Lower impedance means the speaker is less of a roadblock for current, thereby drawing more current from the amplifier and driving the amplifier harder because it has to output more power.
Ok but what's the advantage if any? Seems lower impedance draws more current and is harder on a amp so what use a low impedance speaker seems more disantavages than advantages.
@@72tx340 Andrew Jones gets into a great explanation of his interviews on why he goes for low impedance speaker designs. He's done many interviews, so i can't tell which one. But, here's an explanation from Eric Alexander (Tekton) for the layman ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-tMAO9LPsups.html A whole lotta disinformation floats around in the forums. Listen to the speaker designers (with an active noodle in their heads) and learn instead.
@72tx340. Lower impedance, if amplifier is able to drive, makes the output circuit 'faster', which can be used to provide higher bandwidth/ cut off. But this is mostly a design time parameter to make good use of
I love how this gentleman from India took it upon himself to try and educate Paul and all us hopeless Americans about the world. Sharing knowledge like for like, sounds like a fair deal. Well done Sir👍
Simple analogy: It takes a lot less water (power) to get a steady stream out of a thin hose (8ohm) than it does to get that same stream out of a larger hose (4ohm).
Thanks ! Paul is usually very clear but in this case what he said was counterintuitive to me. Your hose analogy does the job. The water in your hose was crystal clear. In Pauls, muddy as hell. People see power as a force pushing against the resistance in the wire and the more resistance the harder it has to push. It is this misunderstanding which causes the confusion.
Except that in your analogy the "thin" is the bigger number i.e 8 and your "thick" hose is the smaller number i.e 4 😜 Sometimes it's the simple things that trips people up. So basically more/higher resistance/impedance is easier to drive because of how electricity works. However dragging something behind you through mud requires more power because of the resistance as opposed to less power for less resistance dragging something over ice...... makes you think 🤪
I also always struggled with this concept, for the following reason: I understood impedance to mean "resistance". Therefore, to me, it always seemed logical that the higher the resistance / impedance, the more difficult it must be for the amplifier to drive. At school in physics, a parallel was often drawn between electricity and water, with voltage being the pressure in the tap, amperage being the amount of water flowing, and ohms / resistance being the narrowness of the pipe. Therefore, to my mind, the narrower the pipe (higher resistance) the more pressure (voltage) would be needed to get the water / current to flow. While I do "technically" understand why the opposite is true, it remains counter-intuitive to me - even 50 years later! 😀
Yep! Low impedance speakers are truly bad implementation. There's some benefits, but the disadvantages are excessive heat, high power draw, and reliability issues. John DeVore is correct. 8ohms is a sensible target and the best of both worlds.
I think I lot of people find Ohms law counterintuitive because of the perspective. Another way to look at it is that a lower impedance speaker "forces" the amp to work harder.
@@datadaveangelstravelsadven444 I would have to assign differing definitions... I would define "counterintuitive" as something that works the opposite of assumptions generated from an incomplete knowledge whereas "makes no sense" implies something breaking more complete knowledge of operation. In all cases people should remain cognizant of their understanding of the entire situation.
Omne Obstat replace the word “allows” with “forces”. The amp must deliver a certain amount of current to the speakers if impedance goes down. A little class D amp might not have that current available, while some heavy solid state monoblocks won’t have any issue with that.
@@audiofun999 For me, the word should be "demands". A lower impedence speaker demands more current from the amplifier, increasing the chance of it not being able to supply that current.
It makes sense that less resistance = more watts. I think where I, and possibly others, struggle on this topic is that it seems counter intuitive that it is MORE difficult to drive a lower impedance speaker when you have less resistance and get double the power output. It would seem logical that if it's capable of delivering double the wattage at half the load, it would be easier to drive a 4 ohm speaker to 100 watts than it would be an 8 ohm speaker at 100 watts as you're only at 50% volume with 4 ohms at 100 watts rather than 100% volume with 8 ohms at 100 watts. I've, over the years, learned less impedance/resistance = more watts and just really stopped concerning myself with how difficult it is for the amp to drive them so long as it's rated for that load with an acceptable level of THD.
Part of the problem explaining why low impedance speakers are harder to drive is not as simple as running a battery through a wire, etc., the answer is much more complex. How much power an amplifier can deliver to a speaker depends on the power supply, the current capacity of the output section of the amplifier, the stability of the amplifier, etc. Some power supplies adjust the voltage that goes to the output section as the demands for power change, others don't. Some amplifier designs are very stable at very low impedances, others will distort or oscillate. An amplifier may be able to deliver double the power at half the impedance but it may have a lot of distortion. The power rating is at a specified percentage of distortion so an amplifier that is rated at 100 watts at 8 ohms at .1% distortion, and delivers 200 watts at .2% distortion at 4 ohms, would be rated at less than 200W at 4 ohms even though electrically it may be delivering all 200 watts. Also, the output section of the amplifier has to dissipate heat. A class AB amplifier output section has to dissipate more heat when it delivers half power than when running at full power because it has to dissipate the same amount of heat as it delivers to the load. The lower the impedance of the speaker, the more the internal impedance of the output transistors become a factor. In essence, the output transistors in a class AB amplifier work as variable resistors in series with the speakers, connected across the power supply. Their internal resistance change in accordance to the input signal but transistors are not perfect and will have some resistance even when driven to their maximum current. So for example, (using very unrealistic numbers to make the explanation simple) if you are driving an 8 ohm speaker and the internal resistance of the output transistor is 8 ohms, and it's delivering 10 watts to the speaker, then the transistor will also have to dissipate 10 watts of heat. Change the speaker to 4 ohms, now the transistor would have to dissipate twice as much heat as gets delivered to the speaker. That's one reason it's harder to drive lower impedance loads. The lower the impedance of the speaker, the more stress on the output transistors. Before protection circuits became common it was very easy to destroy an amplifier by shorting the speaker wires together while the amplifier was playing. Better designed amplifiers will normally have more output transistors in parallel, heftier heat sinks and better power supplies.
