Car stereos: some inneresting fyi

Awl--

I've posted about removing the stereo from my 1990 Mazda 929S, and some may
think, Why Bother?

The reason is this:
For nigh-on 20 years or more, radio reception at various apts/homes has just
sucked, for me and neighbors. Even on top floors of 12 story apt buildings.
And this is NYC area!!
But car radios *always* seem to have great reception, even in my basement
garage.

I found out, from radio/ham ngs that indeed, the tuning circuitry in car
radios is *significantly different* than in your home stereo!
Some were able to say why, circuitry-wise, but that went over my head.
But I thought that was very interesting, and it raises the Q: Why don't home
stereos incorporate this circuitry?

So anyway, I figger in my senescence, I might as well get some radio
reception in my shop w/ the Panasonic 1263 I'm removing.
Yeah, I'll have to keep a 12 V battery on a trickle charger...
And while I'm at it, climb that 100 foot tree outside, and run up an
antenna...

Also, a good car stereo likely has much better fidelity than even a very
expensive home stereo. The smaller the volume you have to deal with
acoustically, the easier it is to do it accurately.
Which means that headphones are even better than car stereos, fidelity-wise.
Think about that, next time you drop 10 grand on a pair of speakers, that a
$40 pair of Sennheiser headphones are superior.

Lastly, I am curious as to car stereos ito of collectibility/classic-ness.
In home stereo, you have iconic stuff, like old Revox reel-to-reels,
Macintosh amps, AR-3a speakers, KLH radios, Crown DC-300 power amps, Marantz
tuners w/ the built in oscilloscope, etc.
Any *really* good audio stuff from cars (thinking oem), that you would take
out if you were junking the car or had an accident?

Or is car stereo stuff more a fungible commodity?
--
------
Mr. P.V.'d (formerly Droll Troll), Yonkers, NY

Stop Corruption in Congress & Send the Ultimate Message:
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entropic3.14decay at optonline2.718 dot net; remove pi and e to reply--ie,
all d'numbuhs

Well, I *finally* got the radio out, and hours later, finally got it to
operate.
Seems to require *duplicate* hots (from hot wires at slightly different
voltages in the harness--11.5 vs. 12.2 V??) and oddball grounds, that f'sure
I thought were shielded antenna connections, but seem to be the (-)
connection.

This radio, in the car, had fine reception in my garage.
Now, removed, it sucks just like all the other radios in my house.
Even worser.
So much for superior tuning circuitry....

Is the car itself acting as an antenna, beyond the retractable trunk
antenna?

Also, the radio operates the power antenna, which has a decent sized motor.
I'm thinking this wire is acting as a switch for a relay that operates this
motor, but I don't hear a relay.
If there is no relay for the antenna motor, then a fair amount of power
would be going through a moderately delicate radio, which seems odd.

I'll tell you, from a dumpster-diving/save-a-few-scheckels/freebie/salvage
pov, I am way way way behind the eight ball, at this point.
Goodgawd....
--
------
Mr. P.V.'d (formerly Droll Troll), Yonkers, NY

Stop Corruption in Congress & Send the Ultimate Message:
Absolutely Vote, but NOT for a Democrat or a Republican.
Ending Corruption in Congress is the *Single Best Way*
to Materially Improve Your Family's Life.
The Solution is so simple--and inexpensive!

entropic3.14decay at optonline2.718 dot net; remove pi and e to reply--ie,
all d'numbuhs

"Proctologically Violated©®" > wrote in
message ...
> Awl--
>
> I've posted about removing the stereo from my 1990 Mazda 929S, and some
> may think, Why Bother?
>
> The reason is this:
> For nigh-on 20 years or more, radio reception at various apts/homes has
> just sucked, for me and neighbors. Even on top floors of 12 story apt
> buildings. And this is NYC area!!
> But car radios *always* seem to have great reception, even in my basement
> garage.
>
> I found out, from radio/ham ngs that indeed, the tuning circuitry in car
> radios is *significantly different* than in your home stereo!
> Some were able to say why, circuitry-wise, but that went over my head.
> But I thought that was very interesting, and it raises the Q: Why don't
> home stereos incorporate this circuitry?
>
> So anyway, I figger in my senescence, I might as well get some radio
> reception in my shop w/ the Panasonic 1263 I'm removing.
> Yeah, I'll have to keep a 12 V battery on a trickle charger...
> And while I'm at it, climb that 100 foot tree outside, and run up an
> antenna...
>
> Also, a good car stereo likely has much better fidelity than even a very
> expensive home stereo. The smaller the volume you have to deal with
> acoustically, the easier it is to do it accurately.
> Which means that headphones are even better than car stereos,
> fidelity-wise.
> Think about that, next time you drop 10 grand on a pair of speakers, that
> a $40 pair of Sennheiser headphones are superior.
>
> Lastly, I am curious as to car stereos ito of collectibility/classic-ness.
> In home stereo, you have iconic stuff, like old Revox reel-to-reels,
> Macintosh amps, AR-3a speakers, KLH radios, Crown DC-300 power amps,
> Marantz tuners w/ the built in oscilloscope, etc.
> Any *really* good audio stuff from cars (thinking oem), that you would
> take out if you were junking the car or had an accident?
>
> Or is car stereo stuff more a fungible commodity?
> --
> ------
> Mr. P.V.'d (formerly Droll Troll), Yonkers, NY
>
> Stop Corruption in Congress & Send the Ultimate Message:
> Absolutely Vote, but NOT for a Democrat or a Republican.
> Ending Corruption in Congress is the *Single Best Way*
> to Materially Improve Your Family's Life.
> The Solution is so simple--and inexpensive!
>
> entropic3.14decay at optonline2.718 dot net; remove pi and e to reply--ie,
> all d'numbuhs
>
>

