Parallel mixer & bypasser module

[Denyle]

I was just thinking, a 2 to 1 mixer could be done for cheap using IC's for balancing, unbalancing and buffering. Add a relay to bypass the insert. The idea would be to use the rear panel i/o as the insert send/return and put in & out on the front to interface with the patchbay. There could also be an expensive version made using transformers and a discrete op amp. It would be a nice problem solver for people with limited channels and for bypassing units without a bypass or those without a hard bypass. Anyone up for it?

[Sonicmook56]

On most console patch bays, you could yank the insert return to "bypass" a module.

Maybe I don't understand the concept?

Two or more balanced input channels (on front panel) -->summed with level controls ---> Selectable insert out (on back panel) --> to main output (on front panel, mono)

~B

[Denyle]

Chandler actually just released exactly what I was thinking, done with transformers and discrete amps. Theirs is a stereo 19" unit. I still might roll my own IC version for my lunchbox.

[Denyle]

I just rolled one on a euro card. I'll be testing it tomorrow once I locate some trs jacks.

[Denyle]

A simple little 2 into 1 blender using 2 INA134 line receivers and a THAT1642 line driver.

31

[tubemooley]

Is that a pair of big CDE film caps for signal coupling? 10uF @ 100VDC? I am constantly looking for caps like that. I hate using electrolytics for coupling my signal. Ten years after building a circuit, the electrolytics are useless. In fact, they're worse than useless at that point. Not even 10 years. 5 years. Electrolytics stink. DW.

[Denyle]

Yeah, those are big metallized polypropylene coupling caps. I'm sure it's overkill but I used what I had for this project. ;)

[tubemooley]

They're not overkill if they fit and they sound good. Manufacturers often have to make engineering decisions based on marketing. We don't. Use those. DW.

[Denyle]

Front panel & L bracket all fab'd up and assembled.

48

Looking back now, I just thought of another, possibly more useful product. Something that takes a line input and blends it with a stompbox level signal.

[Denyle]

It's alive and sounds like nothing. You don't notice it except for losing a tiny bit of punch. I might bypass those monster caps with something smaller. I found another use for this thing too. Plug your API pre into the return jack and roll back the wet/dry control to attenuate the signal.

It stands out like a sore thumb. :D
61

[tubemooley]

Nice racks. Wet/dry mixer.... That's a fabulous idea. We're always looking for ways to do that. DW.

[Denyle]

I'd do up some pcb's if I can ever figure out Eagle.:confused: I'm spread too thin as it is atm.

[tubemooley]

I have a copy of Eagle but I have not used it much. We use Altium's P-CAD at work and I have a licensed copy of it at home. The PCB design software takes quite a bit of time to learn. It's not that it's hard. It takes time to figure out all the little steps which need to be followed in order to end up with Gerbers to send to the board house. Most important is probably the library work. Everything starts with the library. Anyone can lay down resistors and capacitors into a schematic. It's the laying out which is critical. And the layout footprints are embedded in the library components. A squiggly line resistor in a schematic maps onto a 1/4 watt resistor which is just two plated-thru holes on the board. But those holes have to be the correct size and spaced properly, etc., etc. You get the idea. DW.

[Denyle]

I hear ya. Unfortunately, I'm more of an instant gratification kind of guy. :D