I'm planning a theater and need help with this industries shady spec practices. Here's the scenario, 5.4 channel. External amps powering mains, surrounds, and subs. I'd hate to buy another berry amp to power just the center. So when a receiver is advertised as "140 watts per channel" and in the fine print it says "1 channel driven", does that mean that I can get 140 watts out of the thing if I'm only powering 1 center channel speaker?
I usually go straight to the specs and thd for 2 channels driven and all channels driven, which is typically around 70 watts for x 2 channels, and like 35 watts for all channels. But now I need to know if the misleading "1 channel driven" spec is true if you are actually only driving 1 channel. Thanks guys and girls.
What is the receiver? In the us, most manufacturers interpret FTC rules to require two channels driven output specs. Every channel has separate power transistors, in the last 15 years or so they are all identical. In typical receivers all the channels share the same power supply. When the power supply becomes overtaxed, the output transistors' clean output sags.
One channel or two channel specs do not tell you what the output would be with music or movies with more channels driven to the same levels on accounta it depends on the power supply. Of course no real content, meaning not a test signal, has exactly the same power needs from all channels during any given second of the movie or whatever, so all channels driven is certainly interesting but not necessarily a controlling factor.
Even more so for folks like me that listen at least ten dB (one tenth power) below reference levels for movies. I probably don't need 20 watts to hit peaks in my room with my speakers at the levels ibprefer. A 140 watt amp cannot deliver a different kind of 20 watts than a 50 watt amp. Ohm's law. So for me it doesn't much matter although I probably spent over 100 hours researching third party tests of receivers before I bought mine
Loudspeakers with capacitance and inductance, and especially amplifiers that additionally contain non-linear devices such as transistors, don't fit neatly with;
I = V / R. These devices can't be modeled as a battery and lengths of wire.
The outputs of two different amplifiers at the same output power level; driving a resistance, very likely have different levels of distortion and noise, and different frequency responses. Throw in loudspeakers as loads, that are effectively resistance, capacitance and inductance, and you need more than Ohms law to compare the results.
If you look at the specs, it says "100 W per channel (8 ohms, 1 kHz, 0.9% THD, 1-ch driven)"
This isn't the amp I'll be using, and I'm not sure which one I will be using yet, I'm in the planning stage. I'll be using the cheapest receiver I can get with pre outs. I'll be using these for LCR and surrounds:
I'm want to use external amps for the LR and surrounds. I wanted to know if the "1 channel driven" spec is the power I would get from power ONLY a center channel speaker with the AVR.
If you look at the specs, it says "100 W per channel (8 ohms, 1 kHz, 0.9% THD, 1-ch driven)"
This isn't the amp I'll be using, and I'm not sure which one I will be using yet, I'm in the planning stage. I'll be using the cheapest receiver I can get with pre outs. I'll be using these for LCR and surrounds:
I'm want to use external amps for the LR and surrounds. I wanted to know if the "1 channel driven" spec is the power I would get from power ONLY a center channel speaker with the AVR.
In an average size room, using a heafty sub and the receiver setting the speakers to small, redirecting the power hungry bass to the sub allows for headroom in the receiver. This is usually sufficient volume. Purchase a separate processor and separate power amp with more accurate power specs for higher performance if you have a fat wallet or a high balance on your credit card.
EZ to calculate available output power..
If the specification is only for 1 channel driven then this is maximum the power supply can handle. For example if the 1 channel driven spec is 100W and the AVR has 5 channels, simply divide 5 (# of channels) into 100W equals 20W per channel.
However I would advise U to be very apprehensive...
A product that only discloses a 1 channel driven specifcation is usually a low end, low quality, low performance.
100 W per channel (8 ohms, 1 kHz, 0.9% THD, 1-ch driven)
70 W per channel (8 ohms, 20 Hz-20 kHz, 0.09% THD, 2-ch driven)
The difference in distortion spec indicates that the amp probably sounds good at about 70W but at 100W even with only one channel the distortion is on the verge of audibility. There is more to the picture though.
At 100W that single channel is also only rated at 1KHz. Distortion at 1KHz is just about the easiest target to hit. Over 20Hz-20KHz the distortion is certainly higher than 0.9% and certainly audible. I would not use that number as any indication of anything at all except the desperation of the marketing department to put big numbers out there.
No its not simple math. At least not for you. In fact you are just babbling. Dividing the one channel power by the number of active channels does not give you any useful information. Except to show that you have no clue as to how a power amplifier works or what is really amplified.
Oh really...
An entry-level AVR will not have a stiff, regulated power supply..
Power supply regulation costs significant $, and not affordable in an entry-level, budget AVR.....
Pretty simple math..
In fact...
If U know a design way to obtain continuous, high power multi-channel output for all channels driven in an entry-level, budget AVRs. without increasing material costs....
My recommendation is that U should contact either Marantz, Denon, Yamaha or Onkyo as that is a significant technical breakthrough that would be very valuable and pertinent to them for substantial cost savings...
You are moving the goal posts. That is not what we are "debating". We are debating you claim in #8 :
"If the specification is only for 1 channel driven then this is maximum the power supply can handle. For example if the 1 channel driven spec is 100W and the AVR has 5 channels, simply divide 5 (# of channels) into 100W equals 20W per channel."
This is still not true and never will be. Not for entry level receivers and not for any other receiver. Go look up measurements for a bunch of receivers and see for you self that the relationship between full power in 1, 2 or multiple channels is not what you claim. One channel is not double of two channels, or five times of five channels.
Oh and stop wasting my time with you lame straw man arguments. I'm not biting.
Who is moving the goal posts...
Keep in mind the following as an example...
The power supply for a budget, entry-level AVR is only capable of 35V/8 Amps..
Assuming it is a single power supply with 1 pair of secondaries, and there are 5 amplifiers channels drawing equal power just divide up the available VA. The max VA output of the power supply is incapable of increasing its voltage and current beyond its design limits. Yes, there are other factors to consider including protection circuitry, current limiter schemes and parts tolerances but when trying to estimate the continuous power of all channels driven for a budget entry-level this will provde a reasonable, approximation of its capability. Since the brand doesn't provide this specification. There are additional factors to consider as well, how long is the power output measurement being done? 30 seconds, 1 minute or 5 minutes as the FTC rule specifies.. A higher power output measurement may be obtained if it is a qwik short test for a peak reading, but the longer the test the more heat rise and saturation amd less efficiency of the power supply components
Since we have designed/built/sourced/sold > 5 million budget, entry-level AVRs for the primary brands including Kenwood, Denon, Onkyo, Pioneer, Sony, Harman/Kardon, JBL we do have some experience for this subject..
Final note...
As I previously posted..
If U do in fact have a breakthrough power supply design which delivers more continuous output power with all channels driven that is applicable for an entry-level budget AVR..
Pls forward more technical details and I will put U in contact with certain AVR design teams, who will pay significant $ for this once validated.
You are moving the goal post. Trying to obscure the fact you were wrong in #8 .
Just show some amplifiers that do as you claimed in #8 and explain how your statement still holds true for all (all of them) the amplifier that doesn't follow your claim.
I believe he's saying he has external 2-ch amps covering all but the center, and wants to use the avr for the center rather than buying another amp....
External amps driving all speakers, including subs?
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