help with speaker configuration
 

On Thu, 30 Oct 2003 13:36:51 +0000
Laurence Payne wrote:


Current is measured in amps. If two units are connected in series,
the same amperage will flow through both. If not, where would it go?
The resistance of each unit will determine how much power is drawn by
it.

"Power is conveyed by the EM fields" is meaningless gobbledygook.

Power is not the same as current.

--
Spyros lair: http://www.mnementh.co.uk/ |||| Maintainer: arm26 linux

Do not meddle in the affairs of Dragons, for you are tasty and good with
ketchup.

help with speaker configuration
 

In article ,
Laurence Payne wrote:
Current is measured in amps. If two units are connected in series,
the same amperage will flow through both. If not, where would it go?
The resistance of each unit will determine how much power is drawn by
it.

Exactly. And it's the heating effect of the watts that does the damage.

Think of how a fuse works.

--
*Real women don't have hot flashes, they have power surges.

Dave Plowman London SW 12
RIP Acorn

help with speaker configuration
 

In article ,
Laurence Payne wrote:
Current is measured in amps. If two units are connected in series,
the same amperage will flow through both. If not, where would it go?
The resistance of each unit will determine how much power is drawn by
it.

Exactly. And it's the heating effect of the watts that does the damage.

Think of how a fuse works.

--
*Real women don't have hot flashes, they have power surges.

Dave Plowman London SW 12
RIP Acorn

help with speaker configuration
 

On Wed, 29 Oct 2003 16:59:50 +0000 (GMT), Jim Lesurf
wrote:

All current must go through the 80watt speaker which is in series with
the paralleled others.

Erm... Current is not power. They are quite distinct physical quantities,
albeit ones which have a specific relationship for a specific component.

If the 80watter is in series with the others (my interpretation of the
wiring) then all the current passes through it. What power it
dissipates, of course, depends on its own construction.

Thus, it now becomes the limiting power factor,

Afraid that, again, I'm not quite sure why you are saying this. Each
individual speaker unit has no awareness as such of what voltages or
currents or powers any *other* units experience. It only knows about the
potential between its own terminals, and the current that it then passes.

Sure but if the user is trying to pump a lot of power out of the set,
whatever current that is used by the higher-wattage parallel-pair must
pass through the 80watter which is in series with it. Assuming
identical power dissipation for the moment, the 80watter will blow
before the parallel-pair.

further stressed by the non-linear drive imposed on it by the others.

Are you talking about non-linear impedance here? if so, I'm unsure why. My
own comments on what Steven said were based upon things like frequency
dependence, and linear acoustic effects, not signal-level dependence.

Yes, non-linear impedance (non-linear wrt frequency primarily) whose
effects can be exacerbated at higher levels.

I wish I could suggest a solution but I do not know your goals.

I assume that you mean Steven's goals. :-) My own recommendation to him
would be to avoid using dissimilar speakers in series.

Sorry. I didn't see your name at the top. I agree with your
recommendation.

Kal

help with speaker configuration
 

On Wed, 29 Oct 2003 16:59:50 +0000 (GMT), Jim Lesurf
wrote:

All current must go through the 80watt speaker which is in series with
the paralleled others.

Erm... Current is not power. They are quite distinct physical quantities,
albeit ones which have a specific relationship for a specific component.

If the 80watter is in series with the others (my interpretation of the
wiring) then all the current passes through it. What power it
dissipates, of course, depends on its own construction.

Thus, it now becomes the limiting power factor,

Afraid that, again, I'm not quite sure why you are saying this. Each
individual speaker unit has no awareness as such of what voltages or
currents or powers any *other* units experience. It only knows about the
potential between its own terminals, and the current that it then passes.

Sure but if the user is trying to pump a lot of power out of the set,
whatever current that is used by the higher-wattage parallel-pair must
pass through the 80watter which is in series with it. Assuming
identical power dissipation for the moment, the 80watter will blow
before the parallel-pair.

further stressed by the non-linear drive imposed on it by the others.

Are you talking about non-linear impedance here? if so, I'm unsure why. My
own comments on what Steven said were based upon things like frequency
dependence, and linear acoustic effects, not signal-level dependence.

Yes, non-linear impedance (non-linear wrt frequency primarily) whose
effects can be exacerbated at higher levels.

I wish I could suggest a solution but I do not know your goals.

I assume that you mean Steven's goals. :-) My own recommendation to him
would be to avoid using dissimilar speakers in series.

Sorry. I didn't see your name at the top. I agree with your
recommendation.

Kal

help with speaker configuration
 

In article , Laurence
Payne
wrote:
On Wed, 29 Oct 2003 16:59:50 +0000 (GMT), Jim Lesurf
wrote:

Current is measured in amps.

More precisely: The standard *unit* for current is the Amp. Hence values
are quoted in amps.

If two units are connected in series, the same amperage will flow
through both. If not, where would it go?

Yes, I think I agreed before that the current will pass through both.
However this is not the same as the initial comment which prompted my
response. This was that:

Quote starts ----

On 28 Oct in uk.rec.audio, Kalman Rubinson wrote:

3. The so-called 80watt speaker is in series with the now 100watt
pair and any power disipated goes through both.

Quote ends ----

My initial point was that this is not really the case. The *power* does not
'go through both'. This remains the case even if the current does go
through both, for the reasons I outlined.


