A question about high power amplifiers

[jhoak]

Can someone explain to me the attraction of high powered amplifiers driving high efficiency speakers?

Let’s take for example the Cornwall II. It has a rated efficiency of 101dB @ 1 watt / 1 meter and a maximum acoustic output of 119dB. Based on the rule that it takes doubling the power to get a 3dB increase in volume it works out that 64 watts will drive a Cornwall II to its maximum output.

That said can someone tell me why I would want to drive my Cornwall IIs (hypothetically… I don’t own a pair) with an amp rated at 300 watts per channel. I mean if the speakers will “only” go to 119dB (which is D@MN loud by the way) consuming 64 watts to do so why would I need the other 236 watts that the amp can produce.

In my own case I have a pair of DIY Cornscalas as my main speakers. My very unscientific and rudimentary testing has told me that they put out around 102dB at 1 watt. I have no clue as to what their maximum output is and I have no intention of finding out. Solidly 98% of my listening is at levels below 85dB. By my calculations they’re seeing well less than ¼ of a watt most of the time.

What am I missing here? Should I sell of my 30 w/ch tube amp and buy a monster 300 w/ch amp?

I guess I just don’t “get” it.

[Coytee]

Headroom

I've been debating on doing some amp flipping and if done, would free up a dbx BX3 (configurable between 2,3,4 channels at approximately 100x4 up to maybe 400x2)

If you want to borrow it you are more than welcome to give it a whirl.

If instead, you've got the ability to use an XLR amp then you could instead borrow one of my K2's which are currently sitting idle (I've been too lazy to swap things out)

Either one would give you a chance to play around & see for yourself.

If you ever turn things up to a life like volume then my experience has been that the lower powered amps don't keep up (I've had several since I wanted to give them a fair shake)

I'm in Jacksonville with my toys. If you're interested, I've got a friend who lives in Orlando and goes down there every couple weekends (works in Jax). I'm sure he'd be happy to play Mr. Transport.

Honest offer.

[Chris A]

Can someone explain to me the attraction of high powered amplifiers driving high efficiency speakers?

I think a better question is why so many people use tube amplifiers with too little headroom.

If a higher power amplifier has very low distortion and noise in the milliWatt/microWatt output region, then the added headroom doesn't hurt anything. Granted, most higher power amplifiers have higher noise floors and higher distortion (including crossover distortion) at low outputs, but not all of them do.

Chris

[russ69]

What am I missing here? Should I sell of my 30 w/ch tube amp and buy a monster 300 w/ch amp?

I guess I just dont get it.

Big amps add power and weight to your system, even at low volumes. That's the attraction. Plus the big amps are usually the flagships of the manufacturers and they do a good job making sure they are really good. My advice is to buy or try one, play with it for a year or so, then you can decide if it works to your liking. I have amps from 22 watts, 40 watts and a big 250 watt bruiser. I wouldn't sell any of them.

[jhoak]

I fully understand the concept of "headroom". The fact remains that if your speakers max out (output wise) at well under 100 watts it just doesn't matter if you install a 300 w/ch amp or a 1000 w/ch amp cause they just aren't going to get any louder than the maximum that they can produce.

The question remains... If it only takes 64 watts to drive the speaker to the absolute maximum that they can produce what does another 200+ watts buy me?

For reference I've owned Belles, La Scalas, Forte's, Quartets, some KGs and I still own a pair of Heresys in addition to my Cornscalas. I have also driven some of them (the La Scalas in particular) with a 300 w/ch amp and found that they sounded no better than when driven with a low powered (>100 w/ch) amp. What the high powered amp DID give me was an unacceptable noise floor in the form of hiss. Not to mention the fact that I had VERY little volume adjustment between silent and WAY too loud.

Think of of this way... You have a car that by virtue of its design can go 100MPH and no faster. Period. That speed can be achieved with an engine generating 100HP. It doesn't matter how many HP you stuff under the hood the car can only do 100MPH. Why would you want to drop a 1000HP monster engine in to it? Because it'll get to 100MPH faster perhaps? Obviously the "mechanics" of speakers versus cars don't match up well but I hope you can see the analogy.

[Coytee]

Think of of this way... You have a car that by virtue of its design can go 100MPH and no faster. Period. That speed can be achieved with an engine generating 100HP. It doesn't matter how many HP you stuff under the hood the car can only do 100MPH. Why would you want to drop a 1000HP monster engine in to it? Because it'll get to 100MPH faster perhaps? Obviously the "mechanics" of speakers versus cars don't match up well but I hope you can see the analogy.

Because when the stock engine is driving the car at 100 MPH the engine is really stressing out. If instead, you drop a 1,000 hp engine into said car (even if capped at 100 MPH), the higher powered engine will do the same duty with less stress.

