Electronics question for those geekier than I...

So, I got my '4-channel' stereo running. It's pretty good, and POWERFUL!
But, with the lack of a discrete 4 channel source, it's little better than
Stereo, unless you use one of the 'tricks' built into the amp. It has
Matrix SQ and Quatravox. Matrix SQ was a industry standard to take a 2 or
4 channel source and 'synthesize' 4 channel. It works OK. Quatravox was,
IIRC, developed by Radio Shack and is like "Stereo Wide", it takes a 2 or
4 channel signal and plays with phase relationships to synthesize and
expand a 4 channel 'image'. It works OK but you can hear the phase
shifting.

The real question is this: I used to take a stereo for my car and install
new speakers, esp. decent speakers for the rear deck. In the '80s Matt
Polk came out with his 'imaging' speakers, and they were GREAT. But, you
had to sit in an exact location to get the effect. If anyone remembers
these, they made the band appear to be positioned around the room. It was
100 times better than headphones.

He did this by feeding a 'component' from the opposite channel to the
other channel, at a lower volume. This cancelled out crosstalk and made
pure left and pure right from each speaker.

So, I would add a pair of 6x9 speakers to the rear deck of the car. Since
I almost always had hatchbacks, this would leave the original speakers in
their original locations. So, here's what I would do:

I would add an amp, sometimes two, one for the front and one for the rear.
By tapping the RCA outs from the preamp, this left the 4 original powered
outputs from the stereo intact. So, I would take the stronger channel,
usually the rear, and cross the speakers left as right and right as left.
Since I had 65-75 watt amps, and the outputs were typically 12-20 watts,
there was a 'deficiency' from the head unit's amp. Now for the trick: I
would put the car's original speakers out of phase. Then by playing with
levels and balancing, I would 'even' the system out. I never really
acheived the effect of the Polk speakers (I was trying to emulate $1400
speakers with $100 worth of components...) BUT, what it did do was to make
it appear as if the speakers were about 4 feet 'outside' the car. This
effect worked fairly well.

So, my question is, although I never appeared to do any damage to anything
(I ran this setup in my 'Hachiroku' for four years until the system (and,
indeed the whole car!) got ripped on Good Friday night. I got the car back
but never really built the stereo back up.) Since the RCA outs are picked
up at the preamp, and are a voltage with no 'load' associated, this left
the output stage virutally untouched.

Since the speakers were balanced amp-to-amp (ie, 4 ohms wired to the head
unit amp, and 4 or 8 ohms to the external amps), are there any ill efects
to putting speakers out of phase. In case you don't know what this does,
let's take the woofer: when the 'in-phase' side is pushing out, the 'out
of phase' side is pulling in. Since the load is balanced reactance-wise,
there SHOULD be no ill effect on the amp.


Right?

I think it was Hachiroku ???? <Trueno@AE86.gts> who stated:

[color=blue]
>Since the speakers were balanced amp-to-amp (ie, 4 ohms wired to the head
>unit amp, and 4 or 8 ohms to the external amps), are there any ill efects
>to putting speakers out of phase. In case you don't know what this does,
>let's take the woofer: when the 'in-phase' side is pushing out, the 'out
>of phase' side is pulling in. Since the load is balanced reactance-wise,
>there SHOULD be no ill effect on the amp.
>
>
>Right?[/color]


Right.




But it's been a long time since I was really into electronics
geekiness at this level, so I could be wrong. Unlikely, though, as
amplifiers have become more robust over the years, and even a dead
short won't harm many modern ones . . . .


WOOF!! (rO !!FOOW fi er'uoy tuo fo esahp.)

-D

--
A day without sunshine is like, well, night

On Mon, 01 Jan 2007 08:46:31 -0600, Don Fearn <pooder@charter.net>
wrote:
[color=blue]
>I think it was Hachiroku ???? <Trueno@AE86.gts> who stated:
>
>[color=green]
>>Since the speakers were balanced amp-to-amp (ie, 4 ohms wired to the head
>>unit amp, and 4 or 8 ohms to the external amps), are there any ill efects
>>to putting speakers out of phase. In case you don't know what this does,
>>let's take the woofer: when the 'in-phase' side is pushing out, the 'out
>>of phase' side is pulling in. Since the load is balanced reactance-wise,
>>there SHOULD be no ill effect on the amp.
>>
>>
>>Right?[/color]
>
>
>Right.
>
>
>
>
>But it's been a long time since I was really into electronics
>geekiness at this level, so I could be wrong. Unlikely, though, as
>amplifiers have become more robust over the years, and even a dead
>short won't harm many modern ones . . . .
>
>
>WOOF!! (rO !!FOOW fi er'uoy tuo fo esahp.)
>
>-D[/color]

An amplifier can not be damaged by connecting a speaker out of phase .
Connecting the outputs of 2 amplifiers in parallel in or out of phase
may damage the amplifiers if they don't have overload protection.