Most Manufacturers say, you can run an 8ohm speaker on a 4 ohm amp but not a 4ohm speaker on an 8 ohm amp. Did I say that right? Did they change that, I haven’t bought a speaker in a few years. I know this probably doesn’t help any more than any other comment but me, I think that if I wanted to learn electronic engineering from somebody, I’d want that some body to be Paul. The coolest teacher in the Electronic Audiophile World. Thanks Paul!
You said it right, although today it's hard to find integrated or power amps that are only designed to handle 8 ohm loads. Some receivers may be challenged by 4 ohms.
Depends if the amp is limited in the voltage or current it can put out. If it's limited by the voltage, power capabilty will go up with lower impedance, if it's limited by current, power capability will go down with lower impedance. Higher current requires beefier components, and higher current usually means more heat and more loss so it's less power efficient. Higher voltage only requires better electrical insulation.
A lot of this depends on the internal design of the amplifier. ALL Audio amps are designed around Q-point and something called an SOA (Safe Operating Area). Most linear (class AB/B amps) audio amps have their Q-point between 6 and 8 ohms. Now these amps also come in two basic flavors, bi-polar and MOSFET. In the case of Bi-polar amps, when the impedance drops low (approaches 4 ohms) the amp will run hotter and will have to adjust its internal bias circuits dynamically or "thermal runaway" will occur and the amp may "self destruct". Bipolar transistors conduct more with increase in temperature. MOSFET amps, on the other hand, become more resistive as the internal component temperature increases (ie. the load impedance decreases). So MOSFET (and class D amps) amps seem to "tolerate" low impedance loads better than conventional bi-polars. The exception to this are amps that have several "speaker taps" marked 4,8 (and sometimes 16). These amps (like the MacIntosh) are using output transformers and are designed for this. Other (newer) class D-amps are "optimized" around 3 ohms and like to be run between 60-80% of full power at that load ! However very few (if any) amps are stable if/when the speaker impedance drops to around 1ohm at high power. In either case the stability and reliability of any amp can be improved using an internal or external fan when driving low impedance loads at high power.
BJTs have SOA limitations. MOSFETs do not. BJT output stages need careful bias design which tracks the output-device temperatures, regardless of load impedance. This is not only a low-impedance issue. Amplifier instability, if it occurs for example at 1 ohm load, is not solved by adding a fan.
Is it analogous to using gears on a bicycle? A low gear choice on a flat surface initially takes less energy but actually puts a much greater strain on the "engine" if you're trying to go fast. A higher gear may be harder initially but at faster speeds is much easier on the "engine". So with an amp, getting greater volume (speed) is much easier on that amp with a higher impedance (gear ratio) than with a low impedance circuit/speaker. Is that kinda correct?
It's obvious that this is one of the most difficult concepts in the entire "world of audio" to both properly explain and for most people to grasp. All you have do is read though the comments below and that becomes abundantly clear. A lot of different factors feed into this concept and that's largely what makes it so difficult to convey and to understand. I get the feeling that you could probably teach an entire college-level course on just this one subject alone.
Something that is connected in parallel with something like a battery or amplifier then we want to have resistance otherwise it will be short-circuited. In a series cable that supplies volt we want to have as little resistance as possible so that there is no voltage loss at the other end of the line
Is the proposition always true though? There are some amplifiers like the one in this question for which the power does double with halving of impedance, in keeping with the theory. There are also amplifiers (easy to find example is Rega Brio) for which the power does not double with halving of impedance (I am guessing due to thermal considerations, semiconductor current capability limitations, etc). Can someone clarify if this rule of thumb of lower impedance=harder to drive, applies to both these kinds of amp specifications?
I see it more like when playing at a certain level (voltage output of the amplifier) is like going at a certain speed in a car. Speakers are a load on the amplifier, just like weight in the car. Even small cars can go 60 mph with a person in it. The same can a truck. If you load the small car with lots of weight it might not be able to go at 60 mph anymore. It might even break down, but the truck will still go. A slender amplifier might play at 100 watt/8ohm (28volt) but it takes a strong amplifier to deliver the 28 volt into 1 ohm (28 ampere = 800 watt)
It all comes down to Ohm's Law. Very basic algebra. Google the equations. You have two known values to compute the third unknown. If I have an 8 ohm speaker and put 10 volts into it, it will draw 1.25 amps or 12.5 watts. If I put 10 volts into a 4 ohm speaker it will draw 2.5 amps or 25 watts. So with a four ohm speaker I can get the same output power with half the audio voltage than at 8 ohms, but need twice the current. This was an advantage to use 4 ohm speakers with car stereos before the age of cheap DC/DC converters. You have say 100 amps but only 12 volts to work with. Of course in both cases the amplifier must be able to supply the voltage and current for the desired output power. A disadvantage to 4 ohms is you need a heavier wire gauge for the same power at 8 ohms so with 8 ohms you can have longer speaker wires with less resistance loss. Yes, impedance is not identical to resistance but for this simple example they are interchangeable.
I'm at 3:30, I think what you are trying to compare is sound output vs efficiency of power. High power output is a engine on nitro methane vs a efficient geo giving little bits of power at a time.
Then what is beat for Amps 4 ohm or 6 ohms or 8 ohms, plus Goldenear and Martin Login speakers can go from 4-8 ohms it's like varialbe ohms (400watts) across the 4-8 ohms on speakers very confusing to me
Thanks for the video that actually helps me understand a bit more. I have a Denon AVR for my home theater. I’m running 4ohm speakers and it works great and plenty of volume for everything. I don’t recall what setting it was but Its some kind of safe mode so it won’t try and push too much and fry my receiver.
