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Old 13th February 2013, 01:58 AM   #21
qusp is offline qusp  Australia
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yeah because star earthing has historically always beaten a ground plane.... depends on the layout, but there is nothing inherently wrong with using one ground plane, you just need to be careful with component placement and/or put some slots in the plane to encourage small loop area.
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Old 13th February 2013, 02:01 AM   #22
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Quote:
Originally Posted by qusp View Post
yeah because star earthing has historically always beaten a ground plane....
Nope it hasn't. Feeling at all threatened by my comment qusp ?

Quote:
depends on the layout, but there is nothing inherently wrong with using one ground plane, you just need to be careful with component placement and/or put some slots in the plane to encourage small loop area.
Tangential - nothing wrong with using a single plane for both quiet (signal) grounds and noisy (power) grounds, just sounds crap.
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Old 13th February 2013, 02:13 AM   #23
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Originally Posted by KlipschKid View Post
3rd routing issue. Bottom left corner, FB1, goes to a via, and on the other side there is a power trace that runs at 30 degrees across the MCLK line.
apart from the zero distance decouple capacitor trick for the most demand diyer, the power supply to every pin can also be trick there are unlimited possibility, the fun is here
the bottom line is every version of our pcb is assembled and tested to work with the unmodified layout before released to the public. I think it's better to call it an improvement rather than an issue The PCB is designed for the diyer easy to do trick

many people told i2s line should have series resistor, it do reduce overshoot but it will also reduce the rise time of the signal. There are some exception, the old chip tda1541 do need input series resistor due to the internal architecture. Some new chip has no effect or even causes bad result if added series resistor in the I2S line, diyer are welcome to try and everybody are happy to know the result

Last edited by diyinhk; 13th February 2013 at 02:24 AM.
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Old 13th February 2013, 02:16 AM   #24
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Originally Posted by abraxalito View Post
Nope it hasn't. Feeling at all threatened by my comment qusp ?



Tangential - nothing wrong with using a single plane for both quiet (signal) grounds and noisy (power) grounds, just sounds crap.
I will try to move the power supply connector to the middle of PCB to all new version pcb, it should provide better separating of left and right channel
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Old 13th February 2013, 02:23 AM   #25
qusp is offline qusp  Australia
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Quote:
Originally Posted by abraxalito View Post
Nope it hasn't. Feeling at all threatened by my comment qusp ?
not threatened, I just think star earthing to replace a ground plane is stupid


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Tangential - nothing wrong with using a single plane for both quiet (signal) grounds and noisy (power) grounds, just sounds crap.
citation vs a properly designed PCB with single plane please?
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Old 13th February 2013, 02:28 AM   #26
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Hi,

I'm sure it works great just as it is, but I want to make it better if I can, and this is easier to do before fitting components.

I have removed the power lines completely where they come close to signal lines near the DAC IC, so there is no floating copper traces, and shorted the lines to ground on the input points. I will feed in power.

I have also added extra copper for the use of through hole 620R resistors mounted on the ground plane side, and removed the smd pads and lines for these resistors, to help isolate the op amp power / signals from each other.

I cut and grounded the traces shorting C1-C4 for a continuous ground plane, and shorted the connections with wire on the other side.

I have also cut and grounded the fb1 trace so I can use a through hole ferrite, elevated above the ground plane and perpendicular to the mclk line.

It looks ugly...

Click the image to open in full size.

Click the image to open in full size.

I'll also look at using a different ground routing for the filter caps. Probably the easiest way is to mount the 1000pF directly across the 560R smd.

Thanks !

Last edited by KlipschKid; 13th February 2013 at 02:50 AM.
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Old 13th February 2013, 02:31 AM   #27
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Quote:
Originally Posted by qusp View Post
not threatened, I just think star earthing to replace a ground plane is stupid
Perhaps you haven't fully digested my suggestion. I'm not suggesting it replaces the groundplane, I'm saying to add star earthing and substitute this for groundplane connections only for the signal grounds. Groundplanes are useful in giving low inductance connections for power, the signal connections OTOH don't need to be low inductance because they're not low impedance. Given that low inductance isn't a necessity for these then we can provide cleaner (lower noise) 0V by star earthing.

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citation vs a properly designed PCB with single plane please?
You lost me. You want a citation that signal grounds and power grounds are best kept separate in audio?
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Old 13th February 2013, 02:37 AM   #28
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Henry Ott on mixed signal PCB layout and split ground planes has this to say:

Grounding of Mixes Signal Systems

Quote:
-Partition your PCB with separate analog and digital sections.
-Do not split the ground plane. Use one solid ground plane under both analog and digital sections of the board.
-Route digital signals only in the digital section of the board. This applies to all layers.
-Route analog signals only in the analog section of the board. This applies to all layers.
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Old 13th February 2013, 02:40 AM   #29
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Henry Ott is great but he's not someone (as far as I know) who has listened to high quality digital audio circuit layouts. For those who think I'm just blowing smoke here, try the experiment for yourselves and report back what you hear. I've done that so I know what the result is
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Old 13th February 2013, 02:46 AM   #30
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That's the same place I learned it - buying junk boards from Taobao has taught me cool stuff
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