Hardware design

the digikey series is super good, so is the contextual electronics:

I also highly recommend EEVblog for other electronics related things (especially the episode below on opamps)

here’s a nice one recently on making good schematics (although it’s in eagle, principles still apply)


Thank you for your answer!

I am still far from arriving at the beginning of production run; I’ve got lots of prototyping to do still. 100 units seems like a lot, and it is consequently a good chuck of cash that would need to go into that. I will have to ponder over that.

It is a big chunk of change, and it’s still (3 years in) a bit of a shock sometimes: “The panels cost me what???” Since I am a “real” business now, I just have to have faith that everything will sell. It is weird though, because I know that I can only sell so many X modules, so eventually I’ll have a bunch of stock left over collecting dust…

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How would folk go about getting a panel made? I’m putting together a dual Benjolin, simply two Kweiwen Benjolin under one panel. I’ve adapted the panel template from the GitHub, but not sure about further steps. PCB material or Aluminium would be preferred.

For an aluminum panel, you can have it made at Front Panel Express (https://www.frontpanelexpress.com/). For a PCB panel, you would send it off to a PCB house. OSHPark is a popular US-based PCB house for small amounts, but they produce purple solder mask, so it’s not great for PCB panels (unless you want purple).

Thanks! I should have added that I’m in the UK.

You can also try Schaeffer, which I believe is the parent company of Front Panel Express, and operates out of Europe: https://www.schaeffer-ag.de/en/

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Cheers! If I were to go with something like OSH Park for a PCB panel, can I make a compatible file in something free like KiCad? I have a PDF template as mentioned, but getting that into a format that a PCB fab can use is pretty confusing.

You can! In my opinion, though, using the FPD/Schaeffer program is easier (by a long shot) than learning PCB programs if your goal is just to get a panel or two made.

Hi kisielk,

I’d really like to DIY some 1U intelligel format tiles. Would you share some Eagle files with the basic PCB/PANEL dimensions, hole positions… to make it easier for me to start with ? cheers

Intellijel’s 1U spec sheet may be all you really need!

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Yes, I was just about to link to this. The measurements are on our website.

Just started using Hierarchical Sheets in Kicad, and I’m chiming in to say. Dang. These things are handy!

Also, does anyone have nice simple schematics for a LFO or headphone output stage?



Befaco posts schematics of all of their designs since they offer DIY options. Might be worth a look?

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found a LFO, but haven’t tested it yet

Still looking for a nice simple headphone out.



Douglas Self’s Small Signal Audio Design contains a lot of information on designing headphone outputs, primarily for high-grade studio mixers.


I tried to pick that up, but unfortnately it’s in the “very expensive technical book” category.

That book is incredible!

A question on the headphone amp in the book, (pg.391) – I want to make sure I’m looking at this right, is the Rload the load / headphones in this diagram?

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Yes, although it’s not clear to me why it’s 30R in one schematic and 22R in the other. Maybe just to highlight that the second one is more capable?

Psst! Based on the page reference, you have the first edition. The second edition has an expanded chapter on headphone output design, with a few more example schematics. Happy to send you a scan.

that’s what threw me for the loop, I was scratching my head thinking, why are these different?
I’ve got the second edition now.

To add a volume control to one of these, do you think it’d be better to adjust the gain in the TL072 in the headphone amp itself, or add a volume control output stage?