09-Oct-2015, 08:16
Wow - got a great and detailed answer from Devialet support. That also brings some new insights:
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For a given audio material, between its stereo and its multichannel version, the overall audio energy is either split into 2 or 5.1/7.1 channels. Thus, the energy per channel is always lower on a multichannel programme. That is why, on most AV amps, the average analog voltage level found on the stereo preout is much higher than the average voltage level found on the 5.1/7.1 preouts. The difference can easily reach the 12-20dB range. A CD player commonly outputs 2.0Vrms while reaching 0dBfs. So do analog 2.0 preouts. But 5.1/7.1 preouts feature much lower levels, say 0.5Vrms for 0dBfs. Remember that 0.5Vrms on 7.1 channels deals with more global energy than 2.0Vrms on 2 channels only. Input sensitivity on our analog inputs must be adjusted in order to take those differences into account. If not adjusted, useless operating margins will be provided in our units, in order the ADC input stage to never saturate.
Please check your Denon documentation and determine its output level on 5.1/7.1 analog preouts. Once known, adjust it via our online configurator 'Maximum Level' slider.
Why are our units hotter in bypass mode ? Under normal circumstances, without bypass mode, and especially with digital inputs, the instantaneous digital level of the incoming content is monitored and we do perform minimal ideal biasing conditions, leading to the minimal amount of wasted heat without any compromise on distorsion nor compression of the incoming material.
With bypass mode, the output power isn't known anymore, as our units do not control the output levels anymore. A silent signal or a full amplitude signal will lead to identical bias dissipation, as 99% of other amps do.
Bad input configuration will lead to increased bias and therefore useless heat. If ever we had a 5.1/7.1 amp based on our various technologies, you'd be surprised on how cooler it would run compared to most AV amps.
You really shouldn't worry about temperature.
Our units, although being beautiful objects, are industrial+ grade equipments with most components capables of thousands hours of continuous operation above 100°C and internally limited by us to 70°C, allowing an extremely comfortable thermal margin and therefore component lifetime. There are 10 thermal sensors in each product with thermal shutdown in case maximum temperature is reached. What you experience in bypass mode is way easier than the thermal test run at the factory during production. Again, no risk for your amp.
Now to conclude, we need your configuration file plus all the values of the adjustable parameters (SAM, RAM, tone control, filters, ICM, DPM etc...) in order to investigate this 'power loss' issue. We'd also need the software version running on the amp and the temperatures when this loss of power is experienced. It could be a software/configuration issue. By the way, we'd advise not to use SAM in bypass mode, especially with a subwoofer in the setup. The reason is that the additional bandwidth provided by SAM will pollute the bass management of the AV amp.
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For a given audio material, between its stereo and its multichannel version, the overall audio energy is either split into 2 or 5.1/7.1 channels. Thus, the energy per channel is always lower on a multichannel programme. That is why, on most AV amps, the average analog voltage level found on the stereo preout is much higher than the average voltage level found on the 5.1/7.1 preouts. The difference can easily reach the 12-20dB range. A CD player commonly outputs 2.0Vrms while reaching 0dBfs. So do analog 2.0 preouts. But 5.1/7.1 preouts feature much lower levels, say 0.5Vrms for 0dBfs. Remember that 0.5Vrms on 7.1 channels deals with more global energy than 2.0Vrms on 2 channels only. Input sensitivity on our analog inputs must be adjusted in order to take those differences into account. If not adjusted, useless operating margins will be provided in our units, in order the ADC input stage to never saturate.
Please check your Denon documentation and determine its output level on 5.1/7.1 analog preouts. Once known, adjust it via our online configurator 'Maximum Level' slider.
Why are our units hotter in bypass mode ? Under normal circumstances, without bypass mode, and especially with digital inputs, the instantaneous digital level of the incoming content is monitored and we do perform minimal ideal biasing conditions, leading to the minimal amount of wasted heat without any compromise on distorsion nor compression of the incoming material.
With bypass mode, the output power isn't known anymore, as our units do not control the output levels anymore. A silent signal or a full amplitude signal will lead to identical bias dissipation, as 99% of other amps do.
Bad input configuration will lead to increased bias and therefore useless heat. If ever we had a 5.1/7.1 amp based on our various technologies, you'd be surprised on how cooler it would run compared to most AV amps.
You really shouldn't worry about temperature.
Our units, although being beautiful objects, are industrial+ grade equipments with most components capables of thousands hours of continuous operation above 100°C and internally limited by us to 70°C, allowing an extremely comfortable thermal margin and therefore component lifetime. There are 10 thermal sensors in each product with thermal shutdown in case maximum temperature is reached. What you experience in bypass mode is way easier than the thermal test run at the factory during production. Again, no risk for your amp.
Now to conclude, we need your configuration file plus all the values of the adjustable parameters (SAM, RAM, tone control, filters, ICM, DPM etc...) in order to investigate this 'power loss' issue. We'd also need the software version running on the amp and the temperatures when this loss of power is experienced. It could be a software/configuration issue. By the way, we'd advise not to use SAM in bypass mode, especially with a subwoofer in the setup. The reason is that the additional bandwidth provided by SAM will pollute the bass management of the AV amp.
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