The impedance value of a speaker is nominal, or an average if you will, and is not constant throughout the entire frequency range. Cone speakers do not tend to vary a great deal, but planar speakers do. I have a pair of Sound Lab electrostatics. They vary between 40 and 4 ohms, with a nominal rating of 8 ohms. A high current amp, in essence, automatically adjusts for the impedance swing.
"It's like freakin' magic!" Whew! I thought you said the other word. I had to listen twice more to make sure! LOL! As always, thanks for the good info, Paul. Just Ohm's law.
Answer was oversimplified and may not have addressed the concerns of the person who wrote the question. First principle to clarify, is that amplifiers are essentially voltage sources: They set the voltage, and then the load determines the current. Second principle is that no amplifier is an *ideal* voltage source, and they all have a limit on the amount of current they can output. Third principle is that for the purposes of discussion, we are assuming that the amplifier is not being driven into clipping. As long as one is not reaching the amplifier current limit, then yes, any two amplifiers driving the same music signal into the same load, will pass the same amount of current and power. But the problem that can be encountered, is that there is a plethora of methods used in amplifiers, to protect them against overcurrent. Some of them do a good job at staying "out of the way" of the music, but some schemes have unfortunate sensitivities, especially when the load becomes highly reactive. That can result in distortion caused by protection circuits, which then lowers the power output. Then of course, there are "difficult" speakers (which should never have hit the market, in my opinion) that place unreasonable demands on amplifiers. Driving such speakers at fairly high power levels will require an amplifier specifically designed to be compatible with quite low speaker impedances. Using an amplifier that's not designed for such cases, will again result in distortion and reduced power.
Great advice Paul I really enjoy your videos over the years at PS audio thanks for the advice an information you put out you're one of the best. On the RU-vid network of a lot of videos I know there are other people that are good at doing this but you are one of the best Paul some of them are kind of they talk a lot but don't know much there are some good ones but you are one of the best thank you Paul at PS audio,
That's a weak indicator, which will often lead to an incorrect conclusion. Better to look for an amplifier which is specified for 2 ohm loads, or 4 ohm bridged operation. The only accurate parameter is the overcurrent-protection threshold for the output stage, which you need to consult the schematic to find. Even then, it may not be straightforward, because the current limit usually has a voltage-dependent term to it, so the result of a comparison between two amplifiers can depend on which speaker load is considered.
Well... It does not really say anything if it's messured at the weak 1kHz, 1ch driven @ 1% (or even 10% for some) THD crap instead of the real 20 - 20.000Hz, all ch driven @ 0,0xx% THD. And many don't specify max power draw (often it's nominal instead) so it's hard to do the math to find out if it really can deliver what it says too. MANY manufactures cheat with their watt ratings. Only a few do it properly. I.e NAD messures all ch driven with 20 - 20.000Hz signal and very low THD.
I think Paul don't get it.. W=A*V You can get 50w in many ways (?…): 50w=5A*10V VS 50w=4A*12.5V That is the real question (and not that we cannot do multiplication) :D Or is there a STATIC relationship between A and V (that each change in voltage will give always a certain amount of amps on EVERY different amplifier out there)? I can understand that that is the case for a specific amplifier but between different amplifiers. That use different types of topology, number of transistors, transistors types (MOSFET, jfet, tubes and so on), amplification types (A,A/B, B, D...) and so on..
The relationship between Amps and Volts is set by the load (speaker) impedance, not by the amplifier. For a given speaker, any amplifier connected to it and producing the same voltage, will have to put out the same current. The only time you encounter a discrepancy, is if an amplifier is not capable of the voltage or current demanded of it.
@Alex Defender I haven't seen impedance curves for your Dynaudio speakers, but did note that the design uses dual cabinets with different resonant frequencies. This approach could significantly reduce the impedance variation that single-woofer systems exhibit, making them less demanding of your amplifier. Given that, I would suggest that you select amplifier type according to the kind of amp sound you prefer, not by voltage/current considerations. Speakers that are 4 ohm with a 150W rating like yours are readily driven by any quality amplifier.
