audio amplifiers: +/- X VDC vs 0-X VDC

[Don Bowey]

And what do you think I do?

What you do is make errors and then argue about it when someone points it
out. Do you get paid for that?

You really should be quiet and let this pass, as there is no way you can
show that you are correct.

I can only expect an ignorant answer only because;

1. You don't know me.

I know you enough to know that you make errors and then argue about it when
someone points it out.

2. And I really don't think you know Graham? or Mr. HAM.

Only too well, but so what?

How ever, if you watch the treads pass by like I have for several
months before I voiced my opinions. I have come to learn
who is and who isn't worthy of respect.

Your error indicates that this may not be valid.

Before giving out your ignoramus views. Maybe you should be
more in touched with reality.

Please take your own advice.

(snip)

 

[Eeyore]

Geez! Inverted is not equal to "out of phase". They're precisely in phase,
simply of opposite polarities.

Please don't confuse the newbies.

Not to mention that both are 'sitting' on exactly the *same* DC level (not
opposite).

Graham

 

[Eeyore]

And don't bother asking what I do

You're a fuckwit 'Mr know-it-all' programmer who's so totally out of his depth
it's untrue, but true to form you can never admit you made a simple error.

"I'm never wrong, once i thought i was, but was mistaken"
Real Programmers Do things like this.
http://webpages.charter.net/jamie_5

Real programmers would shut the **** up about stuff they don't understand.

Graham

 

[Jamie]

Rich Grise wrote:




Not to mention that both are 'sitting' on exactly the *same* DC level (not
opposite).

Graham

Ha

 

[Jamie]

Jamie wrote:




You're a fuckwit 'Mr know-it-all' programmer who's so totally out of his depth
it's untrue, but true to form you can never admit you made a simple error.




Real programmers would shut the **** up about stuff they don't understand.

Graham

I wonder about you Mr. Ham. First you try to sound like a Brit, then how
ever with that language, you start sounding more American with
every passing post you make.

And for your information. PC based applications isn't the only thing
I do jerk. Just goes to show you how much you think you know about
programming.

If you were really keeping up with things, you would know that
today's electronics involves programming in various forms of embedded
and non embedded systems more so than ever.

The days of massive board population is over. While you're still
tuning your Stanley Steamer, the rest of us are solving the problems in
a logical manner.

And no, I'm not a know it all how ever, I do know of some individuals
that fit that category, if you know what I mean.

Talking about some one out of their depths.

Look, I know you're up there in years. I just hope this
conflict isn't putting a strain on your system. I really would
feel bad if something happen to prevent you from being here.

No matter how twisted you are. It's kind of a break from dealing
with real life EE work and with other EE/ME's.

 

[Eeyore]

I wonder about you Mr. Ham. First you try to sound like a Brit, then how
ever with that language, you start sounding more American with
every passing post you make.

And for your information. PC based applications isn't the only thing
I do jerk. Just goes to show you how much you think you know about
programming.

Where did I say you only did PC programming ? Something else you've just made up
from nowhere.

I do plenty of embedded programming myself btw. Even done some DSP assembler. Don't
make even more stupid assumptions than you've done already.

Graham

 

[Michael A. Terrell]

I wonder about you Mr. Ham. First you try to sound like a Brit, then how
ever with that language, you start sounding more American with
every passing post you make.

And for your information. PC based applications isn't the only thing
I do jerk.

We don't want to know about anything else you 'jerk'.


--
Service to my country? Been there, Done that, and I've got my DD214 to
prove it.
Member of DAV #85.

Michael A. Terrell
Central Florida

 

[Michael Black]

Geez! Inverted is not equal to "out of phase". They're precisely in phase,
simply of opposite polarities.

Please don't confuse the newbies.

So which part are you taking issue with?

"Your stereo speakers are out of phase", but wait, reversing one pair
of wires will remedy the situation. Both speakers are now pushing out
at the same time.

Stick an inverter in there, and it does the same thing as the reversed
wires.

