I am planning to build a portable DAC/headphone amp with balanced output (not just a part of portable player, but also as an "output soundcard" for my music processing)
I want to use an 18650 battery since their shape allow easy replacing, pretty enough capacity and most important: rechargeable. Also because primary cells occupied a lot of space. But DAC chip and opamps need higher, even isolated or symmetrical power supplies.
But I am considering about choose voltage booster. TPS65135 or other transformerless method vs inverter style (convert DC to AC/pulse before supply to multi-output transformer). Any comparison of small, high efficiency, low EMI, easy-to-suppress ripple? Two later features are more important.
Thanks!
I want to use an 18650 battery since their shape allow easy replacing, pretty enough capacity and most important: rechargeable. Also because primary cells occupied a lot of space. But DAC chip and opamps need higher, even isolated or symmetrical power supplies.
But I am considering about choose voltage booster. TPS65135 or other transformerless method vs inverter style (convert DC to AC/pulse before supply to multi-output transformer). Any comparison of small, high efficiency, low EMI, easy-to-suppress ripple? Two later features are more important.
Thanks!
Depending on what impedance headphones you're driving (and hence the voltage swings likely to be needed) you may only need a voltage doubler IC. I'm using LM2662 for this purpose in my DACs and headphone amp - it has no shortage of output current (200mA) is low cost and lowest EMI (by virtue of being a charge-pump rather than a boost converter needing an inductor). If you need a negative voltage too you can use another LM2662 to deliver that - the boost mode needs an external diode to prevent latch-up.
I use an 16 Ohms orthodynamic headphone. Any suggestion? Many information seem about 32 Ohms dynamic headphones, not ortho.
Mine is 94 dB/mW SPL, seem medium.
Can you also give my suggest about volume control method. I have terrible experience with small stereo potentio. Accuracy enough pot seem only too large. I have no experience with digital volume control.
I think they are not cheap immediately after see the image
Channel matching seem good enough
But I wish I could make smd stepped attenuator
I like the feel of mess up with crazy small stuff
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What about TPS6513x series? I just began feel scare of discrete or low integration method.
By my calculations you'll only need 1.8V peak to reach 120dB so no need for step-up.
My suggestion would be to build an integrated DAC-amp using TDA1387 as your DAC. Its volume can be adjusted by a DC voltage control on its 'ref' pin so no need for any pot. Or alternatively use digital volume.
What a pity! I want something capable of decoding even 32 bit audio files. I don't think 32 bit or how many bit are important but I usually editting audio for film or recording. Always have to convert any thing into 16 bit before play is really a pain in the ***
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