Hello Paul. As you stated in your case of 1000 death, you need to include death rate. The number of deaths ÷ the total number of diagnosis cases. The current rate is 4%. As we test more people and screen more positive cases the death rate will further decrease. Similar to the flu, we need to protect the elderly and immune compromise people. KD Pharm.D/ MBA
While the explanation is a little convoluted, the essence of it is correct. Might be helpful with some illustrations on a board or something. But it's quite simple, it's all Ohm's law. You have 8 ohms, you have 10 volts, then it needs 1.25 amps to reach 10 volts, which then is 12.5 watts. A 275 watts speaker at 4 ohms will have 33 volts at 8.3 amps when it's playing at full load. These figures are calculated for DC, so for an AC signal it will differ slightly but they are in the ballpark. This means that there's no such thing as "speaker A likes an amp with more current than speaker B", if they are both at the same impedance. The only factor would be if amp A has a weaker design and may not be able to drive high enough peak power, compared to another amp rated for the same output power, but this would only apply when playing at full load at very high sound levels, at lower volume this wouldn't be a factor anymore.
So any amp that fails to deliver double the wattage at half the impedance is current limited, at least down to the minimum impedance of the speaker being driven. Unfortunately, amplifier manufacturers rarely specify power output below 4 ohms. It is not uncommon for speaker impedance to drop well below 4 ohms for a portion of the audio band.
Makes me think of many nights in the lab in school trying to get the program to work. The top part with the variables, the body of the program and the end portion with the output. Still not sure why we weren't given a more useful language to learn on besides fortran 77 and 90 and pascal lol. Easier than c plus language for beginners lol. Thanks paul!
Hi Paul as usual is the glass half-full or is the glass half empty?? You remind me of my grandfather with Alzheimer's lol never did get to the question and answer it in a straight up fashion.lol
Hey Paul, good to see that you, your family and the company are in good Health. We here in the Netherlands are anxiuos following the American outbreaks of COVID-19. Stay put and follow the rules of distancing, venting and lowlevel contacts and we maybe seeing eachother next year. All good wishes and prosparity from the Netherlands, Bram
Whatever happened to Nyquist complex impedance plots? At one point years ago they were commonplace, whereas now one rarely encounters such a measurement. There's so much information that can be gleaned from such a measurement, especially in this context of explaining how a more robust high current amplifier design interacts with a difficult load.
There are still some reviewers who compile *Bode* impedance magnitude & phase plots, if it's just the speaker information you are looking for. Beyond that, there is the Nyquist stability criterion (NSC), which uses a complex-plane trace of the open-loop forward transfer function (with load), multiplied by the feedback transfer function. The criterion states that the system will be stable with feedback connected, if there is no net clockwise encirclement of the s = - 1 point. It is a much more robust method of ensuring stability, than using the simple gain and phase margin rules. However, I haven't seen anyone use or even mention NSC since I graduated from the electrical engineering dept.
Hi Paul, love the videos. P = I x V is pretty clear, but the whole speaker resistance business needs to be explained properly. Does this have to do with two resistors being a voltage divider? If so, if the speaker is one of those resistors, what is the other? Resistor in volume control? Output resistance of amp? Does it then matter what output resistance the amp has? The speaker 8 ohm vs. speaker 4 ohm doubling of required current only works if the other resistor is of fixed value, which seems doubtful across all amps ever produced Or, is does it have to do with Ohm's law V = I x R? If an amp output is current-regulated (as opposed to voltage regulated), then with same current and half speaker resistance one gets half voltage. And if voltage = loudness, then that explains different sound level produced by speakers of different resistance. Would love to some clarity on this.
@behexen250 The frequency dependent speaker impedance is something additional. My main question is how the doubling of power requirement of speakers with nominal 4 vs 8 Ohm is explained. Either with voltage splitter between two resistors in series, or with ohm's law and single resistor. Still not clear on that. P = I x V does not explain it.
