High Current, High Voltage, Impedance.

[DANGERDAN]

Hows it guys im back again and im hoping this will be the last
investigation i need help with, iv spent quite a bit of time now
researching about the fundamental physics for electricity to understand
how speakers work in regards to its electrical side and further improve
my understanding for future improvements and knowledge.



I understand almost how electricity works after reading many articles on
the scientific descriptions for electricity physics, i just have a few
hicups in getting my head around a few things but its not specifically
with electricity its with amps and speakers and mostly impedance.



I understand that a speaker determines the load of the signal
(impedance) so depending on the excursion and the difficulties of the
specific frequency depends on how hard it is to drive and what load a
speaker will have.

I don't know a specific question to help me understand this as i think
there are a more than one so i will try my best to ask them.

High current amps vs high voltage amps ?

What relation does low impedance have with these two types of power supply.

In relation to impedance the law states that the lower the resistance
the more power is available to flow through, current is measured in amps
and amps relate to the rate of flow. What im confused at is the way the
electrons are traveling, For eg with the amps measurement that just
measures the rate of flow from one point.

Il try do some math to explain myself.

10 volts x 10 amps = 100 watts

20 volts x 5 amps = 100 watts

Is there a difference in the rate of flow (electron speed) and the
amount of electrons (high flow) that we miss out when measuring amps.

When impedance is lowered from say 8ohm to 4ohm what fills the gap for
this resistance, does the amps increase in the flow or does the voltage
or from what my testing shows me that they both increase ?

Are high current amps better for low impedance dips or can high voltage push supply whats needed for these dips ?.



If there's any articles you could provide me to help me with this
impedance issue i would be greatful and im sorry if i don't make sense,
again thanks.

[DrWho]

What is your definition of a "high current amp" and "high voltage amp"? And what do you want to do with this information? Are you trying to build gear, or use this to help you decide what to buy?

[Quiet_Hollow]

Hows it guys im back again and im hoping this will be the last

investigation i need help with...

No way, bro. You haven't even gotten started. Study the Physics all you want , but electronic design is in large part, MATH. Topics of interest should include, but are not limited to, Complex AC power and DC/AC network analysis to include familiarity with Kirchoff's circuit laws and Thevenin's theorem.See: http://www.youtube.com/watch?v=g0S-XV-BiUAAs evident from just this great video using phasors, you have to have a solid grip on algebra and trigonometry at a minimum. You'll know your getting close when you don't even think about electron flow and you can ascertain the general behavior of a circuit from the equations opposed to the physical topology.

[tube fanatic]

Download this entire book: http://www.paleoelectronics.com/RDH4/

Start at page 1, take your time (you'll have no choice!), and don't stop until you understand everything pertaining to audio amplifiers!!! This may take you a couple of years (no, I'm not joking), but when you're done, all of your questions will be answered, including questions which you haven't even imagined yet! And, as mentioned above, you will need to have solid math skills.

[DANGERDAN]

you will need to have solid math skills.

Im screwed lol, yea i know there's some heavy duty stuff but its mostly just knowledge of amps and whats best for impedance dips etc, i did read a long article that explained that the word flow in the description for electricity was incorrect and that electrons do not flow.

[Islander]

i did read a long article that explained that the word flow in the description for electricity was incorrect and that electrons do not flow.

Of course electrons don't flow. They're round, so they roll. []

[Marvel]

Download this entire book: http://www.paleoelectronics.com/RDH4/

Start at page 1, take your time (you'll have no choice!), and don't stop until you understand everything pertaining to audio amplifiers!!! This may take you a couple of years (no, I'm not joking), but when you're done, all of your questions will be answered, including questions which you haven't even imagined yet! And, as mentioned above, you will need to have solid math skills.

Chapter 20 has a very long explanation of horn speakers, with the Klipsch KHorn being used extensively in the description.

Bruce

[pauln]

In truth we know almost absolutely nothing about electricity (or the rest of physics) at a fundamental level. As others have mentioned, there are lots of theoretical equations that have been developed over the years that describe the measured behavior of electronics. The math is needed to work with those equations; for example impedance is typically characterized by using imaginary numbers in a complex number plane. Everything with waveforms uses trigonometry, and you'll need to brush up on exponents and logarithms.

As far as your questions; solid state amps tend to be current amplifiers and tube amps tend to be voltage amplifiers, but both end up delivering watts (power). Speaker design is complicated by the addition of mechanical physics, which you have already noticed. Do a search on this forum for "The Dope from Hope" to find a copy of Paul Klipsch's informal newsletter collection for Klipsch dealers that covers much of this at a basic level of understanding, oriented to answering questions about amps and speakers, etc.

