help with speaker configuration
 

Jim Lesurf wrote in message ...
In article , steven
robinson wrote:



My problem is the lager 4Ohms 80watt speaker that is in series with the
parallel leg has burn't out. I have no idea why.

----8Ohms---- (50watts)
| |
| |
----8Ohms---- (50watts)
| |
| -------4Ohms------- (80watts)
| |

I read a similar reply recently that stated maybe its because the
wattage is unbalanced or the number of speakers were unbalanced,
resulting in the 4Ohms 80watt speaker doing double the work.

The main concern I have is that calling a speaker '4 Ohm' or '8 Ohm' is an
entirely nominal value.The *actual* value of the impedance is likely to be
very frequency dependent, and at some frequencies it may be a long way
from the quoted nominal value. Putting dissimilar speaker units in series
is a recipy for potential pun disaster for this reason...

At some frequencies the impedance of one unit may be much higher than the
nominal value, and the other(s) much lower. This mean mean the power is
far from being distributed as you might assume from the 'nominal' values.

Also: Since you are not using any crossover networks it may be that at -
for example - low frequencies *all* your speakers have low impedances
(thus drawing more current/power than you assume), and their values are
such that most of the power ends up in one unit - which can then fail.

To say more, I'd need to see impedance/frequency plots for each of the
units.

Another reason putting dissimilar units in series is often a bad idea is
that each one (for the reason given above) will experience a drive voltage
that is frequency dependent. Thus the resulting overall output sound
power/frequency response is likely to be changed. Each unit *used and
driven individually* might be acceptable as a broadband speaker, but
combined, the results may be very different.

There are also some other variables involved, so in general, I would not
expect what you produced to sound particularly good, even if it survived!
However this depends upon the units, and how they were fitted to the
cabinets, etc, etc.

Personally, I'd also use some kind of added network, just to define the
impedance values. For example, some amplifiers may not like the load they
see at LF or HF from a speaker of the kind you describe. This can also
lead to trouble if the amp is not unconditionally stable.

Also occurs to me to point out that when putting reactive components
in series, the magnitudes of the voltages on each, if added, can
actually add up to *more* than the total applied across them all.
( ;- ) So, again, this can be a recipy for problems... (The
voltages add up as vector/complex values, and may be out of
phase with each other, hence leading to this effect.)



Please help if you can, any insight into this problem would be greatly
appreciated, its driving me nuts..

Do you have impedance/frequency plots of the individual units? Any idea
how these values were altered by the cabinets and/or combined useage? What
amplifier did you use, and is it unconditionally stable?

Slainte,

Jim



Hi Jim
Thanks for the reply, a lot of what you are saying is foreign to me,
but this is what I know:
The spec of the 8Ohms 50watt speakers in the parallel leg a
Nominal power 30watts
Peak power 50watts
SPL @ 1W/1m 82db
Frequency range 100Hz to 20kHz
Resonant Frequency 130Hz
Max cone displacement 5mm
Voice coil diameter 20mm
Magnetic inductance 0.8 Tesla
Magnetic flux 200u Weber

Withount using cross overs how can I block damaging frequencies lower
than 100Hz and higher than 20kHz from the drivers? or isn't that a
concern?

Unfortunately I don't know anything about the 4Ohms speaker, except
its Peak power is 80watts.

Likewise the amp is a bit of a mistery, it is an amp called a v-series
manufactured by an amusement company in leeds. Its output is supposed
to be 70watts into 4Ohms.

I'm getting the impresion that putting dis-similat drivers in series
is a bad idea. What if I put two 8Ohms in series twice and parallel
them together, would this be a better idea? I could then use the same
speakers with the same properties. In this configuration you would
expect the output to be spread evenly across the four speakers,
wouldn't you? What do you think?

Thanks Steve

help with speaker configuration
 

In article , steven
robinson wrote:
Jim Lesurf wrote in message
...

[snip loads]


Do you have impedance/frequency plots of the individual units? Any
idea how these values were altered by the cabinets and/or combined
useage? What amplifier did you use, and is it unconditionally stable?


