Aphex mods -- 2 slots standard API

[standup]

I've got an Aphex 4b with two CX-1 compressors that I've had for years. I've ordered a couple of 500 series pre's for the open slots, and have decided it'll be split with Aphex format on the bottom for the compressors and API standard on the two upper slots.

I've got power supply kit from fivefish to replace the ancient Aphex PS and give me 48v phantom.

It looks to me like I can solder the 15v+, 15v- and power ground leads from the new power supply to the PCB and nothing will change. The 48v output from the PS will go directly (please correct me if there's a smarter way!) to the pin 15 'feet' on the backside of the PCB via a jumper wire.

Does it matter if it's a single wire soldered in two places or if I run two wires from the new PS to the cards?

Pin 7 in the Aphex 4b is mysterious to me. A member here noted that a lot of manufacturers link pins 7 and 8. Is that necessary? If I leave it be, will I have a balanced input connection that will pass phantom power to the mic, or is it an unbalanced mic input?

The pre's are from fivefish also, the x-72's. They're transformer balanced, and if they're getting 15+/15- and 48v from the new power supply, won't all of that work out... ?

This is my first project more complex than cable and patchbay wiring and misc. easy stuff, so I might be missing important little details here.

THanks for any thoughts on this,
standup

[pan60]

this may help.

[Denyle]

If I understand this correctly, you're building a new psu for that Aphex 4b-1 rack to include phantom power? I'd be more inclined to buy an external phantom power supply. Anyway, make sure you do not connect phantom power to pin 15 on the slots where the CX-1 will reside. It will damage the CX-1. Also consider disconnecting the meter out jacks as they will have 48vdc.

Pin 6 is normally used for the linking as per API's requirements. That doesn't correspond to the Aphex 4b-1 rack or CX-1. The way it works in this case is the pre-gain out (pin 6) is normalled to the side-chain input (pin 11) through the mini-jack on the 4b-1. The dip switch on the CX-1 should be set to Ext. You can also set the dip switch to pre out in order to use it in other racks. Or post out if you really want to squash something.

[pan60]

if you alter one of these, i thank it would be a great idea to place a label on the top, or somewhere inside that clearly states it has been altered for API specks?
i just wrote a note with a sharpie on mine.

[standup]

I'm running a jumper to pin 15 on two of the slots, which I don't think will affect the other slots (on the PCB it LOOKS like the only connections between slots are +16v, -16v, and GND)

Thanks for the switch info -- they both were set to "EXT" on the CX1's.

Labelling stuff is good, I could forget which is which somehow, or somebody else could pop something in there casually, sometime, somehow.

And I'll probably tape over the sidechain jacks on the phantom-power channels. Mic pre's are going in those slots, so linking won't be missed in this case.

Should I de-solder the sidechain jacks? That would be reversible if needed.

THanks!


If I understand this correctly, you're building a new psu for that Aphex 4b-1 rack to include phantom power? I'd be more inclined to buy an external phantom power supply. Anyway, make sure you do not connect phantom power to pin 15 on the slots where the CX-1 will reside. It will damage the CX-1. Also consider disconnecting the meter out jacks as they will have 48vdc.

Pin 6 is normally used for the linking as per API's requirements. That doesn't correspond to the Aphex 4b-1 rack or CX-1. The way it works in this case is the pre-gain out (pin 6) is normalled to the side-chain input (pin 11) through the mini-jack on the 4b-1. The dip switch on the CX-1 should be set to Ext. You can also set the dip switch to pre out in order to use it in other racks. Or post out if you really want to squash something.

[Denyle]

And I'll probably tape over the sidechain jacks on the phantom-power channels. Mic pre's are going in those slots, so linking won't be missed in this case.

Should I de-solder the sidechain jacks? That would be reversible if needed.

THanks!

Phantom power will find it's way to the external meter via pin 15, not the side-chain jacks. I think the 4b-1 doesn't have meter jacks so it's not an issue. But that brings up another point. Notice on the Aphex pinout that pin 8 is a ground, meant for unbalanced inputs. Take your DMM and verify that pin 8 isn't tied to pin 5 or pin 1 (or chassis) via the pcb. If it is, you'll want to use an exacto knife or dremel to cut the trace otherwise bad stuff will ensue. Cut just enough to break the connection so you can easily repair it in the future. IIRC, pins 5, 8 are tied together inside the Aphex modules, so I think you're safe.

[pan60]

so glad we have Denyle around here for some help: )~ !!!!!
Avedis did mine some time back. seems i remember him telling me something about cut some traces? not 100% sure.
on mine their was no plan to add 48 volt phantom power, as i wanted it mostly for historical purpose's but did want to use it, we decided it would only house some EQs. so no need for phantom power.
i will try to get some time and see if some pic will show just what he did if you all think would be be of any help?
pan

[standup]

Any pic might be helpful if it's easy to do. Denyle, thanks again. Pin 8 doesn't connect to pins 5 or 1 when it's disassembled, think I'll check again once it's back in the chassis and everything's wired up... Thanks y'all.

[pan60]

Any pic might be helpful if it's easy to do. Denyle, thanks again. Pin 8 doesn't connect to pins 5 or 1 when it's disassembled, think I'll check again once it's back in the chassis and everything's wired up... Thanks y'all.

if i don't get to it in a few days p.m. or email me a reminder: )~