Will Adding a Separate Amplifier Make My Speakers Sound Better?
Ask a car enthusiast about their dream car, and they’ll have an answer. Ask a cyclist about their dream bike, and they’ll have an answer. Approach an audio enthusiast about their dream system, and they’ll say “separates.” Most of these people will never buy their dreams because they are too expensive and, most will say, not worth the performance benefits. The car nut will say, “I’m never going to drive that fast and I need more than two seats.” The cyclist will say, “The 0.2kg of weight savings is not what’s keeping me from going up that hill.” The audio enthusiast will admit that they don’t really need an external amp. But they want one. And if you give them enough time they’ll wonder if adding a separate amplifier will make their speakers sound any better.
What Amps Actually Do
In the days before AV receivers, we had preamps and amplifiers. Preamps processed the incoming signals from our record players, eight-tracks, and reel to reel decks. They then were connected to the amplifier that would provide power to your two, massive and oddly designed (by today’s standards) speakers.
Because of the phenomenon of “everything my dad had is better than what I have” known as “Dad Envy™” (trademark pending), separates are still considered the gold standard of home theater. Many of us old guard were brought up lusting after the audio racks (and other things) in those massive Sears catalogues. You know the ones. With the EQ sliders and record player on top?
Having every component in its own enclosure meant that if something broke you could swap it out to a new component. It also meant a ton of cables and not an insignificant number of buttons to push. And who doesn’t like pushing buttons?
In the end, the amplifier really only does one thing: It provides power to the speakers. Today, we have receivers that are a combination of the preamp and the amplifier (and, technically, have to be able to receive FM/AM signals in order to be called a “receiver”). But, with Dad Envy™® (patent pending) in full effect, surely having your amplifier separated from your preamp is better, right?
The Argument for Separates
The rationale for separates is steeped in arguments older than the people making them. People talk about interference between the preamp and amp. They’ll look at the back of their speakers and try to find an amp that has the same power rating. They’ll justify an amp because seriously: How can a receiver REALLY power eleven speakers?
Science. That’s how.
In today’s world, there is still a wattage war. Receiver manufacturers rate their receivers based on two channels driven at sometimes ludicrous levels of THD (total harmonic distortion). You don’t need to know what any of that means to understand it. It’s the same with gas mileage and new cars. You know you’ll never see the numbers on the sticker unless you drive downhill everywhere. It’s the same with receivers. The wattage claims are always exaggerated.
The Truth of Watts
But the dirty secret of the separate lovers is that you don’t really need all those watts. Do you sit within 12 feet of your speakers? You’d be lucky if your speakers are drawing seven watts most of the time. Sure, your speakers can handle up to 250 watts, but you rarely need all that power.
Full reference volume is 105dB peaks. This is loud enough to damage your hearing if experienced for an extended period of time. Most movies aim for an average 85dB at full volume. Using an SPL (Sound Pressure Level) calculator, we can figure out how much power we need to hit these levels. There are a few things we need to know first.
- How far away from the speakers are you sitting?
- What is the sensitivity of your speakers?
- How much instantaneous power can your receiver put out?
- What is the impedance rating of your speakers?
Many people envision the amplifier “pushing” power into the speakers. That’s not the way it works. The signal “tells” the speaker what to do and the speaker “requests” power from the amplifier. If anything, the speaker “pulls” power from the amplifier. Let’s do some math.
Most consumer-level speakers are 8ohm nominal with a sensitivity no lower than 85dB. It is unusual for someone to sit more than 12 feet away from their speakers. When we plug those numbers into a calculator, we see we need about 650 watts to get to 105dB.
That’s a lot of power! We need a separate amp right?
Not so fast. That’s 105dB peaks. After an hour of 105dB noise, you’ll experience permanent hearing loss. Even if you love the movie, you won’t be playing your system that loud continuously. Sure, that explosion might hit 105dB, but most of the movie will hover around 85dB (even that might be too loud for continuous listening for some). To hit 85dB, your amp needs to provide…carry the one…seven watts.
This is assuming an 85dB sensitivity and 12 foot seating distance. Reduce the seating distance to 10 feet and you only need 300 watts to get to 105dB and three watts to get to 85dB. Increase the sensitivity to 87dB and you are down to 190 watts for 105dB and two watts for 85dB. It is easy to see that, for most of us, consumer-level receivers provide more than enough power to give us the volume we want. But that wasn’t the question, was it?
It’s About the Sound, Man!
The question wasn’t about whether or not a separate amp will provide the power we need. It is about sound quality. Can a separate amplifier make your speakers sound better? First, we need to examine what an amplifier can do to make your speakers sound worse.
