1974 API 3224 40ch resto-mod

[boji]

So I assume the 6 pole means this is a variation on the 1st half of a 528 and not just a micpre?

 

[TubeMonkey]

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]

If you look at the channel layout I posted early you can see how the functionality is split.

Ah I see. Thanks.

What's in the first have of the 528?

Mic/line switched 2520 and tx's.

 

[TubeMonkey]

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]

"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.

 

[TubeMonkey]

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]

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.

 

[TubeMonkey]

Alright... really bad at updates but i've been working a lot on other projects as well as the console.  I received the final version of my PCB which passed all tests with flying colors and have already been building them.  The only missing element is the metalwork which I'm working on ordering soon, but having a little difficulty finding someone to do a prototype before I put in the large order....

Also need to source knobs.... I really like the large vintage API knobs but obviously going to have difficulty getting them. I most likely will just send them to my CNC guy and get a pack of 50 or 100 ordered from him.

I took the dive and flipped the console up to do the fader mod... which involved running audio out to the fader bay. I got that work done in about 6 hours over two days... LOTS of delicate wire to sift through and tie back for each channel to ensure I didn't burn through any of it with my iron which would have been a nightmare...    Flipped it back up and have two ongoing issues... one is a bus jumper has become disconnected where they are jumpered between cards...  easy to find and easy fix but it's up under the console so I need to come up with a plan to get in at the awkward angle to fix it.  Also the solo functionality of the input channels isn't working now but that might not be related to flipping the console.  Solo functionality still working on the center section cues and sidecar... but they might be different busses electrically. 

I ended up getting extremely lucky and found an 8 pack of faders on ebay with the correct size faceplate and escutcheon...  and all the correct P&G faders with correct value. Turns out he had 48 total which was perfect for me and I bought them all for WAY less than I was prepared to spend on getting new fader faceplates made/outfitting with mix and patch P&G's.  Got them all dropped in and am working on wiring them all up!

Not sure what to do with the old faders.... might make a coffee table out of them?  ;D
I'm still going to get a single piece of metal made and screen printed for the 16 bus master faders.

I'm 6 preamps deep...  definitely going to be snowballing on that front soon....  cost of a large order of transformers is really the only thing holding me back at this point.

As far as EQ's go I've sourced 4 554's, a 550b, and a datatronix 550a so far... Still would like to design my own EQ but at this point just focusing on getting 8 channels going and filling out the preamps.

also not pictured are the four 525's to the right of the center section.  I converted the console's old pinout to the 500 VPN standard so I can throw whatever I want in there... and obviously converted the 525's to 500 series so they can go anywhere as well.

Coming up: Massive preamp build. Also I'm out of 2520's so I need to do another batch. This time instead of doing 2 5x5 sheets I'm going for the mind numbing 11x11 sheet....    hopefully I'll come out of the other side of that with my sanity. 

Also maybe night need to start scoping out some spaces around town. As this becomes more usable it's killing me to not be able to use it fully.

AnywayHere's a "State of the Console" pic.  Still lots to do!

 

[mjrippe]

Member avdo was selling API style knobs a while back...

 

[TubeMonkey]

Alright friends, time for the Quarterly update!

I've been working a lot in the studio and traveling which has been nice, but only recently dug deeper into the console. About a month ago I was able to figure out DL tape pinouts and which DL connected to the outboard gear patch points.  I had to beep everything out with a multi-meter because for some reason everything after the first 16 tie points weren't in any logical order. 

I ended up re-pinning the female side so that it was in order and matching the other pinouts of the Mic in/tape in/out DL connectors. These were the large 156 point ITT Cannon DL's which were pretty expensive to get ahold of.  I try not to dwell too much on the fact that the original console cables are probably in a dumpster somewhere.... 

I think at this point I've put about 40 hours into cabling, but now have everything up and running.

I also got to re-labeling my patch bay with color-coded labels which are MUCH easier to see from a distance than the old labeling (green red and yellow cellophane tape).

I finished up building a new mounting system for the ACA's in the back of the console and have only to build 4 more for 8 more channels of bussing.... Also have to mount up the talkback mic preamp and re-solder/crimp a few of the slate/tone inject lines as the original API summing blocks had more pins... Jeff's units will work but only have 3 pins for each molex connector so I will simply have to join them before the connector.

