We just went through this about a year ago. Many people put in very good suggestions. It settled on having the receiver have power across the front three L/C/R at its 4 ohm rating. Just going to 4 ohm instead of 8 ohm will help a lot. I know Gene at Audioholics was saying that almost all receivers made would shut down after a few minutes at their rated power. So, if they would stick to what thousands of people told them, set the standard for the front three at 4 ohms and then I think (been awhile) that it was 70% of the rating for all the surround speakers. This would guarantee a nice jump in the robust nature of receiver amps. As it is now the FTC has apparently done NOTHING with the last go around and is putting out a much watered down version to see how it goes. In the end the good old FTC is going to do something that most likely will end up in doing nothing to keep the power ratings realistic. The consumer will get no help at all.
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FTC Power Amplifier Rule
- Thread starter Dennis Murphy
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Above is the link to the draft FTC document. It was not released today (for whatever reason), but it seems they want input on how to measure 2 channel and multichannel. One good point from earlier in the thread is that many current 2 channel amps can't meet any power spec because they use tubes and can't get below 0.1% THD. Aren't most of these very low wattage (like less than 20W @ 8ohm)? If so perhaps allow any 10% THD to 25W or so.
O' yuck! Not going to happen., It's just too much distortion.
MakeMineVinyl
Major Contributor
OK, OK - let's do 9% distortion.
You're in the UK and I'm in the US; perhaps the markets are different. From what I've read, the global projector market was less than US$4B in 2021, while the global smart TV market was more like US$190B in 2021. In the US, large (65" and up) LED/OLED displays are far and away more common. Only one friend of mine has recently switched to projection, and that's because they just completed building a new house with a custom-designed home theater room. (I'm envious.) Many US homes built in the last 20 years have these so-called open floor plans, which are not projection-friendly.
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Typical would be 1% for tubes. An amount likely inaudible with music for what its worth.OK, OK - let's do 9% distortion.
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Just have to buy a light cannon projector. Not likely to get great contrast ratios. OTOH, when you are watching TV, you can turn off all the other lights and have plenty through out the open area.
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Do like they used to do for car amps. Music power. 15,000 watts for a 1 microsecond burst, and yet it used a 5 amp fuse on 12 volts. Of course you'd have a completely useless spec.
I'd say .1% and if it cannot meet that 1% and if it cannot meet that just don't allow it.
MakeMineVinyl
Major Contributor
But if they need to use 1%, they have to say explicitly that they can't meet 0.1%. Otherwise everybody would just use 1%.
Is it normal for US TV rooms to have 8-10 speakers that an AVR will drive? In the UK a standard size room will have difficulty to accommodate 3 speakers let alone 6, the minimum for surround. Only a dedicated home theatre here will have that number of speakers and almost all of those have projection.
restorer-john
Grand Contributor
I have no problem with 0.1% or 1%, as long as it is a hard line in the sand for consistency in rated, continuous output power specifications. Just pick a number that is in the realm of high fidelity and stick to it. It must be across the audible bandwidth- no cherry picking for the 1kHz 'test' only. Make it a requirement for advertising the product for sale in the US. And enforce it.
Obviously some amplifier designs clip hard and fast, others are more gradual- have a look at the latest little SMSL DA-6 class D @amirm just reviewed. 1% (-40dB) would take the power he arrived at into 4R from 30 to 50W and from 13 to 30W into 8R- a huge difference.
I'm not sure what normal in the US is, and I'm especially not sure since most of my friends are likely in the top 10% of the wealth segments, and a bunch are top 5% and better. So my view is tilted towards people who are rich by US standards. That said, a lot of people I know have 5.1 or 5.2 systems. Some were set up by audio/video businesses which specialize in custom home installations. I'm not aware of any 7, 9, or 11 channel set-ups, but the pandemic kept me from seeing many folks recently. Perhaps some have scaled their systems up, but I doubt it. I do remember seeing a lot of subs. Americans seem to like big bass.
I have seen projection done very well, with 100" screens or thereabouts, and it is compelling. Unfortunately, there's no reasonable place for a screen-based system like that in our house.
Interesting as there are almost no 5.1 AVR on the market other than stack-them-high-at-supermarkets models. With Atmos on all major releases a 5.1 setup is pretty archaic. Who are buying the AVRs that ASR tests and discusses passionately then?
None of the systems I'm thinking of use AVRs, they use pre-pros. I've never actually seen an Atmos set-up in the wild; only at a dealer.
MakeMineVinyl
Major Contributor
Like I mentioned earlier in this thread, the gotcha is how long the amplifier can keep up whatever power they rate it at. Working around a virtual sea of 2 to 11 channel amps all day, I've seen that even 1/8th power is very difficult to keep up for any length of time when 8 channels of class A/B are stacked inside a typical box. That's true no matter who makes the amps.
Class D is worlds easier.
Why would it need to be just a 5.1 avr just because you are limited in your speakers? I doubt here in the US that projection is but a fraction of those using tvs (if I had to guess I'd think like a 20/80 split and I think I'm being generous on the projector side). What the averages are these days in terms of speaker count, I'd say those with dedicated theater rooms are probably with the higher speaker/sub count, but many living rooms are setup even with Atmos these days.....hard to get definitive numbers. Personally I have several tv based avr systems in multiple rooms.....projection might be nice but for lighting/room arrangements, would be some work.....
ps as far as an ACD rating, it might be nice, but it's not that important in general. A data sheet with particular bench tests and specs might be nice rather than the marketing fluff, tho....
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AVR sales according to some industry sources was right at $2 billion. Just guessing an average of $500 per purchase you have 4 million units shipped. This is for the USA only. So somebody is buying them.
My guess on how many have projector systems is 5% or less.
I wonder how many of them run in 2.1 mode, or 2.0 mode. I suspect a lot of them.
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I'd guess at least half.
That was EXACTLY what we were telling them. Class D all the way with say 150 at 4ohms for L/C/R all driven at once and the surrounds all had to do 70% of the 150 at 4 ohms to pass. This means class D and if they wanted split the power supplies from everything else in a two box configuration that would be fine. This also means the pre box could increase its measurable (by Amir) performance and bring surround sound up A LOT in the tests. Of course the amp is then just a 7 or 9 channel amp. Very easy, yet none of the majors are willing to go there. They refuse to do what I want done. Can you believe that??
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