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I was thinking more of the method that varies the rail voltage cleanly and efficiently
Should be easily achievable with a SMPS, you're effectively just looking for a 0-50V DC bench power supply, they can be had pretty cheap from China.
Not sure a PC PSU is clean enough for audio
Everything is powered by SMPSs now, obviously to drive just the logic in a class D amp you're looking at something more like the internal PSU of a phone rather than a 250W gaming PC PSU. The RFI issue is greatest at the high power end, and you have that problem from your class D output stage regardless of what you do with the logic PSU.
The alternative to messing with the rail voltage would be to mess with the pulse width, but I don't know whether you can get pulses down to narrow enough for the quiet passages if you also want the volume down to -40dB relative to full power. If your pulses get elongated due to finite rise time, you effectively have a compressor because the short pulses (low amplitude) have more excess area under the graph than long ones.
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Digital people: got my eye on a DACBerry One+ as an upgrade to the Chromecast internal DAC, connected with toslink. Thoughts? Just using the highest quaintly Spotify as input.
For the record, CCA has been great so far. Now we use voice control, switching between apps for radio and Spotify isn’t a problem. Just have to keep the cheap BT received for movie audio as the CCA has too much lag.
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I would guess that something like that would be the way to go. People say the cca dac is pretty decent so cheap upgrades don’t give significant results. RPi based stuff does have a rep for punching above its weight price-wise so hopefully you’d get a decent improvement.
For my TV (as an example of lower res inputs) I run from the headphone socket using its own DAC into the amp, mostly so I can still use the tv remote for volume, but it sounds very good for movies where impact is more important than fidelity and for radio which I very rarely listen to without doing something else at the same time, unless it’s test match special. That’s probably a similar oem DAC implementation as the CCA.
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For my TV (as an example of lower res inputs)
Just as a matter of idle curiosity, what is TV audio these days? The last time I had one, it was NICAM, which I understood, but I have no idea what's in a DVB-T stream
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I’ve no idea but it seems to get better with picture resolution, ie blue ray is noticeably better than broadcast Cash in the Attic on Virgin fibre optic.
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blue ray is noticeably better than broadcast
Minimum audio stream on Bluray is 16bit 48kHz linear PCM, so similar to CD. Can be as high as 24 bit 192kHz.
DVB uses lossy compression (mostly AAC, it seems), bit depth, sample rate and data rate are chosen to suit the content but can be as low as 32kHz sample rate and 32kbit/s data rate for primary streams. -
Anything described as a network streamer. Yes pi and optical out hat will do it.
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Missed out on this weird combo - only really wanted it for the Hypex amp, the DACberry and PSU would have been a bonus.
Actually pretty happy not to mess with the new (to me) simplicity of the CCA, and avoid the incremental DAC upgrade rabbit hole.
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That’s a neat way of putting it all together.
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Recently replaced a lost Chromecast Audio with a Pi Zero + Dac (PCM5102A). No difference in sound quality but the Chromecast is much more convenient in terms of Android app integration. Spotify Connect works well on Volumio (Pi distro) but no such luck with Soundcloud and Mixcloud.
Annoying thing about the Chromecast, with Spotify, is that you can't start a playback session from a computer. You can start casting from Spotify on your phone, and then control it on your computer through Spotify Connect, but you can't use Connect directly from your computer on the Chromecast. The Pi setup is better in that regard.
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Makes sense really as you could use the amp separately or have some kind of further processing like dsp in the loop. Might have been neater with normaled patch cables so that the connection is direct when there's nothing in the socket.
Could lead some to hours changing phono cables looking for that sweet spot :)
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That’s good to know. While I was debating how much to risk on that FrankenNaim I read enough to know the CCA DAC is actually pretty good, good enough that I doubt I’d be able to tell the difference, especially without lossless source.
Really enjoying the convince of the CCA. Google Assistant works way better than with the Sonos. No “session” starting from macbook is a bit annoying, but I’ll normally have it playing something already so by the time I open the Spotify app on phone or macbook it’s already going.
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Got it, no worries.
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@dbr I was excited to find this last night, a 3-way hypex plate amp, 125w to each driver, digital input and DSP active crossover - basically what I’ve been tying out with all the little boxes. Those could be installed in my cabinets and all it would need is the streamer as input and a digital cable linking the 2 speakers. Tidy.
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Yeah, they’re good eh? Troel Gravensen is a fan.
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About
Audiophiles hifi appreciation thread old and new
Posted by
@coppiThat
You can look up the new bits. His DSP and the two little Topping DAC/Amps come to less than £400
Old stuff is free considering how long you've already extracted value from it. Let's say for the sake of argument my speakers and power amps give me £1 worth of pleasure every week, then they were already fully paid for more than a decade ago.