N00b: Studiomaster Mixdown Gold Overhaul

[Fuelthefire]

Hey guys, just wanted to pop in, this is my first post on GroupDIY so I guess I'll give myself a little introduction. I'm in my second year of college majoring in electrical engineering, but I've only taken two actual electronics classes. I have a basic understanding of circuits, and am not completely dumb, but am still very much a n00bz. That said, I bought a big, old, beat up Studiomaster 16-8-16 board that works, aside from the phantom power, for $175 and want to completely overhaul it as a way to help learn myself quicker and easier with a hands on project.

I've cleaned it up and cleaned/lubed all the pots and faders, and tested it and the board sounds pretty decent already. I haven't been able to find ANY schematics for the thing so if anyone has them handy that would be amazing.  (Search revealed a few dead links from about a decade ago.)

I guess what I'm asking for is anything I might do. I've seen a few mods for this, mostly to the power supply by adding .1uF caps to the rails. One of the things I feel might be worth doing is building a brand new power supply and bypassing the internal one completely. I'd just love to have some insight from you guys as I start my little learning experiment.

 

[joaquins]

Hi, welcome!

About the PS, does it have any problems? Is it noisy? You may be just fine changing the big electrolytics in there, I don't think building a new one is a need unless it's really beyond repair. Use that time to build a bench PS which is much more useful and you are learning much more in the way.

JS

 

[Fuelthefire]

The mixer isn't insanely noisy now, but could be quieter.  Only reason I thought of an external PSU is that the general consensus is that external PSU's are quieter, and because I know the original power supply was built to handle the 16 channels on the board, plus up to 8 more.  Mine has 16 channels, plus a 4 channel side care; and I know that the current draw will go up when I recap the channels to higher value caps, plus I love the idea of adding another 4 or even 8 channels to the board later on down the road.

 

[Fuelthefire]

Also, since the phantom power doesn't work on any of the channels I can only assume it's a power supply fault.  That should be a relatively easy fix though.

 

[joaquins]

Noisy hum or hiss? If the first PS may help, of the second not.

Changing the caps on the boards just would increase the turn on current, but after regulators and short protection this current will be limited. Once the peak is gone the current consumption will be the same as before. If anything, smoother.

About the current capability for driving 8 more chanels I can't tell, but you should have some headroom to add a few extra.

If you go for the lab PS will work with the mixer if you need it till you build a new one but also with many other projects in the future.

JS