The behavior of electrons in terms of movement depends on their situation. In a conductor (wire) experiencing a direct current each electron will be in one of two conditions at any one time. He may be bound to the outer shell of an atom, or he may be a free electron unbound among the metal atoms of the conductor. At this point one must distinguish between charge and charge carriers. The charge will travel through the conductor on the order of about half light speed, but the charge carriers (electrons) will only move on the order of centimeters per hour. There is a net flow of electrons (current), but this is quite slow and comprised of individual electrons only moving a tiny distance closer to their neighbor. Some of these movements will be free electrons, others will be bound electrons becoming unbound, others free electrons becoming bound, and bound electrons directly changing the atoms with which they are bound. In all these cases, they interact by exchanging photons (present theory) and basically pass the net charge imbalance along the conductor - kind of like a relay race where each electron runs a short distance and uses photons to hand off the charge difference to the next electron. Since the charge hand off is mediated by photons at light speed, the proportion of the relay leg that is made by light allows for the charge movement to be quite fast even though the charge carriers (electrons) are slow.

In a conductor experiencing alternating current, the same thing is happening except the charge direction is reversing periodically. The charge speed is fast enough to transverse the length of the conductor, even when that length includes the power utility grid distribution system covering hundreds of miles. Yet, the charge carriers are "local" and don't have a net movement.

In a bipolar semiconductor junction the charge is characterized by both charge carriers (electrons) and "holes" (an absent electron which is like a relative net local positive charge), and the semiconductor material has an impurity deliberately added to the material (called doping) which provides atoms with valence (in this case atoms with either one electron in the outer shell or atoms that just need one more electron to fill their outer shell). Electrons moving one direction are like "holes" moving in the other direction... If you look at this you will find there are PNP and NPN bipolar transistors, depending on whether the charge carrier is considered to be the electrons or the "holes".

In an electron tube like a triode or pentode, there is a real flow of electrons from the cathode to the anode (plate) through the vacuum in the tube on order of half light speed.

[DANGERDAN]

Thanks il look up the dope from hope.

Let me ask another question that might help me, Say we had a 8ohm
speaker that dips down to 3-2ohms and say you had a amp that could
supply 300watts into 8ohms but no lower ( and for the sake of being safe
it had a 8ohm tap ).

Now why couldn't the speaker take the power it needs from 8ohm if the
impedance dips ( change ) was to require more power why not take all
from that level of impedance.

Obviously it doesn't so that's why i ask about high current vs high
voltage because you can supply the same amount of watts whether its from
high voltage and low current or low voltage and high current, the
difference seems to be that there's something other than power (watts)
that's needed when the impedance dips.

Meaning when the impedance dips its not the power its looking for its
the current ( more electrons ) now why is it needing these high current
electrons ?? How good are valve amps with impedance i heard that they
don't like low impedance is this because its a high voltage output ?



Lets try one more example

power amp specs:

20 volts (seems to be average)

5 amps

100 watts from ( V x I = W )



Now from this can you work out the lowest this amp can supply into a
impedance ? also when the speaker is resisting at 8ohms and dips to
4ohms what exactly is it resisting ? i presume its the amps and that's
where the extra power comes from ? or does it resist both volts and amps
( i have a digital polimeter which i have been using for studies ).

[DrWho]

In truth we know almost absolutely nothing about electricity (or the rest of physics) at a fundamental level.

Attempting to mystify a subject offers no insight, and I might suggest that the accuracy to which we are able to predict electrical behavior is testament to a rather indepth understanding of how electricity works.

Practically speaking, the understanding of electrical behavior has always been several decades ahead of the manufacturing limitations.

As far as your questions; solid state amps tend to be current amplifiers and tube amps tend to be voltage amplifiers, but both end up delivering watts (power).

If anything, it would be entirely the opposite, but that is also probably one of the worst ways to categorize amplifiers. I also fail to see the insight trying to be imparted with blanket statements like this.

[DrWho]

Thanks il look up the dope from hope.

Let me ask another question that might help me, Say we had a 8ohm
speaker that dips down to 3-2ohms and say you had a amp that could
supply 300watts into 8ohms but no lower ( and for the sake of being safe
it had a 8ohm tap ).

Now why couldn't the speaker take the power it needs from 8ohm if the
impedance dips ( change ) was to require more power why not take all
from that level of impedance.

Obviously it doesn't so that's why i ask about high current vs high
voltage because you can supply the same amount of watts whether its from
high voltage and low current or low voltage and high current, the
difference seems to be that there's something other than power (watts)
that's needed when the impedance dips.

Meaning when the impedance dips its not the power its looking for its
the current ( more electrons ) now why is it needing these high current
electrons ?? How good are valve amps with impedance i heard that they
don't like low impedance is this because its a high voltage output ?



