I’ve been asked by one of our customers to explain why on earth we should or he or she should buy a separate amplifier and processor or amplifier and preamp rather than a complete integrated amplifier that has the preamp and amp in one box or a receiver that has everything – the processor, preamp, and amplifier in one box.
There’s a few reasons that we recommend doing that to get the best performance from your system.
The first is with a modern home theater processor or receiver, there is a lot of digital circuitry in those systems. Those digital circuits produce noise, and that noise inevitably, no matter how well designed, at some small level, is going to get into the amplifier section.
If everything is driven from a common power supply and is all in the same chassis or the same enclosure, which is exactly what you had with a receiver. Once you split the amplifier from that, even though you’re running external cables, you isolate the power amplifier by being on its own from that noise, from that potential to interfere with the signal to the amplifier. It also has its own enclosure, so it’s immune to any radiated noise that may be coming through the air.
That’s one reason why if there’s a benefit. The other reason, and I think the bigger reason, is that if you think about a typical home theater receiver, you’ve got tons of circuitry. You’ve got an amazing amount of complex electronics inside that box and they’re all powered by, usually, one power transformer. Now, that power supply to fit into the box with all those other electronics and all those multitude of amp channels, we’re seeing now receivers with 11 amplifier channels in them. They all have to share that common power supply and what will happen inevitably is that some compromise has to be made to actually fit all that stuff in the box.
And the biggest components in any piece of electronics, like a receiver, is the power supply. Particularly if it uses a traditional transformer and capacitor rectifier power supply configuration.
So what does that mean? Why do I care? So the amps are in the same box and they share that power supply. Well, that power supply usually will not be overbuilt, and by overbuilt, I mean it’s bigger than it needs to be so that you can have dynamic headroom. That means the amplifier can exceed its maximum power specifications for short periods of time. When you have an external power amplifier, that power supply has been designed and dedicated just to the amplifier section itself. It’s not sharing power with the rest of the components.
So what happens is that you can get better dynamic headroom in most situations with that external amplifier.
Now, if I don’t listen very loud, why do I care about that?
Well, if you think about let’s say movie program material, you can have it a very comfortable listening level. You can hear the dialogue well and as we know, in action movies and other films like that, you can have a sudden explosion or a gunshot or something that instantaneously requires – in some cases – 10 or 20 times the amplifier power then the vocal track that you were just listening to, or the voice track. So what happens is that when those dynamics are reproduced accurately, because you have that extra power in on-demand on top for short periods of time, it’s clean, it’s clear, and it frightens you, and that’s exactly what it should do.
The movie mixers and producers have made those effects louder so they startle you. So they get an emotional response from you.
If you have a system where you can’t have that clean power available because the power supply can’t deliver more than the rated amplifier power, the dynamics are going to be squashed. That means that special effect isn’t as impressive, it’s not as scary, you don’t have the same emotional reaction, and it’s just not as fun to listen to.
So that’s one reason why we recommend in most systems beyond the certain level that if you can afford it, a separate power amplifier is a very good idea to get that clean dynamic power.