What's the difference between amplifier gain and watts?
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- Опубликовано: 20 фев 2019
- Amplifiers have different wattage ratings but their gains are very similar. How can a small wattage amplifier have the same gain as a large wattage power amp? Have a question you want to ask Paul? www.psaudio.com/ask-paul/
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I'm no expert, but it seems this would have benefited greatly with the inclusion of a brief overview of Ohm's Law (fittingly). Two excerpts of this can be used to flesh out the illustrations of "40 volts into 8 ohms is 200 watts," and "40 volts into 4 ohms is 400 watts."
Two excerpts from Ohm's Law:
1. Volts = Amps x Resistance (V=IR) [for those unfamiliar, amps/amperes is the unit for electric current, often represented by an "I" in equations, and ohms is the unit for electrical resistance]
2. Power = Amps x Volts (W=IV) [for those unfamiliar, watts is the unit for power, electrical in this scenario]
Plug in the relevant units from the first illustration into the first, then second equations above:
1. 40 = I x 8, solve for I:
I = 5 amps... then,
2. W = 5 x 40, solve for W:
W = 200 watts
Plug in the relevant units from the second illustration into the first, then second equations above:
1. 40 = I x 4, solve for I:
I = 10 amps... then,
2. W = 10 x 40, solve for W:
W = 400 watts
As Paul mentioned, Gain is just a term for a simple multiplier applied to the voltage prior to plugging numbers into the equations above. As voltage is increased, the amount of current (amps) needed will increase.
The severity of increase in current (amps) will depend on the load (resistance, ohms) of the speakers; bear in mind that the resistance is a fixed value determined by the speaker's construction, and as such it is the only constant in these equations.
With both the voltage and current (amps) increasing, the power (watts) consumed by the system increases also. If your gain setting calls for more current than your amplifier can provide, you'll get clipping. And if your amplifier pulls more power than your breaker can handle, it'll trip. Let's hope for neither!
Bottom line: Never ask that question again!
Paul said it clearly, if you did not understand, please watch the video again.!!
Thank you Paul for the effort you put in making these videos.!!
Paul has really helped me understand something -the relationship between gain, ‘volume,’ and power- I thought I knew (kinda). 🙂 Thanks, Paul.
oh boy...the gain of understanding is clipping my mind...thanks Paul
My protection kicked in.
@@andysummersthxcinemaandmyc7748 you're a real classy guy, do you talk that way around your mother ???
@@andysummersthxcinemaandmyc7748 Go play in your own goddamn sand box. Don't shit in ours. Go out to Fry's for your pitiful portable picknick player to play your fuzzy warbles on.
Most systems have too much gain. One thing I keep hearing over and over: "my system plays loudly even with the volume only 1/4 way up. It therefore has a lot of power". Not correct! And this could be a bad thing for sound quality.
2.83 volts = 1W into 8ohm
(2.83)^2 / 8 = ~1
If the amp gains takes in 2.83V and gains it by 20dB, that’s 100W (10x to gain +10dB, so 100x to gain +20dB).
However, amps don’t need 2.83V, they are able to output max power with usually 1.3V to 2.0V.
If 2.0V input, with no gain that’s 0.5W into 8ohm (2^2 / 8 = 0.5), and would need a gain of:
3dB to be 1W
6dB to be 2W
9dB to be 4W
12dB to be 8W
15dB to be 16W
18dB to be 32W
21dB to be 64W
24dB to be 128W
etc.
So yes, 20dB to 30dB of gain is typical. If an amp doesn’t need as much input voltage, that means it’s internal gain must be higher to compensate.
clear as mud that paul!
Thank you; Takes me back to my engineering classes at the university.....
I actually understood that, and it makes sense! Thanks Paul!
Clear as mud
Amplifier gain is the ratio of output voltage vs input voltage. Wattage of an amplifier is the energy per time available on the output side to move your speaker cones. One Watt is one Joule per second. A 100 Watt amplifier is producing 100 Joules per second. Not actually much. The energy of a single BigMac is 2,250,000 Joules or your 100 Watt speaker power for 2,250,000/100 = 22,500 seconds or approx 6 hours of playing music at maximum! In other words, a 600 Watt amplifier produces as much power as that of eating a BigMac per hour 🤔
sorry , didn't understand one bit of what you said !!
Don't feel alone mate! That was tough one
Perfect explanation 😃 Paul is the teacher i had 😃😃
This gain is what I’ve always struggled with as I have to set these in my car. I’ve seen your earlier videos on it too and this was the best so far. Here is a funny question. If my active setup in car running on a very good 4 channel amp has a gain ‘A’ for my tweeters with 92db sensitivity and now I change to a new pair of tweeters having 96 dB sensitivity will my gain need to come down? Having everything else remain same. Hope to own a PS Audio amp one day. Thanks and regards.
"The Gain Remains the Same."
