I came off sounding like a smart butt last night wasn't my
intention.

Dennis Stiefel
72 Fastback FI MT
71 STD. Beetle
67 Ford F-100 (hart of Crown Vic)
Rainsville, AL