The difference between preamps and power amps

What is different between a preamplifier and a power amplifier?

[@khalid969]

Best explanation I've heard yet. Now let's hope I can remember what I just learned.

[@esphilee]

If you do not have electrical back ground, think about the Pre-amp as a bicycle pump. You can create very high air pressure if you pluck the nozzle (high impedance) while you pump, or connect it small bicycle tyre that is full. But once you connect it to a truck tyres, it lost its function, because there isn’t enough air flow to inflate the tyre to keep the pressure high. The power amp is like a air compressor. It too increases the pressure of tyres, but it also has large air flow that can fill up the truck tyres.

[@FazlayElahi]

Thanks a lot

[@blackburd]

This makes sense but I still don't understand why we need the bicycle pump. I don't have two engines in my car, one tiny and one big. I have one big motor. Surely the pre-amplifer brings something to the table other than being in the chain?

[@esphilee]

@@blackburd Pre-amp could be a dedicated one that is designed for a specific source or a instrument, like guitar, mic, line-in, keyboard, audio decks, radio-tuner…. Keep in mind that these devices or instruments generate signals at different level. Or it could be one that is designed to handle multiple inputs, selectable with switches on the front panel. It may also include filters or equalizer. In short, it deals with input or inputs, amplify the signals to a controlled level, so that when they are connected to the main-amp, user can switch between sources without having to adjust the main-amp. The main-amp deals with the Speakers. Different speakers work best with different Amplifier. So they work in pair with the speakers system, depend on how loud you want the output to be. Using separate amp systems for source and output, makes it easier to manage and upgrade.

[@stimpy1226]

Perfect explanation for me Paul. I am happy that you broke down the function of the preamp as a voltage device and the power amp as both a voltage and current device. The way you presented it today was very clear.

[@josephrizk9850]

Watt is this video all about? I'm a little behind on Current events ;)

[@hugobloemers4425]

It seems you have high tension levels.

[@googoo-gjoob]

standby......

[@perherbert]

😂👍

[@GS-HIFI-AUDIO]

Ohm my! I'm so amped for the next vid!!

[@goldenguns2659]

No need to get your pairs twisted.

Paul, love the very easy and simple explanation of the difference between preamps and power amps. Thank you!!

[@MrDoneboy]

Paul, this is your greatest video, by far!

[@scottyo64]

That was a nice simple explanation, thank you!

[@justanobody4983]

Thats the easiest explanation of preamp and power amp ive heard! Thank you paul as always!

[@Paulmcgowanpsaudio]

My pleasure. Thanks for the kind words.

[@kebello10]

@@Paulmcgowanpsaudio So to play my record with my new turntable I need preamp and amp? I thought I only need a preamp and connected with the speakers

[@Paulmcgowanpsaudio]

@@kebello10 Some amps have built in preamps so it depends on what kind of amp. But if we are separating the gear as we do in high end audio, then yes, you need a phono preamplifier (or a preamp with a phono input). This gets the music off of the record and amplifies it to a useable level. But the output signal from a preamplifier does not have the strength necessary to drive a loudspeaker. That requires power from an amplifier.

[@ocfranco4]

Excelente seus comentários, Paul, são pequenos, porém bastante didáticos, obrigado.

[@circuitblog01]

Well explained and said thank you Paul.

[@asianyangster916]

Never knew that. Perfect explanation.

[@neilshirley]

Really useful video, thank you.

[@NoveyBoy]

Perfect explanation.

[@plebmike8997]

So wouldnt you only need a Power amp? What is the point of a preamp if its just the same thing? I have watched 4 or 5 videos on this topic and still just don't understand.

[@fixnreview]

Watching & listening Paul

[@Mr.Robert1]

A pre-amplifier doesn't have any speaker line-out. Only an amplifier does. I can explain this in about 2 seconds. The difference between an amplifier. Do I need a pre-amplifier? Do I need a mixer? Do I need a signal processor? Or do I have everything I need? I've yet to see a simple explanation that to me has a very simple answer.

[@uog293]

Why do we need two separate devices ( preamp and amp) when av receiver can do both these functions?

[@tragicevans4157]

Separates no compromise quality components, easy to upgrade and swappable. Receiver the DAC, Preamp and Amp in one box. The integrated circuits share the same power from the wall (compromise) if something breaks hard to troubleshoot.

[@jeremiahchamberlin4499]

Learned something I didn’t know today.

[@finnlabel]

Thank you very much !

[@alaafahmyofficial]

Thanks a lot, Thats so clear

[@octaverecordsanddsdstudios1285]

Thanks and glad that helped. Thanks for being part of our community.