Put a bit different... I used to have an Oldsmobile 442. When I moved myself out of state, I opted to mount a trailer hitch and simply pull a trailer rather than get a truck and tow the car.

That 442 would probably break 100 mph and would get there pretty quick. For normal driving though, nobody needed that kind of power. What was interesting was when I was towing the trailer (loaded I'll add)

I could STILL pass someone on the highway if I needed to or if at a stop light, I could still "take them" even with the added drag of the loaded trailer behind me. (it was their largest pull behind, not a little lawn mower sized trailer)

So my (weird) point is, the 442 had the power to do the job but it also had enough power in reserve to do the job with ease, even when the pulling got tough.

End of the story: some idiot T-boned me and wiped out the car. one of only 1,300 convertables made that year from what I recall. Fun stuff.

[Coytee]

The dreaded duplicate post monster

[Guest " "]

it's in our genes. bigger is better. when our ancestors were running the plains chasing wild game to decide what they would spear to eat, those who killed bigger game, ate better, had more babies, genes were passed on. Those that were ok with easy small game, did not eat as well, had less babies, less genes were passed on. bigger breasted women fed our young better. bigger butt women could run from preditors easier than women with flat butts. over time, the bigger is better gene pool survived. we want bigger engines, bigger boats, bigger trucks, bigger houses, bigger speakers, bigger amps. we can't help it....it's embedded in our genes.

[russ69]

I fully understand the concept of "headroom".

It's not a headroom question (although for some it is). What we are saying is that big amps improve your system even at low volumes. You'll have to try one to see.

[twistedcrankcammer]

Propper headroom is more about wattage peaks then RMS wattage capability. If at full volume you have a kick drum that hits 400 peak watts for an instance, can the amp deliver, and yes, the cornwall is rated to take an instantaneous peak as such. At what level is that 100 watt amp clipping??? My Nakamichi PA-7 amps are dead quiet at idle, so no increased noise floor. Also, an increased high amperage off idle improves bass at lower volumes. Just because you couldn't tell a differance with one particular amp, don't equate that to all amps. Some people like the way Bose speakers color the sound. Some people like the way tube amplification colors the sound. Not all people like aditions made to the orriginal sound. I play my stuff flat response.

Roger

[Ski Bum]

Let’s take for example the Cornwall II. It has a rated efficiency of 101dB @ 1 watt / 1 meter and a maximum acoustic output of 119dB. Based on the rule that it takes doubling the power to get a 3dB increase in volume it works out that 64 watts will drive a Cornwall II to its maximum output.

No one has mentioned this, and I could be completely wrong, but I think it would be important to factor in impedance dips and phase angles in the bass region when calculating power demands. With that taken into account, I'm guessing the Cornwall will draw more power than 64 watts at it's max output, and may draw more at considerably lower output. Yes? No? It just seems that in spite of their sensitivity, speakers such as Cornwalls can literally suck lesser amps dry.

Ok, that image didn't work, but it is the impedance of the CWII, which is below 4 ohms at about 40 Hz, and near 4 ohms from about 90 Hz all the way up to about 600 Hz. If there are any negative phase angles in there (I couldn't find that info), the effective impedance will be lower, and power draw goes up even more. That low impedance range covers where most of the music's energy lies. Any amp had better be capable of delivering the goods. Something that doubles down as impedance is halved is a good start. Such amps tend to be more expensive, higher power amps.

[artarama]

Can someone explain to me the attraction of high powered amplifiers driving high efficiency speakers?

I can't really explain the "phenomenon" technically, but when you hear it, you know it and it can be phenominal. It does make a difference. For me a Big difference. Period!

Now as Cask pointed out it has to be quality power. I think it has something to do with how a large amplifier is better able to control the drivers and make them respond harder and faster to signal input than a smaller amp. For another off topic analogy, It's like closing a hollow core door or slamming a solid core door shut. Bang!

So here is where my attraction of high powered amps comes from:

My journey started with RF-25's and led to purchasing all the Heritage line with the exception of the Belle's. I was on a mission. It soon became apparant my electronics couldn't keep up with the Klipsch. I have used a Scott 299 tube, 60wpc Luxman ss, 120 wpc JVC ss, 200wpc Kenwood ss and 180wpc Luxman ss and a few other non-factors.

The smaller Luxman was super clean, great for critical listening (still love it with the Heresy's but it just seemed to be thin and lacking in overall authority when I wanted to go loud and fill the room. The larger JVC and Kenwood were pretty good but not as clean as the smalller Luxman, I enjoyed the 299 tube for a long time it has that lush, full, rich sound that is the sirens song to tubes. But, I still missed the transparant clarity, detail and "livelyness" of the smaller Luxman.

