By itself, the lme49721 is too weak to serve as amp, you need an output buffer.
Here is a suggestion for an usb powered headphones amp. It is tailored for a 2Vrms input and 4.5Vp-p output. If the input level is usually lower (like 1vrms), R9 can be reduced or deleted and R2 adjusted to provide the required gain.
R8 is a 10k log pot as volume control.
Obviously missing are decoupling caps, an input filter (a simple cap to gnd after R9 would do).
Here is a suggestion for an usb powered headphones amp. It is tailored for a 2Vrms input and 4.5Vp-p output. If the input level is usually lower (like 1vrms), R9 can be reduced or deleted and R2 adjusted to provide the required gain.
R8 is a 10k log pot as volume control.
Obviously missing are decoupling caps, an input filter (a simple cap to gnd after R9 would do).
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The Bravo sa9023 works without any drivers, however, I’m not sure if it requires any programming. I would consider it the next step up from the pcm27xx, but not sure if it will be as simple to implement.
I have the sa9023 in a dac on a separate board, have recently done some work on it since it had the wrong spec capacitors on it, were too far from the regulators as well. Doesn’t sound too bad.
I have the sa9023 in a dac on a separate board, have recently done some work on it since it had the wrong spec capacitors on it, were too far from the regulators as well. Doesn’t sound too bad.
SaviAudio aka Bravo is price to performance products but due to poor documentation and supply , I don't think I can get hands on it.
C-media CM6631A available in my local part's shop. The shopkeeper said it performs good . I want your opinion guys.
I have two PM1794A DAC but I don't whether it would performance good from USB . I need a 5v to 3.3v convertor.
C-media CM6631A available in my local part's shop. The shopkeeper said it performs good . I want your opinion guys.
I have two PM1794A DAC but I don't whether it would performance good from USB . I need a 5v to 3.3v convertor.
The pcm1794 needs at least 4.75V for the analog section. If USB power isn't clean, a CLC filter and a low dropout reg can do the trick. Same for the digital section, with another reg.
You can pretty much take the PS section from here: http://www.diyaudio.com/forums/digi...d650-request-design-critique.html#post4066067 Obviously you replace one of the tps79333 by a TPS793475
The cm6631a is ok but documentation is a bit scarce. I've used a ready made board by diyinhk that wasn't bad.
You can pretty much take the PS section from here: http://www.diyaudio.com/forums/digi...d650-request-design-critique.html#post4066067 Obviously you replace one of the tps79333 by a TPS793475
The cm6631a is ok but documentation is a bit scarce. I've used a ready made board by diyinhk that wasn't bad.
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Yes it is very satisfying. When pluggeded it into USB I lost in heaven. I was playing five finger death punch wrong side of heaven and yanni keys to imagination. I never thought it will work at first run . I made everything with veroboard since I don't know to make PCB. I collected components very hardly since I live in a village which is sparsely populated. I am so happy. Hope my friend will be too for whome I made it. I will make one for me too but this time I want to design a PCB myself . Which software shall I use ?☺️ My PC specs are not good but still work fine. I7 3770k +128GB ssd +gtx 980 +32gb
All I use is XP professional x64 Do I have to upgrade my PC or operating system to design PCB?
All I use is XP professional x64 Do I have to upgrade my PC or operating system to design PCB?
PCB software aren't very hungry, your computer is more powerful than mine by far.
There are two possible good free options in my experience.
Either Kicad, which is an open source pcb layout editor. It is unrestricted and pretty powerful. It used to be hard to use and not very popular but it's getting better and more widely used.
Or Eagle, which has a free license version. The catch is that it is limited to 80cm² and two layers. The upside is that it is fairly common among hobbyists.
I started with Eagle and I stick to it as most of my projects fit under those restrictions. But if I were to start now, I'd probably go with kicad. It's quite a steep learning curve with any of these programs anyway.
There are two possible good free options in my experience.
Either Kicad, which is an open source pcb layout editor. It is unrestricted and pretty powerful. It used to be hard to use and not very popular but it's getting better and more widely used.
Or Eagle, which has a free license version. The catch is that it is limited to 80cm² and two layers. The upside is that it is fairly common among hobbyists.
I started with Eagle and I stick to it as most of my projects fit under those restrictions. But if I were to start now, I'd probably go with kicad. It's quite a steep learning curve with any of these programs anyway.
Well, good look if you´re beginner!
I´ve attached block diagram then I´m working on similar project:
- own stamp sized UAC2 receiver based on XMOS XU208 (under test)
- own stamp sized PCM/DSD DAC based on AKM AK4490 (in progress)
- COTS chinese aptX HD receiver (waiting for CSR8675 availability)
- Line levet input
- volume before Class A amplifier section
- microcontroller for UAC2 receiver, DAC configuration, Charger and gauge control, OLED visualization
- Lithium batterie with 5000mAh
- one booster and Nx LDO´s
- mostly SMD components
I´m using successfully EAGLE (evaluating today new version).
JP
I´ve attached block diagram then I´m working on similar project:
- own stamp sized UAC2 receiver based on XMOS XU208 (under test)
- own stamp sized PCM/DSD DAC based on AKM AK4490 (in progress)
- COTS chinese aptX HD receiver (waiting for CSR8675 availability)
- Line levet input
- volume before Class A amplifier section
- microcontroller for UAC2 receiver, DAC configuration, Charger and gauge control, OLED visualization
- Lithium batterie with 5000mAh
- one booster and Nx LDO´s
- mostly SMD components
I´m using successfully EAGLE (evaluating today new version).
JP
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