Mono Vs. Stereo amplifiers

Are monoblock amplifiers better than stereo amplifiers and, if so, why? Paul answers this vexing question once and for all.

[@channelzero2252]

What you have to consider is whether or not the performance gain is worth it. Can you hear a difference? If you can hear a difference, is it enough of a difference to make you want to spend the extra money? If the answer is yes, then by all means go for it. But if the answer to either question is no then a stereo amplifier will suit your needs just fine.

[@stevec.6119]

Congrat's Paul ???? One of the absolute best explanations of how an amplifier works (to the lay person) I have ever heard. How you can simplify technical theories, and procedures, is fantastic. I used to be able to afford quality equipment like yours in the distant past, but, sorrowfully, now I have to rely on aging vintage gear. Watching your videos make me yearn for my past audiophile days of upgrades, trade ins, experiments, and sometimes follies. Semper Hi-Fi"

[@zebarzebra]

Well if only it where true.. they have done thousands of double blind test which determined without a doubt that it doesn't make a difference to the listener. Yes speakers and rooms can make music sound very different and of course there is a certain standard that should be adhere to, but you cant hear the difference between 50000$ monoblocks and a 500 Yamaha amp, if both use the same speakers, the same input signal and don't change the signal artificially. Don't believe me? Check out Richard Clarks challenge? Think you can determine the different with your years? GO get your self that nice juicy money 10.000$ is a good deal ;-) All the best to you though! Look back with a smile - you had all that and now you have fun with some vintage equipment!

[@wilcalint]

Excellent description Paul. Additionally packing all the goodness of two mono amps into the chassis of one increases the weight, and size, by at least 50%.

[@adem5178]

So brilliantly explained. Thank you for these insightful videos.

[@tuck1s]

Perhaps worth mentioning that most power is needed for the low frequencies (bass) and usually that will be mostly in-phase between left and right channels. It’s unusual to have one channel drawing a lot of current while the other one isn’t. That’s why a single power supply of adequate capacity is a reasonable engineering compromise for cost reasons, in a stereo amp. Another factor is - what are the limits of channel separation in your sources? Digital sources can achieve 100dB or better channel separation. Tape and vinyl, not so much. Your sources are already modulating left and right channels with each other.

[@Enemji]

@@jim9930 - Bose did, and hence his Acoustimass design pushes all signals below 200hz to a single speaker.

[@thunderpooch]

@@jim9930 That's because at live venues the bass is so loud the audience doesn't much care about stereo bass or imaging effects. And a left vs right sound stage is quite hard to achieve (below 200hz) when people are positioned all over the place. But at home, you'll appreciate when the recording engineer has the bass skipping around a bit from left to right. It's fun and people like it. The Bose system is a complete joke in that regard. Live sound isn't hifi. The bass module plays too high and also not low enough. Chuck it in the garbage. Bass is still quite directional down to 70 hz. Don't believe me? Just about everyone can point to where the subwoofer is if they're blindfolded and tones from 70hz to 150hz are played.

[@thunderpooch]

@@jim9930 ah, ok.

[@ryuh.s9558]

Always thank you for your video.

[@AudioVideoReviews]

Hi Paul, I’m a big fan of your videos! I have a follow up question: some stereo power amps offer the ability to be bridged and operate as a mono block (some at a turn of a switch). Is there any performance degradation in using 2 such bridged power amps, compared to mono blocks?

[@darrenspooner1482]

Always learn something new. In this channel thank you !!!

[@mysock351C]

Few comments on power supplies. If your using an unregulated linear power supply, even _one_ amplifier running on its own supply will generate at least some ripple consisting of the rectified audio on each respective rail, not to mention 120Hz ripple when its loaded. Even though its correlated to the audio, it will still contain _copious_ amounts of harmonics that must be rejected via the PSRR of the amplifier (via feedback). You don't really gain a lot by segregating each stage since even the ripple from the solitary amplifier will still produce quite objectionable distortion if it gets into the audio. Additionally pretty much most music (and all music on vinyl) will have its L/R bass tracks more or less equalized (with the possible exception of classical music), which is where almost all of your power is going to, so the lions share of the ripple from each amplifier on each respective channel will both more or less be correlated to each other since its at lower audio frequencies. An argument could be made for the falling PSRR with frequency and the listener being much more sensitive to higher frequency distortion, but with the large quantity of higher frequency harmonics present from even one amp on the power supply rails, it doesn't seem to really hold much water. You still have to reject that somehow, so the ripple from opposing channels amplifier will likewise be rejected equally well.

