Racking Trident 24 modules

[andYz00m]

Hey there! Went full hybrid is the studio this year and have been collecting preamps to round out my 16 channels of input needed for my tracking purposes. I have plenty of the classic stuff and looking for unique colors. I love having EQ on the way in, and also love projects, so racking buckets has been my plan.

I found another user here offering Trident 24 channel buckets and thought that they would make a good candidate. I have used multiple consoles from that era and love the EQ. I have read a few posts here about the pres lacking headroom, but for the music I make, I dont think thats a problem (We track loudly).

The seller has replacement caps and pots for servicing the boards, and at this point Im thinking about where and how to chop the boards down to fit two channels in a 2U rack.

Im looking for any advice on power supply options (+/- 18V, +5V) including what current draw these channels have. Also looking for advice on how to integrate either the actual fader, or a pot to replace the fader. The seller gave me the idea of just using the first aux out as the O/P and using the AUX pot as the fader. Seems like a good idea. I do like the sexiness of racking the actual fader, but not attached to the idea.

Also considering output transformers to make these actually balanced outputs. Not sure I need this but am considering it.

Any ideas or recommendations welcome including, "dont rack those you idiot".

Below are my dumb ideas.

 

[grid_stopper]

I used to own one of these consoles. EQ's sounded great! That being said, I imagine the first hurdle you would have to over come is the actual dimensions. The entire strip is on one long PCB(if memory serves...) and are definitely longer than the inside of a rack case. Not insurmountable, but definitely presents a challenge. Its also worth noting that the connectors used on the PCB's really suck(at least that was my experience. They would go intermittent and require cleaning every few months-so if you do decide to rack them, hardwiring would be a diligent move.

 

[andYz00m]

That does seem like the problem. Looking at the physical layout, it seems likely there are sections of the circuit spread out along the board. I’m hoping that the group section doesn’t contain anything essential and I can find a spot to cut that part off.

Of course, the other option is to not do this project and find other buckets as donors….

 

[grid_stopper]

im speaking entirely from memory here, so please take this with a large grain of salt but-i do believe it is laid out in chunks that more or less follow the controls on the panel, so in theory chopping part of the board could work. That being said, i would see if the seller would be able to check that nothing critical is on the wrong end of the board.

 

[Phantasm]

Projects like this can be great as long as you don't end up spending more than buying a nice off the shelf unit. I'm in the middle of very long winded racking of a Raindirk channel strip from a broadcast console that I got for peanuts which has the input and output transformers (Cinemag if I remember correctly) still fitted. I did some removal of unnecessary front panel switches and rewired some of the remaining switches as had loose wires but then kinda lost the impetus with it as was waiting on Cyril from Raindirk to supply me a custom PSU but he always seems busy on another project although he did supply me with a schematic so have all that I need. Should get back to it but the PSU side of things has held it up. I've been thinking about something like a Five Fish Audio PSU perhaps so something like this might work for you:- FiveFish Audio - PSU-4448 Power Supply Kit

 

[andYz00m]

Nice! That power supply does look like it might work. Ideally I would be able to supply phantom power too which this would do.

 

[Phantasm]

Nice! That power supply does look like it might work. Ideally I would be able to supply phantom power too which this would do.

Cool. I think they're designed to fit a 1U rack and are adjustable. I've been putting it off due to other things and also in the hope that Cyril comes through with a custom supply that would be built for the exact purpose. This has reinvigorated my interest though so will chase him up and see if he's free to do it now. Report back as interested to see how you get on.

 

[andYz00m]

Will do. Im drawing up the whole schematic now and getting some cases and switches lined up.

Then I bust out the band saw to chop these mofos down. HAHA!

 

[Phantasm]

Will do. Im drawing up the whole schematic now and getting some cases and switches lined up.

Then I bust out the band saw to chop these mofos down. HAHA!

Nice! Be careful not to take out a rail/remember where to reconnect rails!

 

[andYz00m]

Yeah for sure! I'll probably post aton of photos before I chop anything.

The seller had some great recommendations for easy circuit mods too. Will post everything when I start

 

[Phantasm]

Yeah for sure! I'll probably post aton of photos before I chop anything.

The seller had some great recommendations for easy circuit mods too. Will post everything when I start

Look forward to seeing - sounds like a perfect DIY venture.

 

[iampoor1]

Look for a small console power supply like a soundcraft cp150. Way beefier than the fivefish and once you recap it probablly the same price Edit: if your only doing a pair ignore this post...i meant for a whole bucket haha

 

[Phantasm]

Look for a small console power supply like a soundcraft cp150. Way beefier than the fivefish and once you recap it probablly the same price Edit: if your only doing a pair ignore this post...i meant for a whole bucket haha

Are sure about this? Soundcraft PSU's in my experience are quite poor - I've repaired the PSU in my 328XD twice and had to improve the inrush protection - unless it's only the 328 PSU that's poor although i've read several gear threads of people with multiple models of dead Soundcraft consoles where the PSU has died. Shame as the 328 is a great console for the home studio for those that don't like to use a DAW.

 

[iampoor1]

Are sure about this? Soundcraft PSU's in my experience are quite poor - I've repaired the PSU in my 328XD twice and had to improve the inrush protection - unless it's only the 328 PSU that's poor although i've read several gear threads of people with multiple models of dead Soundcraft consoles where the PSU has died. Shame as the 328 is a great console for the home studio for those that don't like to use a DAW.