Amplifiers are voltage sources, i.e., yes, the output is voltage-regulated. This remains true as long as you don't try to pull *too much* current from the output, and the amplifier will keep putting out the same voltage for a range of loads. The equivalent resistance of a typical solid state amplifier output is extremely small and can be neglected, as long as you don't demand excessive current from it. So the equation P = V^2 / Z is most appropriate to understand how power varies with speaker impedance. You can treat V as constant, then P varies inversely with Z. That is assuming that you have chosen a V that is within the amplifier's ability for all of the values of Z you want to use, and again, that you're not trying to pull more current than the amp's limit. But for all real amplifiers, the voltage clipping point will decrease as load impedance is decreased. That is why the max power rating of the amplifier doesn't quite go up with 1/Z. Max power ratings reflect other internal limitations of amplifiers, which you don't see the effect of when using them below max rated power.
An amp's current capability may be a factor when you start driving it to loud volumes, an amp with larger power supply will have less vdroop, and also amplifiers with higher damping may have slightly higher impedance to the same speaker due to more rise.
Power is energy per time. One Joule of energy per second is 1 Watt. Like you eat to make energy to move your body, a speaker needs energy to move the speaker cones. Approx. 100 Watts is what your body needs to stay alive. A Bic Mac has approx 2,300,000 Joules and can run your body or a food powered 100W amp for (2,300,000/3600)/100=about 6 hours.
A body power dissipation of 100W average, equates to 2000 cal/day diet, which includes some physical activity. Basal metabolism is only around 70-80W typically, but it varies with both weight and age. My little 70-year-old 100lb friend probably dissipates no more than 50W at rest, while a 25-year-old weightlifter in training might need to consume 5000 cal per day to maintain weight (250W average). I like the idea of a food-powered amp. Much better use of a Big Mac, than eating it - but also much more expensive than the electricity, of course.
Marianne Oelund Yes, 100 Watts is just an easy typical human body power consumption number to remember and sort of in audio amplifier territory. Yes, if you could make a power plant turning the chemical energy of Big Macs into electricity with 100% efficiency, your electricity would end up being expensive. One Big Mac contains approx 0.6kWh of electricity and you might pay less than 10 cents for that wherever you live. A Big Mac is perhaps 40 times more expensive so even using junk food for feeding your food powered audio amp is not good economics 🤔
I love these videos from PS audio, I used to love to read the comments, but lately I notice if Paul says anything about staying safe it turns into a political discussion. What the f*** people. The people that say nobody's dying have no idea what's going on. I'm not going to blame anybody, personally I'm not a fan of Donald Trump but blaming him isn't going to help anything . Stay safe and try and remember that we're all Americans. Great job as always Paul, keep doing what you always do. all love to you people from overseas who are having an easier time with this than the US.
If you're playing music that's not highly compressed, and you are avoiding clipping, the speakers will be fine. You should be more concerned about your ears, if playing such a system in a modest sized room. Even if running continuous sinusoidal test signals through the amplifier (woofer frequency range, of course), it can only exceed the speaker current rating by 29%, so it would take a while to damage the speaker. But how large of an amplifier is safe to use, is a complex topic. Of course it depends on the kind of music and how it was recorded/produced. One of these days I will do a study of some recordings, to see what the typical power crest factors are, and look at power spectral distribution (PSD) as well. Then I could also look at the impact of clipping on PSD, and . . . There is probably no end to the investigations that could be done. Good thing I'm retired now.
I have an NAD amp whose specifications are 150 watts into both 8 ohms and 4 ohms. Is there something that would explain this without concluding that it is underpowered into a 4 ohm load?