[@kencohagen4967]

Back in the 80’s my roommate’s sister turned 21, leagsl drinking age and we threw her a party. I brought my speakers and some music, her brother brought an amp and his albums and we put things together. I put together a couple mix tapes so that we could have some time away from the amp to re supply our beer stock, food and restroom breaks. While making the mix tape one of the songs request3 was Pink Cadillac by Bruce Springsteen. I discover while record that onto tape that it just didn’t sound good, at all. I tried eating the song, no luck. I tried taking it off of a 45, and that didn’t work. I tried a CD, and although it was cleaner it still sounded horrible. Then I tried recording it in mon. Bingo. All the bad harmonics and distortion was gone. So I recorded the song in mono. Later on we met to go over what we had put together and I showed the guys what I had discovered, and none of us had a clue why the song was recorded the way it was in the studio. So, in that one instance and that one only, Monk was better. Every other song I’ve ever heard in my life sounded better in stereo. Even the Beatles who didn’t really have the hang of setting up a soundstage 8n their recordings were better in stereo than mono. Most of the older music had been remastered in stereo and rereleased.

[@spacemissing]

Sansui AU-710 / 717: Stereo integrated amplifier. Two transformers, each with a set of diodes and capacitors. Doesn't have a stereo / mono switch (but I wish it did). Close enough to separate monos for My budget.

[@billd9667]

“Dual mono” stereo amps were relatively common back in the day. I don’t know why more manufacturers don’t offer them. It doesn’t have to be expensive. I’d rather have two EI transformers in a single chassis than one toroidal any day of the week.

[@golfjunkymusicjunky8370]

Have also a au 717 love it......

[@golfjunkymusicjunky8370]

Use it as a preamp and than 2 xtz edges. And you are goingTo Heaven ....

[@antiWhiteism777]

@paulmcgowanpsaudio --- Should PSU be integrated or discreet from the amplifier?

[@Kev1966K]

I always wondered if because of this if a monoblock preamp would yield any gain and I do understand that power requirements are lower but then I would guess the preamp power supply is smaller too. would it be better with a method of balancing the attenuation link and how does PS Audio avoid the modulation issue in the Preamps.

[@holliswong8519]

What’s your view on audio note AN-E corner loaded speakers? Hollis, Melbourne, Australia.

[@robh9079]

Great answer of course, though just to shoot the breeze; I guess another slant on the question might be a comparison of a pair of mono's and a stereo at the same price point, and of course a BHK250 stereo is more expensive than a pair of Stella 1200's. If you need power for synergy sacrificing mono'ism for more watts might be worth it. Dual power supplies in one box I guess is a way to save on expensive casework - would trade the cost for bigger transformers/power caps...

[@BarryBernau]

Fantastic channel!

[@adamk4716]

What a great teacher

[@1crenshaw488]

what if you have two stereo a21+ paasound amps and bi-amp and setup vertical with the switch on stereo on both identical amps.

[@ThinkingBetter]

A great power amplifier isn't cheap. Most importantly is excellent engineering. A stereo amp can be excellent also through careful passionate engineering e.g. making sure the power supply inside is very robust with the headroom to deliver power during the peaks. A stereo amp can also be made with separate power supplies for left and right in one cabinet (e.g. Hegel does that). Doing so will save some money without sacrificing quality.

[@iamhungry4000]

Hi, I have a guitar amp with mono and stereo outputs. It's 120 Watts. If I use stereo will it split the load so it's 60w and 60w?

[@laurentzduba1298]

Monoblock amps with separate power supplies offer better channel separation - some are even spec'ed at having a channel separation rating of up to 130 dB.

[@marianneoelund2940]

Channel separation specification for a mono amplifier doesn't exactly make sense. At the system level where that spec applies, it has nothing to do with the mono amplifiers and rather has only to do with the source and signal/power cabling configuration.

[@bertoray5497]

I had always heard about separation, never gave it much thought, but when I actually ran with two mono-blocks, my jaw dropped. With better dynamics and separation, boy-o-boy, what a difference mono amps make.

[@scottyo64]

All I know is when I switched to fully balanced monoblocks the sound stage is incredible. My monoblocks are cheap in thd grand scheme but the effect is wonderful.

