September 7, 2004

Amped up

Oooh, ESPN2 in HD for Jan '05. Not that I ever watch anything on the deuce, but it's yet another sign that HD programming is taking off.

Did anyone catch the five (5!) college games this weekend on ESPN-HD? Is there any better way to kick off the college season? I'm so stoked for the NFL this weekend. With Fox in HD, it's gonna be sweeeeet.

Today I bought a Parasound A51, a 250Wx5 separate amp which I'll use to drive my Denon in the basement. Now let me give you a little education. That's not 250W total, that's per channel with all channels driven (into 8 ohms).

Normally when you see a receiver at your local electronics store, they'll list the "total" power (eg, "500W receiver" meaning 100W for each of 5 channels) or they'll list per channel but be deceptive about how it's computed. Sometimes they'll say something like 150Wx5, but fail to mention that they're only driving one channel at a time. Gee, that's easy. But how many blockbuster movies only have sound in one speaker at a time? It's when you start driving all channels that you separate the wheat from the chaff. If they do happen to list power ratings with all channels driven, look at the total harmonic distortion (THD). Less than 0.1% is the standard. Some bargain receivers list their full power with 10% distortion!

Why is any this important? Most people think that the most common cause of damage to your speakers is by overpowering them. In some limited cases this is true, but by far the more serious problem is caused by underpowered amps. When an amp is driven too hard, it doesn't have enough power to generate a clean signal and clips. Clipping is downright terrible for a speaker and the easiest way to destroy it. What's the solution? An amp that has enough oomph to give a clean signal in the most harrowing of action sequences.

Thus ends this month's home theater lecture. Next time you get itchy to buy that l33t 500W receiver at Stereos R Us rating 10% THD with all channels driven, save your money. Now you know better.

Posted by pinkerton at September 7, 2004 7:41 PM