I've also made some progress on acquiring more EQ's and building some more mic pre/input modules.  All 4 525's are working great. There is one that sounds way more magical than the others. I'm going to try and match the internal trim pots of the other three to the one I like most. Also picked up a pair of B&B eq's which are a good utility EQ... jenson output transformers. They don't sound as good as the API's but got the pair for $250 so i'm not complaining!  3 more API 554's in the shop waiting for metal brackets. That will bring me to 6*554's, 2*B&B EQ, 4*525's, 1*Datatronix 550a, 1*550b

Looking for some more EQ options....  I think I'll be going for a pair of CAPI LC40's soon for master bus duties. Also looking at a pair of JLM FREQ500 Eq's  as they seem pretty versatile.  What have you guys been diggin  for 500 series EQ's?

Currently mixing with 16 by patching pro tools -> outboard eqiupment -> console fader in -> Ch. direct out.  Still not utilizing busses 1-8 as I need to fine-tune the gain of the Line amp (currently giving approx. 6db gain boost). (1-16 currently have no ACA).

Was happy to use the Overdub functionality of the mic pre modules on some guitar overdubs on a clients song the last couple of days!

What else? I think the only things really slowing me down at this point are getting the funds for 30 more Preamps and EQ's.

 

[TubeMonkey]

June 2019 console pic!

 

[TwentyTrees]

Great to see the progress you’re making! Always a fascinating read, and your bus compressor looks brilliant in the centre section, really well matched to the rest of the console.

As for EQs, there are obviously lots of great options out there but I wanted to drop in a plug for Chambord Audio’s CA-250,  as it’s flying under the radar slightly  - three bands of Sontec-based full parametric EQ for a very reasonable whack. Sounds great, and super flexible.

https://groupdiy.com/index.php?topic=66011.0

 

[TubeMonkey]

Great to see the progress you’re making!

https://groupdiy.com/index.php?topic=66011.0

Thanks! Yes chopping the center section was a little stressful... but it fits in there nicely! 

The Chambord EQ's look interesting! Do you know if they still offer them in a kit? Trying to keep my EQ cost to <$400 each

 

[TwentyTrees]

The Chambord EQ's look interesting! Do you know if they still offer them in a kit? Trying to keep my EQ cost to <$400 each

Good question - I think Elskardio is only doing complete modules now, but if it’s something you’re interested in then it may be worth asking him the question!

 

[gar381]

WOW...

Just caught this thread for the first time.
I Love what your doing here.  Much respect !
This looks my kind of fun !!

GARY

 

[boji]

Woah!  She's alive!!!  Missed your update.  Congrats!  I'm jealous how quickly you turned this around.  Hard worker, that TM!

Pictures motivate...so...  moar pix plox!  =D

 

[TubeMonkey]

WOW...

Just caught this thread for the first time.
GARY

Hey Gary,  you have no idea how acquainted I am with the gar2520s. Thanks for all your work with DOA's!

If you haven't noticed EVERYTHING in this desk is 2520's.... I've probably built around 200 at this point.  Last time i was running out and realized I needed to build more I was trying to heckle Jeff into selling me an 11x11 sheet of 121. I wanted to be the only guy to ever assemble an entire sheet of them.... Jeff said they aren't made in the 11x11 sheets anymore so i've been sticking with the 5x5 sheets. It's probably a good thing because I'm not sure how much sanity I would have left after doing a big sheet. haha!

I've been doing 50 at a time lately...

 

[gar381]

Tube Monkey

Looks Goods on your 2520 build!!

When I build Assembled gar2520s for jeff I generally break off my 5x5 cards into 2x5 for assembly.  I tried 5x5 one time
and found it a bit frustrating for me doing the millmax pins.  BTW.. the 11x11 card sitting on my ATR102 is the only one ever
made in that format.  Carry on with your build !  Someday on a visit to Nash I hope you will give me a peek and a listen
to your baby. 

Best

Gary

 

[TubeMonkey]

More updates coming soon! In the meantime here's a cool picture I found of Leon in front of the console in Tulsa sometime between 1974 and 1978. Still trying to track down some more information on the console history!

 

[boji]

Looking good TM! Mind showing us the back of the patch sometime?  I'd like to see how you made sense of it.

Regarding EQ's:

Also looking at a pair of JLM FREQ500 Eq's  as they seem pretty versatile.

I scooped a pair and I can say with some cursory listening they are nice and broad-sloped.

Incidentally I also got a pair of the Chambord's a few months ago (prebuilt but fair-priced...so many slots to fill, cost is an issue). Both brands are transparent and very quiet but if I had to choose only one I'd go JLM. It has a few more bands to play with and you can't make it sound bad-- even at max settings.  But they are different beasts.  I'll probably end up with JLM's on bus, Chambords on a few channels for its surgical boost/cut Q.