Lets try one more example

power amp specs:

20 volts (seems to be average)

5 amps

100 watts from ( V x I = W )



Now from this can you work out the lowest this amp can supply into a
impedance ? also when the speaker is resisting at 8ohms and dips to
4ohms what exactly is it resisting ? i presume its the amps and that's
where the extra power comes from ? or does it resist both volts and amps
( i have a digital polimeter which i have been using for studies ).

In normal audio applications, voltage is the medium used for describing the musical signal....so the signal fed from a good amplifier to your speaker will be the same voltage at every frequency.

As you note, the same voltage at each frequency will result in different amounts of power being delivered to the speaker at different frequencies. This is expected because the efficiency of the speaker is not the same at every frequency....so although you are delivering more power when the speaker impedance is lower, the speaker itself is less efficient, so the final tonal balance ends up being flat (only on-axis, but we don't need to get into the polar response for this discussion).

All that to say, rating amplifiers in terms of power is probably one of the most misleading trends in the industry since you can't directly measure it. When amplifier power ratings are created, they are measuring the voltage and then assuming the speaker is 8ohms at every frequency.

[pauln]

Dr. Who, I'm not mystifying physics; modern theory does plenty of that all by itself. When modern theory is able to explain how a point particle has mass, what charge is, how massless particles have momentum, and how point particles and massless particles have angular momentum... then I will begin to believe that physics has some fundamental understanding of these things. Until then it is just math that works and conceptual analysis that doesn't.

I'm kind of interested in why you think the general ss-current and tube-volts characterization is backwards. The most common solid state power amp stage is probably the common collector or emmiter follower, which has a voltage gain of less than unity. It is certainly a current amplifier. Except for the cathode follower, which is kind of rare and not highly regarded in the audio world these days, I think most of the tube amp power stages are voltage amps. Maybe I'm missing something?

[Don Richard]

I'm kind of interested in why you think the general ss-current and tube-volts characterization is backwards

SS amps are mostly voltage source power amplifiers. Tube designs are mostly current source power amps.

That is what audio amplifiers do, not how they work.

[DrWho]

Dr. Who, I'm not mystifying physics; modern theory does plenty of that all by itself. When modern theory is able to explain how a point particle has mass, what charge is, how massless particles have momentum, and how point particles and massless particles have angular momentum... then I will begin to believe that physics has some fundamental understanding of these things. Until then it is just math that works and conceptual analysis that doesn't.

I was under the impression that the modern theory is demonstrating how the concepts of "mass" and "particles" should no longer be used. I guess I just don't have any issue with the Schroedinger Wave Equation and ultimately the limits that the speed of light (or the propogation of reality) imposes on our observations. It's very much like the limitations of using frequency vs time to analyze acoustic behavior.

But regardless, answering those questions to your satisfaction really isn't going to change my understanding of how larger electrical circuits work. Or just to pick an example, how do you think that will change the design of an isolated flyback converter? Will engineers be able to extract better performance as a direct result of being able to conceptualize the behavior of a single electron in a lattice structure?

I'm kind of interested in why you think the general ss-current and tube-volts characterization is backwards. The most common solid state power amp stage is probably the common collector or emmiter follower, which has a voltage gain of less than unity. It is certainly a current amplifier. Except for the cathode follower, which is kind of rare and not highly regarded in the audio world these days, I think most of the tube amp power stages are voltage amps. Maybe I'm missing something?

If you connect a perfect current source to a load, then the load impedance determines the voltage seen across the load.

If you connect a perfect voltage source to a load, then the load impedance determines the amount of current that flows through the load.

It is far more common for the output voltage of solid state amplifiers to be a direct function of the input voltage with very little variation due to load impedance. This would model more closely to a perfect voltage source.

With tube amps, you typically have to convert very large voltages to smaller voltages, and those techniques raise the output impedance. A lot of tube amps are also designed to maximize power transfer, which puts the output impedance near the nominal loudspeaker impedance. It is not uncommon to see more variation in the output voltage of a tube amp with varying load impedance (when compared to an equivalent SS design). I've seen as large as 3dB swings in tonal balance depending on the speaker/amplifier combination.

Even though the output of an isolated NPN transistor stage is based on the current through the base, the total circuit is still a voltage amplifier. I would even argue that tube amps are still voltage amplifiers, but not because the isolated tube stage output is based on its grid voltage. Higher output impedance has voltage fluctuation effects similar to a current amplifier, which is why I would lean towards using that category...

At the end of the day, what we really want is a voltage amplifier...how accurately that is achieved is a totally different subject.

[DANGERDAN]

Post from another forum of mine, light bold is seperate person and bold text is me answering.

A signal amplifier is separate from the power amp, and if
you have a separate setup the signal amp will be in the preamp.

