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PC board for RCA/XLR SE<->balanced switching?


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Has any one of you done something like this, accommodating a pair of RCAs and a pair of XLRs, with the appropriate switching for these? I know I'll get told to just use the Neutrik or whatever RCA->XLR adapters for this, but I was thinking about doing up a PCB with a pair of something like the Neutrik NC3MAV/FAV and a pair of RCAs.

Has anyone ever used the vertical Vampire RCAs (pcb2f/s)? They don't list any dimensions or PCB layout for these, but just wondering height-wise if these could work well?

I had thought I would probably use relay switching instead of a mechanical switch, as the 4PDT are a PITA to wire up, but I suppose just going into a board with connectorization could make things more palatable.

Thanks for your thoughts, or if you have seen anything like this around.

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I'm pretty sure that Justin used those Vampire RACs on multiple products.  There's a chance that I have a pair downstairs and if so, I can send them your way for prototyping. I used them on multiple projects (KGSS, Exstata, etc.).

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  • 2 weeks later...
Posted (edited)

Bought a pair of the Vampire RCAs (ebay) and measured them. I've attached an Eagle library with these in them as well as a board layout using these and Neutrik jacks and NKK switch. I haven't verified any of the board <-> panel spacings yet, but they seem reasonable, with some soldering slop.

Change the file extensions from zip to lbr for the library file.

1028415160_bal-unbalboard.thumb.png.c97bdec40d38eb3574d747725c35f0be.png

con-audio.zip

Edited by Pars
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Are you not worried about the fact that the grounds aren’t switched? I have a recent use-case where it was needed - the two sources were on different electrical circuits.

Regardless, I would consider a jumper for XLR pin 1 to either be connected to the chassis or to GND.

https://www.ranecommercial.com/kb_article.php?article=2107

Edited by luvdunhill
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From Rane 110, it appears that the "right" way to do it is to tie pin 1 to chassis. The two pins in the lower right corners of the XLRs are also supposed to go to chassis, correct? If so, I could wire these together to a pad to wire to chassis ground.

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2 hours ago, Pars said:

From Rane 110, it appears that the "right" way to do it is to tie pin 1 to chassis. The two pins in the lower right corners of the XLRs are also supposed to go to chassis, correct? If so, I could wire these together to a pad to wire to chassis ground.

I would tie the shell to the chassis and have a jumper for the pin 1 to go either to AGND or Earth.

Does the vertical height of the two parts match up well enough?

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Posted (edited)

You mean the 3 parts (XLRs, RCAs and switch)? It seems to though I haven't measured or done any sort of mock up. I think there will probably be enough slop possible in assembly to get them to match, but I'll play around with it. The switch is an NKK m2042xxxxx, and the Neutriks are NC3FAV2.

I tied the two chassis gnd connections from the Neutriks together with a pad in the middle, and did the same with the pin 1s. Then put two pads in connected to the board gnd plane. I'll probably add another pad for chassis ground to give the most flexibility.

On my Pass Aleph P, the XLR grounds both go to board ground. Same on Kerry's SS Mini. I haven't had any hum problems whatsoever on my stuff, but everyone has different issues potentially.

Thanks for getting me thinking about this shit though :)  I also used a drawing of the Cardas GRFA DBL PRT that someone had provided on a diya thread you were participating in to draw up that part in Eagle as well, in case I wanted to go that route.

Edited by Pars
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