Some amplifiers, and some speakers, have a switch, perhaps rotary, to select impedance. Look! Read the manual! Ask! If in doubt, you can put two, or even three speakers (if you have a powerful amp) for each channel, in SERIES. NOT Parallel! Check carefully. This will ADD their impedances, and unless you desire hearing impairment (not recommended!) this should work, fine. If the speakers are not the same, by the same manufacturer, or check this anyway, check for phasing. Years ago, I made a reel tape of the single: "Autobahn" by Kraftwerk, so in mono. Thie begins with low bass. Or, any low frequency source. (Eric Burdon & The Animals: "It's My Life" or "We Gotta Get Outta This Place" should also be good, and not boring! Hope I'm not 'dating' myself, too much!). Since I was in an auditorium, I'd put the speakers onto the stage, butted up to each other, side by side. In series, or in stereo. At first, polarity doesn't matter - you'll hear the difference! If the speakers are In phase, you'll hear lots of bass, & good sound. If out of phase, there will be NO bass, & if you turn up the volume a bit. there will be a raspy sound like a really big guy farting right into your face! (Hopefully sans any smell!) Just change the wire polarity on ONE speaker, & listen again. Should be fine, a quick, easy check. There are graphs of speaker impedance per frequencey. On the low end, with a nominally rated 4 or 8 ohm rated speaker, the actual load that the speaker will present to the amp, can drop to around 2 to 2 and a half ohms. For a speaker with a sizable woofer, a lot of the power will go to this section, anyway. This is one reason why placing speakers in series will not hurt.
Thank you Paul. So what is better? I have Infinity RS.... speakers that are 4 ohms. Was it just a way for the speaker makers to make "high power" speakers while just dumping off the waste power on the Amp? I mean what is the point of having a 200 watt speaker if its just dumping most of that power back in the Amp (pass through) because it's 4 ohms? Why not make a speaker that is like 32 ohms that would use all the power? Now I also see why I killed a lot of receivers when I was younger. It was all that damn pass through power going back into them. I think in this day and age the next biggest breakthrough should be a way to re-use that power that is just going to ground.
Low impedance speakers don't dissipate any more power back into the amp, than high impedance speakers do. But it is true that for linear (non-switching) amplifiers, the power dissipated into its heat sinks is higher with a lower-impedance load, at the same power level. However that is only an efficiency concern, and it is addressed well with class G and H designs.
Hi Paul - I really appreciate all your good advice. Recently I've purchased a Yamaha as-501 integrated amplifier (85-rms/channel @ 8-ohms) - resulting in the depletion of my very limited finances. Now I don't have the means to buy matching Yamaha speakers. But I have a pair of Pioneer ts-6997 car speakers in wooden enclosures ( 4-ohms, 150-rms/each ). Please let me know if I can use them without causing any damage ? The as-501 Amp has an Impedance Selector switch - Should I set it to 4--8 ohms, or should I leave it at 8-ohms ?
I liked the dissertation actually. Paul you did good! You get some very fascinating questions to answer. I mean I knew this on basic form. You had a ball answering this and that was fun LOL LOL...
When it comes to impedance, that is based on DC resistance as a constant and inductance reactance AC component at a chosen resonant frequency/ overall band pass frequency, (vector analysis). Just off the top of my head, many things could determine the reasons why a speaker is not handling better at a higher impedance. It could be a weaker magnet, and the gap is wider (to handle more wattage), the wire is thinner for the voice coil, or the cone or voice coil for the woofer is thicker and larger which makes it heavier. If it's a two way system it can have a lot more boost, if it's a three way, you have a mid-range which would actually bring the mids out more but shunts the amp more if the setting on the speaker is set to full mid-range. It depends!! I've got some old pioneer speakers from 1971: CS 77s, 65 watt, 8 ohm, 4 way system. I tied the two together in series as a center channel for my Sony 5.1 surround sound, which the amp says it produces 145 watts at 1 k hz. Overall it's 90 watts at 20-20,000 hz per channel at 6 ohms. Since the pioneer speakers are rated 65 watts per spkr.. Which in series calculated at 130 watts handling, but at 16 ohms, which would actually be a little more handling power...which, I haven't calculated it...but of course it's a four way system which handles wattage well. I have cranked it up full volume, no distortion, and the clarity is superb. I always use a slightly lower wattage speaker system for a higher wattage amplifier, it just works better. I have Dayton audio towers for my two front. They are 6 ohm per spkr, 145 peak and 90 rms. I was surprised the capabilities they have, they shake the whole house. For the rear some old Sony SS-RG 444, 6 ohm, speakers. they handle allot more power than my system produces actually, but they're fine for now. I built my sub woofer from an old cabinet that goes in a car, two 15's in the cab, I'm using a Powermax DC 12 volt supply to power my amp, a old Car amp, 250 watt Mosfet stereo amp by Road Gear, bridged, spkrs in series, 4 into 8 ohms. It is TOO much BASS for the house, example, a movie explosion, is an EXPLOSION under my feet.... I don't have termites, rats or mice anymore. I'll shut up now lol. LMBO. I Enjoyed the video thanks! :)
Think of it this way… The amplifier rated for 100 watts into 8 ohms is like a top fuel dragster racing down the 1/4 mile with the parachute deployed the entire time. The same amplifier producing 200 watts into 4 ohms is like the top fuel dragster racing down the 1/4 mile with no parachute or brakes whatsoever. A speaker(the dragster) with a lower impedance is going to ask for more fuel and power than the amplifier(the engine) is capable of producing without running the risk of overheating.
I'm surprised that Paul didn't mention speaker sensitivity. This is also important. I'm sure that he & his designers keep this in mind, when they engineer their speakers for the best sound, in their price ranges. If you're worried about too low speaker impedance, please see my reply to Dan Donna, below. Regardless of impedance, when a speaker is efficient, less power is needed for a certain 'loudness' (S P L - Sound Pressure Level, the end result, assuming acceptable fidelity.)