It's a very generic claim, not an engineering specification. The takeaway is the amp should be able to drive 4 ohm speakers and not blow up. Having said that, I just sold an NAD 326BEE because it really did not like my Magnepans (kept triggering the protection circuit). Weird because all kinds of people use NAD and Magnepan. Brought NAD to a repair shop no problem found. So, traded the NAD for an Outlaw RR2150 and it seems to be a good match, ;-)
I presume you are talking about the C275BEE? If so, this amplifier has two different internal supply (Vcc/Vss) voltages that it can switch between. The automatic control over that switching is a bit complex, so without spending an inordinate amount of time to analyze it, it appears that in the case of the higher currents involved with 4 ohm loads, it will only select the lower supply voltage. In other words, the fact that continuous rated power is still 150W at 4 ohms, is a very intentional part of the design, rather than an unintended effect of any design weaknesses. Another important aspect of this amplifier design, is that it has much higher dynamic power capability for music transients. That is 410W into 4 ohms or 600W into 2 ohms. The lower numbers are for continuous output, so do not give a fair indication of the amplifier's capabilities for music programming (unless you're listening to severely compressed/limited music). If you want any more detail than that, I could spend more time looking into the circuit design.
@behexen250 It's bridgeable, but in that configuration is only spec'd for continuous power into 8 ohms, 330W. The 4 ohm power rating is for normal stereo operation, and is for *continuous* output. The amplifier is capable of much higher power into 4 ohms (>410W) and even more into 2 ohms (>600W), but only short-term, i.e., not continuous. In other words, its design is oriented toward typical music signals, not lab test signals.
i make the best of it. listening to music and thinking about which speakers will be built next. better ones for the 1000€ zyklob-II sub, bluetooth center speaker, wall center speaker, bookshelf or studio/near fields..so much to choose from :)
If you only had a cave in your backyard... I’m sure you’d rock a lecture about its acoustics LOL But seriously, you’ve got a beautiful garden there. However, that cave-thing could be interesting. There’s that Balve Cave in Germany, where they play different kinds of live music on a regular basis. I’ve never been there but I wonder what it sounds like. It must be unique, I’d say.
It helps to look for a power rating messured at 20 - 20.000Hz, all ch driven with 0,0xx% THD. Too many manufactures messure at only 1kHz, 1 ch driven @ 1% (or even as high as 10%) THD.. That gives ALOT higher numbers on paper but in reality it's only 2/3 or maybe even 1/2 of the power. And check how big the power supply is so you can do the math and see if it even can be capable of delivering enough power to get the rated wattage out to the speakers. But to do that you also need to know ho efficient the amp is.. If it's a class A, A/B, D etc..
Hi Paul Quick question: will I hear an appreciable difference in SQ listening to a 450 watt vs 1200 watt amp at the exact same volume level on the preamp? Everything remains the same except for the amps.
Depends on the amps but generally, yes. If you're system is resolving, if the music you're playing is dynamic, then generally speaking, the increase in headroom plus (and this is important) the increase in linearity (of using less of what's there) will be evident in playback.
Not that simple. Sources with over-current protection will put out very little power into a load that's equal to their Zout, before shutting down or limiting the current.
@@PebblesChan Fortunately for the world, Moritz didn't have modern audio amplifiers or regulated power supplies with current limiting to fuss over. Otherwise we would never have had such a simple and elegant statement. But you need to know more than the rules - you also need to know when they do, or do not, apply. R(source) is not a constant in many cases. But to be a bit more helpful, here is a modified rule which can be used for real amplifiers: Max power transfer can be achieved when R(load) = Vpeak(source)/Imax(source), where Vpeak is the clipping point while output current is at Imax.
While the equation is true speaker impedance varies quire a lot making it impossible to match impedance ,also in order to deliver a lot of current to low impedance speakers the amplifier must have a low output impedance.
Yes ! You are right, Paul. We are not out of the woods yet. Currently, I’m living in Taiwan, one of the safest places-if not the safest place-in the world to live during this pandemic. Still, I know that the war against COVID-19 has only begun. We’ll be lucky enough to have our lives return to normal before 2021 is over. If not careful, we could either become a victim or an accomplice of the virus.