So it's my use of "inverter"? My Radio Shack dictionary gives the
same basic definition for "inverter" and "inverting amplifier".

If you don't have a 180 degree inversion there, then the
speaker sees no difference between the terminals no matter
how much sound gets pumped into it. Because the ac signal
on both leads of the speaker is the same. It cancels in
the same way as the DC on the two amplifier outputs cancel.

Take two LM380 audio amplifiers, feed the audio signal to
the non-inverting input of one and the inverting input of
the other, and you get the same effect. It doesn't matter
what DC voltage is on the output, since each device rests
at the same point. But since one is an "inverter" for
the audio signal, one of the 380's output is going more
positive while the other 380's output is going more negative,
which feeding the speaker puts an AC signal across it.

Michael

 

[DJ Delorie]

Given this signal:

/\ /\ /\
/ \ / \ / \
_____/ \_____/ \_____/ \

This is inverted:
_____ _____ _____
\ / \ / \ /
\ / \ / \ /
\/ \/ \/

While this is out of phase:

/\ /\ /\
/ \ / \ / \
/ \_____/ \_____/ \_____


While with a pure sine wave signal it's pretty much equivalent (except
for noise on the line), audio is not a pure sine wave.

Note that the difference is VERY important when dealing with three
phase motor control, or R/C/L filters.

 

[Eeyore]

If you don't have a 180 degree inversion there, then the
speaker sees no difference between the terminals no matter
how much sound gets pumped into it. Because the ac signal
on both leads of the speaker is the same. It cancels in
the same way as the DC on the two amplifier outputs cancel.

To be totally accurate it's not a phase shift but a polarity inversion (of the
audio part of the signal only).

Take two LM380 audio amplifiers, feed the audio signal to
the non-inverting input of one and the inverting input of
the other, and you get the same effect. It doesn't matter
what DC voltage is on the output, since each device rests
at the same point.

IF AC coupled. Choosing an IC that is designed to be AC coupled is highly
disingenuous of you as it obscures the true operation required. Casual readers
might not know that about the LM380.

Graham

 

[Rich Grise]

So which part are you taking issue with?

Using the term "out of phase" when there is no phase difference.

Imagine a pulse train:

_ _ _
__________| |__________| |__________| |_____


THIS is 180 degrees out of phase:
_ _ _
___| |__________| |__________| |_____


THIS is merely inverted:
__________ __________ __________ ______
|_| |_| |_|


Get it now?

Thanks,
Rich

 

[zhafran]

Using the term "out of phase" when there is no phase difference.

Imagine a pulse train:

_ _ _
__________| |__________| |__________| |_____

THIS is 180 degrees out of phase:
_ _ _
___| |__________| |__________| |_____

THIS is merely inverted:
__________ __________ __________ ______
|_| |_| |_|

Get it now?

Thanks,
Rich

I'm just confuse about some basics here. can the 2 sinusoidal waves
that is 180 degrees out of phase with each other be said as inverted?
and, for waveforms other than sinusoidal shape is not necessarily
inverted when they are 180 degrees out of phase?

 

[Jamie]

Using the term "out of phase" when there is no phase difference.

Imagine a pulse train:

_ _ _
__________| |__________| |__________| |_____


THIS is 180 degrees out of phase:
_ _ _
___| |__________| |__________| |_____


THIS is merely inverted:
__________ __________ __________ ______
|_| |_| |_|


Get it now?

Thanks,
Rich

Really, well there is another way to look at that.

imagine a CT (center Tapped) xformer where the CT is the
common. both X1, X4 (X2 and X3 being joined as the CT) are now 180
degrees out of phase from each other with respect to common.

Both are in time with each other how ever, polarities are
opposite.

In the case of Audio circuits using a dual rail +/- with
respect to common. These circuits do not apply their +/-
rails simultaneously through it's output as it's being driven. If they
did, that would obviously cancel each other out with the exception of
low current needed to bring the complemary pairs out of cut off. Real
basic circuits often use a couple of diodes in series to list the bias
between the NPN/PNP's base circuits.