My integrated stereo amplifier has a switch in the back to set either at 4 ohm or 8 ohm. I wonder which is the correct setting for driving speakers that are rated at 6 ohm?
@@bigpapa12 I don't think the Audioholics advice here is universally sound. They are advising to NEVER move the selector switch to the 4-ohm position. In the Yamaha example they included in the table, power at 8 ohms is 155W, and power at 4 ohms is 144W with the selector in the 4 ohm position. For that amplifier, I definitely recommend using the selector switch as labeled, for 4 ohm speakers. In the Denon example, there seems to be something seriously amiss with the amplifier, as it's losing 80% of its power capability into 8 ohms, if the selector switch is moved to the 4 ohm setting. It shouldn't lose more than 50%.
200w at 8ohms is tighter than 200w at 1 ohm. More control at higher ohms but it’s harder to reach higher wattages. Due to the resistance. There’s always a trade off.
A good way to get the point across, is to handle a DC permanent-magnet servo motor, being used as a generator with various loads. When there is little or no load on the generator, the shaft turns easily. But put a low resistance load on it (or worst-case short circuit) and it becomes much harder to turn the shaft at the same speed. Many people don't understand that outputting higher current (at the same voltage) equates to more work. There is another distinction that is important: Amplifiers are voltage sources which try to maintain the same voltage regardless of the load; that is what makes power rise as load impedance decreases. If you designed an amplifier that is a current source, it would be the opposite: As load impedance rises, it needs to produce more voltage, and the power (work) increases. There are mechanical analogs which can also cause confusion. One might think of pushing shopping carts with various quality wheels so that some are easier to push than others. Obviously, the cart that is harder to push (high friction wheels) would be more work - or is it? Actually it depends on how the person pushing behaves, or what they are trying to achieve: If the pusher is trying to create the same *speed* for all carts, then they do need to work harder with the high-friction cart (analogous to the current amplifier). But if the pusher is regulating the *force* that they use against the cart (not caring about speed), then it is actually less work to push the high-friction cart because it won't move as fast (analogous to the voltage amplifier).
Maybe the concept can be more intuitively illustrated as flooring the gas pedal on a car going up hill (high impedance) and flooring the gas pedal on a car in neutral (low impedance).
The problem is that manufacturers state average impedance, so when they say a speaker is 4ohms it means it will have frequency ranges where it drops under that (3, 2 even under 1 ohm). Not that it does not happen with 8 ohm speakers, but to a smaller extent. This drop under 4 ohms is the difficult load, most amps will drive 4 ohms easily, but very few 2 ohms.
The lower the impedance goes, the nearer it gets to a short circuit and hence will want to draw more current. If and amplifier is not man enough to be able to supply the extra current deeded, it will cause the amplifier to clip. This will quickly destroy the amp. That's why speakers such as the Apogee scintillas which had a very low impedance where called amp killers and that's where amplifiers such as the big Krell class A came into there own, as they could drive down to a very low impedance and thus draw more current with out clipping.
Yes, they're kind of a nightmare! Like the old Infinity Kappa 9 that goes down to 0,5 ohm in the deepest bass with the bass on "Extended". Try do make a Class D or Class A tube-amp happy with that load.
If designed correctly, a class D amp most easily handles such loads. The class A tube amp might be happy - it's just that your ears wouldn't be happy with the result. I agree the Kappa 9's are a nightmare for amplifiers. Even in Normal mode, they drop down to about 1.2 ohms at 40Hz. In Extended mode I calculate 0.85 ohms at 36Hz to be the impedance minimum. What might be even more troublesome for some amps, is the current phase shift of about 80 degrees around 20Hz. The reason for all of this impedance ugliness, is Arnie's choice to incorporate a highly resonant LC tank circuit to boost audio output in the 30-40Hz region. It functions similarly to a step-up transformer, using high current draw to provide more voltage to the woofer. But the same boost could be accomplished in a much more amplifier-friendly manner, by using a parametric equalizer instead.
Please help me Paul, tube amplifiers ( 4-8 ohm ) able to drive whole Infinity Kappa 9 or tubes only for highs & mids? i know Infinity k9 is 0.7 ohm Someone told me tubes regardless impedance load not like SS. Thanks
The Kappa 9 low impedance point occurs at 36Hz. Tube amps are fine for the midrange/tweeter sections, but you want a good high-current amp for the woofer.
@@JRabbi-sb5bf Sure, it has output transformers with 1 ohm taps. But you can add a transformer to ANY amplifier and make it 1-ohm compatible - without spending $10K or dissipating 680W quiescent into your room.
So the amplifier provides 200w when there's less resistance *because* of the lower resistance, whereas with more resistance it will operate at 100w? That does seem counterintuitive. So then, if an 8Ω speaker draws 100w, and a 4Ω speaker draws 200w, would a 6Ω speaker draw 150w?
For a given signal and volume setting, an amplifier attempts to produce a voltage. For our example, let's say it wants to produce 24V. Using ohms law (v=ir) we have: 24 = ir If we have 8ohm speakers, we can calculate how much current the amplifier must produce to generate the 24V: 24 = 8i i = 3 amps We can multiply the volts times the amps to get the power in watts: p = iv 24×3 = 72 watts If we attempt to get the same 24V across a 4ohm speaker, we can calculate the current and power in the same way: 24 = 4i i = 6 amps 24×6 = 144W So yes, assuming the voltage stays the same, the watts increase as the impedance goes down.