Hi Jim Thanks for the reply, a lot of what you are saying is foreign to
me, but this is what I know: The spec of the 8Ohms 50watt speakers in
the parallel leg a Nominal power 30watts Peak power 50watts SPL @
1W/1m 82db Frequency range 100Hz to 20kHz Resonant Frequency 130Hz Max
cone displacement 5mm Voice coil diameter 20mm Magnetic inductance 0.8
Tesla Magnetic flux 200u Weber

Alas, the above does not tell you what you'd need to know to be able to
start the process of trying to design an 'in series' design. TBH such
designs, using dissimilar speakers, would be a nightmare to get right
without a lot of test gear, etc. Best avoided in my view as trying this (as
you have found) can be more grief that you'd expect.

Withount using cross overs how can I block damaging frequencies lower
than 100Hz and higher than 20kHz from the drivers? or isn't that a
concern?

I can't tell what may or may not be the real cause of the problem you had.
The problem is that there is too much we don't know that might have an
effect. However the resonance frequency (which I assume is 'free air') of
130 Hz seems quite high for a 'full range' speaker. I may well be wrong as
I lack data. Someone who knows more about speaker building may well be able
to give a better comment on this. However I'd suspect that below 100 Hz the
cone movements might become too great unless you use the unit in a cabinet
that acts as a closed box to limit this.

Otherwise, to control movements, you will need a cross-over - although this
could be an 'active' type applied before using distinct power-amps to drive
the individual units. This may all be to complicated for you to wish to do,
though.

For the above reasons it is possible that the speaker was damaged by being
forced to move too far to provide LF output. i.e. by exceeding its
mechanical limits, not by overheating by excessive power.

It is unlikely that signals above 20kHz will do any damage. Chances are
that there is only a little power at such frequencies, and the units will
essentially ignore it. :-) (This assumption may not be correct if the
amplifier went into oscillations and was producing very high powers at an
ultrasonic frequency. However normal music and speech does not usually have
much in the way of sustained high powers above 20kHz.)

Unfortunately I don't know anything about the 4Ohms speaker, except its
Peak power is 80watts.

Likewise the amp is a bit of a mistery, it is an amp called a v-series
manufactured by an amusement company in leeds. Its output is supposed to
be 70watts into 4Ohms.

Unless you can establish that it is an unconditionally stable design, then
it is possible that it went into oscillation and this caused problems. This
is probably less likely than other causes, but I can't rule it out at this
point.

I'm getting the impresion that putting dis-similat drivers in series is
a bad idea.

It is, unless you know a great deal about the units, and can carry out the
relevant design/measurement process. Afraid it isn't as simple as assuming
the power is divided up as if the units were plain resistors. In general,
'hi fi' designs avoid speakers in series without any cross-over or
adjustment networks.

What if I put two 8Ohms in series twice and parallel them
together, would this be a better idea? I could then use the same
speakers with the same properties.

This is more likely to work as the inherent properties of the units are the
same. However it may still not work as you expect for various reasons. For
example: Putting the units into the same cabinet mean they couple
acoustically. This alters their properties, so even though you have
connected them in 'series/parallel' the resulting impedances, etc may not
be the same as for a single driver in the same cabinet.

In this configuration you would expect the output to be spread evenly
across the four speakers, wouldn't you? What do you think?

The output would probably be distributed reasonably evenly, but it is hard
to be certain about this as the cabinet has an effect. It would be better
than using dissimilar units, but it is not something I'd normally recommend
as the results may still not be what you anticipate. For example: there
will be acoustic interference between the units that will alter the
resulting total response, etc.

To be honest, trying to do anything like this is risky without having a
fair amount of data, and/or doing the right measurements, or proceeding
with care and taking a long time experimenting.

FWIW I've happily designed and build various amplifiers, and tuners, and
other 'electronic' items over the years. I also cheerfully modify
commercial electronics to alter the performance to suit. However I have
always avoided trying to self-design speakers. Simply too difficult and
time-consuming to get right. :-) That said, many people do develop their
own designs, and produce good results. However this can involve a lot of
effort and patience and understanding. Some of the 'kits' and published
designs can work well if made with care, but these are obviously based upon
someone else having already put in the time and effort to sort out the
necessary details!