John

On Mon, 01 Jan 2007 18:07:43 -0500, John wrote:
[color=blue]
> On Mon, 01 Jan 2007 08:46:31 -0600, Don Fearn <pooder@charter.net> wrote:
>[color=green]
>>I think it was Hachiroku ???? <Trueno@AE86.gts> who stated:
>>
>>[color=darkred]
>>>Since the speakers were balanced amp-to-amp (ie, 4 ohms wired to the
>>>head unit amp, and 4 or 8 ohms to the external amps), are there any ill
>>>efects to putting speakers out of phase. In case you don't know what
>>>this does, let's take the woofer: when the 'in-phase' side is pushing
>>>out, the 'out of phase' side is pulling in. Since the load is balanced
>>>reactance-wise, there SHOULD be no ill effect on the amp.
>>>
>>>
>>>Right?[/color]
>>
>>
>>Right.
>>
>>
>>
>>
>>But it's been a long time since I was really into electronics geekiness
>>at this level, so I could be wrong. Unlikely, though, as amplifiers have
>>become more robust over the years, and even a dead short won't harm many
>>modern ones . . . .
>>
>>
>>WOOF!! (rO !!FOOW fi er'uoy tuo fo esahp.)
>>
>>-D[/color]
>
> An amplifier can not be damaged by connecting a speaker out of phase .
> Connecting the outputs of 2 amplifiers in parallel in or out of phase may
> damage the amplifiers if they don't have overload protection.
>
> John[/color]


Thanks guys. I was an Elect Tech for 18 years, and have worked with amps
of different kinds, but in Industrial applications, mostly Power Supplies,
where we used Differential Amps in circuits for current control, and Op
Amps in switching supplies. But my theory falls short on power amps, esp
without a schematic. It would seem that out-of-phase speakers wouldn't
cause any damage, but mis-matched loads or trying to tie to amps to one
load like you mentioned.

On Tue, 02 Jan 2007 04:44:16 GMT, Hachiroku ???? <Trueno@AE86.gts>
wrote:

[color=blue]
>Thanks guys. I was an Elect Tech for 18 years, and have worked with amps
>of different kinds, but in Industrial applications, mostly Power Supplies,
>where we used Differential Amps in circuits for current control, and Op
>Amps in switching supplies. But my theory falls short on power amps, esp
>without a schematic. It would seem that out-of-phase speakers wouldn't
>cause any damage, but mis-matched loads or trying to tie to amps to one
>load like you mentioned.[/color]

But it will cause much mayhem with the audio listening in the car -
you get one speaker out of phase, and you get standing wave patterns
creating null spots and loud spots.

Move your head a few inches one way and you get the Cone Of Silence
at certain frequencies, the other way and extra loud...

--<< Bruce >>--

On Tue, 02 Jan 2007 17:43:37 +0000, Bruce L. Bergman wrote:
[color=blue]
> On Tue, 02 Jan 2007 04:44:16 GMT, Hachiroku ???? <Trueno@AE86.gts> wrote:
>
>[color=green]
>>Thanks guys. I was an Elect Tech for 18 years, and have worked with amps
>>of different kinds, but in Industrial applications, mostly Power
>>Supplies, where we used Differential Amps in circuits for current
>>control, and Op Amps in switching supplies. But my theory falls short on
>>power amps, esp without a schematic. It would seem that out-of-phase
>>speakers wouldn't cause any damage, but mis-matched loads or trying to
>>tie to amps to one load like you mentioned.[/color]
>
> But it will cause much mayhem with the audio listening in the car -
> you get one speaker out of phase, and you get standing wave patterns
> creating null spots and loud spots.
>
> Move your head a few inches one way and you get the Cone Of Silence
> at certain frequencies, the other way and extra loud...
>
> --<< Bruce >>--[/color]


LOL! Cone of silence...OK, Max...

Yeah, I have noticed thia, but usually right between the speakers. Like I
said, from the Driver's seat, it seems like the speakera are outside the
car.

I was more concerned with Amp damage.