How to I find out what power my amp is capable to support at 8 and 4 ohm if I have no documentation Yes please stay safe. Our planet needs good people like you who share knowledge
Why does Adcom claim high current in their amps such as the older 5800, 5802 etc. but the spec sheets only rate the amps at 50% more power into 4 ohm loads over 8 ohm loads. This doesn't seem to indicate any more current than traditionally available from solid state amps. Every high current amp I've owned almost doubled (on paper did double) the power into 4 ohms and some again into 2 and 1 ohm loads. What gives?
The real question is, why do most amplifiers that claim such high power at 2 ohms or 1 ohm, not have the power transformer VA rating, or line fuse rating, or max power consumption (UL) rating, to provide anywhere near that power? I consider it remotely likely that they've invented any kind of over-unity power conversion technology. If you really want to find a "high current" amp, then shouldn't those be the numbers to go by? The Adcom 5800 is rated 250W/ch into 8 ohms and 400W/ch into 4 ohms, but the latter is nowhere near the amp's current limit of 22A peak. Keep in mind the spec sheet rating is for the same level of distortion, so at 4 ohms it probably has some headroom and I wouldn't be surprised if it can deliver >450W into 4 ohms at the threshold of clipping. Ultimate power capability would be about 600W into a 2.5 ohm load.
Yes you re confused and don't they teach how to spell impedance in engineering classes anymore? My point was any true high current bridgeable amp should quadruple it's stereo rating. A high current amp will double it's rated stereo power into 4 ohms and come close into 2 ohms. Any less than this and it's only average in current delivery. I have true high current amps that double down into 1 and even 1/2 ohm loads.
22 amps peak is not high current at all. High current amps typically have greater than 50 amps peak in that power class. Transformer size alone isn't an indication of ability to work into low impedances. I have an amp with a 3.3kva transformer that is not 2 ohm stable.
2dB of headroom is typical in an amp and only an indication of how loose the power supply operates. Some amps have a stiffly relegated power supply and will have much less headroom yet can have massive current. The two have absolutely nothing to do with each other. FYI you abbreviated decibel incorrectly. It's named after a person so the B is capitalized but not the d. Are you sure you're an engineer?
Nice to hear an American speak reason for once 👏 what is the problem with wearing a mask ? why people politicizing it?! as it is said do your bit duty for your Countryman just by wearing a mask and extra hygiene not too much to ask. !! America going to be hardest the longest hit because of political foollery and selfishness. Yes but why an amp of less wattage can drive a hard load better then higher wattage amp if it go by your theory?
My nephew and niece work in the COVID19 Ward in their hospitals, here in So Cal. Paul, You are correct; it is BAD out there; people are dying. *Donald* *TRUMP'S* *APOLOGISTS* are blindly following their Handlers (Fox "news" Rush Limbo Sean Hannity Laura Ingrown, et al) in order quell their doubts because they are finally realizing that their "EMPEROR (Trump) HAS NO CLOTHES". "There is no one so blind as he/she who refuses to *LOOOOK!"*
@Larry Niles it is shameful by Republican leadership to push this ridiculous negative and trump himself of not wearing masks, how does it make any sense?? its not taking away your freedom but by not wearing your mask you could be taken away somebody else's freedom to live
John sweda vendors rate their amps themselves. How much the signal fails at X watts is measured in THD and there’s no standard which THD it must be measured it. THD ~= problems with the audio. A shitty manufacturer could rate a device like 400W even if it barely can produce listenable audio at 100W, very rough THD. It’s kind of producing a signal at those levels, but it uncontrolled and probably peaking instead of getting the correct current. It’s like saying a car can drive 400km/h when it barely can do it theoretically, much less stay on the road in the real world. Between same manufacturer (or manufacturers measuring in the same way) you’d expect the 50W amp be less able to drive hard loads than the 100W version, because you’d expect them to be measured at same THD. The 100W version you’d then expect be able to be able to handle roughly twice as hard load as the 50W version. You could for example play the same speaker twice as loud (increase the voltage) or switch to a speaker that’s half the resistance (ohm) with the amp that is rated double.
