(1) Using Audyssey results for the measurement, one Salon2 bi-amped with a AHB2 in stereo mode, produces 103dB SPL at my listening position with 2V input to the AHB2. The listening position is 10 ft. from the speaker in a treated room. The AHB2 is set for maximum sensativity. This means that the output is equivalent to 100W into 8 ohm or 200W into 4 ohm with a 2V input. Bi-amping has no effect on these calculations.
Typically I use various D/M gear for home theater so this means that as long as I watch a movie at a 78/-2 volume control setting I'm not clipping the AHB2 even if the Salon is used full range. Like most people I listen at -10 or less vs. reference level, so I'm not close to clipping the AHB2.
- Omitted -
Very interesting and are a close match to my the computation based on measuring 2.83 volts at my 11 foot listening position.
At XMC-1 volume -13 I computed 104 dB requires 128 watts that will not clip driving the Salon2s that are closer to 4 Ohms than 8 through most frequencies.
Playing music at -10 (Salon2s), I could consistently clip using music tracks but not at -13.
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Movies are tough to gauge, especially with the RMC-1.
The volume level varies with the source component and the source format. For example, with TiVo and Dolby Digital, I never go below -28. On the ATV4K, Atmos, and BDs, I may go as low as -12. I attribute this to overzealous attenuation decisions made by the processor that are tuned for 16 channels. It seems that this processor sometimes applying up to 18 dB attenuation to allow for 14 channels of bass management.
This is an issue for all digital processors with high-channel counts. Some may not provide as much attenuation and rely on probability to avoid digital clipping or could apply bass attenuation/compression. There are no standardized rules for digital bass management with digital clipping.
I have observed that -12 (loud) on some concert movies, the AHB2s are not clipping.
For example, my family watched a "A Star is Born" (Gaga version) and "Yesterday" (great movie) on my 5.1 system as loud as my family would tolerate and there were no signs of strain or clipping.
Measurements and use have shown the AHB2 need not be bridged to achieve my estimation of loud listening levels.
There was a time, that I would turn up the system to concert loud for fun. I did that with the Sunfire Signature (400 WPC) amps and the Salon1s and cooked a midrange. I have no desire to repeat this experience. My hearing is important to me now that I am well past my 40'th birthday.
I love the AHB2 performance and have also come to love, excellent clip indicators and well implemented clipping protection that assures my speakers are not damaged.
- Rich
Determining Power Requirements and Actual Output Using Audyssey
I don't think I did a good enough job of explaining the proposed use of Audyssey to determine power output levels. The idea is that the maximum required and available power levels are known based on the gain structure of Denon/Marantz AVR's and AVP's. Other than running Audyssey, no other measurements are required. OK, one pea, three shells...
The concept of the original post above is that at 0dBFS into the DAC IC the Denon/Marantz gain structure will present 2V SE to the volume control. The varying output levels of a digital source don't enter into any of this. 0dBFS from the digital processing will be the maximum input level to the DAC section, with 2V output, regardless of the digital source. This is fixed circuitry, and is after all digital processing, and all potential gain changes except via the volume control IC.
The volume control IC will provide an output of 2V SE at the RCA outputs for a channel when the external volume control is set at 2.5dB or 82.5dB and the Audyssey offset for that channel is 0dB. These volume control settings represent the same actual output voltage from the RCA outputs. These settings are based on the configuration of the Denon unit by the user. Let's stick with 2.5dB.
This means that at an external indicated volume setting of 2.5dB, the maximum SE output is 2V with 0dBFS into the DAC IC. This output is with the Audyssey offset for the channel set at 0dB.
With a 0dB Audyssey offset for a channel, reference level, which is 0dB indicated on the the external volume control control will result in an SE output of 2V - 2.5dB, and an acoustic output of 105dB SPL at the listening position from each Salon2. The input to an external power amplifier would be 2V - 2.5dB.
For an example with easier numbers, an Audyssey offset of -3.5 dB for a channel would result in an output of 2V - 2.5dB - 3.5dB = 2V - 6dB, that is 1V, at 0dBFS for the channel. If an AHB2 was connected to the SE output, and set for maximum sensativity, the output would be 100W at 2V input. With 1V input the output would be 25W into 8 ohm. This would mean that at reference level of 105dB SPL at the listening position, the output of the AHB2 would be 25W into 8 ohm.
Actually of course the output of the AHB2 would be a voltage. Power output would be determined by whatever current was required to obtain that voltage at any particular instant, since the AHB2 is a voltage source. 25W into 8 ohm, 50W into 4 ohm, xxW into y ohm, etc. Any of these outputs is the result of the same voltage input. If possible, it's best to stick to dB's, voltage and current for these sort of calculations. The AHB2 is an excellent voltage source. Lesser power amplifiers and certainly the mediocre amplifiers in AVR's the voltage would drop off a dB or two into 4 ohms, especially if more channels were driven. This drop-off in voltage limits the maximum SPL output into lower impendences, but we'll ignore that effect.
Another example, an Audyssey offset of +2.5dB for a channel would result in an output of 2V -2.5dB + 2.5dB = 2V. If an AHB2 was connected to the SE output, and set for maximum sensativity, the output would be 100W at 2V input into 8 ohm.
In my case, the Audyssey offset for the Salon2's is 4.5 dB. This means an SE output of 2V -2.5dB +4.5dB = 2V + 2dB would be required for an output of 105dB at the listening position from a Salon2. This means that 105dB can't be achieved since driving an AHB2 with over 2V would result in clipping. The maximum that can be achieved is 105dB - 2dB or 103dB at the listening position. This output would obtained at an indicated setting of -2dB on the external volume control.
Since I rarely listen to material with a reference output (DVD's, Blu-Rays) at over -10dB indicated on the external volume control the AHB2 isn't driven into clipping. At -10dB on the volume control the maximum output from one of the Salon2's of 95dB SPL. There is still headroom to turnup the volume by 8dB.
Material from Amazon Prime or YouTube, or about anywhere else seems referenced to who knows what, but ultimately maximum digital level will be 0dBFS. If listening at the same subjective loudness to these other sources then the maximum output should again be 95dB SPL. There is headroom to 103dB SPL, in case for some reason playback is at higher subjective level. Some material may have a maximum level far below 95dB SPL, other material may be compressed and loud, and continually operate near 95dB SPL.
Thoughts?