AUX8 Build thread

[Joe Malone]

I'm going for these knobs.

Wow That is looking amazing

[fragletrollet]

Been a while since I've had time for DIY, but picked this one out of storage to try to finish it and put it to good use. After a few solid days of soldering I've finished the power supply (AC/DCv4), the LED circuit (ended up with simple backlighting of the scribble strips instead of a fully fledged peak indicator pr channel, at least so far) and the wiring and power/ground distro. First power up is completed with no magic smoke, a relief considering the amount of opamps in this thing.

Everything is working fine, however AUX 5/6 and 7/8 seem to have some weirdness in connection to ACA or booster stage. Similar symptom on all channels, so should be a simple wiring issue.
Also somehow channel 9/10 appear on 11/12. There is also some volume inconsistencies on some channels (within 1-2dB), wondering if this is just less than ideal connection between the IDC and that pin/channel.

All in all I am confident that the project is going towards "finished status". It sounds really cool, a slightly cleaner shade compared to my api summing mixer with discrete 2520's on all inputs. The UC1608 ( ) uses JLM Palpigrades on inputs, 8 JLM aux8 boards into 8 channels of Capi ACA with GAR2520's, into second half of JLM SUM8 for post summing gain before going to a JLM Tardigrade for final balancing. Used 47k bus resistors between AUX and ACA, and 10k resistors between ACA and SUM8 which lands at about unity gain overall.

[fragletrollet]

And another of the front

[Joe Malone]

And another of the front

Wow that is an amazing build. That is a lot in one box but the layout makes it roomy enough to work on

Let me know if you need any help sorting the Ch 9,10 & 11,12 problem.

[fragletrollet]

Just think how messy it would be without the pcb's

[Quint]

So I'm interested in incorporating the Aux8 and Sum8 into part of a larger build I'm contemplating but, when looking at the Aux8 schematic, I'm confused by how it works. I don't see where the bussing actually happens on the Aux8?

If you follow the signal flow (using Input 1 as an example), it passes thru the full circuit and shows up at Bus 1 on the other end of the circuit, but ONLY Bus 1. To be able to use the Aux8, at least as I thought I originally understood it to work, you would need to be able to send each input to all 8 busses, but it looks like input one only ever goes to Bus 1, and input two only ever goes to Bus 2, and so on and so forth.

I was expecting, for example, the Aux8 card, labelled as Input 1/2, to extract ONLY channels 1 and 2 from the input IDC cable, and then provide the ability to individually send those channels, at whatever volume you like, to each of the available busses. Similarly, I was the expecting the Aux 8 card, labelled as Input 3/4, to extract ONLY channels 3 and 4 from the input IDC cable, and then provide the ability to individually send those channels, at whatever volume you like, to each of the available busses. And so on and so forth.

I must be missing something?

Also, what is the intent of the OYWRB pads for Bus 1-4 and Bus 5-8 outputs. I would have thought you would want to just use the output bus IDC header off the Aux8 boards to get that signal to the Sum8?

[Joe Malone]

So I'm interested in incorporating the Aux8 and Sum8 into part of a larger build I'm contemplating but, when looking at the Aux8 schematic, I'm confused by how it works. I don't see where the bussing actually happens on the Aux8?

If you follow the signal flow (using Input 1 as an example), it passes thru the full circuit and shows up at Bus 1 on the other end of the circuit, but ONLY Bus 1. To be able to use the Aux8, at least as I thought I originally understood it to work, you would need to be able to send each input to all 8 busses, but it looks like input one only ever goes to Bus 1, and input two only ever goes to Bus 2, and so on and so forth.

I was expecting, for example, the Aux8 card, labelled as Input 1/2, to extract ONLY channels 1 and 2 from the input IDC cable, and then provide the ability to individually send those channels, at whatever volume you like, to each of the available busses. Similarly, I was the expecting the Aux 8 card, labelled as Input 3/4, to extract ONLY channels 3 and 4 from the input IDC cable, and then provide the ability to individually send those channels, at whatever volume you like, to each of the available busses. And so on and so forth.

I must be missing something?

Also, what is the intent of the OYWRB pads for Bus 1-4 and Bus 5-8 outputs. I would have thought you would want to just use the output bus IDC header off the Aux8 boards to get that signal to the Sum8?

I think you are mixing up channel 1-8 with aux 1-8 outputs. It is to make 8 x 8 matrix mixer. Channel 1-2 can level mix to aux 1-8. Buss resistors are on aux pcb and summing amps on sum pcb.