[@davidlane1169]

'Ole Audiophile to Paul: ...a well thought out explaination. Unless one has a bevy of heavy duty AC outlets, one better be talking straight stereo because an AC cord every channel becomes it's own headache. We did skip over mono bridging on some stereo amps but that can seriously complicate the ohm load formula for us ginks. I consider load first when deciding between mono & stereo. Am I hooking up a normal load or something that drops off the face of the earth? Nothing beats a mono block amp when it comes to driving low ohm loads at moderate volumes safely. Wow, I can't stress that lesson enough.Thanx (general rule of thumb)

[@alphinpeter2847]

Thanku ❤

[@laika25]

The "hello Paul" reminds me of Casey Kasem 😅

[@Oystein87]

I have a integrated stereo amp that have a dual mono amp config and both channels have their own seperate power supplies. And I think actually there even is a small seperate power supply for the pre-amp. And it also have direct inputs to the power amps so I can use it as a pure power amp. 2x 150watts into 8ohms, 2x 300 into 4ohms (all ch driven at 20-20.000Hz with less than 0.05% THD) 1000watt total power supply. And it is class A for the first watts and then it works as a class A/B from there.

[@yuriwalter385]

Brand and model name/number, please?! :)

[@WaqasMalik-er7jt]

Waqas from pakistan, big fan of yours...i currently have a Krell 3250e to power my 2 x b&w cm9. i am getting 2 NAD C272 amps, i can run them as mono blocks, will they outperform the Krell 3250e? the krell is 250watt p channel i think and the nad is 300watt per channel as monos. thankyou

[@QoraxAudio]

If stereo channels interfere with each other via the PSU, you need to implement proper isolation. Decoupling caps, coupling caps, optocouplers, isolation transformers... a solution to every situation. But you need to take the effort to design it of course.

[@HareDeLune]

What about simplicity and elegance? The philosophy of "less is more"? : )

[@QoraxAudio]

@@HareDeLune Yes, exactly. Adding just two isolation transformers will probably suffice. No need to build two full enclosures and to full power supplies, simply to get things separated. That's just inefficient overengineering.

[@HareDeLune]

@@QoraxAudio Hmmm...

[@danielgeiger7739]

The size of the dip in the other channel will depend a lot on overall volume. At what percentage of volume setting (on pre-amp) will it make a difference? 10/25% doubtful. 50% maybe, 75% likely. Those are just my uneducated guesses. Could you therefore circumvent the problem by getting a decent sized stereo amp, maybe with dual-mono internal design?

[@allansh828]

should input stage also has its own power supply?

[@laurentzduba1298]

Very expensive ones usually do, at least the ones I've serviced back in the 1990s in the 5,000 USD and up price range.

[@linandy1]

I find putting my unit into mono when playing old mono records just sounds alot better, more uniform.

[@GusdeHbg]

I think, mono might better electric/electronic wise due the separation of components and gives you more power of course, but this can be done also in the same chasis stereo wise. If you do not need the power mono will give you and you have a little room or a non acoustic one I dont think you will hear the difference in a blind test at same loudness. Nice video by the way.

[@ajaybhaiya1511]

A006 bluetooth speaker ki amplifier plets kaise order karu koi link bhejo

[@jimfarrell4635]

Of course a good stereo power amp or integrated will still beat a poorer set of monoblocks. I have a large integrated with dual mono configuration and it does a great job. Better than the valve monoblocks it replaced. And they were by no means bad amps.

[@markfischer3626]

If the power supply is large enough it won't matter. We all share power in our homes with our neighbors through a common utility company transformer. If your neighbor turns his light on the effect it has on your appliances is so small you'd never notice it and it would take very sensitive equipment to measure it. If you have city water from a water main and you are taking a shower your neighbor turning the faucet on his kitchen sink will have no effect on you. On inexpensive equipment there might be a slight noticeable difference. On expensive multithousand dollar audio equipment there just is no valid excuse.

[@jamesplotkin4674]

So when I hit "play" on my cassette deck and the lights dim, I should look into that? ;-)

[@markfischer3626]

@@jamesplotkin4674 I'd go see an eye doctor.

