I now have the Merus HAT amp working with piCorePlayer and playing music very well.
I had to SSH into the pi to make changes to ALSAmixer settings. For some reason I couldn't change the settings within the piCorePlayer menus (even though the settings can be seen, they couldn't be saved).
It sounds quite good. I understand how these amps have surprised people. I like the silent background and abundance of detail. The overall balance from low to high frequencies is impressive. Maybe just a bit light on bass, but it's just a wee little thing with ~20VDC rails. There is a bit of power output limitation because of the internal limiter settings, but it gets plenty loud enough for my listening.
A very interesting find!
I had to SSH into the pi to make changes to ALSAmixer settings. For some reason I couldn't change the settings within the piCorePlayer menus (even though the settings can be seen, they couldn't be saved).
It sounds quite good. I understand how these amps have surprised people. I like the silent background and abundance of detail. The overall balance from low to high frequencies is impressive. Maybe just a bit light on bass, but it's just a wee little thing with ~20VDC rails. There is a bit of power output limitation because of the internal limiter settings, but it gets plenty loud enough for my listening.
A very interesting find!
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How are you powering it? In your photo I can't see a supply connected to either of the power connections?
I was using one of these GAN usb-c chargers:
https://www.amazon.com/gp/product/B083J229RJ/
Worked the same whether plugged into the pi or the HAT with a TB3 cable.
That's the same supply I'm using (EU version).
Are you saying that if you power the RPi4 using this supply via the USB-C port it powers the amp HAT via GPIO? I'm surprised, as I thought GPIO could only pass 5v maximum?
I measured the DC voltage at the power-in terminal block on the HAT. I’m not going to try to measure at the IC. I’d definitely fry something.
Oddly, though. The ALSA mixer settings didn't save from last night. I even used 'sudo alsactl store' to make them stay, but no dice. I'll need to find what exact files I can change to keep the right settings.
- TB3 cable into HAT: 20.16V
- TB3 cable into the Pi: 4.6V
Oddly, though. The ALSA mixer settings didn't save from last night. I even used 'sudo alsactl store' to make them stay, but no dice. I'll need to find what exact files I can change to keep the right settings.
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I was unaware of USB-c Power Delivery until your posts.
Ya, ALSA settings are pain. Somehow I discovered how to save them, but can't remember
They use filterstages to get best specs. Because 99% of their customers buy because of these specs. Last 40 years the best DAC"s i heard where without those standard opamp filters or even with no filtration at all.
You'll fry it if you supply 24v (despite the board saying 26v max). Ask me how I know!Normal that it works with the pi power supply.
your Hat card is equipped with a buck boost.
I have a Pi that no longer serves me .... This tempts me seriously ...
Is it really ma12070 which accepts 24 volts or its little brother limited to 19 volts?
Enjoy!!!
The board designer stated the board is setup for 20v supply, but will tolerate 22v. See his post here:
https://www.diyaudio.com/community/threads/infineon-ma12070-class-d.347422/post-6814624
Thank you for the link... It's clear... Too bad not to exploit the full potential of this WONDERFUL CHIP... If
I understand it is the components that revolve around the chip that limits?
If you remove the CH224K (10 pin package near to the USB input) and use the screw terminals, then you can run at 24v
Tube guys measure with their ears, I know. It are reconstruction filters and they happen to filter out RF as well which is a phenomenon that occurs with modern high res DAC chips running at quite high clock frequencies. Example: ESS chips running on 100 MHz oscillators. 40 Years ago that was a frequency you tuned your FM tuner at
16.9344 MHz in a DAC was then already a high frequency.
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