John, there are plenty of Americans who can think for themselves and make wise choices, regardless of the prevailing political banter. Of course, there are also plenty of Americans who think that easing of lockdown restrictions means they can pile into crowded bars without risk of becoming ill. They are now finding out otherwise. Eventually, careless people will learn from experience and start protecting themselves.
I have seen and noticed with some brands of speaker with variable ohms in the specs sample 300 watts but compatible with 8 ohms what the hack does this mean??
Mr. Paul. don´t be afraid, A lie don´t stand in front of Truth. More sooner than later, we all will see what is really the Truth. nice video and thanks as usual. greetings.
Rule of thumb, a beefy power supply (translating into a heavy amplifier), means ample current delivery at any situation. The power in watts, is more related to the output transistors specifications.
Does the Impedance of a speaker effect the sesitivity level of this speaker? If not, its better to go for a higher impedance speaker, right? So the Amp does not need to deliver that much current at high voltage output = Loudness. Correct?
This is always a point of confusion. If you test speakers at a fixed *power* level, then you obtain a fair and meaningful measure of its sensitivity. The standard test level is 1W. With an 8 ohm speaker, the voltage corresponding to 1W is 2.83V rms. Sometimes, speaker sensitivity is tested at 2.83V, without consideration given to the speaker impedance. If you test that way, then lower-impedance speakers would certainly seem to have a higher sensitivity, as they will draw more than 1W. There is much debate about whether testing at 1W, or testing at 2.83V, is more meaningful. The reasoning for the latter is that most amplifiers can put out more power into a lower-impedance speaker, so such speakers should receive credit for that fact. That is, they do play louder before the amplifier starts to clip.
My experience tells me that there is no relationship between impedance and sensitivity. Impedance determines the current that the transducer is "demanding". Higher impedance will pull less current. So yes the amp will be having an easier time. Is that necessarily better? No. Impedance and current don't determine sound quality in any way. Unless someone with engineering knowledge can prove me wrong. Sensitivity is basically the efficiency in dB per unit of power or voltage e.g. dB/mW or dB/V. To my ears, low efficiency speakers tend to have a more authoritative sound? Not always, just a tendency.
@@woopygoman Thank you! What drove me to this question is the comparison of two sertain Speaker chassis, the: Dayton Audio RS225P-8A and Dayton Audio RS225P-4A. Same construction, but different impedance levels - one 8 and the other 4 Ohms. specified at 2.83V/1m: 8 Ohms = 89.1 db 4 Ohms = 92.9 db So the 8 Ohms chassis draws 1 Watt at 2.83 V, the 4 Ohms chassis draws 2 Watts at 2.83 V. Is that the reason for +4 db? drawing doubble current? And can the 4 Ohms chassis play 4 db louder at maximum load? so 4 db more distance to distortion at lower levels?
@@marianneoelund2940 All right!, thank you! I understood that only voltage gives the level of loudness. thats exacly the confusion. Like I metioned in my other answer.
@@JeanKatana All other things equal, the 4 ohm version should only play 3dB louder, so I think the nearly 4dB difference is due mostly to measurement inaccuracies. Most direct-coupled solid state amplifiers can produce almost, but not quite, twice as much power into a 4 ohm load. So in reality, you might achieve 2dB headroom improvement with the 4 ohm speakers. The drawback to using 4 ohm speakers, if you care about efficiency, is that the amplifier will typically dissipate 50-60% more heat, than it would with the 8 ohm speakers at the same power level.
Lots of formulas exist for how electronics work. There are books of information more. When circuits involve capacitance, inductance, active components, non-linear components etc., things can get exponentially more complex than a simple resistor circuit. Speakers are not resistors and amps are not resistors either.
True. It ignores the reactive loading (capacitive/inductive) which varies with frequency. Voltage and current are not in perfect syncronization because the load stores energy and then feeds it back to the source on a delayed basis (reactive load).
