[ruffrecords]

@Tim

For a line level mixer this is an excellent approach. Additional screening around the tubes themselves is always a good idea. Signal cables should always be shielded as well but ground connections should not need it. Make sure all the sign writer's aluminium sheeting is electrically connected together and that there is a single connection from it to analog 0V (HT -ve) right where the power inlet socket is located.

47K bus feed resistors are fine in all cases. Make sure the LCR switch grounds any unused 47K to minimise crosstalk. If you use 100K pots for FX sends you can use LOG or LIN parts. LOG pots will typically give you 20dB down at 50% rotation. To make them more like slider faders which are  normally 10dB down at 50% travel you can use a LIN pot. The 47K bus resistor then acts also as a slugging resistor to give 10dB down at 50% rotation.

The only thing I am not sure about are the input transformers you have chosen. Which mixer did you pull them from. Could be useful to see a schematic of how they were used originally.

All in all an excellent project.

Cheers

Ian

[Tom snich]

Hello Ian

I bought this cable https://www.thomann.de/se/concab_lastkabel_8x15qmm.htm for the power to the mixer, the extra wires will come in handy for the analog 0V HT-ve, good!

Glad 47k bus works I have wired the the LCR using your concept, and I used 100k LIN for sends.

Been reading tons here on the forum trying to apply it to this mixer.

[Tom snich]

The Transformers come from 80's broadcast mixer AMIX CSL AV 20 French.
I contacted AMIX but they would not help me with schematics :/ Gears-Lutz gave nothing either. I am a bit doubtful that they will work, just would be nice to save some money on the transformers. Here's a pic of the PCB  the transformers go in to 39k resistors and then surrounding the NE5532's are  39k 10k 100k  22k, I know this does not help much. They look about the same size as an OEP transformer.

Cheers
Ben     

[ruffrecords]

Your block diagram looks fine!!

Hard to say about the transformers. The AMIX CSL AV 20  definitely appears to be a line in only mixer so the transformers should be good enough. I think it is worth trying them.

That Concab cable is good. I recently bought some myself to try out.

Cheers

ian

[scott2000]

Just happened across this site looking for some extrusion profiles..... didn't look too closely at the dimensions of these enclosures but still neat..

https://www.prioline.de/en/enclosure-types/sloped-enclosure/sloped-enclosure-type-3/#c155

[ruffrecords]

Just happened across this site looking for some extrusion profiles..... didn't look too closely at the dimensions of these enclosures but still neat..

https://www.prioline.de/en/enclosure-types/sloped-enclosure/sloped-enclosure-type-3/#c155

Interesting. I have not come across this company before. Definitely worth looking at in more detail. Thanks for the link.

Cheers

IAn

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