I got surprised when my 2x460 watt in 2 Ohm amplifier "turned itself off" when I had the volume on around 10 o'clock and I had 2 cables to my Infinity Kappa 8 using the "Extended mode". I had the midrange/treble to speaker connection A on my amplifier and the bass to Connection B and when I played the end of song 6 on "Roger Waters - Amused To Death", when the bomb goes off, my amplifier got quiet. I later learned how difficult my Kappa 8 was for an amplifier and what the "A and B connections" on my amplifier really meant for how much more difficult it became for my amplifier but when it happened I got really surprised. I was happy that my amplifier just turned itself off anyway so that it didn't break.
Aren't you kind of sidestepping the amperage versus wattage versus available power versus demand issue? As far as the amplifier is concerned this is more of a thermal efficiency delimma. Lower impedance demands the amplifier to supply more power on a continuos basis which the amplifier will do. The result may be that the amplifier will run hotter risking thermal break down. Or the amplifier may run out of reserve power during peak demands and go into clipping. These are only two of the possibilities all which I believe include excessive distortion and an amplifier working itself to death trying to meet the demands of a load that it acknowledges, but may not be able to satisfy. To be on the safer side, an amplifier should be constructed to supply at least twice it's rated output into one-half of it's rated load capacity. IMO.
That with which we are struggling here is the concept of load, and its effect on work. The analogy I like here is rowing a boat with the oars out of the water; a great deal of effort is expended, but no work is done, i.e. the boat does not move. All work, like an amplifier driving a speaker, like a cartridge driving a phono stage, like a motor turning a platter, is done into some kind of load. A zero impedance speaker would present no load with which the amplifier could work.
It needs some concept of power, or energy transmitted to somewhere/transformed into something. When you just want to pass a signal from A to B, you do not want the energy of the signal transformed into anything on the wire. But if you pass it through a speaker, you want all of its energy to be transformed into the sound. And in electronics the power (the amount of energy transformed into something per second on an element in the circuit) is proportional to resistance/impedance. (And it is actually proportional to other things, so the resistance is not all of the story.)
Dave Micolichek parallel I think. An old gf did it to a cheap HiFi, I told her not to but she did it to rub my nose in it, it sounded OK having four speakers in 2 outlets in parallel
Do how would it sound in series? Obviously a delay between speakers but if electricity travels at the spead of light would we be able to tell in an average house with 2 speakers per room?
I walking around with this question in my head for years, en never could find the answer. Thanks PAUL, NOW I KNOW! And now yes its very logical and simple, NOW I know. It's the same way asking a direction to a in that area familiar person, Ohh that's easy, you must drive so and there. Yes EASY but ONLY if you know it, that's for everything in life (in my opinion :)
Some amplifiers can do 3 Ohm, the lower they can get the better. It is easier for the amplifier to go 8 ohm than 4 ohm. This is all you need to know. Amplifiers get hot when they go lower ohm.
Think about a river that you put a pump which pumps the water in the same direction as the water flows in. If the river flows fast, the pump obviously do not have to work (Watts) hard, i.e. there is not a lot of impedance (Low impedance) the river have to the flow of the pump. But keep in mind that the pump in this scenario that the pump is less important to the flow of the river. Thus, the pump has to work harder (More Watts required) to have the same effect on the flow of the river (I.e. it is harder for the pump to drive the river) as say a pump that you put in a slow flowing river where the pump has to do less work (Lower watts) to have the same effect.
Every Solid State amplifier design has a unique output impedance of it's own. Maximum power transfer occurs when the amps impedance matches the load impedance. Tube amps, because of the output transformers, are a match for 8 ohms usually and only 8 ohms
Resistance and Impedance are two different things, resistance based on DC circuits and impedance refers to AC circuits. This is where Ohms law is important to know, you use it a lot for a basic understanding of electronic circuits and measurements.
What I have never understood is how a speaker can be either "hard" or "easy" to drive. I have encountered some that seem easy and some that seem hard, but most are in the middle. What makes a speaker "hard" to drive? Driver compression? A crossover that wastes a lot of power? Something else? Logic says that any speaker that is "linear" should be easy to drive and should be preferable over one that isn't linear, but logic and the response of transducers don't always meet at square corners.
Hard to drive refers to the amount of AMPS that are drawn. Typically this refers to low impedance devices (speakers). The path around the circuit is less impeded, meaning more current (amps) are drawn continuously… thus a lower voltage is required to satisfy Watts law (which is only ever calculated after Ohms law spits out the numbers to use). Typically, bigger wires (and fewer winds on the coil) provide less impedance (resistance)… thus more amps not only can flow… but WILL flow. The BIG question is whether or not the Power Supply can provide the amount of AMPS at such a steady and frequent rate. So the stress is on the amplifier to provide the AMPS. Or more specifically… more stress on the amps Power Supply. Volts are easy… Amps are hard. So why go low impedance? Well you need to look up the Lorentz Force. The more current you can provide, the stronger the lorentz force. Furthermore, the current can flow more freely in a low impedance scenario, which means the more nimble the response. You see a lot of 2 Ohm speakers in subs and in car stereo. Car stereo because they have low voltage power supply (12 volt battery), but lots of AMPS available (hence those big beefy wires). You run big speakers at 2 Ohms because of the strength behind the lorentz force… allowing you to move more mass (bigger cone) which needs to move more air (mass in its own right). Or more importantly… an ability to move more mass quicker and with more fidelity. Lower impedance allows you to lift more…. but The Law of Energy Conservation demands that lifting more, requires more work. Lower impedance means less volts and more Amps. Do you have the amps to satisfy the requirements? That is going to depend on your amp.
Actually I learned ohms law in junior high school.... You don't have to be an engineer to understand the concept. Higher watt is always harder to drive. Less resistance means higher current for same voltage.
If you consider lowest impedance possible of 0 Ohms or a short circuit of the amplifier output, you can imagine how that is equivalent to when someone short circuit the mains power and a fuse breaks. Lower impedance means higher currents and at some point, unless the amplifier has a protection circuit, the transistors will heat up beyond good and potentially blow as a fuse.