If your speakers demand more power than an amplifier can provide, the amp can clip. This is when the amplifier runs out of power and the waveform flattens out. That 650 watts we were talking about earlier? Most amps can provide that much power instantaneously for a very short period of time because of the power stored in their capacitors. As long as they have time to refill, it isn’t a problem. Putting out large amounts of power continuously can be an issue and lead to clipping. Clipping can create distortion that you can hear. It can also damage more sensitive parts of your speakers like the tweeters. As we’ve already discussed, if you have normal speakers and are sitting a reasonable distance from them, power shouldn’t be a problem.
The second way an amplifier can harm your sound is by introducing interference. The audiophile will say that the other components within your receiver can introduce interference that can be heard. By separating the amplification from the processing, you reduce this potential source of unwanted sound. Again, most modern receivers don’t have this problem. You can look up reviews of your receiver and find one that includes measurements. This might have been a problem with early receivers, but it hasn’t been one in years.
Lastly, amplifiers do have a noise floor. This is a general hum that you’ll hear out of your speakers with nothing actually playing through them. All amplifiers put out some noise and manufacturers try to dampen it at much as possible. In your system, you only need to turn on your system, sit in your seat, and listen. Adjust the volume knob to the highest setting you ever use (in my system, that is around -5dB). Do you hear any hum? No? Then don’t worry about it. If you walk up to your speaker will you hear something? Probably. But if you can’t hear it from your seat, what does it matter?
But Can a Separate Amplifier Make your Speakers Sound Better?
Amplifiers do nothing but provide the power requested by your speakers. Does having a bigger engine make you drive faster? No. It gives you the ability to drive faster. But if you never press the gas pedal any harder, you’ll never use that power. Amplifiers are the same. If your speakers are never asking for more than a handful of watts, having a bigger amplifier does nothing but make you feel good about having a separate amplifier.
Amplifiers are the spinning rims of the AV world. Some people insist they need them but the rest of us just shake our heads at the waste of money. Just like overpriced “audiophile” cables, amplifiers can make your speakers sound worse, but they cannot make them sound better. If they are doing anything to the signal other than amplifying it, they are adding distortion. And distortion is bad.
Dad Envy™®© (copyright, me) or no, there are real reasons to need a separate amplifier. If your speakers have a lower than 8ohm nominal impedance, if you sit farther away than 12 feet, if your receiver has a high noise floor…these can all justify the purchase of an amp. But for most of us, buying a separate amplifier does nothing for our system and certainly doesn’t affect the sound coming out of our speakers. With that said, if you like spinning rims, who are we to say you shouldn’t buy them? Just don’t try to tell us that you “needed” them. Cause you didn’t.
Very good article that debunks everything I’ve been told, Thank you Tom.
Ok so 7 watts…. that’s 7 watts per channel continuously
For my 91db sensitive speakers its 5 watts, per channel – lets say 3 channels continuous for the front stage 15 watts continuous.
I don’t buy into the better sound on separates personally, however, the 7 watts you list is per channel continuously and headroom is a real thing.
Many action movies will have plenty of scenes that demand volume over the mean level.
For my 91db sensitive speakers its 5 watts, per channel (15ft) – lets say 3 channels continuous for the front stage 15 watts continuous. I get instantaneous wattage is short lived, but to get 20db of headroom, my amp needs 336 watts of power…. per channel. so that’s 1000+ watts just for the front stage.. not to mention, I have a 7.2.4 setup so that’s theoretically 3600+ watts instantaneously.
Now, obviously, I’d bet there’s almost never a time where all 11 channels will receive signal at the same time, let alone at 105db, but 260 watts (Denon x4300) certainly is not enough, IMO, even for the front stage.
Love to hear your thoughts,
This is the key. There are loud scenes. They are VERY loud at reference level. But most of that sound is coming from your front two speakers (not the center) and your sub (which has its own amp). Those extremely loud sounds are usually (almost universally) instantaneous and the “rest” of the sound is much lower needing only a couple of watts. Very rarely do we see sounds that are at peak loudness for any length of time.
So what happens is that the receiver will dump all the power it has from its capacitors to the speakers for that instantaneous sound and then refills them during the less loud parts. This puts you closer (using your numbers) to 224 watts. Just about any receiver on the market has those resources available.
The real proof here is in the pudding. When you are watching a movie just as loud as you want (which normally isn’t at reference volume), does your receiver clip or go into protection mode? The answer for nearly everyone that worries about watts is “No.” Well then, you don’t need an amp.
Home theater, too often, suffers from overanalysis. Nearly 1 in 3 questions I get starts with, “I never noticed a problem but then I read that X can be a problem…do I have a problem?” You answered your own question there buddy. If you don’t hear a problem, you don’t have one. Having an audio problem in your home theater is like having a flat tire. You may wonder what that sound is at first, but it quickly becomes apparent that you have an issue. Home theater is the same.