Oh ya, I forget that not everyone has a dedicated HT. It seems though, that companies selling 300 wpc amps would be selling to crazy nutjob enthusiasts who would have the ability for dual circuits. Crazy advertising I guess that keeps the market going. Here is an interesting article I found about the Sherwood Newcastle. It has a few paragraphs related to UL labels, NTRL and OSHA. Dated July/August 2006 by David Rich.
http://www.sherwoodamerica.com/pdf/A...TSS_review.pdf
Maybe people are catching on.
Roly
That is a good article with great references to UL and OSHA but the author is way off assuming a Linear A/B amp will deliver 70% efficiency #s for power. The best case scenario is more likely around 50-55%. Again, the power spec listed in that review is ACD for instantaneous NOT continuous power.
This is the most comprehensive article I have seen anywhere on the subject relating to power ratings of amplifiers. Before anyone believing in things like, "watts are watts", "its current not power that counts", "ACD power ratings more important than individual channel's dynamic ratings" etc., should read this article first.
I don't know how much time Gene spent on this article but I, for one, really appreciate it.
Thanks Peng for your compliments. It took me a couple of months to organize all of my thoughts, get feedback and peer reviews, etc to complete this article. Its sorta a primer to the new Amplifier Measurement Standard I am now working on. While my testing methodology will be much more labor intensive, I and many industry folks believe its a step in the right direction for testing multi channel amplifiers.
Gene,
Holy Cow. I am not sure that article did anything but depress me. Now I think that I can't believe any of the ratings. It does impress me that the Sherbourn is the only company I have seen that employs dual power cords. I am a little confused about the power cords and wall ratings and equipment ratings. So if my amp has a 15A power cord, but I am using a 20A breaker, does that increase my risk of fire? Or if I use a 20A breaker and get a 20A rated cord, but my amp isn't rated for 20A, what happens? Also, say I use the Sherbourn 200 WPC with dual power cords, and use both cords on a 20A breaker, does that cause any problems? I would think that would get me closer to the power requirements to generate the amps potential of 200 wpc.
If the amp is designed in accordance to UL, you will have little benefit trying to feed each power cord 20A. The amp should blow a fuse or turn off if you try to make it source this much current on a continuous basis.
Like my article states, you will never run your 7CH amp at full power with all channels driven unless you are running a continuous correlated test tone on all channels to measure power. Just for fun, I plugged in a 400wpc x 2 amplifier and 2 500 watt subwoofer amps into my APC S15 power conditioner. I cranked the volume levels up to over 100dB at my listening position 18 ft away from my speakers in a nearly 6000 cu ft room. The power meter was showing a continuous power consumption of only a few hundred watts. Despite the amps were pumping out hundreds of watts, they weren't doing so continuously because music doesn't operate that way.
Again, you want an amp that can deliver its power rating into at least 2 channels, but also have plenty of headroom to handle dynamic passages unclipped, while also having a stable enough power supply to drive low impedance loads (if your speakers dip below 6 ohms) and have a low enough output impedance to not cause frequency response variations when presented with a reactive load such as a speaker. Most importantly, it shouldn't be noisy, especially at low power levels where the amp functions most of the time.