[@davep2945]

Exactly, Mark. If I had two fire hoses attached to a hydrant that could flow 800 gallons a minute but each hose and nozzle (or valve as Paul described it) could only flow 300 gallons a minutes then there would be no loss of pressure or flow through either hose. I audio terms if I had a power supply capable of delivering 1000 watts of power continuously and 2000 briefly on demand and the most my speakers ever demanded was 400 watts each on the most difficult passages then it would take test equipment to measure any difference in supply to either speaker.

[@dexeter3033]

If I could afford two quality mono-blocks, I would definitely have them. For now, I'll stick with my $200.00-ish Yamaha stereo receiver. It's the best I can do monetarily and I enjoy its sound.

[@khoi83]

Yamaha is good for the money. Enjoy it!

[@livinaftermidnight9651]

So happy to hear this. I have a pair of Parasound A23 amps that I plan on monoblocking as soon as I change my speakers to 8 ohm units. I've had many people tell me this was a bad idea. I didn't think so.

[@alternateunreleasedshellac505]

I'm a mono purist and I only use stereo equipment with consumer grade electronics.

[@bilguana11]

A tube in the power supply. The old rectifier tubes used to be much larger.

[@saquibhussain6000]

Great explanation Paul. I'd extend this question - What makes a bigger difference? Separate amps for high and low frequencies and using bi wiring, or using amps as mono blocks for left and channel but all frequencies on each channel are managed by each amp? This is given we could only go one of these two routes and not both. Thanks again and look forward to your valuable insights.

[@marianneoelund2940]

If you have separate amps for high and low frequencies, with bi-wiring, then you must have 4 amplifier channels. If you want to compare that to "using amps as mono blocks" then you must be thinking of putting two stereo amps into bridged mode. In that case, most direct-coupled SS amplifiers will give you more system power in the mono block configuration, so that's potentially an advantage. But if you have 4 amplifier channels, there is an opportunity to go to active crossovers and bypass the passive crossovers, at least to some extent, and that has another set of advantages. Bottom line, it's down to whether a little more power will give you more benefit than an improvement in crossover technology. I suspect that most owners would find the latter to have more benefit, if they are willing to make the DSP investment and spend the time to do the setup and crossover mods.

[@ThinkingBetter]

Mono amps are better when there is no budget limit, but per Dollar, you can get more audio fidelity in a stereo amp as you don’t end up paying extra for cabinet and other parts that aren’t contributing to better sound. Most of the power is in the bass where both channels usually are in synch and thus you wont hear any slight left/right load interference. But a stereo amp with a poor power supply, due to bad design or perhaps due to old dried-out capacitors, can struggle keeping the channels free from cross interference.

[@rudykraker4905]

Would 2 carver tfm-35 stereo amplifiers sound better bridge mono

[@williamstewart2727]

Great idea. Carvers sound superb.

[@jeffwalther]

Two mono amps for the price of one stereo amp? Sold!

[@mkshffr4936]

Technically better but as a practical matter it may not be quite so clear. With a well designed PS the difference may well be inaudible especially in class A amps.

[@ProjectOverseer]

Agreed, but there are exceptions.

[@davidf1985]

Why can't a 2 channel power amp have 2 power cords & 2 power supplies ?

[@user-od9iz9cv1w]

Right on Paul! I even use monoblocks on the output of my DAC. Beyone the performance gain, the other benefit of mono power amps is the ability to place them in the room next to the speakers.

[@tedjensen8841]

To add to the confusion there are also dual mono stereo amplifiers out there.

[@dandonna852]

Is that crosstalk or is it something alse

[@Lobo243]

Cool I have 2 Emerald Physics EP-100.2 😁👍

[@Davidkxf]

What about bridging two stereo amps

[@marianneoelund2940]

Suggestion: Paul, if you're going to talk about interaction between two channels via their shared unregulated supply, do not start off the video by showing an amplifier module that has a *regulated* supply.

[@chefchutardo5215]

My 5 channel harman kardon signature 2.1 has 5 individual power supplys. Problem solved, one giant case with 5 monoblocks.

[@lio1234234]

I would love you to comment on budget class D amplifiers and how to recognise what is a good board or a bad board and recognising a good power supply vs a bad one. Thank you Paul! 😉

[@veryunclear]

I miss quadraphonic sound.

[@jamband4230]

That was way to simple. It was basically an opinion. You gave one reason and barely explained it. You could've given a little more of a technical explanation being a engineer and all

[@scottyo64]

I understood, he didnt need to go into detail.

[@QoraxAudio]

Paul is not an engineer, he's the CEO of PS Audio.