Then I found a vintage M-4000, 180 wpc Luxman ss and it literally changed my world. I am a believer! Big (clean) Power = Big difference!

[Danzo]

It's in the amperes, not watts for me. High current amps will help you battle those woofer dips.

Those big amps sound better to me, even with sensitive speakers and at lower listening levels.

Sticking with AB from Emotiva and Bryston for now, but will try out some ice from Bel Canto or Wyred or Red Dragon soon.

[Schu]

the question isn't why buy a big amp... it's why NOT buy a big amp!

if you can give me a single legitimate reason, you win... and guess what, the old "it's a waste of power and money" are NOT good reasons.

[Schu]

It's in the amperes, not watts for me. High current amps will help you battle those woofer dips.

Those big amps sound better to me, even with sensitive speakers and at lower listening levels.

Sticking with AB from Emotiva and Bryston for now, but will try out some ice from Bel Canto or Wyred or Red Dragon soon.

exactly the boat I am in right now... I want either a bryston(used) or emotiva(new) or I am going with Ice Amp... period. right now, I am leaning towards ICE

[StephenM]

the old "it's a waste of...money" are NOT good reasons

Why not? I don't have money to burn. I'd rather take my wife out to a nice dinner than have an 80 pound amplifier staring back at me if it adds nothing except a bunch of headroom I'll never use.

As far as I'm concerned, if all else is equal (and there is no guarantee of this, especially when discussing solid state vs tubes), there won't be a difference between a 300 watt amplifier and a 30 watt amplifier when you're never asking more than a fraction of a watt even for peak levels.

[tube fanatic]

At risk of inflaming this issue, there are 2 factors which need to be considered in choosing how much power is needed. The first is whether the amp can drive the minimum impedance of the speakers, and the second is whether it can play loudly and cleanly enough to make you happy. In the case of tube amps in particular, distortion rises with power output. So, if your usual listening level only requires flea power (as you stated around 0.25 watts, which isn't unusual with CWs), it's likely that your tube amp is producing very low distortion at that level. And as long as the amp's distortion stays acceptably low when called upon to deliver what's needed to handle peaks, you're in good shape. As to high power amps sounding better at low volume levels than low power amps, that isn't necessarily true. If the distortion of both is the same over the needed range of power output, and the high power amp sounds better, it's more likely due to differences in circuit design than anything else. It's also unfair to compare tube amps to solid state amps because the operating parameters (such as damping factor) are so different. OK guys, tear me apart- I'm heading back to the bench!!!

[StephenM]

At risk of inflaming this issue, there are 2 factors which need to be considered in choosing how much power is needed. The first is whether the amp can drive the minimum impedance of the speakers, and the second is whether it can play loudly and cleanly enough to make you happy.

If it makes you feel any better, I fully agree with this sentiment []

[mark1101]

I agree with that too. I use pro amps for bass and sub duty to provide the power for those applications. But every single pro amp I've tried on a passively crossed speaker, or on my active system MF and HF horns.............I was completely disappointed. None of them.......had the resolve or detail even close to a good home audio amp.......s/s or tubed.

The pro amps excel in the power area............They do not provide audiophile "detail and clarity".

It's a touchy subject because I see forum members rave about the great sound they get with certain pro amps I won't mention. I know from what I've done in my own house how those sound, and so I can't agree with those posts. And you have to be careful what you say or people get pissed..........but that's what I found out from my own audio ventures.

I love my QSC PLX 2 1104 & 1804 for MWM bass cabinet and KPT-684 sub duty. When I tried those amps on my upper horns they were unacceptable. My vintage rebuilds McIntosh MC-250 (bridged) & MC-2100, which are 100 watts and cost about the same or less...........blew the QSC away in sound quality on the upper frequencies. I won't even mention the other pro amps I tried because people will get pissed.

Edit: For a cornwall or other Heritage model passively crossed you need an amp with some power but also audiophile resolve for detail and clarity. I'd look at the 60 watt VRDs for tubed, and old McIntosh s/s rebuilds like the ones I mention above for value with good amount of power, excellent clarity, and also a very tubey sound.

[Schu]

the old "it's a waste of...money" are NOT good reasons

Why not? I don't have money to burn. I'd rather take my wife out to a nice dinner than have an 80 pound amplifier staring back at me if it adds nothing except a bunch of headroom I'll never use.




As far as I'm concerned, if all else is equal (and there is no guarantee of this, especially when discussing solid state vs tubes), there won't be a difference between a 300 watt amplifier and a 30 watt amplifier when you're never asking more than a fraction of a watt even for peak levels.

so we all have to live life according to your personal strategies otherwise a fool? come on now.

Ah hell, I better stop using 92 octane petrol also.

personally, I never understood this "lowest common denominator" philosophy...

OP, take into account any upgrades you may be choosing to do in the future!