boji

Re: 1974 API 3224 40ch resto-mod
« Reply #20 on: November 11, 2018, 08:16:01 PM »
So I assume the 6 pole means this is a variation on the 1st half of a 528 and not just a micpre?


TubeMonkey

Re: 1974 API 3224 40ch resto-mod
« Reply #21 on: November 11, 2018, 09:10:30 PM »
What's in the first have of the 528? I'm unfamiliar with that module.   My desk split what would be the 528/544 module into two separate modules.... the 912 preamp card, and the 915 group card. If you look at the channel layout I posted early you can see how the functionality is split.

the 915 card contains another opamp and 2623 transformer (except channel 1-16) for direct outs on each channel.

boji

Re: 1974 API 3224 40ch resto-mod
« Reply #22 on: November 11, 2018, 09:20:22 PM »
Quote
If you look at the channel layout I posted early you can see how the functionality is split.
Ah I see. Thanks.

Quote
What's in the first have of the 528?
Mic/line switched 2520 and tx's.

TubeMonkey

Re: 1974 API 3224 40ch resto-mod
« Reply #23 on: November 11, 2018, 10:36:26 PM »
Mic/line switched 2520 and tx's.

That's actually exactly what it is...  Just switching an impedance matching pad in front of the trafo  instead of using two separate ones, switching physical source for "desk preamp" Mode and switching  pad in for line mode in "500 series" Mode. I designed them in a way which lets them be compatible in my desk or in a 500 series lunchbox, as well as the console slots being compatible with my preamp or any 500 series module.  Most of that is taken care of with the relay's in desk mode.... but there isn't relay power in 500 series mode so it has to be physical switching. I also didn't see a point in having  two separate 2520's driving the channel as they serve the same purpose, but still wanted a separate mic/line control, so the switching actually changes the negative feedback part of the circuit from a stepped pot for mic to a potentiometer for line mode.  this also means the settings between mic mode and line mode are independently preserved while saving from having to use 2* 2520's per channel.

boji

Re: 1974 API 3224 40ch resto-mod
« Reply #24 on: November 12, 2018, 10:49:57 AM »
"switching actually changes the negative feedback part of the circuit from a stepped pot for mic to a potentiometer for line mode."
interesting! Sounds like you've given the whole thing plenty of thought and functionality.   In my first bucket (which will be the end bucket once finished), I kept it line-in only but stayed true to the skiz mostly, and plan to use the daw for prefade gain, or 500 slots ahead of input card.
« Last Edit: November 12, 2018, 10:58:23 AM by boji »

TubeMonkey

Re: 1974 API 3224 40ch resto-mod
« Reply #25 on: November 15, 2018, 03:16:01 PM »
Getting into some metalwork the past few days. Finishing up the L-bracket design and looking for prototyping options. The previous 4 preamps I had hand-drilled which was cumbersome and imperfect....

Also rebuilding the mounts for the ACA's in the back of the console. There are 19 total ACA's/booster cards. I currently have around 10 running. Still need to build one for each pair of buses, as well as a few center section functions such as delay sends. Other than that the center section is 95% operational.

Here is a before pic of one side of the console with 4 ACA's installed. I've built and and am installing a stacking system with metal brackets to make everything look nice and for cable management.

boji

Re: 1974 API 3224 40ch resto-mod
« Reply #26 on: November 20, 2018, 10:10:52 PM »
Quite a bit of iron you got there!  Yes, send a pict of the stack.  I think I may take the same route in a U5 or U6 rack.


 

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