Make sure your IC smd footprints are DIY assembly friendly. They don't look it.
It may be just hard to tell from the photo...
Make sure your IC smd footprints are DIY assembly friendly. They don't look it.
It may be just hard to tell from the photo...
Good point. I've got fairly good with SMD soldering, but longer pads do make things easier.
I wish KiCad's auto router could handle dragging components with the traces still attached. It can become a pain in the neck moving a component after it's fully laid out.
Make sure your IC smd footprints are DIY assembly friendly. They don't look it.
It may be just hard to tell from the photo...
Good point. I've got fairly good with SMD soldering, but longer pads do make things easier.
I wish KiCad's auto router could handle dragging components with the traces still attached. It can become a pain in the neck moving a component after it's fully laid out.
Don't just make them blindly longer.
Make sure your IC smd footprints are DIY assembly friendly. They don't look it.
It may be just hard to tell from the photo...
Good point. I've got fairly good with SMD soldering, but longer pads do make things easier.
I wish KiCad's auto router could handle dragging components with the traces still attached. It can become a pain in the neck moving a component after it's fully laid out.
Don't just make them blindly longer.
I made them 0.5x1.75 and rounded. They look slightly easier.
Since you PCB isn't 4 layer, and now you have parts on both sides, sorry, no recommendations. Otherwise, I would say reserve the entire bottom as 1 single ground fill except for the odd trace here and there you need to pass.
That looks very well, though a bit over engineered with some extra wet capacitors.
The confusing thing is... if you look at the user guide:
http://www.ti.com/lit/ug/sbau195/sbau195.pdf
The confusing thing is... if you look at the user guide:
http://www.ti.com/lit/ug/sbau195/sbau195.pdfWarning, that is not a user guide to the PCM2904 IC which was made by BurrBrown. That's a user guide for a cheap eval board made by TI.
The PCM290x has not one but 5 different grounds. 3 analogue, 2 digital + the Vcom for the opamps. Vcom I have kept separate as a starred to the amps, but the others are just dumped onto the flood fill ground.
* Digital USB Ground
* Digital Ground
* Analogue side DAC ground
* PLL ground
* Oscillator Ground
Separating even the analogue and digital grounds into two planes with stars back to the USB plug, but will take a lot of rerouting. I might be able to split off the Oscillator ground and (I assume) use it just for the crystal.
The question is... on such a small low powered board which is getting it's ground from the single noisy USB source anyway (excluding of course the audio grounds from the jacks)... how critical is the ground paths?
I expect it will work, but I might suffer some minor noise issues.
Any suggestions?
Or probably wise to buy them capable of being used in other projects so 16V ones:
https://uk.rs-online.com/web/p/ceramic-multilayer-capacitors/8467313/
£4.10
Or probably wise to buy them capable of being used in other projects so 16V ones:
https://uk.rs-online.com/web/p/ceramic-multilayer-capacitors/8467313/
£4.10Those are X6S dialect.
Go for these, they are top of the line X7R dialect:
https://uk.rs-online.com/web/p/ceramic-multilayer-capacitors/7661104/ (35v, Free shipping next day)
https://uk.rs-online.com/web/p/ceramic-multilayer-capacitors/1721635/
For 0805 16v, X5R second best dialect, this is you best bet.
https://uk.rs-online.com/web/p/ceramic-multilayer-capacitors/8851698/
I know the 25v/35v ones are 1206, a fraction of a mm wider, and a little longer, but, they are X7R dialect and 25v. Good for decoupling on your pre-amp as well with a +/- 18v supply.
You do realize that 10uf 1206 or 10uf 0805 in ceramic has better performance and costs less than half as much as electrolytic and takes up 1/8th the PCB area.
Type II/III MLCCs in series of a high current (a few mA for headphone drive or later OPAMP stage) audio signal path. Recipe for disaster.
MLCCs should only be used when voltage across them remain the same and change very little to none due to the nonlinearity, in audio, this practically means only for power decoupling or very high Z signal AC coupling (you still have microphonic issues).
For DC blocking and AC coupling, electrolytic is better. If you don't care about cost and just want the smaller size, go with tantalum, and bias them properly.
And no, don't go MLCC only, even for power decoupling. Use at least one low ESR electrolytic per rail to dampen microphonic noise from MLCCs.
But, I don't think much will be effected in this project.
Sorry for the pedantry from someone who reads diyaudio often and designs high spec DACs on his own .