The resistance of each unit will determine how much power is drawn by it.

Yes. However let's consider that we can choose almost any value we like for
the value of an impedance to place in series with our load. Provided we
then choose an appropriate potential to apply across both in series, we can
get the same 'I' value in our load. Hence our load isn't directly concerned
by the choice of what it in series with it. Just with the value of the
current that then happens to flow through the load.

"Power is conveyed by the EM fields" is meaningless gobbledygook.

Sorry if what I wrote was not clear to you. If you examine the energy of
the EM fields in and around components you will find that what I said is
formally correct. For example, look at the Poynting vector values around
conducting wires and resistors. You then find that the actual power is
conveyed 'along' wires by the EM fields external to the wires. The levels of
the internal field powers are relatively tiny. Similarly, the Poynting
vector on the surface of a resistor points inwards, and its integral over
the surface equals the power dissipation. Thus the field is 'guided' to the
resistive component by the fields outside the conductors, and for all
practical purposes only that portion which is dissipated in a component
actually enters it.

If my explanations are not clear, I'd recommend the texts by people like
Kraus (Electromagnetics) or Ramo et al as they cover this sort of thing in
much more detail that I can explain here.

Some estimates (based upon the standard EM texts) of the kinds of values
for the power levels in the external fields and in wires are on some of the
pages in the 'Scots Guide' in my sig if you are interested. Similar
calculations are probably findable in some of the standard texts.

Slainte,

Jim

--
Electronics http://www.st-and.ac.uk/~www_pa/Scot...o/electron.htm
Audio Misc http://www.st-and.demon.co.uk/AudioMisc/index.html
Armstrong Audio http://www.st-and.demon.co.uk/Audio/armstrong.html
Barbirolli Soc. http://www.st-and.demon.co.uk/JBSoc/JBSoc.html

help with speaker configuration
 

In article , Laurence
Payne
wrote:
On Wed, 29 Oct 2003 16:59:50 +0000 (GMT), Jim Lesurf
wrote:

Current is measured in amps.

More precisely: The standard *unit* for current is the Amp. Hence values
are quoted in amps.

If two units are connected in series, the same amperage will flow
through both. If not, where would it go?

Yes, I think I agreed before that the current will pass through both.
However this is not the same as the initial comment which prompted my
response. This was that:

Quote starts ----

On 28 Oct in uk.rec.audio, Kalman Rubinson wrote:

3. The so-called 80watt speaker is in series with the now 100watt
pair and any power disipated goes through both.

Quote ends ----

My initial point was that this is not really the case. The *power* does not
'go through both'. This remains the case even if the current does go
through both, for the reasons I outlined.


The resistance of each unit will determine how much power is drawn by it.

Yes. However let's consider that we can choose almost any value we like for
the value of an impedance to place in series with our load. Provided we
then choose an appropriate potential to apply across both in series, we can
get the same 'I' value in our load. Hence our load isn't directly concerned
by the choice of what it in series with it. Just with the value of the
current that then happens to flow through the load.

"Power is conveyed by the EM fields" is meaningless gobbledygook.

Sorry if what I wrote was not clear to you. If you examine the energy of
the EM fields in and around components you will find that what I said is
formally correct. For example, look at the Poynting vector values around
conducting wires and resistors. You then find that the actual power is
conveyed 'along' wires by the EM fields external to the wires. The levels of
the internal field powers are relatively tiny. Similarly, the Poynting
vector on the surface of a resistor points inwards, and its integral over
the surface equals the power dissipation. Thus the field is 'guided' to the
resistive component by the fields outside the conductors, and for all
practical purposes only that portion which is dissipated in a component
actually enters it.

If my explanations are not clear, I'd recommend the texts by people like
Kraus (Electromagnetics) or Ramo et al as they cover this sort of thing in
much more detail that I can explain here.

Some estimates (based upon the standard EM texts) of the kinds of values
for the power levels in the external fields and in wires are on some of the
pages in the 'Scots Guide' in my sig if you are interested. Similar
calculations are probably findable in some of the standard texts.

Slainte,

Jim

--
Electronics http://www.st-and.ac.uk/~www_pa/Scot...o/electron.htm
Audio Misc http://www.st-and.demon.co.uk/AudioMisc/index.html
Armstrong Audio http://www.st-and.demon.co.uk/Audio/armstrong.html
Barbirolli Soc. http://www.st-and.demon.co.uk/JBSoc/JBSoc.html

help with speaker configuration
 

In article , Kalman
Rubinson
wrote:
On Wed, 29 Oct 2003 16:59:50 +0000 (GMT), Jim Lesurf
wrote:

All current must go through the 80watt speaker which is in series
with the paralleled others.

Erm... Current is not power. They are quite distinct physical
quantities, albeit ones which have a specific relationship for a
specific component.

If the 80watter is in series with the others (my interpretation of the
wiring) then all the current passes through it. What power it
dissipates, of course, depends on its own construction.

