Maker Pro
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8 (7.1) channel analog volume control

(*steve*)

¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd
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My only comments are:

1) you have to get this manufactured (you can't make it yourself)

2) We glossed over decoupling of logic and audio power supplies. I would recommend that each have their own connections back to the power on the board where you should have some low ESR capacitors. I would also consider bypassing all the chips with small caps to help eliminate noise.
 

CommanderLake

Oct 2, 2012
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Thanks CocaCola (I like zero personally) for the critics that's mighty helpful I made all the holes 0.1 or 0.2mm bigger than the pins keeping them tight so the components don't move around when I'm soldering them.

I have been through all the datasheets looking at the dimensions etc. I have all the components fully functional on a breadboard, they are screw terminal blocks.

OK, all traces were 0.5mm so I increased the size of all traces carrying power to 1mm and all other traces to 0.6mm and I fixed the trace aesthetics R6, C3 and C4 to make them look better.

Steve, I still need to find somewhere I can get it manufactured. I have 0.1µ 100v Wima polypropylene bypass caps on all 4 volume chips in addition to 10µ 50v Panasonic aluminium electrolytic caps on all analog +- and digital pins as you can see and just the 0.1µ Wima on the picaxe and I have sockets for all chips.

I tested it on the breadboard with RMAA and my X-FI Elite Pro sound card and it performs exceptionally with >102db noise floor and dynamic range and <0.007% THD+N!
 

CommanderLake

Oct 2, 2012
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Just updated the PCB images, they are 200% magnification and the dots are 5mm apart

If they dont appear to have been updated that's because they are the same file names and your browser has cached them just refresh your browser.

Top:
PCBtop.png


Bottom:
PCBbottom.png
 
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(*steve*)

¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd
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I tested it on the breadboard with RMAA and my X-FI Elite Pro sound card and it performs exceptionally with >102db noise floor and dynamic range and <0.007% THD+N!

That's excellent. Performance on a PCB should be no worse than the breadboard.
 

CommanderLake

Oct 2, 2012
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That's excellent. Performance on a PCB should be no worse than the breadboard.

I have 3 rails on the breadboard for +5, 0 and -5v and no fancy separation of digital and analog and with those results I wonder why I need to keep the supply's separate?
 

CocaCola

Apr 7, 2012
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As I said most of my suggestions were just personal preferences...

I wonder why I need to keep the supply's separate?

You don't 'have to' but it reduces the risk of potential induced noise, interference and/or potential for ground loops...
 

CommanderLake

Oct 2, 2012
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Well with 102db SNR on the breadboard I wont bother splitting digital and analog right to the power supply.

How about copper pour what do you recommend?
 
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CocaCola

Apr 7, 2012
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How about copper pour what do you recommend?

On two sided boards, you can pour the ground/power plane if it works/suits your design, but in general most of my 'pours' on two sided boards is simply for heat sinking purposes... Or if you are home etching to save etchant, but since I no longer bother etching my own stuff this doesn't factor in anymore...

There are reasons you would want to do pours and they do pay off in providing shielding in some cases but it's overkill in most applications...

There are lots of articles on pours all over the Internet that go into much more detail, but this PDF gives a quick and dirty overview...

http://www.icd.com.au/articles/Copper_Ground_Pours_AN2010_4.pdf

And last but not least, sometimes pours 'look cool' I have been known to layout/define boundaries and pour designs just because... I have also been known to use pours to 'highlight' and 'create' text or graphics on the bottom of a board instead paying for a bottom silk... Same on the top of a board, sometimes the contrast of test written in the copper layer vs the silk is nice looking or more permanent... Consider this on the top of a board for 'highlighting' something... Using creativity you can get quite a bit of definition and highlight using the silkscreen layer, the 'poured' layer, the 'bare pcb' layer, and the exposed copper 'pad' layer, especially nice now that ROHS kicked in and gold plating has made it's way to mainstream or at least very cost competitive... Think black (or another dark color) board with gold text, or even silver text ;)
 
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CocaCola

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Yep, that would be the basics of it, you can get real creative with it if you play around... There is one layer not shown there, that would be the bare board with no resist, usually a pail translucent yellowish color...

attachment.php


On thing this does not show is layering these layers, say for example you put the gold pad text over slightly larger copper with resist, and then outlined it with silk... Something like this... I know all Arty Fartsy but for me it makes designing boards fun, even more when the client compliments you on how nice the board looks...

attachment.php
 

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CommanderLake

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I seem to have created that effect by putting the same text on 2 layers, signal and solder mask diptrace has a 3d viewer.
 

CocaCola

Apr 7, 2012
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I seem to have created that effect by putting the same text on 2 layers, signal and solder mask diptrace has a 3d viewer.

That will result in a significantly raised white text, another option...

As I said all this stuff is just Artsy stuff, it's simply fun stuff to do not really a part of 'legit' pc board design...
 

CommanderLake

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I love all this fancy stuff I want my PCB to look like the one in that picture!
What do you mean significantly raised white text? I assume the mask layer is to cut out parts of the solder mask and the signal layer is to put copper there which would be gold with an immersion gold finish (looking at the pcb quote page on rushpcb.co.uk) I removed the text from the silk screen layer if that's what you were thinking, in the 3d viewer the text is the same colour as the pads round the thru holes it looks nice, I can give you a VRML file so you can see it in a VRML viewer if you like?
 

CocaCola

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What do you mean significantly raised white text?

I misread, sorry I though you put the silk layer on top of a trace...

The board will be layered like this...

There is the PC board substrait aka the fiberglass board itself... There is a full coverage bonded layer of copper applied to this board... The board is 'etched' and copper is removed where it's not need, so you are back to bare board in these locations... Then there is a layer of resist applied to the board over everything except the pads, this can be an applied ink resist or a film resist (depends on the manufacture)... Then there is a layer of raised silk screened ink printed on top of everything... And last but no least any exposed pads are plated... All these layers are significant enough that they create ups and downs...

And last but not least the end results will vary slightly from manufacture to manufacture and from what the 3d render looks like... Once you establish a relationship with a board house you will get a better idea of what the final boards will look like... Some of the things that really vary is the translucency of the resist... From some board houses it's so opaque you sometimes have a hard time seeing the traces, from other houses it's drastic... There is also a world of difference in silk screens... Some companies are crisp and clear with high details, others have real soft details... Also some silks are really raised others hardly at all...
 

CommanderLake

Oct 2, 2012
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Got my preamp board all working! Sadly I messed up a TP2050 on the amplifier board I was assembling but its cheap at just £30 so I'm ordering a pre made one, I was getting pretty good with all the SMT resistors/capacitors too!
 
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