[@discy12345]

Thanks Paul

[@doowopper1951]

So, Paul, if I understand this, I assume that in the BHK300, the tubes serve as the voltage amplifier, and the MOSFETs serve as the current amplifier. Is this correct?

[@stimpy1226]

Hi Neil, in case Paul doesn’t get back to you quickly enough you are correct. There are many companies that are using the same design philosophy lately and it’s a good design.

[@doowopper1951]

@@stimpy1226 thank you.

[@stimpy1226]

@@doowopper1951 You’re very welcome.

[@ford1546]

you are wrong. vacuum tubes are on the preamplifier section and work in the same way as transistors but tubes give a different sound type. Both are volt amplifiers Tubes in PS audio equipment are only used in the preamplifier input section to provide a special sound type.

[@stimpy1226]

@@ford1546 Check again. The BHK 300 is a mono block tube amplifier with a tube input stage for voltage gain feeding MOSFET voltage devices in the output stage. Both stages our voltage and amplification with the power stage being able to supply the current demand to power the speakers. This is the unit that is under discussion.

[@milkman100001]

after all these years im still learning ..

[@durgasoundspayyanur7223]

Great question

[@johnacosta5625]

I arrogantly clicked on this & actually learned something!

[@nunofernandes4501]

Also, does the amp pump watts into the speakers or do the speakers pull watts from the amp?

[@gg0297]

Those ATCs, damn... 👌

[@AzimApurbo]

Thank you.

[@BrooklynGuy1988]

you don't address why the voltage needs to be amplified twice. that would be interesting to know.

[@peterjones4621]

Thank you Paul for this very understandable explanation on the differences between a preamp and a power amp. So, do I need a preamp or can I just live with a power amp to power my speakers? Does the preamp give me some additional features when used in conjunction with the power amp? I can only guess that there must be a physical connection between the preamp to the power amp and then to the speakers and in that order? I'm an infant in my knowledge of this but I'd like to finally learn more about it. Thank you Paul. Excellent video.

[@Paulmcgowanpsaudio]

The preamp controls volume and provides input selection. In some "amps" called integrated, it is built it. A strict power amplifier has no means of controlling volume or selecting different inputs. So, that's always the preamp's job in an analog system. In a digital system (CD player or streamer) the preamp chores are often handled on your phone or tablet, so no need for a separate preamp.

[@PetraKann]

Are there power amplifiers that only boost the current?

[@durgasoundspayyanur7223]

Sir keep ur style,

[@letstalk3265]

Hi Guys, Paul, I'm of your ilk/age ie on the downhill slide, looking to make that journey better and enjoyable with my mostly mint vinyl, cassette and CD collection. I have a excellent power amp of 50W and definitely need a pre-amp. This is where I need help. What power output on the pre-amp to suit/match my amp? What is optimal? Most efficient? No idea, need guidance. Thanks in advance.

[@jbjb303]

Can this be done? "Alexa" to "Power Amp" to "1/input 8/out Zone Controls" to "Speakers" or I need the Pre Amp also?

[@AllboroLCD]

The placement of that ATC speaker there I find quite interesting, Single track monitoring perhaps?

[@graxjpg]

I think there may be another tucked right off camera

[@AllboroLCD]

@@graxjpg Id be surprised to find out theyre recording in 5.1

[@jamescassidy4045]

Dumb dumb question, but if i hook up my passive speakers to something like a Yamaha CR-600 Sterio amp, those types of home Hifi Amps have both the preamp and power amp built in right?

[@dhoonygo]

I appreciate your explanation. I was just thinking if the ultimate purpose of the system is to make audible sound to humans, is it really necessary to divide the 'integrated' amp into two? We might define a device at the first time of the invention which can control voltage and current as 'amp' because both functions are necessary afterall.

[@glichasasha750]

Those ATCs!

[@kuri_nova]

Dale william carajo!

[@sanjaayanandhgopal2840]

Are those ATC monitors,Paul? If so how are they? Just your opinion pls

[@Paulmcgowanpsaudio]

I am not a big fan.

[@user-od9iz9cv1w]

Great explanation. Instead of a preamp, I use autoformer volume control. With 12 3dB stops, it is like a 12 speed transmission. Each click is 3dB less volume(voltage), but instead of using resistors it converts voltage into current. Less volume but greater drive.

[@shineon7641]

Hi there Super-Paul. I have another question for you: I have a set of 6 Loudspeakers with a 4 ohm impedance. I have also found a Pre-Amp rated at 8000 watts pushing 2-8 ohm Loudspeakers. Will this Amp suffice to power my 4 ohm impedance Loudspeakers? Thank You in advance Paul.