Agreed. :-) However I was above really referring back to the previous
posting that described the *power* as if flowing through each component.
This is not strictly correct, although the comment about current normally
is correct. My later comments were then just to clarify that power and
current are distinct quantities even though they have a specific individual
relationship for a specific individual component.

Sure but if the user is trying to pump a lot of power out of the set,
whatever current that is used by the higher-wattage parallel-pair must
pass through the 80watter which is in series with it. Assuming
identical power dissipation for the moment, the 80watter will blow
before the parallel-pair.

Yes, I'd agree. (If we take steven's initial values as being a faithful
repesentation.)

IIRC the original diagram that steven drew showed two '8 Ohm 50 W' speakers
in parallel combination - thus (if we take this literally) making a
composite load of 4 Ohms with a total dissipation capability of 100 W.

Putting this combination in series with a 4 Ohm 80 load, then I'd agree
that if we wound up the input we could expect the 4 Ohm 80 W speaker to
fail first.

further stressed by the non-linear drive imposed on it by the others.

Are you talking about non-linear impedance here? if so, I'm unsure why.
My own comments on what Steven said were based upon things like
frequency dependence, and linear acoustic effects, not signal-level
dependence.

Yes, non-linear impedance (non-linear wrt frequency primarily) whose
effects can be exacerbated at higher levels.

OK. Can you explain a bit more on how you were expecting this to lead to
the '4 Ohm 80W' speaker to fail first? Curious about this. I am aware that
speakers show non-linearity, but do not know much more than that about
conventional speakers...

Slainte,

Jim

--
Electronics http://www.st-and.ac.uk/~www_pa/Scot...o/electron.htm
Audio Misc http://www.st-and.demon.co.uk/AudioMisc/index.html
Armstrong Audio http://www.st-and.demon.co.uk/Audio/armstrong.html
Barbirolli Soc. http://www.st-and.demon.co.uk/JBSoc/JBSoc.html

help with speaker configuration
 

In article , Kalman
Rubinson
wrote:
On Wed, 29 Oct 2003 16:59:50 +0000 (GMT), Jim Lesurf
wrote:

All current must go through the 80watt speaker which is in series
with the paralleled others.

Erm... Current is not power. They are quite distinct physical
quantities, albeit ones which have a specific relationship for a
specific component.

If the 80watter is in series with the others (my interpretation of the
wiring) then all the current passes through it. What power it
dissipates, of course, depends on its own construction.

Agreed. :-) However I was above really referring back to the previous
posting that described the *power* as if flowing through each component.
This is not strictly correct, although the comment about current normally
is correct. My later comments were then just to clarify that power and
current are distinct quantities even though they have a specific individual
relationship for a specific individual component.

Sure but if the user is trying to pump a lot of power out of the set,
whatever current that is used by the higher-wattage parallel-pair must
pass through the 80watter which is in series with it. Assuming
identical power dissipation for the moment, the 80watter will blow
before the parallel-pair.

Yes, I'd agree. (If we take steven's initial values as being a faithful
repesentation.)

IIRC the original diagram that steven drew showed two '8 Ohm 50 W' speakers
in parallel combination - thus (if we take this literally) making a
composite load of 4 Ohms with a total dissipation capability of 100 W.

Putting this combination in series with a 4 Ohm 80 load, then I'd agree
that if we wound up the input we could expect the 4 Ohm 80 W speaker to
fail first.

further stressed by the non-linear drive imposed on it by the others.

Are you talking about non-linear impedance here? if so, I'm unsure why.
My own comments on what Steven said were based upon things like
frequency dependence, and linear acoustic effects, not signal-level
dependence.

Yes, non-linear impedance (non-linear wrt frequency primarily) whose
effects can be exacerbated at higher levels.

OK. Can you explain a bit more on how you were expecting this to lead to
the '4 Ohm 80W' speaker to fail first? Curious about this. I am aware that
speakers show non-linearity, but do not know much more than that about
conventional speakers...

Slainte,

Jim

--
Electronics http://www.st-and.ac.uk/~www_pa/Scot...o/electron.htm
Audio Misc http://www.st-and.demon.co.uk/AudioMisc/index.html
Armstrong Audio http://www.st-and.demon.co.uk/Audio/armstrong.html
Barbirolli Soc. http://www.st-and.demon.co.uk/JBSoc/JBSoc.html

help with speaker configuration
 

On Thu, 30 Oct 2003 17:09:03 +0000 (GMT), Jim Lesurf
wrote:

In article , Kalman
Rubinson
Yes, non-linear impedance (non-linear wrt frequency primarily) whose
effects can be exacerbated at higher levels.

OK. Can you explain a bit more on how you were expecting this to lead to
the '4 Ohm 80W' speaker to fail first? Curious about this. I am aware that
speakers show non-linearity, but do not know much more than that about
conventional speakers...

Only that the non-linearity of the parallel-pair will effect the
80watter (and vice versa) and that pulling more current through the
whole network at certain frequencies is likely to stress the weaker
link. OTOH, without knowing the impedance plots of the various
drivers wrt frequency and power, one cannot be certain.

Kal