No impedance = the amplifier thinking it's got a direct short across the speaker outputs and with good protection circuitry this should place the amp in a "protect" mode. Amplifiers are happier at their "rated" power say 4 or 8 ohms. In most all my systems since I care about clarity, I run mine at 4 ohms. I only ever touch on 2 ohms when it comes to subs, but as far as mids and highs, always 4, 6 or 8 ohm. Most people don't get that each ohm halving (if you will) not only doubles the power, but also doubles the THD, and that's not always a good thing. Also, don't forget about the heat that gets produced at these "low impedance" loads. I'd rather my amp run cooler, produce less noise at the cost of some power. If I want more power, I'll just get a more powerful amp, simple as that.
Why are many hifi speakers 4 ohms, and why not make as high impedance speaker as possible if it’s easier to drive? As far as I know, some headphones are 600 ohms?
It's a question of whether you want to increase power through voltage or current. Lower impedance speakers produce higher power by increasing current at the same voltage.
As a former teacher I remember one of the hardest things to do as a teacher is to explain something so incredibly obvious to someone who doesn't understand the concept AT ALL! This matter is further complicated when dealing with a topic that doesn't inherently make sense. You talk about it being easier to drive current through something that has greater resistance. THAT MAKES NO SENSE! It reminds me of times when I would tell the students that matter with a higher heat capacity retains heat longer. They would ask, "Why?" And I would say because it just does.
That seems a terse commentary. It makes perfect sense if you look at the power flowing as a function of the voltage available combined with the impedances of the output transistors in series with and in relation to the load of the speakers. If you simplify things and don't consider 2 of the 3 main variables, how could any of it make sense? You need to provide students with a complete picture and the immutable laws of physics do the rest.
@@JazzinBlues But amplifiers don't push harder when there is more resistance. This is contrary to human behavior. When we try to move something, our goal is usually to achieve a certain speed. We don't apply the same force to something that is harder to move - we naturally increase the force to compensate. Amplifiers don't do that; they use the same amount of force when the resistance increases so the result is less movement (current) and less work (power).
If it was a matter of driving a certain amount of current, then it would be harder with a higher resistance. But that's not how it works. Amplifiers don't try to drive a certain current. They output a specific voltage, then the load determines the current. At the same voltage, producing more current for the lower resistance is definitely more work! Thus harder, not easier.
The way that I look at it is that with less ohm's, the amplifier has a harder time controlling itself. The higher the ohm's, the easier it is to control its output, this would be like saying that with larger brakes on a car, the faster you can brake and vice versa.
It’s very fortunate I understand impedance VS resistance but even that I had a hard time fowling your explanation impedance and the efficiency combined they determine the requirement of drive required all power amps have low impedance stated this is determined by internal impedance of the amp circuit and it’s power supply, nothing else . As long as the speakers load impedance is above minimum stated by the amp manufacturer everything is good for the equipment not to say how well the combination works but that’s part is done now it’s acoustics and that in a very complex question
I'd put it this way: both impedance and resistance are measurements of how much a conductor or other electrical component partially blocks the physical flow of electrons, also known as current. The higher the resistance/impedance, the less current/electrons per second floor through that component. The lower the resistance/impedance, the more current/electrons per second flow through the conductor or device. In this case, electrons are glowing or of the amplifier and into our speakers. The lower the impedance, the less the speaker is partially blocking the flow of electrons. The more electrons per second that get pushed through the speakers, then we could say there is more electrical power slowing through the speaker. Is there is more power flowing through it, it will of course, be louder. In this case, more power means more watts. The problem is that the more electrons per second we flow through a component, the hotter it gets. In the case of our speaker, if we push to much power through them, they may over heat and burn up, so ideally, we match the speakers to an amplifier with a sensible amount of power so as to get the most out of them, without blowing them up. But here's the thing, the electrons are also flowing through the internal components of the amplifier. Those components can also become thermally damaged if too many electrons flow through them pretty second. They will hear up and be destroyed, in particular, the transistors. But any component has the potential to be damaged. The internal components can be quite sensitive to this kind of damage and while it may not always damage it, it can cause strain on those components. This is why higher impedances are safer than lower ones. Most high quality amplifiers have protection against this kind of damage, but even then, those amplifiers have the potential to be caught off guard by a very low impedance. So 4-8 ohms is the safest range for most amplifiers. Love love love your videos Paul!!
Just one thing wrong with your statement, just because a speaker draws more current doesn’t mean it’ll be louder, the extra current will be dissipated as heat in the voice coils. A high sensitivity 8 ohm speaker will play louder than a lower sensitivity 4 ohm speaker.