[@virustwin]

Wow thank you so much. This is the only video or article I have encountered so far as an aspiring audiophile that has finally allowed me to understand it. Thank you so much. I have one question though, given the role of the power amp as described, am I to understand that the audio signal will travel on the voltage line to the drivers/speakers, while the current allows the drivers to be able to move thanks to the power/force (wattage)?

[@Paulmcgowanpsaudio]

Sort of. Think of a power amp as two blocks, one feeding the other. The first block is the voltage amplifier that makes the signal bigger (1 volt in equals 30 volts out). This feeds (in series) the second block which is current (power). The current output stage is all that connects up to your speakers to move your drivers.

[@virustwin]

@@Paulmcgowanpsaudio oh wow. i had to read that a couple times to grasp it but i think i finally understand what you are saying. thank you so much my friend 👍

[@Paulmcgowanpsaudio]

@@virustwin Thanks for that. This is what makes my day when the light bulb begins to shine. Sometimes it just takes a long time and many different tries. Congrats!

[@stevekirby7333]

Maybe the old water analogy would help here. The preamp takes a small amount of pressure and increases it. The power amplifier also increases the pressure but adds to the amount or volume of water so that it can actually do something. 'Watts' simply being the combination of the amount of water and the pressure it's at. Tube amplifiers for example are primarily voltage amplification devices, and require an output transformer to convert that voltage down to something reasonable and thus increase the current so it can push the mechanical device of a speaker to make useful sound levels.

[@MONK-7]

Hi Paul I've subscribed to your channel because I know you talk a lot of sence. I have a question regarding impedance. Can I reduce an amplifier that is rated at 4 ohms to 2 ohms without series-parallel ?!? Many Thanks!

[@MONK-7]

@Sblackfll if an amps impedance is rated at 4 ohms then the amp decides the load not the speakers

[@MONK-7]

@Sblackfll no matter way you look at it. An amp will have a rated impedance thus governing what load of ohms you can put into it. Why do you think you can have an amps impedance rated at 4 or 2 ohms.

[@MONK-7]

@Sblackfll look I'm enjoying the banter so no worries but my question to Paul was and I should have went more in-depth with the question. Was more of changimg the circuitry to achieve 2 ohms. But I stand by what I said amplifiers Have an impedance ratio. Think about it I've got 4 speakers rated at 8 ohms each. Two on A/1/L and the same on the side B/2/R and the amp is rated at 4 ohms it's a perfect match. But if I add another speaker of same or greater/lower impedance the amplifier will overheat and quite possibly pack in. Thus the need for resistance as the amplifier requires to run at a safe level. Impedance Ω ohms. Please say after me Ohmmmmmmm Ohmmmmmmm 🙏

[@MONK-7]

It's also the speaker that can overload an amps impedance this is why the amp has a limit. 8,4,2 ohm's

[@69eddieD]

@@MONK-7 It has a minimum rated speaker impedance that it can drive. It DOES NOT DOES NOT have an impedance. (Actually it does nave an output impedance, typically a fraction of an ohm.) In an amplifier is rated fort 4 ohm speakers, then it can drive 4 or 8 ohm speakers. It cannot drive two ohm speakers.

[@Mr.Robert1]

I have the answer for you guys. Go out and purchase a receiver. A receiver has everything you need all-in-one. If you're not understanding it and you're still asking questions, perhaps it's something that you should not have. I grew up when this equipment was coming out. That's the only reason I understand it backwards and forwards. We needed an amplifier, then we needed a pre-amplifier, then we needed a tuner. Or we could buy an all-in-one a receiver.

[@Mr.Robert1]

@pt265 For those that know the difference. For those that can hear the difference. For those that can understand the technology, not for people that need an education on the simplest thing in the world. When I was 13 years old I had all separate components. Amplifier, preamplifier, tuner, Reverb. You name it I had it. Over the years I added to it. I'm referring to people that are clueless not the people in the know.

[@stonefarmer3005]

As a kid of the 70’s-80’s, I’m sad to see today’s people don’t understand what an Amp vs Pre-Amps are. Next you’ll tell me that people try to hookup there phonograph not knowing what a moving magnet is!

[@NoEgg4u]

How does a phono-amp fit in to this scenario? Is it similar to a power amp, but at a lesser amount of current?

[@Ascania]

What do you mean with phono-amp? A phono stage (or phono preamp) is a preamplifier that amplifies the signal from your turntable to line level and also applies the RIAA curve. It can be standalone or part of an integrated amplifier. An integrated amplifier combines both a preamplifier and a power amplifier in a single case. Usually such an integrated amplifier has multiple switchable inputs, one of which is for the turntable (because on this one the RIAA curve is applied as well as the input being matched to the output of the cartridge in your turntable - and that's why there's a little switch there to allow you to switch between magnet and crystal cartridge). To the others you would connect your other sources, the radio receiver, the tape player, the computer... Now while there probably are some integrated amplifiers out there that only provide a phono input (and thus could rightfully be called phono-amps) I haven't seen any such limited device out in the wild.