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 , steven
robinson wrote:
Jim Lesurf wrote in message
...

[snip loads]


Do you have impedance/frequency plots of the individual units? Any
idea how these values were altered by the cabinets and/or combined
useage? What amplifier did you use, and is it unconditionally stable?


Hi Jim Thanks for the reply, a lot of what you are saying is foreign to
me, but this is what I know: The spec of the 8Ohms 50watt speakers in
the parallel leg a Nominal power 30watts Peak power 50watts SPL @
1W/1m 82db Frequency range 100Hz to 20kHz Resonant Frequency 130Hz Max
cone displacement 5mm Voice coil diameter 20mm Magnetic inductance 0.8
Tesla Magnetic flux 200u Weber

Alas, the above does not tell you what you'd need to know to be able to
start the process of trying to design an 'in series' design. TBH such
designs, using dissimilar speakers, would be a nightmare to get right
without a lot of test gear, etc. Best avoided in my view as trying this (as
you have found) can be more grief that you'd expect.

Withount using cross overs how can I block damaging frequencies lower
than 100Hz and higher than 20kHz from the drivers? or isn't that a
concern?

I can't tell what may or may not be the real cause of the problem you had.
The problem is that there is too much we don't know that might have an
effect. However the resonance frequency (which I assume is 'free air') of
130 Hz seems quite high for a 'full range' speaker. I may well be wrong as
I lack data. Someone who knows more about speaker building may well be able
to give a better comment on this. However I'd suspect that below 100 Hz the
cone movements might become too great unless you use the unit in a cabinet
that acts as a closed box to limit this.

Otherwise, to control movements, you will need a cross-over - although this
could be an 'active' type applied before using distinct power-amps to drive
the individual units. This may all be to complicated for you to wish to do,
though.

For the above reasons it is possible that the speaker was damaged by being
forced to move too far to provide LF output. i.e. by exceeding its
mechanical limits, not by overheating by excessive power.

It is unlikely that signals above 20kHz will do any damage. Chances are
that there is only a little power at such frequencies, and the units will
essentially ignore it. :-) (This assumption may not be correct if the
amplifier went into oscillations and was producing very high powers at an
ultrasonic frequency. However normal music and speech does not usually have
much in the way of sustained high powers above 20kHz.)

Unfortunately I don't know anything about the 4Ohms speaker, except its
Peak power is 80watts.

Likewise the amp is a bit of a mistery, it is an amp called a v-series
manufactured by an amusement company in leeds. Its output is supposed to
be 70watts into 4Ohms.

Unless you can establish that it is an unconditionally stable design, then
it is possible that it went into oscillation and this caused problems. This
is probably less likely than other causes, but I can't rule it out at this
point.

I'm getting the impresion that putting dis-similat drivers in series is
a bad idea.

It is, unless you know a great deal about the units, and can carry out the
relevant design/measurement process. Afraid it isn't as simple as assuming
the power is divided up as if the units were plain resistors. In general,
'hi fi' designs avoid speakers in series without any cross-over or
adjustment networks.

What if I put two 8Ohms in series twice and parallel them
together, would this be a better idea? I could then use the same
speakers with the same properties.

This is more likely to work as the inherent properties of the units are the
same. However it may still not work as you expect for various reasons. For
example: Putting the units into the same cabinet mean they couple
acoustically. This alters their properties, so even though you have
connected them in 'series/parallel' the resulting impedances, etc may not
be the same as for a single driver in the same cabinet.

In this configuration you would expect the output to be spread evenly
across the four speakers, wouldn't you? What do you think?

The output would probably be distributed reasonably evenly, but it is hard
to be certain about this as the cabinet has an effect. It would be better
than using dissimilar units, but it is not something I'd normally recommend
as the results may still not be what you anticipate. For example: there
will be acoustic interference between the units that will alter the
resulting total response, etc.

