Yamaha AV-33 question about output power

krowmagnum

Compulsive speaker freak
I picked up an early Yamaha AV-33 surround amp and I can't find any info on-line about the output power. (watts per channel). The back of the amp has 360w printed near the power cord. Is that the power consumption ? Or the output ?

The previous owner thought it was total watts speaker output. 90x4=360 but I found the specs on a later AV-35 and the manual listed it as 100wx2 for front channel and 20wx2 for rear. So I'm thinking 90x4 cannot be correct.

This amp does not seem like 90w per channel. I have a newer Yamaha AV receiver with 100w per channel and it's noticeably louder.

Am I right that the 360w is the power consumption ?

Thanks,
K
 
360 watts is the consumption, not the output. A generally accurate rule of thumb for TWO-channel amps is that the output per channel is about 1/3 the power consumption, so in your case that'd be 120 wpc or 240 watts total. But yours is a surround (5.1?) amp, so your available 240 watts is going to be spread over 5 channels. Let's say 90 watts per channel for front L&R. That leaves 60w to power the two rear channels and the center channel... 20w + 20W + 20W maybe. Best guess. Does this amp use a switch-mode power supply?

This amp, unless it's got a monster power transformer, gargantuan power supply caps, and enormous heatsinks, is NEVER going to put out that much power continuously over the audible spectrum. HT amps are notorious for over-inflated power ratings. Whereas back in the 70's government regulations mandated that an amp be rated to put out a particular amount of power for a period of time over the audible spectrum, now they're rated to put out their rated voltage for MILLISECONDS at 1kHz only.
 
dspear99ca, I appreciate the info. I'll keep that "rule of thumb" in mind when looking at other bargains.

I thought that 360w was the power consumption rating but the guy I got it from is "tech" and he was positive it was the total output. I'm a noob at this stuff so I accepted what he said until I hooked it up and couldn't get as much volume as my RX-V480 receiver. After looking the RX-V480 on-line I found an ad listing the RX-V480 as 65w per channel for the front, not 100w that I thought originally. The Power consumption is listed at 220w so the 65w per channel sounds about right ?

Now I'm wondering if something is wrong with the AV-33 amp because it should have more volume than it has compared to the RX-V480 using just the front L & R speaker outputs. It didn't sound all that great compared to the RX-V480 either.
 
It's hard to make many generalizations about the relationship of power consumption to power output. The biggest issue is that the operating/test output condition for the power consumption rating is seldom known.

Assuming the back panel shows maximum power consumption (thus maximum output) is a mistake in many, or most, cases.
 
It's hard to make many generalizations about the relationship of power consumption to power output.

Not to be snarky, but it wasn't hard at all. In my personal experience (and that of many others although that would be considered hearsay in a courtroom) the 1/3 ratio for traditional transformer-based power supply audio gear is generally close to the the mark for two-channel class AB consumer-grade amplifiers. As far as HT multi-channel class D switching amplifiers, of course it doesn't work... as I noted the ratings for newer gear should not inspire confidence in their performance given the amazingly dodgy test conditions under which the rated output power was obtained...
 
Yeah, I've applied similar rules of thumb too. Sometime it's close, sometimes it's not.

Yamaha M-80 #1 = Back panel 850W / 3 = 283W. Power spec 250WPC. Not bad...fairly close.

Yamaha M-80 #2 = Back panel 600W / 3 = 200W. Power spec 250WPC. Ehhh...depends on how one defines close.

Yamaha M-40 #1 = Back panel 500W / 3 = 166W. Power spec 120WPC. Same as above, depends on what you call close.

Yamaha M-40 #2 = Back panel 660VA/500W / 3 = 166W. Power spec 120WPC. Same as above, depends on what you call close.

Spectro Acoustics 202 = Back panel 500W / 3 = 166W. Power spec 100WPC (afaik). Quite a difference here.

Audio Research 100.2 = Back panel 800W / 3 = 266W. Power spec 100WPC. Not close at all.

Mark Levinson No. 23 = Back panel 1200W / 3 = 400W. Power spec 200WPC. Not close at all.

So, as you see, some are close, some are high, some are low, some have poor correlation. The latter is the only point I'm trying to make. A generalization may generally work, or not.

EDIT: These are all straight 2-ch power amps where there is no consideration for preamp and tuner circuits, although they're generally a very small part of receiver power use.
 
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Thanks for the link. Do you find their information to be pretty accurate ?

I ask because I honestly find it hard to believe the AV-33 is 100w per channel based on listening to it. Plus, Audiogon only mentions 2 channels (100w x 2) and this is a surround sound amp. Shouldn't surround sound amps be listed with more than 2 channels when describing the output ?

Any idea where I can download a manual ? Yamaha's site seems to be just about worthless for finding a manual or anything but a replacement remote for the AV-33. I did find that it's part of the Home Theater in a Box
 
Shouldn't surround sound amps be listed with more than 2 channels when describing the output ?

Many of today's surround receivers are rated in 2-ch mode and in their 5 or 7 channel modes. Note though, that even when looking at the 5 or 7 channel ratings, they don't necessarily mean all channels driven. If it does not specifically say "all channels driven" assume it is not.
 
Many of today's surround receivers are rated in 2-ch mode and in their 5 or 7 channel modes. Note though, that even when looking at the 5 or 7 channel ratings, they don't necessarily mean all channels driven. If it does not specifically say "all channels driven" assume it is not.

It keeps getting more confusing all the time...

Well. I've given up on the AV-33. The guy is going to take it back and give me something else. This was a multi-piece trade deal for a computer I built and he has more goodies I can choose from so maybe I'll find a treasure in his stash.

I did get a nice Harmon-Kardon 330C receiver in the trade so maybe he has more old stuff. If I find anything good I'll post it.
 
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