Can you or anyone use an analogy for why you need MORE amps to maintain the voltage (volume) the LOWER the OHMS/impedance/resistance gets? I know it's correct but it sounds counterintuitive to me still. I would have thought that the higher resistance you have across a given load, the more amps/current needed to push the voltage (? or vice versa?) I still have a problem understanding this. I would think the less resistance/lower ohms, the easier electricity will flow so the less " pressure " or voltage you need to drive something like a speaker. But the reverse is true. Correct? Help!
Victor E i think you just answered your own question in the second paragraph... since when there is less resistance, i.e. counter force, it would be “harder” for the same level of electric current to mount the pressure.
@@haomeister Thanks for reply. I have tried to use highway traffic as an analogy. Does this sound correct: Low resistance- Multi lane highway allowing many cars (electrons/voltage?) to flow. But this free flow ends up in higher avg speed, requiring more gas to keep moving (current) and also heats up the pavement (wattage?) High resistance - a single lane road where much fewer cars can flow, butrequiring less gas (assuming the avg speed is slower but constant) and producing less heat (watts)? I still feel like I'm getting it wrong. 🤔
Victor E I am no expert on this topic. I use water thru pipe, with one end elevated, analogy, to help myself understanding the works of electricity. Wattage is already a time related, like speed.
I always think voltage difference is the cause for electric flow. Not sure about the relationship between loudness and voltage in audio equipment, though, as Paul mentioned in the video. Equations derived from Ohms Law show computational relationship of the three variables, and wattage. I may have contradicted myself in the above comment.
@@haomeister It's a simple ohms law equation Power in watts = the current squared times the resistance ,so if the resistance goes down the current must go up to keep the watts the same.at a given volume setting.
You have a speaker that needs more A cheap amp has 100 watts at 8 ohms, but at 4 ohms is has 100 watts. A great amp has 60 watts at 8 ohms, but will double its power at 4 ohms at 120 watts A great amp delivers more power at lower volumes. Its like a little engine outruns big car on top end, but dont pull as good as big engine.
There are many counterexamples to the claim that a "great" amp will double its max power rating at 4 ohms, relative to 8 ohms. It certainly doesn't apply to tube amps, or solid state amps with output transformers. And I wouldn't say that amps with an 8ohm/4ohm selector switch can't be "great" amps, or that amps with variable or multiple internal supplies that provide lower rails for low-impedance loads have any performance deficiencies. I think the audio community has become rather spoiled by direct-coupled SS amps that have much higher power ratings at low load impedances, to the point that they believe it's now mandatory, in order for any amplifier to be considered a high-end design.
@@marianneoelund2940 Thanks for clarifying my commment. Seems like amps are little understood compared to speakers. I have a Krell amp, & a tube pre amp, but I wished I knew what a great amp for the money is. I enjoy the cheap old NAD 3020 because of its warm tone & the cheap PSB bookshelf speakers because of it warm tone. Both were gigantic sellers. I have 2 cheap sony amps. One is harsh, seems like cheap stuff is harsh. My other cheap Sony amp makes the tweeter with a real warm sound, so I got another one exactly the same amp for a friend. Maybe there is something good in the designs that gives a warm tone. But the cheap Sony amp with a good warm tone, it looks like all cheap amps could be designed that way. Even though a cheap isnt clear, some are enjoyable to listen to. Also I have heard that a 4th order distortion is naturally great sounding for warmth That swome want to remove the distortion. An example, dolby noise reduction removes distortion & removes good sound. I have a Nakamichi receiver with a Nelson Pass circuit That is suppose to be Class A only a low volume= that sounds great. I wonder if all amps run Class A at low volume. The Nakamichi runs cool. I have heard that class D ampsarent that great. I have heard that Class G is better, but I cant find any information on class G. Im thinking of trying a class D amp for cheap speakers..
