Racking Quad Eight (QE) Modules
Posted: Mon Apr 27, 2015 8:33 pm
Hi,
I have just bought some CA-127 cards which I would like to rack as preamps. I have seen you mention doing this many times, so I hope I can pick your brain.
My plan is to use an AC/DC kit for a pair of channels, with a Go Between and a FET on each. I have a few questions / assumptions I would like to check:
- Is a 25V 15VA toroidal suitable for 2 channels? (85ma per CA127 plus the DI)
- I have read that I need to change Rload from 15K to 360K, and to jumper the 4.7uF bypass cap on the input. Does that sound right? Would you recommend anything else?
- The Go Between is wired between the XLR input and the input transformer. What is the advantage of the Plus if I am using a different transformer (Cinemag CM-QEE-3440a)?
- Grounding: If I tie all XLR pin 1to the chassis at the ground lug (e.g https://pcbgrinder.com/download/PDF/WIRE_GUIDE_DONE.pdf), do I need to take it to the 0V pad on the Go Between as well (my gut says yes for phantom to work).
- In the document above, the mains IEC ground runs to the chassis ground lug only and not the PS board. Is this the same for the AC/DC?
Colm
I have just bought some CA-127 cards which I would like to rack as preamps. I have seen you mention doing this many times, so I hope I can pick your brain.
My plan is to use an AC/DC kit for a pair of channels, with a Go Between and a FET on each. I have a few questions / assumptions I would like to check:
- Is a 25V 15VA toroidal suitable for 2 channels? (85ma per CA127 plus the DI)
- I have read that I need to change Rload from 15K to 360K, and to jumper the 4.7uF bypass cap on the input. Does that sound right? Would you recommend anything else?
- The Go Between is wired between the XLR input and the input transformer. What is the advantage of the Plus if I am using a different transformer (Cinemag CM-QEE-3440a)?
- Grounding: If I tie all XLR pin 1to the chassis at the ground lug (e.g https://pcbgrinder.com/download/PDF/WIRE_GUIDE_DONE.pdf), do I need to take it to the 0V pad on the Go Between as well (my gut says yes for phantom to work).
- In the document above, the mains IEC ground runs to the chassis ground lug only and not the PS board. Is this the same for the AC/DC?
Colm