To be honest, trying to do anything like this is risky without having a
fair amount of data, and/or doing the right measurements, or proceeding
with care and taking a long time experimenting.

FWIW I've happily designed and build various amplifiers, and tuners, and
other 'electronic' items over the years. I also cheerfully modify
commercial electronics to alter the performance to suit. However I have
always avoided trying to self-design speakers. Simply too difficult and
time-consuming to get right. :-) That said, many people do develop their
own designs, and produce good results. However this can involve a lot of
effort and patience and understanding. Some of the 'kits' and published
designs can work well if made with care, but these are obviously based upon
someone else having already put in the time and effort to sort out the
necessary details!

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 Tue, 28 Oct 2003 17:41:53 +0000 (GMT), Jim Lesurf
wrote:

In article , Kalman Rubinson
wrote:
3. The so-called 80watt speaker is in series with the now 100watt pair
and any power disipated goes through both.

Not sure what you mean by the above. Can you clarify?

Just from your wiring. All current must go through the 80watt speaker
which is in series with the paralleled others. Thus, it now becomes
the limiting power factor, further stressed by the non-linear drive
imposed on it by the others.

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

Kal

help with speaker configuration
 

On Tue, 28 Oct 2003 17:41:53 +0000 (GMT), Jim Lesurf
wrote:

In article , Kalman Rubinson
wrote:
3. The so-called 80watt speaker is in series with the now 100watt pair
and any power disipated goes through both.

Not sure what you mean by the above. Can you clarify?

Just from your wiring. All current must go through the 80watt speaker
which is in series with the paralleled others. Thus, it now becomes
the limiting power factor, further stressed by the non-linear drive
imposed on it by the others.

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

Kal

help with speaker configuration
 

In article , Kalman Rubinson
wrote:
On Tue, 28 Oct 2003 17:41:53 +0000 (GMT), Jim Lesurf
wrote:

In article , Kalman
Rubinson wrote:
3. The so-called 80watt speaker is in series with the now 100watt
pair and any power disipated goes through both.

Not sure what you mean by the above. Can you clarify?

Just from your wiring.

The wiring was, I think, Steven's, not mine.

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.

The current will pass through the '80 watt' speaker, but this does not
necessarily mean that the 'power' passes though the speaker on its way to
the others. This is because the actual power is conveyed by the EM fields,
and the 80 Watt speaker has no way to know what electric potential
('voltage') is across any *other* loads in series with it. Hence it does
not actually experience the power being dissipated by the other units.

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.

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.

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.

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 Tue, 28 Oct 2003 17:41:53 +0000 (GMT), Jim Lesurf
wrote:

In article , Kalman
Rubinson wrote:
3. The so-called 80watt speaker is in series with the now 100watt
pair and any power disipated goes through both.

Not sure what you mean by the above. Can you clarify?

Just from your wiring.

The wiring was, I think, Steven's, not mine.

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.

The current will pass through the '80 watt' speaker, but this does not
necessarily mean that the 'power' passes though the speaker on its way to
the others. This is because the actual power is conveyed by the EM fields,
and the 80 Watt speaker has no way to know what electric potential
('voltage') is across any *other* loads in series with it. Hence it does
not actually experience the power being dissipated by the other units.

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.

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.

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.

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


The current will pass through the '80 watt' speaker, but this does not
necessarily mean that the 'power' passes though the speaker on its way to
the others. This is because the actual power is conveyed by the EM fields,
and the 80 Watt speaker has no way to know what electric potential
('voltage') is across any *other* loads in series with it. Hence it does
not actually experience the power being dissipated by the other units.

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.


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.

help with speaker configuration
 

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


The current will pass through the '80 watt' speaker, but this does not
necessarily mean that the 'power' passes though the speaker on its way to
the others. This is because the actual power is conveyed by the EM fields,
and the 80 Watt speaker has no way to know what electric potential
('voltage') is across any *other* loads in series with it. Hence it does
not actually experience the power being dissipated by the other units.

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.


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.

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.