Doest the 328 use a switching power supply? The cps150 is a bog standard lm338 linear psu....it would be hard to build for the 150$ or so they sell for. I've done a couple rack up jobs using them with no issues. I know some people that have left them on for 10+ years powering a 32 channel console and that will kill them...but I think that's more about it being a bit margininal for a full 32ch cobsole rather than it being a poor design.

 

[Phantasm]

Doest the 328 use a switching power supply? The cps150 is a bog standard lm338 linear psu....it would be hard to build for the 150$ or so they sell for. I've done a couple rack up jobs using them with no issues. I know some people that have left them on for 10+ years powering a 32 channel console and that will kill them...but I think that's more about it being a bit margininal for a full 32ch cobsole rather than it being a poor design.

Interesting - yes it seems to be people running whole consoles having the trouble so maybe you're right about being right on the margin of proper operation. The 328 PSU seems to suffer more from the inrush when powering on which I fixed by upping the rating of the thyristor on the input and did the trick as worked fine ever since. Had to replace some scorched parts also but the weak point was the thyristor for sure.

 

[andYz00m]

OK, I have some updates! I have reworked the boards and removed all the components I wont need. Replaced all lytics, pots and switches for new. Cleaned and reflowed some stuff. Tested grounds, etc.

I jumpered the pre/post switch and the Aux 5/6 switch. Also jumpered the insert loop as the signal always going through that loop on these cards. Will not be using the automute/line driver IC on the card and not using the fader section or fader IC. Taking the output directly from the Aux 1 pot wiper to the line driver board using a THAT 1646 then to balanced XLR on the back panel.

I purchased a case (thanks to Dan with collective cases!) with a blank front panel and basic stereo XLR connections on the back to allow for me to drill the holes for the pots, LEDs, power switch and power indicator. Will also be adding 1/4" TRS line inputs to the back panel.

Huge thanks to @nielsk for hooking me up with the boards, the replacement components well organized and some great ideas for racking these.

Things I still need to decide and execute:

1. Power supply decisions. NEED HELP HERE I have found some simple boards that would do 48V and 18V for purchase on ebay that are alibaba reposts that would work but wanting a proper solution.
   1. Toroidal mains power
   2. Phantom power sub board
   3. +/-18V supply
   4. +5V supply
   5. Current requirements are low
      1. 20 mA for two phantom input boards
      2. 40 mA for both input cards
      3. ~20mA for two 1646 line drivers
      4. Shoot for 150mA total supply (Unless I need to consider more current for some reason)
2. Line driver/balanced output cards built on THAT 1646
   1. 
   2. Planning on using the above layout (do I need common mode offset reduction? I dont understand this beyond basic theory)
   3. I can use bipolar power supply as I will already have the +/-18v for the input cards.
   4. Taking the output from the Aux wiper and sending to the 1646 then to XLR out.
3. KNOBS! Need to find some D pots that I like.
   1. Need knobs for the pots as well as circular caps for the switches to make drilling holes easy (the originals were square and unless anyone has a square drill bit ill have to go with circular)
4. Layout the front panel with space for the cards to mount and for power switch and power indicator. ( will use 5V for power indicator)
5. Chop the PCBS!!! Its going to be a tight fit but I think I found a spot on the board that will not affect the traces I need and will fit in the case. Photo attached.
   1. Any recommendations for best PCB saw? Never had to cut one up before... I own a bandsaw but that seem overkill.
6. Still need to map out the whole schematic, right now using the original schematic as reference and theorizing, but want to draw up the whole thing at some point.

Thanks! Excited about the project. Specifically being able to patch these at line level after some of my nicer tube based pres for tracking.

 

[andYz00m]

Here is the schematic with all the stuff im not using ripped out and the line driver added. Here is original manual with schematics.

 

[Phantasm]

Not experienced enough to advise on much that you've asked about but to cut down a PCB you should do ok with a normal junior hacksaw as they aren't too tough and should give a decent clean cut. I'd advise a little file down of the cut edge as PCB's can give fiber glass splinters and wont leave a sharp edge finish. Keep the updates coming as interested to see it.

 

[MidnightArrakis]

Here is the schematic with all the stuff im not using ripped out and the line driver added. Here is original manual with schematics.

View attachment 94721

I would just design myself a PCB to be exactly as I would want it to be and place it into my enclosure. To me, there is just too much of a possibility of something going wrong to deal with all of the "hacking and whacking" to make something that -- might -- work!!! And, you are lucky that in today's world, there are plenty of really good and -- FREE -- PCB design programs available to use. Then, there are "Old Farts" like myself who already have the software and 40-years of experience who can do exactly what you are looking to accomplish. I do that all of the time, anyway!!!

A -- Dremel -- tool with the correct type of blade should cut your existing PCB down to whatever it is that you are looking for. But, again.....it's still kind of a "hit or miss" proposition.

GOOD LUCK!!!

/

 

[andYz00m]

Thanks for the advice!

Chopped my PCBs with the bandsaw and it worked great. Video attached!

Ordered all the power supppy parts. Going to use premade THAT 1646 breakout cards (12$) for the line driver/balanced output. Using a dual rail voltage regulator after taking mains from a Hammond toroidal and a dual full wave rectifier (one inverted for -18V supply). Filter and into the VR for bipolar power! Going to just use the 18V supply for the power indicator lamp with a voltage dropping resistor.

Just tested the IC sockets after chopping the boards to make sure they all are getting power and things are looking good. I think I’m golden. Now I just wait to get all the parts and assemble and test. I also punched holes in the front panel for the pots and switches. Instead of ordering expensive switch buttons, just gunna make ‘em out of wood doweling and use a chisel to make the square receiving holes. More photos to come.