[@zulumax1]

The simple answer is it is another voltage amplifier that brings up a signal that is less than 5 millivolts to a signal that is over a volt or two, besides the EQ that must be done. A gain amplifier if you will.

[@NoEgg4u]

@@zulumax1 Is that the same as saying that a phono-amp is identical to a pre-amp, but with a fixed volume setting (a fixed gain setting)? And the above is done to bring the voltage up enough for the pre-amp to continue the voltage increase via its volume control? And I understand that some phono-amps have more than one gain setting. But putting that aside, it is the same as a pre-amp, but for a fixed voltage increase?

[@zulumax1]

@@NoEgg4u There are equalization of the bass and high frequencies that needs to be made right, other than that the gain is measured in decibels. Moving magnet aprox. 40db of gain, moving coil probably 60db of gain. The gain of an amplifier has nothing to do with how many watts it puts out, only voltage gain into a given load, phono usually into 47,000 ohms. (moving magnet)

[@Itsadrianyay]

Oh yeah, baby.. hot dog. Love this stuff

[@Kulumuli]

I have a gain selector on my preamp. I set this to zero and I can hear the sound improves a lot. So is it the voltage amplifier in the preamp that is very crucial to sound quality?

[@roofpizza1250]

You have noise in your system that is noticable when the gain is turned up.

[@Kulumuli]

@@roofpizza1250 Yes, and the sound is somehow more 'flat'. I have a TAG Mclaren PA20r preamp partnered up with two 125m mono blocks of the same brand. I saw a review on the PA20r and they stated; Why isn't a gain selector more used on amps? I don't know if my preamp at gain zero could be classified as Class A. But I think it is closing in the gap. I almost never use any other gain than zero. And with this my system is loud enough at half volume.

[@Kulumuli]

@Douglas Blake Yes. I think where my system's weak links are. In this order; 1. Speakers (Epos ES11) 2. The room. Not too bad but definitely not optimal. 3. Turntable (Lenco L75, shure m75 mk2 PU) 4. Speaker cables. OK i guess for now. 5. Phono preamp MM (Holfi Ellipse, a good RIAA). 6. Amps. Preamp; TAG Mclaren PA20r with gain selector. Mono blocks; 2x TAG Mclaren 125m. Let me know if any one of you disagree.

[@shockafter7]

I get it, but I don’t at the same time? Like, why is a high impedance 600ohm headphone “difficult” to drive, when a low impedance speaker needs POWER? Why is a 16ohm to 32ohm easily able to be driven by a phone when the number is closer to an impedance of a speaker, but a 600ohm headphone, although works, isn’t great? What’s a purpose of a headphone to be that high of an impedance, when a good speaker that is low impedance sounds good too? I would have thought a high ohm headphone would need power too if it’s got the “headphone equivalent” of what a speaker needs to sound good. Like, does a 600ohm headphone have more components than a 32ohm? I got a DT 900 standard headphones that I got in 32ohm, but I had a choice to go higher. Why? When a 32ohm can be driven easily. Would that same model sound any different plugged into my DAC/amp than my current ones? Or is it suit people’s needs in what amp they have? Argh!!!! Excuse my ignorance. I didn’t think when I got into audio I had to understand the same things as an electrician haha clearly I should just stick to asking if “this” would work with “this” gear and never think about it again lol

[@KG5SNU]

Great explanation. So why use a pre amp?

[@tjb99yt]

Nope. A preamp does not increase voltage, it lowers voltage. The power amp has a fixed amount of gain and in order to regulate the volume, the voltage has to be lowered at the input. Some preamps (phono, microphone) actually amplify but not your regular hifi preamp.

[@laika25]

Can a (typical) preamp do the job of a phono amp?

[@laika25]

@Sblackfll Thanks.

[@DENVEROUTDOORMAN]

Only if you pay it enough

[@Mr.Robert1]

The problem is very simple the average KZbinr that is watching this video is getting more confused then anything else. This needs to be explained like you're talking to a five-year-old. You're making it more complicated. Talking about voltage, talking about impedance. Why confuse them even more? Don't add additional things to there vocabulary if they'll already lost.

[@rmj2031]

😅😅😅

[@johnsweda2999]

What about transformer gaining in the preamp as the volume control can't think of any manufacturers doing that why

[@johnsweda2999]

@Douglas Blake I meant multitap single winding transformer

[@hugobloemers4425]

@@johnsweda2999 Sowter makes those, find the website and select attenuators under the products menu.

[@AviZvi]

So why buy a preamp when an amp does everything,?