Help with API 312 PCB build

[anythingcansoundgood]

Hi! If anyone here has more experience in designing pcb boards, I could use a little help!

I'm trying to adapt the API 312 schematic on KiCad, but it's only my second pcb design, and by far the most complicated for me. I want it to fit in my 500 series rack, so I found the footprint for that on a Github page. I designed all the transformers/opamp footprints myself.

I wanted to make it as easy as possible for my first build, so I gave up on the 48v, phase flipping stuff, etc... I only put an impedance switch before the input transformer because it was easy enough (and very useful).

The gain pot won't be a resistor ladder. To simplify and cut the cost, I'll put a 1k Lin.

I didn't take much time thinking about dimensions (to make the potentiometer fit nicely in the rack). I'll simply wire it "by hand" if it doesn't fit. I'll also wire the switch like that.

Here are the original schematic and my work :

Any help is really appreciated, thanks !

 

[Johnny1234]

gain pot should be 20 -25 k ohms.

 

[anythingcansoundgood]

gain pot should be 20 -25 k ohms.

Yeah I saw that right after I posted ! I think there is an incorrect schematic out there..

 

[Walrus]

…..and it should be Reverse Log too.

 

[anythingcansoundgood]

…..and it should be Reverse Log too.

Yup the original plan was Reverse log 22k, but I forgot that when doing the schematic and saw 1k on a random image trying to remember the actual value

 

[Whoops]

Any help is really appreciated, thanks !

Let us know more about what you're trying to do, what are your goals?
Why are you trying to design a PCB and not buying an already made 312 type PCB for the 500 series?

 

[anythingcansoundgood]

Let us know more about what you're trying to do, what are your goals?
Why are you trying to design a PCB and not buying an already made 312 type PCB for the 500 series?

My goal is to learn Kicad and pcb design. I already ordered them and they arrived this morning

 

[Whoops]

My goal is to learn Kicad and pcb design. I already ordered them and they arrived this morning

Very cool, so if the goal is learning then you’re doing well

Wish you all good

 

[MidnightArrakis]

Hi! If anyone here has more experience in designing pcb boards, I could use a little help!

I'm trying to adapt the API 312 schematic on KiCad, but it's only my second pcb design, and by far the most complicated for me. I want it to fit in my 500 series rack, so I found the footprint for that on a Github page. I designed all the transformers/opamp footprints myself.

I wanted to make it as easy as possible for my first build, so I gave up on the 48v, phase flipping stuff, etc... I only put an impedance switch before the input transformer because it was easy enough (and very useful).

The gain pot won't be a resistor ladder. To simplify and cut the cost, I'll put a 1k Lin.

I didn't take much time thinking about dimensions (to make the potentiometer fit nicely in the rack). I'll simply wire it "by hand" if it doesn't fit. I'll also wire the switch like that.

Here are the original schematic and my work :

Any help is really appreciated, thanks !

1) Fatten up all of your tracks!!! You've got plenty of room there on this PCB and your circuit performance will "THANK YOU!!" for the fat tracks!!!

2) R3 and C4 are in parallel with one another.....so, rotate C4 180-degrees and place it underneath R3. Doing so will eliminate that long loopy track going through the transformer pins.

3) Rotate R4 90-degrees counter-clockwise and kinda center it on TR2 Pins 6 & 7. Then, also rotate C5 90-degrees counter-clockwise and center it on R4. This will also eliminate all sorts of unneeded and unwanted long tracks.

4) C7 is basically "hung out to dry" on an unnecessarily long "stub-route" and therefore, it becomes almost useless. Try placing it closer to your switch, which is where the "click noise" will be generated.

5) Take your "Copper Pours" and back them away from the board-edge by at least 50-mils. Your PCB-fabricator will "THANK YOU!!" for doing that!!! In addition, your audio equipment will also "THANK YOU!!" for doing that because of the possibility of creating a "Ground Loop" should the "GND" of the PCB come in contact with the "GND" of anything else that might be nearby.

6) Speaking of "mils".....go into your KiCAD PCB system configuration setup and set your "Units" to "Mils" instead of "Millimeters". Again.....your PCB-fabricator will immensely "THANK YOU!!" for making their life so much easier!!! Especially, here in the States!!!

7) Move the "TR2" silkscreen -- OUT -- from inside the component outline. Once you insert the transformer on the PCB, you won't be able to see it. The silkscreens for C3 and R3 create an interference with the "2520" component outline silkscreen and that's a "NO!!! - NO!!!". Clean that up.

8) I believe you need to have posted a minimum of 10-messages on this forum before you are able to send another member a PM (Private Message). Whenever you manage to reach that milestone, send me -- ALL -- of your KiCAD files and I can assist you better privately. Sound like a plan???

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[MidnightArrakis]

My goal is to learn Kicad and pcb design. I already ordered them and they arrived this morning

[My goal is to learn Kicad and pcb design] -- Go to my personal link shown below and download all of the material that is there and that will get you started. There is even a large KiCAD file in there to learn from:

https://mega.nz/folder/HvYSGYxJ#neKRiXvslZs_gotylWTwOg

Here's the KiCAD link by itself:

https://mega.nz/folder/HvYSGYxJ#neKRiXvslZs_gotylWTwOg/file/bz4DzZrI

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