@@myronhelton4441 Strictly speaking, all Class AB amps do operate class A at low power, but sometimes that means only a fraction of a watt. Regarding Class D, keep in mind that the technology is still improving, both the switching FETs and the circuit design techniques. It's still not quite a mature design class, but some of the newest designs are quite good and the future looks bright for Class D.
David Covid 19 will not be over unless we have a vaccine. If we don't get a vaccine it will take years until it is over. It will not magically dissapear to the election in US.
@@marianneoelund2940 Hardly. Really? OMG, are you actually this petty and small? It would be helpful if you made an adult contribution that actually provides useful information.
@@marianneoelund2940 That may well be. Nonetheless, the intent of my post was to express that I like the way he boiled down the basics of the concept. In depth information I will glean from an electronics and electrical engineering manual. Not comments from punters on you tube. No thank you.
Hey Paul that's a great explanation. I hear a lot of nonsense on this topic but you pretty much nailed it. We could take it one step further to discuss how a loudspeaker is not a constant impedance but actually varies over the audio spectrum. Also the impedance is not purely resistive but it's complex. That would just confuse people though; I think you explanation is quite good. Now... Onto your explanation about masks. I'd like for you to explain how it is that a cloth mask won't protect the wearer but it protects other people. Does it function like a diode? NO! Masks don't protect the wearer and they DON'T protect anyone else either. The virus is 0.1uM in diameter and easily passes in or out of any mask you find people wearing. They don't work and there is no point in wearing one. Sure it will stop a little bit of mucus from going through if you cough or sneeze but the virus particles will go through just fine. On the other hand masks are a cesspool of your own bacteria and viruses which you then re-inhale back into your lungs if worn for any length of time. No I'm not contradicting myself here. The mask does collect some of these particles and others go through. Sound like a good time? Then wear a mask. People who have a little common sense and some critical thinking ability will see through this mask nonsense. Keep up the good work!
A thousand people a day. Shooowiee, 365,000 in a whole year is roughly 0.1% of the population of the United States. Lock your doors board up the windows and spray everything down with Lysol and don't let anybody within fifty feet of you until they have been thoroughly irradiated. But most important of all make sure to abide by your local contact tracing surveillance program.
Fat Rat I read some test showing 80% protective effectiveness. So let’s say both a person who is infected and a person who is non-infected are in close proximity using 80% masks, you have 100%-20%x20%=96% effectiveness. This is why consistent use of masks has worked well in countries like China and Korea while scattered use in the USA has totally failed.
Fat Rat Yes, not bad compared to the 130,000 deaths we got. Trump often say we have lots of infections because we do a lot of tests but these tests don’t kill people. Medical experts say the death statistics is undercounted as many die from indirect causes without getting a test, while some crackpot conspiracy makers here claim hospitals are making money out of reporting COVID 19 deaths thus the number is inflated. America lacks leadership either way. Why can’t we simply have mandatory proper traceable test for every dead person?
Stay safe.. Until you get into your car! Still the biggest danger. Car crash. I Think we need the ban cars. Or put a special masks on the cars to make everyone safe.😁 Perspective that's witty.
Talking about delivering high current from an amplifiers you need either a humongous power supply or a tracking power supply that keeps less than 10 V above ground across the transistor that is how a Sunfire amplifiers can supply enormous amounts of current and run cool and be light hometheaterhifi.com/volume_2_3/v2n3f.html .
If someone asked you to "please wear your seat belt" when you were headed off on a long drive, would you respond with "please don't try to play an expert?" SMH.
@@amitraam1270 I'm not talking about the mask thing I'm talking about the whole thing in general. It's been an absolute cluster of information. It survives On Solid Surfaces then it doesn't. 6 feet apart. This that the other thing. At some point we need to all move on. Let me guess, if a so-called doctor told you to wear a mask for five years straight you would be the one to follow them wouldn't you. At some point I use common sense. I stayed in with my family for a good two months and practiced social distancing. Think about any other disease or flu or anything else were you were instructed to wear a mask. It never happened. Why is this? It just doesn't make sense.