I was under the impression that the preamp has a op amp and its main
use is for the control of the signal not really to help with voltage,
the main power amp is more than enough capable to supply enough voltage
from what i can see they reach up to 30v's quite easy.



A good amplifier can handle as low as 2 ohms sometimes. Some car
amplifiers often rate their systems as 1 ohm capable. A normal receiver
that handles 8 ohm speakers can't handle the power load that would occur
if the speakers were in a 2 ohm range. It has to do with a limitation
on the amplification system. If the power to drive the speaker isnt
there, you risk a burn out from power draw that exceeds specifications.

I already understand all of this but this doesn't answer my question
as to why this impedance change is important, current is not power it
carries power and it is a combination of current x volts that creates
power.

Current to me seems to be needed for low resistance so the more current you have the better you it can handle.

Most of this is best guess but i don't think voltage is constant and nor
is current because of resistance, as the excursion changes due to the
frequency the impedance changes and the impedance is just a efficiency
change so with that when more power is needed the efficiency of the
speaker changes. Electrons in a high voltage source move in a smaller
line but really fast and in a high current source there are more
electrons together but move slower, with the right combination they will
provide the same power but with different applications they give a
different effect.



Because Power is based on I*V it is actually pretty accurate to say that
more power needs more current. The thing is all of these are all
related, one affects another. P=I^2*R=IV What does stay consistent is
the voltage that is supplied through the power amp. The power amp boosts
the power by supplying an amperage that compensates for the speaker's
impedance.

This doesn't sound right to me, when you say more power needs more
current you are indicating that current needs to be raised for more
power and that volts are consistent but they really are not, it depends
on what your talking about but if you were talking about speakers it
still wouldn't be a solid voltage level.

Power plants run 1 million volts and only 1 amp to a transformer this
was considered the easier way to transfer power instead of 1 million
amps and 1 volt as this would create a lot of heat dissipation, power
loss and would require a much bigger cable. This is the difference im
looking at "high voltage, high current" if you consider 1 million volts x
1 amp to be high current i think your incorrect, from my testing with a
digital multimeter when you scan through the frequency range from 20hz
to 20khz the voltage and the amps are constantly changing so im
guessing the resistance is causing this change, volume is derived from
the power output (watts) so the more watts you have the louder its going
to be.

Amps can fail in two ways either by overheating from excessive load from
a speaker or fails to provide stable power for the signal and starts
clipping the signal and potentially harms the speaker coil.

But isn't there a max output on amps from the transistor ?? like my amp (
marantz sr4320) from best guess has about 4 amps is 80 watts 20hz to
20khz 0.08 thd and puts out about 25-30 volts max with full signal
(testing with multimeter), so thats 20 volts x 4 amps = 80 watts but if
the speaker required more current ( impedance drop ) wouldn't the amp transistor max out or does it still try to increase the current?.

Summing it up i think my question is when impedance drops is it
wanting more power (watts) or is it after just current ( more amps )
because if it was just power it wouldn't make sense to me because why
could it not take its required power from 8ohms, with speakers that are
100db @ 1 watt @ 8ohm they don't really need a lot more watts at 4ohms
because it would only be 2 watts @ 100db for 4ohm so its a little
confusing for me. Im just saying it has to be something else other than
just watts.

[DANGERDAN]

Bump,

I got told that Impedance change has nothing to do with the driver "wanting" more power,
it is just change that happens due to movement of the coil.

What truth in this and can someone further explain what this means. ?

[DrWho]

Your question was already answered:

In normal audio applications, voltage is the medium used for describing the musical signal....so the signal fed from a good amplifier to your speaker will be the same voltage at every frequency.

As you note, the same voltage at each frequency will result in different amounts of power being delivered to the speaker at different frequencies. This is expected because the efficiency of the speaker is not the same at every frequency....so although you are delivering more power when the speaker impedance is lower, the speaker itself is less efficient, so the final tonal balance ends up being flat (only on-axis, but we don't need to get into the polar response for this discussion).

All that to say, rating amplifiers in terms of power is probably one of the most misleading trends in the industry since you can't directly measure it. When amplifier power ratings are created, they are measuring the voltage and then assuming the speaker is 8ohms at every frequency.

[DrWho]

Again, what do you want to do with this information? Rules of thumb and quick little conceptual remedies really aren't science and their applicability is directly dependant on their context...which means most of the time they are misleading.

[DANGERDAN]

I wish to understand more about impedance and current to better select a new amp over my current one.

[DrWho]

Look for low output impedance, low noise, and low distortion. The low output impedance tells you it is good at driving a speaker impedance. The nominal impedances the amp is rated for has more to do with output stability (not oscillating).