So your AV7705 and AV7706 AVP's + all your ACD amps were "Optimal" vs AVR?
What's the definition of Optimal?
Just like how the AV10 (2024) engineering has improved over the AV7706 (2020), perhaps the engineering of the X6800H (2024) has also improved over the x6700 (2020).
So perhaps "Optimal" is more about technology/engineering and less about AVP vs AVR.
And if you want to discuss the Audioholics articles about ACD, here it is.
This article explores the All Channels Driven power test popularized by some print magazines and manufacturers. It discusses its relevancy and real world implications.
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So the ACD is entirely invalid?
The answer to this question is a qualified "It depends." ACD can be thought of as a conditionally valid test to determine if an amplifier is capable of instantaneously consuming all of the power from the wall outlet. In the best case scenario, it can reveal the absolute capability of the amplifier's power supply. If the amp has a robust power supply then you will simply be testing for line voltage sag on an unregulated line up to the fuse limit of the amplifier.
The problem however (as documented in our previous article: The All Channels Driven Test Controversy) is that many budget products are designed for real world performance and must make trade offs for safety and heat dissipation reasons. As a result, they design their amps to be dynamic, but limit the total output capability of the product with a limiter that activates if more than three channels are driven at full power. The result of driving more than three channels at full power is reduced power delivery to all channels to satisfy the heat dissipation requirements of UL, as well as the manufacturer's requirements for dependability and reliability. Thus, when a publication does the classic ACD test into 5 or 7 channels, the reader can get the wrong impression that the amplifier isn't very capable at delivering power despite the fact it exceeds manufacturers specs with flying colors with only one or two channels driven continuously, and also satisfies the old FTC mandate for rating power into two channels.
So What Have We Learned?
- Most of the ACD power figured in magazines and/or in manufacturers product literature are highly conditional, vary from publication to publication, and are usually not product representative. These ratings are typically taken using the 1kHz Psweep test for 8 ohms at amplifier clipping and almost never done at 4 ohms for all channels.
- The ACD test is NOT representative of normal program material.
- Compromises in budget gear must be incorporated to produce dynamic amps while meeting stringent UL/CSA heat dissipation requirements under continuous loading conditions.
- Despite many manufacturers' boasts to the contrary, most multi-channel amplifiers' ACD power ratings are, at best, a highly conditional rating.
- The ACD test isn't a clear indication of the power capabilities of an amplifier designed for dynamic power delivery as a primary metric.
If ACD Doesn't Matter, Then What Does?
The following metrics can provide a far more insightful view of real world amplifier performance:
- Amplifier Bandwidth Linearity
- Output Impedance
- Amplifier Distortion + Noise at Various Power Levels
- Signal to Noise Ratio
- Channel to Channel Isolation
- Amplifier Stability under reactive load testing
- True continuous undistorted power delivery into one or two channels under various loading conditions
- Amplifier power stability with multiple channels driven at reduced power while the primary one or two channels are driven at full rated power.
