Would the Sherwood RX 773 be better than the Marantz nr1402? The Sherwood has 100w per channel and 400W total. The marantz nr1402 only has 50W per channel and 5 channels so i guess its around... idk 250W? this is confuuuusing hahaha I appreciate the help I really dont want to damage or overload my Receiver/amp or speakers. the JBL 180 speakers are huge and seem like they would need so much to power them. marantz nr1402 seems like it couldnt handle 2 of them. maybe I am just looking at this wrong. hmmmm? haha so confusing!
Punctuate. Please.
Anyways, to your questions:
1. You only count per-channel wattage because that's what each individual speaker sees. So if the receiver puts out 50W per channel (and it doesn't matter if that's into 2, or 2000, channels), you estimate at 50W into your speaker (at 88 dB/W/1M -> your distance).
2. Larger speakers are actually generally more efficient, in keeping with Hoffman's Iron Law (Hoffman is the H in KLH, and his law roughly says: efficiency, extension, and size - you get to pick two; so big and efficient, big and extended, small and efficient, small and extended, etc and the third one suffers (that's why those little "supercube" subwoofers need 1000W+ amplifiers)).
3. The NR1402 probably puts out more actual power than the Sherwood, because most manufacturer's power ratings are flat-out lies, and Sherwood is one of the worst (most of their AVRs claim 100Wx7 or something, and usually will blow up at 10Wx7 or less). Marantz is a better company to deal with for customer service as well.
4. In in a normal setting, either receiver will realistically be fine, and you aren't risking damage to the speakers. The easy way to figure this out is to look at the speakers' impedance rating, and then look at what the amplifier says it can do. Usually they're pretty explicit about the minimum impedance the amplifier can handle (there's usually big warning stickers - and we don't care about maximums, because those aren't what cause things to overheat and blow up).
I got 98.3 dB SPL at listening postion
What is that equal to? is that loud? I am not savy at audiofile lingo. I dont wanna bust eardrums i just want a home theater in my room. haha. I only put 50W for the amp should i have put 100W because I am using 2 channel stereo? thanks so much for this tool? the link is great!
98 dB is very loud. I think that site has a small list of things to compare loudness to, but the rule of thumb (which comes from OSHA and CCOHS) is 85 dB is the maximum SPL for long-term exposure, any higher and you risk hearing damage (that doesn't mean 86 dB will make you deaf instantly, but 90 dB or 100 dB constantly over long periods of time will cause noise-induced hearing-loss (NIHL)). Dolby and THX suggest calibrating to 85 dB (so "0 dB" on the volume dial is going to produce 85 dB if you're feeding a full-scale sine-wave through), and planning for 20 dB of dynamic headroom (allowing peaks up to 105 dB). A lot of people calibrate to 75 dB though, because 85 dB can get fatiguing real quick (most movie theaters, like IMAX or AMC, are calibrated to 85 dB - to give you an idea of loudness).
Try this for more:
http://www.animations.physics.unsw.edu.au/jw/dB.htm
and these:
http://www.osha.gov/pls/oshaweb/owadisp.show_document?p_table=standards&p_id=9735
http://www.ccohs.ca/oshanswers/phys_agents/noise_auditory.html
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