In the last example, using "phase" comparison isn't a proper way of
explaining it, since you normally need two or more signals to compare
against for evaluating phase shifts How ever!, if you were dealing with
bridged circuits, then you could say, one output is out of phase 180
degrees from the other. Since both outputs can be measured with respect
to common, this is just the same as the first example.

I think I broke that down simple enough.

 

[Jamie]

I'm just confuse about some basics here. can the 2 sinusoidal waves
that is 180 degrees out of phase with each other be said as inverted?
and, for waveforms other than sinusoidal shape is not necessarily
inverted when they are 180 degrees out of phase?

In case you didn't see my other reply. You need 2 of more signals to
say that one is out of time(PHASE) from the other. In the case of for
example, AC wave form (sinusoidal). Using the term PHASE shift normally
refers to comparing one reference with another at the
same time.
The closes example I can give that you may understand is a bridged
Audio amplifier. the outputs are 180 degrees out of phase because they
are from 2 difference sources that can be measured with with respect to
common.
With amplifier circuits that use a common for one of the speaker
terminals generates only 1 output ref. You have nothing to compare it to
that has the same signal applied.

 

[Rich Grise]

I'm just confuse about some basics here. can the 2 sinusoidal waves that
is 180 degrees out of phase with each other be said as inverted? and, for
waveforms other than sinusoidal shape is not necessarily inverted when
they are 180 degrees out of phase?

To invert a signal, you run it through an inverter, To phase shift it, you
run it through some sort of phase shift network; this will be frequency-
sensitive, depending on the frequency and the parameters of your phase
shifter.

And anyone who tells you that an inversion is the same as a 180 degree
phase shift just wasn't paying attention in class that day.

Admittedly, with a sine wave, they LOOK exactly the same; this is
probably the confusion factor for those who don't know the difference
yet.

Hope This Helps!
Rich

 

[Rich Grise]

Really, well there is another way to look at that.

imagine a CT (center Tapped) xformer where the CT is the
common. both X1, X4 (X2 and X3 being joined as the CT) are now 180 degrees
out of phase from each other with respect to common.

THEY ARE NOT OUT OF PHASE!!!!! They are opposite ends of THE SAME SIGNAL!

If you continue to believe that the two ends of a transformer winding
are "out of phase", then please point out where the phase shifting takes
place.

Thanks,
Rich

 

[Eeyore]

I'm just confuse about some basics here. can the 2 sinusoidal waves
that is 180 degrees out of phase with each other be said as inverted?

In that specific instance they could be either one of the other. Where a circuit
inverts a signal it's better practice to call the signal inverted than '180
degrees out of phase' since it describes better what's happening.

and, for waveforms other than sinusoidal shape is not necessarily
inverted when they are 180 degrees out of phase?

Indeed.

Graham

 

[Eeyore]

In the case of Audio circuits using a dual rail +/- with
respect to common. These circuits do not apply their +/-
rails simultaneously through it's output as it's being driven. If they
did, that would obviously cancel each other out with the exception of
low current needed to bring the complemary pairs out of cut off. Real
basic circuits often use a couple of diodes in series to list the bias
between the NPN/PNP's base circuits.

What a load of drivel.

Don't you ever feel embarassed writing such junk ?

Graham

 

[Don Bowey]

THEY ARE NOT OUT OF PHASE!!!!! They are opposite ends of THE SAME SIGNAL!

Yes they are, by 180 degrees, which is what you want in the amp type being
discussed.

If you continue to believe that the two ends of a transformer winding
are "out of phase", then please point out where the phase shifting takes
place.

Either in a phase inverter stage (Yes, that's what it's called), or in an
interstage transformer, where the center-tap is common reference for both
stages being driven.

 

[Jamie]

Jamie wrote:




What a load of drivel.

Don't you ever feel embarassed writing such junk ?

Graham

You're such a smuck.

You must of been a real prize in your day.