[@stimpy1226]

@@QoraxAudio Paul is the CEO but he is also an engineer, perhaps not designing as much as he used to or designing at all. I believe that the original P 300 power conditioner was his idea and his design. He knows how to make a decent presentation and if he doesn't satisfy everyone in every video… I'm not exactly sure what each of you is expecting on a daily basis from his explanations. There are many different viewers with some electronics knowledge and others without any. Why not just go with the flow and see if Paul expands on his basic presentation.

[@HareDeLune]

Yup, and a more technical explanation would've gone right over most people's heads, which is one reason for not doing it.

[@jamesplotkin4674]

@Fat Rat A properly designed power supply should have enough capability to sustain clean rail voltages without being thousands fo $$.

[@stephensmith3111]

If you have the money, go with dual mono amplifiers. If you don't have the money (like me), go with what you can afford, but chose wisely. A good stereo amp (power, integrated, even a receiver (remember those)) may not quite be quite as good as those dual mono amps, but these days it can come surprisingly close if you do your homework. There is a lot of really good gear out there that is affordable by mere mortals. Most PS Audio gear is expensive, yes, but it is also quality gear by the accounts I've read/watched and Paul should be commended for not wandering into bat-sierra crazy expensive territory. Good music reproduction is infinitely better than no music reproduction. Especially in these troubled times of very few, almost no, live performances with the actual musicians on stage in front of actual you. In the mean time, God bless the stereo system.

[@khoi83]

Buy used gear (like me) :) 😀 many mono amps Will be very affordable Cheers.

[@jer069]

Well visualized: The DC current is just 'sitting there' and the amp is just a big 'ol valve. Personally I only use active speakers. Where you have the psu and amp perfectly matched to the speaker and mere inches away from the drivers. My question. Why are passive speakers still a thing?

[@revelationsoundstudio]

He is talking more about tube amps. Class D, much less of an issue. Company's design a power supply to handle both channels without issues

[@osirismarbles5177]

What would the impact of using a stereo amp in bridged mono mode be? Will it essentially be the same as a dedicated mono amp?

[@osirismarbles5177]

@blackened 1 thanks. what about with regard to power modulation as Paul was explaining? just curious as to how it works.

[@PebblesChan]

It depends. To get the best stereo separation occurs if the amps do not have a common power supply or linkage. i.e. two separate batteries is nearly ideal. Even with that the loud speakers will interact with each other due to physics.

[@Sams911]

McIntosh has a 3-box mono bloc.. 2 power supplies and one "amp" box.. MC2KW.

[@paullazarro4295]

No cursing please. LOL

[@metalheadmalta]

Got your book... and in the first chapter, I am already hooked... why oh why did you not repair those Austin Healey's lights????

[@peter-mathijslinsen8219]

Very good explanation. Now I have to buy two more amps! Dang!

[@chrisharper2658]

Realistically, because most people don't play their amps at full volume and there should be fairly decent common mode rejection and power supply sag would be sub-audible due to the large bulk charge capacitors, it probably doesn't matter much. But more is better right?

[@chrisharper2658]

@@jim9930 I'm sorry, are having problems with Noise? You know batteries are electro-chemical and that reaction can make noise too. Not many people think about that.

[@paulaj2829]

I have lost the plot guys!!! i have always listened to music through 2 speakers or Headphones !!! before that it came from the front of my old Ferranty record player!! which was Mono !! what is the Mono V Stereo.. or am i just way off the science thing here.. Please help me in simple words..

[@scarabeo500gt]

I love my Mono Block Amps! A pair of Bob Carver Cherry 180's Tube Amps...For the money NOTHING comes close....

[@gerardvoughnfaust4167]

I think masud is comparing the stereo and bridge mono applications. He is asking which set up got a better sound quality. Coz a stereo set up can handle two speakers basically and In bridge mono is only one, thats why he will use two amps for two speakers. I think he will use it for his subs.

[@gerardvoughnfaust4167]

@Fat Rat i think youll understand my point if you are really into mobile sounds.

[@QoraxAudio]

@@gerardvoughnfaust4167 I'm into mobile sounds too, those sounds from mobile fidelity sound labs. But what has a poweramp to do with MoFi? 😜

[@PebblesChan]

Paul looks like he’s pretending to be under water.

[@QoraxAudio]

Jup, he turned the valve open way too far and his power supply is outta juice now.