"Proctologically Violated©®" >
wrote in :

> Well, I *finally* got the radio out, and hours later, finally got it
> to operate.
> Seems to require *duplicate* hots (from hot wires at slightly
> different voltages in the harness--11.5 vs. 12.2 V??) and oddball
> grounds, that f'sure I thought were shielded antenna connections, but
> seem to be the (-) connection.
>
> This radio, in the car, had fine reception in my garage.
> Now, removed, it sucks just like all the other radios in my house.
> Even worser.
> So much for superior tuning circuitry....
>
> Is the car itself acting as an antenna, beyond the retractable trunk
> antenna?
>
> Also, the radio operates the power antenna, which has a decent sized
> motor. I'm thinking this wire is acting as a switch for a relay that
> operates this motor, but I don't hear a relay.
> If there is no relay for the antenna motor, then a fair amount of
> power would be going through a moderately delicate radio, which seems
> odd.
>
> I'll tell you, from a
> dumpster-diving/save-a-few-scheckels/freebie/salvage pov, I am way way
> way behind the eight ball, at this point. Goodgawd....

actually the horizontal panel(s) the auto antenna mounts to is a 'plane'
that increases reception wheather it be CB, HAM, or regular
AM/FM..........normally the radio simply sends a 12v signal to antenna
motor assy. which contains 2 relays and an amp sensing motor. ie: 12v to
up relay when on. motor senses high amps and stops when full up..remove
12v and down relay engages till amps stop motor at full down (simular to
electrc window motor operation).........

"Seems to require *duplicate* hots (from hot wires at slightly
> different voltages in the harness--11.5 vs. 12.2 V??) and oddball
> grounds, that f'sure I thought were shielded antenna connections, but
> seem to be the (-) connection."

lost me on that paragraph!
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> "Seems to require *duplicate* hots (from hot wires at slightly
>> different voltages in the harness--11.5 vs. 12.2 V??) and oddball
>> grounds, that f'sure I thought were shielded antenna connections, but
>> seem to be the (-) connection."

One hot is for the radio, the other is for the illumination, since the dash
lights can be lowered.

Grounds for the speakers DON'T have to be grounded to the chassis/stereo
body, and many aren't. I'm guessing the same could be said for the antenna
sheilding, but don't really know.

As I recall, the low level interconnects (i.e. RCAs, etc) should be grounded
at the head unit (floating signal ground) - most head units are designed
this way nowadays anyway. You are correct about not grounding the high
level speaker outputs (speaker wires). The best way to avoid noise/loops is
to establish a good clean common grounding point and run all grounds for
your system to that point. As for the antenna, I don't believe that it's
ground plane is shared by the chasis ground itself (I believe it's coax
sheilding is connected through DC filters/chokes inside the head unit itself
but I'm far from certain about this one/RF ground planes).

If anyone cares...
Thanks.
Andrew.

in article 1bK9i.806$1i1.513@pd7urf3no, Noozer at wrote on
6/6/07 10:36 PM:

> Grounds for the speakers DON'T have to be grounded to the chassis/stereo
> body, and many aren't. I'm guessing the same could be said for the antenna
> sheilding, but don't really know.

It seems that with this project, I was way behind the eightball before I
even started, without even knowing it. Sheeesh....
Altho I learnt a lot, mostly what I learnt was not to try it again.

An ass-kicking by a car radio-- what next??
--
------
Mr. P.V.'d (formerly Droll Troll), Yonkers, NY

Stop Corruption in Congress & Send the Ultimate Message:
Absolutely Vote, but NOT for a Democrat or a Republican.
Ending Corruption in Congress is the *Single Best Way*
to Materially Improve Your Family's Life.
The Solution is so simple--and inexpensive!

entropic3.14decay at optonline2.718 dot net; remove pi and e to reply--ie,
all d'numbuhs

"AWN" > wrote in message
...
> As I recall, the low level interconnects (i.e. RCAs, etc) should be
> grounded
> at the head unit (floating signal ground) - most head units are designed
> this way nowadays anyway. You are correct about not grounding the high
> level speaker outputs (speaker wires). The best way to avoid noise/loops
> is
> to establish a good clean common grounding point and run all grounds for
> your system to that point. As for the antenna, I don't believe that it's
> ground plane is shared by the chasis ground itself (I believe it's coax
> sheilding is connected through DC filters/chokes inside the head unit
> itself
> but I'm far from certain about this one/RF ground planes).
>
> If anyone cares...
> Thanks.
> Andrew.
>
> in article 1bK9i.806$1i1.513@pd7urf3no, Noozer at wrote
> on
> 6/6/07 10:36 PM:
>
>> Grounds for the speakers DON'T have to be grounded to the chassis/stereo
>> body, and many aren't. I'm guessing the same could be said for the
>> antenna
>> sheilding, but don't really know.
>

If you can find a car radio which dates back to the 1960s and earlier
and make or find a sheet metal box/cabinet for the radio,(the larger,the
better for a ground plane) that will probally work ok.You can buy some
galvanized sheet metal at a sheet metal shop or probally at a junk
yard.Most of those car radios have a little threaded metal stud on the
back or bottom of the radios.Drill a hole in the metal box/cabinet for
the stud and put a washer and a nut on the stud.The metal box/cabinet is
suppose to act as a ground plane, I think.
cuhulin