I don't think anyone is laughing at you. Please don't take offence - I have a habit of doing that to people here as other contributors in this thread have stated previously!
The table appears to be measurements of an amplifier that responds differently to different loads. The subject of this thread is coil resistance - which if the power input is the same, has no effect on the power output (of the driver). Of course, this might well require an amplifier tailored to a specific load. The changing power outputs in the table is really a topic of amplifier design not coil resistance.
Thinking about the effects of VC inductance, its reactance will serve to limit the current at any given frequency, and it will provide the back e.m.f. which is the voltage which damps it from movement, most of it being 're-applied' to the VC.
If you take your (analogue) multimeter, and with open cct terminals, and in its most sensitive current range, wave it around the needle axis, the needle will swing around the zero mark.
If you then short the I/P terminals and do the same it will have a very restricted needle movement because of damping from back e.m.f..
Of course it will have to be analogue.
If you take your (analogue) multimeter, and with open cct terminals, and in its most sensitive current range, wave it around the needle axis, the needle will swing around the zero mark.
If you then short the I/P terminals and do the same it will have a very restricted needle movement because of damping from back e.m.f..
Of course it will have to be analogue.
That's a wide proposal, and it want's some qualifying. I can't agree that inductance and resistance are equivalents unless you want to be more specific. I don't know whether slurring transients is as bad as that without more information.camplo said:
"Inductance is the tendency of an electrical conductor to oppose a change" and this opposition to change is what causes the signal to be limited to a certain frequency before it distorts the signal, by means of a slur of the transient. Slur meaning "to utter with such reduction, substitution, or omission of sounds" as seen by the "break up" where basically the driver cannot keep up accurately with the speed of the frequency because inductance has reached a high enough level.
So I proposed that resistance, in some kind of way, sharpens the electrical signal at its edges. A theory.
So I proposed that resistance, in some kind of way, sharpens the electrical signal at its edges. A theory.
I haven't read this whole thread but to answer the title...
No, it doesn't.
Most modern amplifiers have very low output impedances, often in 10ths of an ohm. You can see this by looking at their "Damping Factor" specification. DF is simply the ratio between the output impedance and the load impedance... For example, a DF of 100 means that for an 8 ohm load the amp's output impedance is 8/100 == .08 ohms.
This is known as "Impedance Bridging" where a lower output impedance feeds a higher load impedance. Thus eliminating the need for exact "Impedance Matching " entirely.
The way this works is that an amplifier sets a voltage on it's outputs that mirrors the voltage on it's input. Once this voltage is set, it then becomes the amplifier's job to provide enough current to drive a connected load. Ohm's law tells us that current = voltage/resistance or I == E/R. Thus for a 10 volt output into an 8 ohm load 10/8 == 1.25 amps of current will flow. On a 4 ohm load it doubles to 2.5 amps of current. It is the amplifier's job to provide that current without the voltage rolling off.
The problems start when the amplifier can't provide the needed current without overheating or breaking down.
Since higher impedance loads require less current, it is likely the opposite is true ... that a modern amplifier would get into less trouble on a 16 ohm load.
No, it doesn't.
Most modern amplifiers have very low output impedances, often in 10ths of an ohm. You can see this by looking at their "Damping Factor" specification. DF is simply the ratio between the output impedance and the load impedance... For example, a DF of 100 means that for an 8 ohm load the amp's output impedance is 8/100 == .08 ohms.
This is known as "Impedance Bridging" where a lower output impedance feeds a higher load impedance. Thus eliminating the need for exact "Impedance Matching " entirely.
The way this works is that an amplifier sets a voltage on it's outputs that mirrors the voltage on it's input. Once this voltage is set, it then becomes the amplifier's job to provide enough current to drive a connected load. Ohm's law tells us that current = voltage/resistance or I == E/R. Thus for a 10 volt output into an 8 ohm load 10/8 == 1.25 amps of current will flow. On a 4 ohm load it doubles to 2.5 amps of current. It is the amplifier's job to provide that current without the voltage rolling off.
The problems start when the amplifier can't provide the needed current without overheating or breaking down.
Since higher impedance loads require less current, it is likely the opposite is true ... that a modern amplifier would get into less trouble on a 16 ohm load.
This could be said about any reactive influence in broad terms.
You mean a change in level with a corresponding minimum phase change.
Ok, you're moving a bit fast for me there.
I meant comparing the two in contrast. This statement was intended to imply that if you use a single amp that you didn't design yourself and tried it with different loads, being at the mercy of it's limitations, without knowing those limitations specifically, then you might be in this generic dilemma that could give rise to an unfair stereotype.
