08-17-2022, 05:55 PM
Hi, Peter.
I'd think the first people to ask about heating issues are Nubert staff themselves, via their forum.
Of the amplification process, i cite this quote from a 8moons.com review (because the review was published in English, not German).
Bottom line for me is the speakers should not get hot with zero audio input. The German-language spec sheet says the standby power consumption is
I'm intrigued by this sentence in your original post
There should not be any noise. What is the nature of it? A broad-frequency hiss-like sound or a low-frequency hum-like sound?
The latter in particular could be hinting that a ground loop exists in the wiring interconnecting your Pi/DAC, your Nupro speakers, and their respective power sources. An unwanted AC signal generated in the group loop could be driving the Nupros continuously even with zero audio signal from the DAC. This, in turn, could cause both "noise" and heating.
Or not. I'm just conjecturing here in the face of almost no information.
Quick tests:
Regards,
Kent
I'd think the first people to ask about heating issues are Nubert staff themselves, via their forum.
Of the amplification process, i cite this quote from a 8moons.com review (because the review was published in English, not German).
Quote:With that in mind I asked Markus Pedal, key developer in the nuPro range, what distinguishes their so-called digital amps.
[Markus said] "As you know, class D generates a PWM signal by comparing the analog signal to a triangle wave. The result is a signal with two amplitude states at variable pulse width. It's neither fully digital nor analog but a type of hybrid which shouldn't be called a digital amplifier. In our nuPro models there's no D/A conversion after the DSP stage which mathematically converts incoming PCM data to PWM which now switches the output transistors directly. Unlike conventional class D this is purely digital [hence NAD and NuForce refer to their equivalents as direct-digital amplification – Ed]. The elimination of a D/A stage creates astonishing S/N ratio particularly when the digital inputs are used to avoid conversion losses."
[the reviewer added] To reiterate, the most direct input path is via digital since the analog input relies on conversion to digital by Cirrus Logic CS5364.
Bottom line for me is the speakers should not get hot with zero audio input. The German-language spec sheet says the standby power consumption is
Quote:Standby-Leistungsaufnahme 0,4 Watt
I'm intrigued by this sentence in your original post
Quote:In addition, the speaker emits a "noise" in standby.
There should not be any noise. What is the nature of it? A broad-frequency hiss-like sound or a low-frequency hum-like sound?
The latter in particular could be hinting that a ground loop exists in the wiring interconnecting your Pi/DAC, your Nupro speakers, and their respective power sources. An unwanted AC signal generated in the group loop could be driving the Nupros continuously even with zero audio signal from the DAC. This, in turn, could cause both "noise" and heating.
Or not. I'm just conjecturing here in the face of almost no information.
Quick tests:
- Do the speakers get hot when they're disconnected from the Pi/DAC (or when the Pi/DAC is disconnected from its power source)?
- Do they get hot when they're connected to some other AC-powered line-level music source, a CD player perhaps, via the same aux-input RCA connectors?
- In either case, does the noise go away or does it remain?
Regards,
Kent
