Integarted Amp with DAC, Power Amp and Headphones Amp

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One might be able to use one amp depending on the details. For example, its not optimal to use a 100w power amp for high sensitivity headphones, although a big attenuator with low output impedance might be made to work. Something like that.

Regarding switching the dac from one amplifier to another, a switch or a relay could do it. It could also be done with solid state switching. Another way might be to leave the dac outputs connected to both amps, and turn off power or turn down the volume on the amp not in use. Again, it all depends on the details and what one is trying accomplish. The highest fidelity? The lowest overall cost? And so on.

If an important feature is to have the HPA jack do the switching, then I would probably use it to control a miniature relay maybe with gold plated contacts. Depends on how I would be planning to use the relay. But, that's just me, and there are lots of ways to do it.
 
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Ha, misspelled and cannot edit it anymore. So from now on it will be called 'Integarted' Amp :)
You have pretty cool project. I hope you will place the power switch on the front in the final version ;)
I'm building something similar but in two separate boxes. One box will have Pi with 7.9" display and relays module which will switch power for connected hard drives:
https://www.diyaudio.com/forums/pc-based/360380-nas-streamer-2.html
Another block will be "Integarted" Amp :)
Could you share the details about your amp? What DAC and Amp do you use?

Thanks!
 
Thanks

No power switch planned - there are only wires to and from the transformers, everything else is PCB

The amp is a lateral mosfet class b, has offset protection, soft-start.
This particular version is about 140w in 4R impedance and will have another ver soon.
The signal chain has no capacitors in line. I use Jensen sig transformers at the DAC.
Had to design my own DAC in order to fit everything well.
New ver DAC coming soon too with line receivers option.
This ver design will work with a FIFO option as well

Next unit ver in a year or so may be quite exceptional if I decide to continue

Check this link for a utility called hdparm for spinning down your drives..
hdparm - ArchWiki
 
I was recommended to use this USB DAC:
https://www.amazon.com/gp/product/B07KN6P9QB

My reckoning would be that an amp-camp power amp would probably have more potential to sound good than such a dac could ever produce. The newer 'Kahdas Tone 2 Pro' would likely be a better fit. Another good quality for the buck option might be an Allo Revolution dac.

On another note, bare dac boards tend produce their own EMI/RFI. They can also be sensitive to external sources of it. Better to use one that is designed into a properly engineered, purpose-built case, at least if sound quality is more of a concern than the visual appeal of having it all in one box. That's what I would say to the non-EE or even an EE without experience in that area.
 
synonymous,
Which DAC do you use? Is it your own design? Is Amp also your own design?
I'm aware of hdparam and udiskctl. I'm not sure that they work for USB hub. It should be verified.

Markw4,
Yes, I'm waiting for Tone 2 Pro which should be released in February to see if it's really a better one.
 
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Custom - built around the PCM5242
My requirements are hardware volume control (since my unit has no knob) and balanced drive (since the opening and closing of the Pi sound system produces nuances).

My amplifier has no attenuation at it's input and is incredibly silent, dare I say impeccably silent. There are no capacitors in the signal chain with only the signal transformers between the DAC and amplifier. It is amazing.

Each is in their pursuit of their own ideas - mine is simplicity
I have about 2k worth of new parts just mailed to me ready to apply to the next beta of PCB sitting in another box. About a years worth of fine tuning. This DAC ver will test line recievers in place of the signal transformers. One of the RPi engineers developed a new feature based on my idea and in the same motion provided me with my very own overlay-driver that just got included in the latest RPi release! In the last year other unrelated but welcome improvements have occurred with other projects in the software realms that I have now included and am testing with great positive results. One has been the spotify connect functionality. Last year it was not so good with issues with gapless playback not working, while now I take another look to see that it's working like a pro now. Many many many things considered here that have sharpened the machine, i.e space for the FIFO and much more. I'll give a shot and video in a few weeks most likely about it with the new version.

S

Screenshot from 2021-01-10 18-59-59.png
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No
I haven't yet decided on the path for the unit(s)
I think at the least I will sell a few batches of PCB for those interested here DIY
There are so many that like to build their own amps that I imagine theyd maybe just want the Pi - DAC - start - and protection integration, so thinking about options there..
This is most likely the amp I will be with for life, so if there's any other design put onto the mainboard it would be for fun for me for somebody that was truly interested. My intention here is to make the DAC part of the chain interchangeable for futureproofing. There is also the potential of one having their own scheme and PCB made and then soldered over the top of what I have here and using the pins for all the applicable parts of the circuit. They would have to manually add holes to the heatsink depending on what they designed onto it. Honestly, the weakest link in this chain are the speakers and the listening room by far far far - into the - far far future.

I will probably sell these personally in my area and maybe online, but am not against sharing with the community here in diy.
I think you get my drift
S
 
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