If you have two speakers with every other parameter the same, mms and qts in particular, and you connect them to the same amplifier, the lower impedance of the 4 ohm speaker will be louder then the 8ohm because the coil will have double power running through it and this 3db louder. If you start running the coil to its limits, the coil will heat up and you will run into thermal compression, which is what you are referring to. The higher temp of the coil will add to the resistance of the coil, limiting the current flow. This resistance/temperature interaction is not exactly linear though, and at lower "room temp" ranges, the coil resistance does not vary a lot. Maybe a few fractions of an ohm. However, as you get to really high temps, such as to hot to safely touch, the resistance may increase by half an ohm or more. As it approaches thermal limits it may be several ohms higher at room temperature. But as audiophiles, we don't go around pushing our speakers as hard as that, as it obviously eats into dynamics due to mechanical, thermal and electrical reasons. Just to clear something up, if you have two coils made of the same wire, but one has double the turns of wire and this double the impedance, you have more wire, and this now electrons, right? In theory, this should produce double the magnetic flux, however, with the impedance doubled, you have those electrons traveling at half the speed as the current is halved via the doubled resistance. So the advantages kinda of cancel out in terms of magnetic flux generated on a standard amplifier. There are some amplifiers that have what's called a regulated output meaning no matter the impedance, the power is the same, but these are not so common. In this case, the magnetic flux generated would be identical, assuming the coil isn't driver to high temps. Now, there are so many other reasons why different impedances can effect sensitivity that are not immediately obvious. For example, if you have two identical drivers, but one driver is 4 ohm while the other is 8ohm, the 8 ohm coil either has double the turns of wire which would double the mass, or it has half the cross section area of wire with double the turns which effects a lot which may include impedance curve, heat dissipation, fs, etc A higher impedance coil with more turns of write is also going to produce more back emf that the amplifier needs to control, and so it may sound different depending on the dampening factor of the amplifier. This may eat into its "real world" loudness, especially at the low end. Please be aware though, I am agreeing with your statement..peer commission is absolutely a real thing and can reduce the output by several db, but is only really noticeable if the coils are getting really toasty. Sensitivity can get quite complex. I do thank you for your reply though my friend ☺ I love talking about this stuff! Maybe a little too much lol
Engineer here. I think Paul did a commendable job on this one. Correct me if I’m wrong. A speakers “impedance” by industry default is measured at 1Khz, 1W constant signal. I think it’s been that way for a very long time. But except for a few speakers they are complex motor generators and the impedance varies widely by frequency and energy dissipated in the motor generator that a speaker is. In fact the speaker may go inductive at 8Khz. And the impedance may change wildly with a constant signal and heat buildup.
Therefore a custom tailored Zobel network should be applied across the speaker terminals in parallel to eliminate the impedance rise in conjunction with frequency rise!!!
@@fookingsog That needs to be done directly at the driver, i.e., after the crossover. But crossovers can be designed to work without the Zobel, as long as the designer is taking the voice coil inductance into consideration.
The motor/generator characteristics are a tame problem, compared to what some passive crossovers do. Look at the woofer network in the Infinity Kappa 9: www.infinity-classics.de/technik/manuals/Kappa_9_technical_sheet.pdf
OK....here goes. I own a mint pair of AR 3As speakers that are 4 OHM. I drive them with a new Yamaha R-N303 receiver rated at 100 WPC at 8 OHMS. When played at some high volume levels, the receiver runs very hot and then.....ALWAYS shuts off! I switched the receiver to several other I have and the same results. SHUT OFF! Very annoying. So.....I switched the ARs with my mint Large Advents rated at 8 OHMS. Slowly cranked the volume to near ear splitting levels and...NO SHUT OFF! Chassis was barely warm. Did the same thing with ALL my receivers and running the Advents, NO SHUT OFF.! So please educate me as to why it is OK to drive 4 OHM speakers with an 8 OHM power supply. In the real world, this just does not work! Dr. Z (Lou)
Paul picked the wrong location to deal with this question... he should have gone to the conference room where there is a whiteboard... he could have drawn a simple graph .. the y axis being the impedance of the driver and the horizontal x axis representing the frequency... you would have seen a curvy line that can go all over the place ...
The perspective is from the amp or from the speaker. The consumer looks at the speaker impedance being easier to push current through. But the amp is worked harder. The engineer see from the amp and the lower impedance makes the amp works harder.
With the same voltage this is true. With the same output (in SPL or current) this is not true. Then the amplifier only needs half the voltage and half the power. And there is also less stress on the driver with less voltage and less power, and that gives less power compression (and more dynamics). And yes, I'm an electrical engineer with understanding of the working of drivers.
That's what I always thought. I mean 20 watts is 20 watts right? Let's say you are feeding an 8 ohm speaker 20 watts with volume setting of say '5' on your amplifier. If you switch out the speaker for a 4 ohm speaker and keep running the amp at setting '5' on the dial, won't it now be feeding it 40 watts and the speaker will be a louder volume (+3db)? This is saying the speaker is exact same sensitivity.
@@brydon10 In my opinion that's true, theoretical ánd practical. So with drivers with lower impedance you need less voltage and less power (theoretically). But if you have an impedance drop at a certain frequency the amplifier has to deliver more power at that frequency (with a normal voltage-drive amplifier, with current-drive amplifiers you need more power with impedance peaks). With a rather flat impedance curve you better have a low impedance (practically).
An Amplifier supplies both Volts And current. The current is a product of the voltage but both the voltage and the current are limited ( by the system's supply rails etc ). The high impedance load finds the limit in voltage of the amp, current is low, amplifier " idling ". ( supply rail voltage ). The low impedance finds the limit in current from the amp ( internal resistance, heat making more smoke leak etc ). The amplifiers voltage should be following the signal closely up to the supply rails ( signal not to clipping ) where the current will start to "clip" as the supply is exceeded so bad sound and massive heat ( probably all the smoke out and an unwanted loud bang ). The "perfect" amplifier has zero ohms internally, zero ohms on the speaker wires and ALL the load on the speakers ( power= voltage drop times current=current squared times impedance ) where the impedance is is where the power is dissipated. Obviously there is no such thing as a " perfect " amplifier and as the speaker impedance goes down the effect of the internal impedance goes up ( limits the current to the load but increases the power being dumped into the amps components which has to be processed by the cooling system ) So very high impedance means the amp ends up idling and very low impedance leads to BANG.
Think Paul should have stuck with the car analogy but introduced a turbo or nitrous. So car goes from 200hp to 400hp. The engine or the amp has to worked harder under that load and the engine works harder under that boost. Some amps are better than others when lowering their impedance. Some people add fans to reduce heat. I have been a firm believer of using amps at their highest impedance rating which for home speakers are normally 8 ohms. This way the amp is more on cruise control. A 200w x 2 amp 20hz-20khz +-3db at 8 ohms is normally better than an amp rated at 100 x 2 at 8 ohms and 200 x 2 at 4 ohms. Not too many home stereo amps go to 2 ohms. Car stereo is different. Car amps can do better at low impedance.