Agreed
Yes
Its just my imagination of what the electrical signal is doing which causes what we see in the real world. I can imagine the signal passing through the system and being affected by inductance as the signal changes direction. I see slur lol, inductance literally causes the signal only to be able to switch directions so fast as it reaches a level a of type of electrical compliance, so low, that it cannot change direction fast enough to keep up.....sluuurrrr
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Ok, but look at it rationally. Minimum phase variations are not known to be problematic. The primary audible manifestation is a reduction in level. Besides, an inductive filter of simple nature bottoms out at 90degrees. No need for all the 'rrrr' in slur 😀
A large amount of electrical power in a very short time transfered to a damped moving mass that have to be contolled by this electrical power requie a huge peaking current capabilty, which kind of guy will choose a high impedance voice coil ?
It is so is easy to be logic, why d'ont ?
It is so is easy to be logic, why d'ont ?
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The/a "break up" is a mechanical event (mass, stiffness, damping, bending mode, resonance) and has not so much to do with a drivers electrical properties.
//
A 4ohm coil version of a driver does not necessarily have a heavier or lighter coil than an 8ohm version. The 4ohm version will have less turns of wire in the coil, but the wire will be a larger gauge to handle the higher current needed to achieve the same power handling as the 8ohm coil, or the same gauge wire is used but multiple coils are wound on the same former and then connected in parallel or series to the tinsel leads to achieve the desired impedance.
Afaik if the voicecoil mass does not change, and the voicecoil material (e.g. copper) does not change, then T/S parameters do not change as the ratio between Le and Re has not changed and the flux density for a given output power has not changed. In reality there may be slight variations, either deliberate or simply because the 4ohm and 8ohm coils are not equivalent - maybe they source the coils from a different supplier that uses a lighter/heavier former, more glue, or by choosing the nearest standard gauge of wire results in a slight error. Deliberate changes might be due to marketing e.g. a 4ohm version of a woofer might be engineered with a weaker magnet, resulting in higher Qts to suit a car audio application, being mounted infinite baffle in a door.
The choice of impedance is completely arbitrary when considering sound quality alone. There is no reason why a 100ohm speaker can't deliver the same sound as a 1ohm speaker. The main reason consumer speakers are around the 4-8ohm impedance is that it is a compromise of voltage and current requirements. If the impedance was a lot higher than 8ohms the voltages required from the amplifier would become hazardous at louder volumes. If the impedance was significantly lower than 8ohms the current required becomes quite high, requiring very thick cables to reduce resistive losses. 8ohm is a nice compromise where the voltages are safe and the speaker cables don't have to resemble car jumper cables.
FWIW, it is (imho) easier to design a solid state amplifier that produces lower distortion at 8ohms than 4ohms.
Afaik if the voicecoil mass does not change, and the voicecoil material (e.g. copper) does not change, then T/S parameters do not change as the ratio between Le and Re has not changed and the flux density for a given output power has not changed. In reality there may be slight variations, either deliberate or simply because the 4ohm and 8ohm coils are not equivalent - maybe they source the coils from a different supplier that uses a lighter/heavier former, more glue, or by choosing the nearest standard gauge of wire results in a slight error. Deliberate changes might be due to marketing e.g. a 4ohm version of a woofer might be engineered with a weaker magnet, resulting in higher Qts to suit a car audio application, being mounted infinite baffle in a door.
The choice of impedance is completely arbitrary when considering sound quality alone. There is no reason why a 100ohm speaker can't deliver the same sound as a 1ohm speaker. The main reason consumer speakers are around the 4-8ohm impedance is that it is a compromise of voltage and current requirements. If the impedance was a lot higher than 8ohms the voltages required from the amplifier would become hazardous at louder volumes. If the impedance was significantly lower than 8ohms the current required becomes quite high, requiring very thick cables to reduce resistive losses. 8ohm is a nice compromise where the voltages are safe and the speaker cables don't have to resemble car jumper cables.
FWIW, it is (imho) easier to design a solid state amplifier that produces lower distortion at 8ohms than 4ohms.
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You are talking about the lumped parameters that are the basis of the long-established Thiele-Small parameters and describe the low frequency alignment of a loudspeaker. The notion of a "slur" is incorrect: The signal output in time is precisely that which results from the low frequency alignment - the audible effects of which are also well documented.
This condition is not the constant power input/output that is required when discussing the effects of coil resistance.