Any excuse to listen to Led Zeppelin.
very interesting so essentially what you are saying is the following. if you power amplifier can deliver 10000 watts it essentially can keep any voltage you throw at it between the terminals of the speaker. if instead your amp is a 1 watt power amp it can maintain the voltage needed to supply 1 watt of power to the speaker but not more. so if ypu put 20 volts into the power amp you will only deliver 1 watt so the voltage across the speaker is a lot less than the 20 volts that came in and the rest is noise compression. essentially the volume you hear how loud it actually gets has all to do with the voltage sent out by the preamp. correct? are lineouputs from a preamp line out supposed to carry signals of such high voltages? i thought the libeouput peak voltages rarely went above 1.7 volts
I really can't follow it (or communicate it?) by measurement. My understanding comes through playing with guitar amplifiers and overdrive pedals (not distortion pedals, to be clear). Gain, volume, headroom are mutable concepts that are best understood by playing around with them. Go to a guitar store and mess around with a combo amp. Find one with gain (sometimes called overdrive), volume, and master volume. You will then see how these elements relate and behave (if you can find an amp with an attenuator, even better). You'll be no wiser in terms of measurements, but you'll understand it.
So technically speaking turning the gain down on your amplifier should reduce output wattage correct? Just asking because I'm running a big amp at 2.67 ohms 8k and just going to turn the gain down
Thought subject to master in 5 min. Well done Paul for trying.
Hi Paul, what happened to good old V=IR, P=I(2)R and P=VI? I learned this back in high school, and it obviously stuck.
Ohm's law
The rails...reminds me of the 500v rails in my Dynaco Mk3 monoblocks.
Before I did't understand, now I am totally confused.
It will get clearer over time. Consider that another name for voltage is ‘potential.’ With the volume knob at ‘0’ there should be no voltage at the output of the amplifier. As the volume is increased, the voltage at the output of the amplifier increases. (Be careful testing this, since some ancient amps must have a load, or they will self-destruct.) Now add a speaker to the output: without any intervention from the amplifier, two things will happen (1) part of the voltage will now drop across the speaker, (2) current will flow out on the ‘hot’ wire and back on the return or ‘common.’ In this situation power is now being consumed by the load (that is, the speaker), and the voltage ‘potential’ is now being realized. The power consumed is noted in Watts (Voltage x Current, V x I).
But wait, there is more: since there is a ‘power’ amplifier in the circuit, and since there is a speaker also in the circuit, and music or other tones are being played two more things happen: (1) the speaker presents a varying load to the amplifier, and (2) the amplifier varies the amount of current delivered to the speaker terminals in order to maintain the voltage called for by the volume knob. [It does get a bit more involved in that the ‘gain’ and current levels may be a DC component setting the bias or average level which is more or less modulated by the AC signal waveform, but generally speaking the volume knob sets the voltage target the amp tries to achieve while the speaker load sets the current demand required to achieve it.] At any rate, if the amplifier is unable to supply the current required by the load to do its work, bad things start to happen: (1) the amplifier begins to clip, tops and bottoms of signal voltage are cut off because the amp is unable to produce enough current to achieve the peaks and valleys, the user hears distortion, if this situation continues long enough, things start to heat up and thermal protection circuits are triggered. If no corrective action is taken, and the situation continues, or gets worse (volume is increased further to ‘get past’ distortion, something is going to blow. The signal will start to resemble an elevated straight DC signal, the voice coil will heat up, and the amp’s fuses (if equipped) will blow, or the speaker fuses (if equipped (will blow). If neither the amp nor the speaker is equipped with fuses, the voice coil will weld itself to magnet, which will present a dead short to the output of the amplifier, where parts damage to the output stage could result before the fuse at the power supply inlet finally blows, if so equipped. Hope this explanation helps. It is really important to understand that a load will pull down a supply voltage. In weightlifting terms, most everyone can manage (has the potential) to lift 25 lbs.; not everyone can manage to lift 300 lbs., at least for very long, although it it probably true to say we could potentially do it, flow of adrenaline, etc. So, when you turn up the volume, especially into low-efficiency speakers, you are piling ever more weights on the bar; if the amp isn’t strong enough, something will buckle. With very efficient speakers, 25 Watts (or even 2) can be enough to achieve decent levels of loudness; with less efficient speakers, even 500 Watts May not be enough, or so they tell me.
No matter how well it's explained, this subject just doesn't make sense to some people.
Those of us who Do comprehend it will never understand why others can't.
Because they talk about volts and gain is displayed in DB
It just did become complicated...
Always hated db, it's unintuitive, for me at least. Basic stuff but so hard to describe simply. Good job Paul.
aren't they part of the same thing? Gain bringing up,the input signal to a usable level and the other an overall level.
Hey Paul how are you? I hope you and yours are all doing well. I have a question regarding tube amplifiers, if an amp is left on continuously although only listening to it upon arriving home how much of the tube life is diminished or is it. As I'm sure you already a tube amp usually needs warming up at least a half hour and better to sound it's best. Also which one your power conditioners or ac regenerators would you recommend without going crazy price wise say between $200-$1000 I've heard a lot of buzz over the Audioquest Niagara power conditioners. Thanks in advance I enjoy your friendly videos and your knowledge of audio equipment.
tube life will be diminished, how fast depends on output or input tube and how the mfg. pushes the tubes with circuit design as some mfg.designs run the tubes less "hard" than others
I have a tube amp: I try to remember to turn it off if I will not be listening for a couple of hours or more.