Well Mike I think I can tell you all about it back in the mid to late eighties when I took my dc measurements ac measurements and ac+dc measurements classes this was the prerequisites for just about anything from the phone co cable or electrical I was looking at becoming an electrician back then no RU-vid I had a stereo review magazine and I was looking at surround sound receivers and onkyo had a model that was very impressive that delivered something incredible like 1000 watts into one ohm before it clipped it may have been 2 ohms but ok I bought one it was actually a bigger model that was 110 watts per channel to the front left and right and they all dropped down when you turned on surround but the front two In stereo could drive 6 ohms and rated at 110w into 8 so this is the same thing that ran 1000watts before clipping into 2 ohms cerwin vega makes a pair called VS 120 or VS 150 vs was for velocity sensitive their sensitivity was 98db and I liked the sound of the 120 better than the 15s but the real selling point was that are 4 ohm speakers and that brighter like an incandescent lamp is in a dimmer only these speakers are taking this dimmer and making it more than twice as loud as this receiver can drive 8 ohm speakers. I do look at things quite a bit different now .. I have a GAINCELL/DAC and 3m700monoblocks now with 3 elacs a marantz av7706 for HT just got a SACD transport all of my old way of looking at impedance was they are brighter lamps
I looked for understanding this question from multiple angles. Speaker design is one, amplifer design another and also crossovers. So using sound as an example i determined what frequency and sensitivity each combination had. It's complicated but in the end it's all in the way; it sounds. So, a higher impedance speaker won't sound as loud as a low impedance speaker because of the speakers sensitivity. I really don't know what's going on inside the speaker or amplifier. check out this example: ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-DNfpYncOQRc.html
First thing to understand is speaker impedance is not static. It varies with frequency and design of the speaker. Second 8 ohms is the easiest impedance for speakers to drive. As the impedance lowers it requires more current from the amplifier. Better designed amplifiers should be able to drive lower impedances. These are amplifiers with larger better regulated power supplies and discreet output stages. Where it becomes a issue is with many of the receiver's on the market today. Especially the cheaper made receivers. Many of these cheaper receivers use cheap and poor power supplies AND IC on the output stages. These IC output stages do a poor job of dissipating heat and delivering high amounts of current. So if you try and ask these receivers to drive lower impedance loads they can either go into thermal shut down OR go completely unstable and damage the output stages of the amplifier. So it is very important to choose a amplifier that can drive the speakers you choose both electrically and complement them sonically. I have seen receivers literally go up in flames trying to drive speakers that presented to difficult a load on the amplifier.
@@kokofun1 no. It is not the same way with headphones. I only have 600 ohm headphones. 600 ohms is much harder to drive than a 80ohm headphone. O cant explain to u how it works, bec i forgot. Just search it up. It its like the other way around with headphones. Lets say headphone amps, i got a very powerful amp , cost about 1500$ ... It can deliver 3 watts. Thats alooot with headphones. Its something about current instead of watts with headphones. Sorry for the poor English
Even though my receiver (Pioneer SX 1250) is rated to drive 4 ohm speakers, I prefer to run 8 ohm speakers for just that reason. The lower the ohms, the closer you get to a dead short. If a person wants more sound, buy a bigger amp.
The amount of power you can run through a speaker is set by the relation of the speaker's impedance to available voltage so if you have less voltage available, you need lower impedance to get more power thus the 4Ω output standard for 12V powered amplifiers while home audio typically runs on considerably higher voltages. There are many reasons for shifting from 8Ω to 6Ω. Dropping speaker impedance by 25% allows for more power dissipation from the same output voltage, and it allows for larger magnet wire to be used or for smaller geometries to be employed. If your drivers are less efficient, running more current through them may bring their specification up to matching the sound output of a more efficient driver at 8Ω.
Speaker resistance (impedance) varies with frequency, so the number is _nominal_ (arbitrary). Most speakers have been nominated as 8 ohms because that's the impedance "expected" by the average amp. Some amps become unstable when driving an unusually low resistance. Unless you possess speakers that dip to an exceptionally low resistance, or an amplifier that's exceptionally unstable into low resistances, it's not something to worry about. Most amplifiers are stable in regard to speaker impedance. Back in the olden days of vacuum tech, most speakers were rated at 16 ohms, but 8 and 4 were also around. It didn't matter much since the amp invariably had a transformer, frequently with taps for 4, 8 and 16 ohms. In the early days of solid state 32 ohm speakers were often used in pocket transistor radios.
Larger Mass Motor structure of the surround, speaker cone, voice coil & Spider in addition to the compliance/stiffness of the movement structure helps to determine the current necessary (OOMPH!) to move that mass!!!
fookingsoc so low eficency speakers is desirable for bass? just seeing a lot bass guitar speakers 16ohm 32ohm... i cant see such tendencies in sub box choices... just refering to that point. its a ... listen what paul is saying ;) Your point is a equasion of components that determine your choice, but i say if you cant explain it simply enough you dont understand it...
Gareth Smith nop... its a basic question to understand it... car audio uses 12v but it gets boosted to much higer / for the amp. that uses 2ohm sub. So why isnt used 16ohm .. why its that way... & i look its 85db eficient at best at 1w.. It just buffles my mind. Am i stupid or its for us to use more power . for noneficient speakers that will heat up the circuit ... So in sence it will ware up quicker. Am i rigth? Than wy we dont make 16ohm more eficient speakers & 16ohm amps for car audio ( for example ) Its awayability issue... money issue ... or just simply stupidity for the sake of tradition, we do this way and we will keep doing it... Its what i get out of it ... What Is this disscousion about? how do you get this?
I think 16 ohms is old school. Both the tweeters and midranges in my speakers are about 16 ohms. (As you might expect, they're horns - and it takes a 4 ohm woofer to keep up with them in spite of the fact they're turned down by L-pads.)