This arises from using an inappropriate amplifier for the driver rather than being a consequence of having a different coil resistance.
No.
Do not forget the current dependent driver non-linearities.
No. You describe the linear dispersion in time that results in the low-frequency alignment of the loudspeaker.
There are issues from the non-linearity of the "inductance" and from the heating of the coil resistance, but you are describing the effect of a linear system.
If it was not for the fundamental resonance, then the driver would be a very inefficient sound radiator with a response rising at 6dB/octave rather than the nominal second-order high-pass response that gives a nominally flat pass-band.
Yes! 🙂 As shown earlier, it is the volume of the conductor in the magnetic field that is the variable and not its resistance.
It has been said multiple times before: If we compare the 4 and the 8 ohms variants of basically the same driver, the latter one has sqrt2 times the turns number of the former one, i.e. sqrt2 times the BL value. Hence, it requires 1/sqrt2 times the current for the same power.
As, with the exception of BL, all TSP's are the same, why should two drivers with different impedances behave differently?
Best regards!
Examples from the real world:
ScanSpeak 21WE/4542T00 Re=3.4 ohm Fs=38 Hz Qts=0.28 Vas=54 L
ScanSpeak 21WE/8542T00 Re=6.3 ohm Fs=36 Hz Qts=0.38 Vas=54 L
ScanSpeak 15WU/4741T00 Re=3.2 ohm Fs=34 Hz Qts=0.23 Vas=20 L
ScanSpeak 15WU/8741T00 Re=5.9 ohm Fs=35 Hz Qts=0.26 Vas=20 L
ScanSpeak 12W/4524G00 Re=3.1 ohm Fs=50 Hz Qts=0.27 Vas=8 L
ScanSpeak 12W/8524G00 Re=5.7 ohm Fs=52 Hz Qts=0.32 Vas=8 L
ScanSpeak 26W/4534G00 Re=3.8 ohm Fs=23 Hz Qts=0.36 Vas=156 L
ScanSpeak 26W/8534G00 Re=5.7 ohm Fs=23 Hz Qts=0.40 Vas=150 L
The only significant difference between 4 and 8 ohm versions is Qts parameter, which is lower in the 4-ohm versions.
On the other hand:
JBL 2226G Re=2.5 ohm Fs=40 Hz Qts=0.31 Vas=175.6 L
JBL 2226H Re=5 ohm Fs=40 Hz Qts=0.31 Vas=175.6 L
JBL 2226J Re=10 ohm Fs=40 Hz Qts=0.31 Vas=175.6 L
No difference!
ScanSpeak 21WE/4542T00 Re=3.4 ohm Fs=38 Hz Qts=0.28 Vas=54 L
ScanSpeak 21WE/8542T00 Re=6.3 ohm Fs=36 Hz Qts=0.38 Vas=54 L
ScanSpeak 15WU/4741T00 Re=3.2 ohm Fs=34 Hz Qts=0.23 Vas=20 L
ScanSpeak 15WU/8741T00 Re=5.9 ohm Fs=35 Hz Qts=0.26 Vas=20 L
ScanSpeak 12W/4524G00 Re=3.1 ohm Fs=50 Hz Qts=0.27 Vas=8 L
ScanSpeak 12W/8524G00 Re=5.7 ohm Fs=52 Hz Qts=0.32 Vas=8 L
ScanSpeak 26W/4534G00 Re=3.8 ohm Fs=23 Hz Qts=0.36 Vas=156 L
ScanSpeak 26W/8534G00 Re=5.7 ohm Fs=23 Hz Qts=0.40 Vas=150 L
The only significant difference between 4 and 8 ohm versions is Qts parameter, which is lower in the 4-ohm versions.
On the other hand:
JBL 2226G Re=2.5 ohm Fs=40 Hz Qts=0.31 Vas=175.6 L
JBL 2226H Re=5 ohm Fs=40 Hz Qts=0.31 Vas=175.6 L
JBL 2226J Re=10 ohm Fs=40 Hz Qts=0.31 Vas=175.6 L
No difference!
Correct ... it is describing the way amplifiers behave in the real world.
The question was whether low impedance gives better sound. The answer is no, and for the reasons I explained. Lower speaker impedance merely puts more current load on amplifiers. Up to the point where the amplifier can't provide enough current, there should be little or no difference in sound quality. This is largely due to the use of negative feedback to correct output voltage errors.
One of the biggest reasons modern speakers are favouring 6 ohms --look around, lots of them out there-- is that it lets them use less copper in the voice coil, making for a smaller motor assembly.
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