Thanks for the two replies lady and gentleman. Very refreshing to hear from a woman audio enthusiast. Now let's see what uncle Paul says on the subject of tube life whether or not to lean on when not in use. Happy listening.
I'm more of a visual learner ... Could you draw it? 😜
I'm not an engineer but I think I get the idea, so maybe I can offer a straighter explanation.
Let's start with volts. the amount of volts across a connection between two devices determines how hard one device is trying to pull electrons from the other device. If the preamp output 1 volt to the amplifier, that means the amplifier tries to pull an amount of electricity that represents one volt. If the amplifier output 30 volts to the speakers, that means the speakers try to pull 30 times more electricity. But this is only how much they try to pull, not how much they actually pull.
So, the gain of an amplifier is simply how much higher can the amplifier make the pulling force it receives from the preamp. If the gain is 30, and the preamp gives 1 volt, the amplifier makes it 30 volts.
The wattage is what determines how much electricity can actually be pulled. The more powerful the amplifier, the more electricity it can actually provide the speaker, while it's trying to pull more and more out of it.
So, let's take two amplifiers, one with a power of 20 watts, and one with 200 watts. They both have the same gain, so the speakers in both cases are trying to pull the same amount of electricity. In the 20 watts amp, it can deliver up to 20 watts to the speaker and then it stops. It can't deliver any more electricity, and the volume is limited by this. If you would connect the 200 watts amp instead, it could deliver the speakers 10 times more electricity, so it can go louder.
Because both amplifiers have the same gain, if you output enough volts from the preamp through the 200 watts amp to drive the speakers to full volume, the same amount of volts from the preamp to the 20 watts amp will cause the speakers to clip before they get to that volume. So to drive the smaller amp to its full volume (just before the clipping point), you will need to provide it with smaller voltage from the preamp output - basically meaning, lowering the volume knob until it stops clipping.
In conclusion, higher watts mean you can turn the volume knob higher. Gain is basically the same in every amplifier, so don't worry about that.
You aren’t considering current in your equation. Watts = Power = Voltage x Current (V x I). The gain, as Paul explains, is set by voltage; but the Watts are determined more by the speaker load where V = Current x Resistance (V = I x R). So the resistance of the speaker has a great deal to do with the Voltage at the output of the amplifier. To make things more interesting, the resistance at the speaker varies with frequency, in fact, resistance to an AC waveform is called Impedance. (Impedance itself has two components, Capacitive and Inductive; Capacitive decreases with frequency, Inductive increases with frequency. Capacitive resistance [or reactance] current leads voltage [capacitors take time to charge]; Inductive resistance [or reactance] Voltage leads current [inductors take time to build the all important electro magnetic field]. The math to figure out AC signal characteristics is quite involved, and not easily measured, at least its component parts called out above, but its nature assured us that every speaker and amp design will be a bit different. Crossovers can be as much art as science and are peculiar to the drivers chosen.
Getting back to your equations, more power will be required of different speakers presenting different loads to the amplifier. Generally speaking, highly efficient speakers present less of a load to the amplifier than less efficient speakers, but less efficient speakers seem to offer the speaker designer with more options in shaping the sound (judging by their preponderance in the market).
Finally, as to power requirements vs ‘loudness.’ The relationship is not linear, as Paul mentioned at the top of his video, and I think he helped us all by eliminating from his discussion, but just as twice the voltage does not equal twice the power in practical terms (ideally this is true P=IV), twice the power does not equal twice the volume, due to the (relatively) sensitive nature of the human ear. Power increases along a logarithmic curve, such that: For a two-fold increase in electrical power, there is 3 dB increase in sound power, for a four-fold increase in electrical power, there is a 6-fold increase in sound power, and only when there is a ten-fold increase in power, do you get a corresponding ten-fold increase in sound power. As a Goggle search reminded me, decibel itself merely expresses a ratio of powers. Generally speaking, you need a lot more electrical power to gain a similar increase in sound power. So, while the values chosen for your example are valid, it wouldn’t work well unless you continued to add zeros (10 fold at a time). Anyway, I think you’re close to gaining an understanding, keep at it, and be careful. I’m not an engineer, either.
#wattafier .... gain is cheap to make, watts is not.
more watts or higher efficiency drivers
Discuss below :)
I'd say chose a loudspeaker that you prefer the sound of and then consider what amplification you need and want.
More watts and good old 85db bookshelf speakers
Both thanks
Oh my....
This is like trying to explain the difference with car engines the difference between torque and horsepower. No one could explain that one clearly... and I asked quite a few people who were car savvy.
WHEN will you answer my question I submitted it over 3 months ago!?
The man owes you *nothing* , douchebag.
Gain is laundry detergent and watts is a hell hole in California
Good god man.
😳
I got nothin’...
Hope that clarifies things yevall.
Lol
??? ...scratching my head..??? Nope...i'm still none the wiser...
came to learn ..now really confused
That was awful. Thank God you ain't in the teaching business.
Palestine