Hi guys I am new here. I am looking forward to make a pcm2707 usb DAC + headphone amp . I am planning to use TPA6120A2 High Fidelity Headphone Amplifier to drive the headphone.
I am actually doing it for my friend who got a Audio technica m50x but his built in sound card of laptop is a crap. Realtek HDA is producing crappy sound.
So guys and gals please suggest me something . Is my design can do the work?
I am actually doing it for my friend who got a Audio technica m50x but his built in sound card of laptop is a crap. Realtek HDA is producing crappy sound.
So guys and gals please suggest me something . Is my design can do the work?
Yes, it can work. Some issues to consider:
- will it be usb powered ? Then you need a dc-dc converter for the amp.
- the tpa6120a is very sensitive to pcb layout. Have a good look at the app note and the design from TI.
- you probably need a buffer in between the dac, the volume control and the tpa. It's best driven from a low impedance.
- make a search on jcx and tpa6120. The tpa is sensitive to capacitive loading and need either a ferrite or a small resistor on its output.
- will it be usb powered ? Then you need a dc-dc converter for the amp.
- the tpa6120a is very sensitive to pcb layout. Have a good look at the app note and the design from TI.
- you probably need a buffer in between the dac, the volume control and the tpa. It's best driven from a low impedance.
- make a search on jcx and tpa6120. The tpa is sensitive to capacitive loading and need either a ferrite or a small resistor on its output.
No.
That DAC is poor and HPA is ugly.
Try this HPA first, then we'll speak about DAC.
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Actually, the tpa can be an extremely good amp. It can be used in multiloop config without much problems, which makes it even better.
Still, I think that if you have to ask those questions, you're not quite ready to start such a project from scratch. The tpa6120 is a bit touchy to get right wrt pcb layout. You'll easily spend as much on this project as on a new Fiio E10K (or even a S.M.S.L X4) and the results aren't certain.
Still, I think that if you have to ask those questions, you're not quite ready to start such a project from scratch. The tpa6120 is a bit touchy to get right wrt pcb layout. You'll easily spend as much on this project as on a new Fiio E10K (or even a S.M.S.L X4) and the results aren't certain.
I already have a TPA6120a home made amp for my headphones. I used minimal space between TPA and components. 39.2ohms resistor 1/8 for output.
Only question is pcm2707 is a good Idea or not. If not then I will pair with wm8741 DAC + pcm2707.
@00940 why I need a DC to DC converter? TPA run from 5v to 15v. Please explain me.
Only question is pcm2707 is a good Idea or not. If not then I will pair with wm8741 DAC + pcm2707.
@00940 why I need a DC to DC converter? TPA run from 5v to 15v. Please explain me.
The tpa6120 runs from +/-5V at worst so you at least need an inverter to get +/-5V from the single 5V from usb (or use a single 10V supply).
The pcm2707 is not a very good dac by itself. It's decent but not great. You might want to look at the pcm5102 or something to pair it with. I've built along those lines and it works fine: PCM5102 USB DAC for sennheiser HD650 - request for design critique
For the amp section, I used a composite opa134+lme49713
One of the problems with the tpa6120 is that it has to be driven from a low impedance and the inputs must be well matched to avoid DC offset. So if you want an analog volume control, you really need a jfet opamp in front of it.
The pcm2707 is not a very good dac by itself. It's decent but not great. You might want to look at the pcm5102 or something to pair it with. I've built along those lines and it works fine: PCM5102 USB DAC for sennheiser HD650 - request for design critique
For the amp section, I used a composite opa134+lme49713
One of the problems with the tpa6120 is that it has to be driven from a low impedance and the inputs must be well matched to avoid DC offset. So if you want an analog volume control, you really need a jfet opamp in front of it.
Maybe this would do the trick?
New 384KHZ/32bit Original XMOS+ PCM5102 + TDA1308 USB Decoder Board USB DAC | eBay
Whether it is better than the laptop is still unknown.
New 384KHZ/32bit Original XMOS+ PCM5102 + TDA1308 USB Decoder Board USB DAC | eBay
Whether it is better than the laptop is still unknown.
I am bit worried.
TPA6120a2 is run horrible from usb power.
I want a small PCB .
Atm50x doesn't require any headphone amp so I will go with TPA .I will give him my DAC from cavin to my friend.
Still experiment with TPA going fun so help me to run it from usb . I want to keep this little project around for sometime.
TPA6120a2 is run horrible from usb power.
I want a small PCB .
Atm50x doesn't require any headphone amp so I will go with TPA .I will give him my DAC from cavin to my friend.
Still experiment with TPA going fun so help me to run it from usb . I want to keep this little project around for sometime.
AD815 works from just 5V total supply. Probably need to run it inverting though as the input common mode range won't permit a 3V swing.
If you don't like the look of AD815's largeish package, there's always AD8017 which also is quite happy at 5V.
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You could do it this way if you really want everything powered from usb: pcm2707-i2s-pcm5102-potentiometer-lme49721 as buffer-opa1688 as output.
The pcm5102 has a 2vrms output centered at gnd so it's not putting any dc on the pot. 2Vrms (5.7vp-p) is too much for the usb powered opamps, so you need to reduce it down to at least 1.5vrms (4.25vp-p). Easily done by a resistor ahead of the pot. The lme49721 has rail to rail input so you can use it in non-inverting fashion, granting you a high impedance load for the potentiometer. And the opa1688 has a high current, rail to rail output. So you can use it inverting as the output.
Obviously, you need a cap ahead of the opamps and at the output.
The pcm5102 has a 2vrms output centered at gnd so it's not putting any dc on the pot. 2Vrms (5.7vp-p) is too much for the usb powered opamps, so you need to reduce it down to at least 1.5vrms (4.25vp-p). Easily done by a resistor ahead of the pot. The lme49721 has rail to rail input so you can use it in non-inverting fashion, granting you a high impedance load for the potentiometer. And the opa1688 has a high current, rail to rail output. So you can use it inverting as the output.
Obviously, you need a cap ahead of the opamps and at the output.
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