Passive ABY

mkstewartesq

Well-known member
Not a whole lot to say about this. It’s a passive ABY box that allows you to run your signal to two different amps either individually or in conjunction. That being said, while it’s pretty simple in function and intent, it’s an indispensable tool if you have more than one amplifier, so I appreciate it being made available.

The build - low parts count, although not necessarily parts you might already have in your stash unless you regularly work with board-mounted power and I/O jacks. I’ve never had a need for Cliff washers so I ordered a few of those from Robert when I bought the board, so I also appreciate him making those available through the store.

Because everything is board-mounted on this project and components are actually mounted on both sides, it can be a bit confusing at first to figure out where everything should go (obviously, you don’t want to make a mistake on this because desoldering board-mounted jacks and 3PDTs would be a nightmare (ask me how I know – see below). This thread gives clarification on where everything should go.

My only glitch was my own fault, not due to confusion about where things went. For whatever reason I had a real mental block as to how to secure the board properly when soldering the stomp switches so I didn’t notice it shifting a bit when I was soldering the AB switch and ended up with a switch that was tilted in a way that it would not have fit through the hole in the enclosure. So I had to sacrifice that switch to desolder it - in the process I lifted some pads but luckily on the opposite side of the board so, once I verified that there was still continuity everywhere there should be, I was able to install a new switch. But that’s why the board around the switch for the AB control looks a little cooked.

A little heads up on the LEDs, at least on my build. Like everything else, the LEDs are intended to be board-mounted. Normally I locate my LEDs elsewhere and run wires to them but this time I decided to just go stock and board mount the LEDs so they went straight up through the enclosure per the drill template. But be aware that, at least with the 5 mm LEDs I used, the placement of the jacks dictates the depth of the board in the enclosure, which means that the distance from the top of the enclosure to the board is at the very limit of the length of the LED leads – so if you want the LEDs to come up through the top of the enclosure, the ends of the leads that you solder to the board are literally going to be flush to the board, with no excess sticking out for you to bend to hold the LED in place or to snip off after you solder.

Because everything is mounted on the side of the board facing inside the enclosure, the gutshot is exceedingly boring.

Graphics - just a film free decal over an aluminum enclosure that I sanded to about 600 grit and then polished with some metal polish. Because I’ve had garbage luck with clearcoat lately due to the temperature fluctuations here, I didn’t even clearcoat this one – I’ll just have to trust that I baked the decal enough that it’s going to be durable. And if it isn’t, again this is a utility pedal so I don’t mind all that much if it shows some wear and tear eventually.

Ha – I said there wasn’t much to say about this pedal yet somehow I still wrote my standard doctoral thesis-length report on it.

Mike

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Hmmm I've been led to believe that these at least need buffers on each output as well as the ability to flip the phase on one of them. This looks great, but can someone tell me why this is different to, say, using a Y splitter cable? (which you absolutely should never do to run two amps).
 
Hmmm I've been led to believe that these at least need buffers on each output as well as the ability to flip the phase on one of them. This looks great, but can someone tell me why this is different to, say, using a Y splitter cable? (which you absolutely should never do to run two amps).
You may get away with a passive splitter depending on the application. If you don’t need both outputs, then you can use it for a variety of applications (choosing between two amps or two guitars for example). If you have a buffer in front of it you could use it to route the signal to two different destinations. Although that can probably cause phase or ground loop issues without a transformer.
 
You may get away with a passive splitter depending on the application. If you don’t need both outputs, then you can use it for a variety of applications (choosing between two amps or two guitars for example). If you have a buffer in front of it you could use it to route the signal to two different destinations. Although that can probably cause phase or ground loop issues without a transformer.
Yeah for sure, I'm just wondering about the Y part in the ABY, the conjunction in this sentence

"ABY box that allows you to run your signal to two different amps either individually or in conjunction"

It's something I'm keen on trying but need to know more about it
 
Yeah for sure, I'm just wondering about the Y part in the ABY, the conjunction in this sentence

"ABY box that allows you to run your signal to two different amps either individually or in conjunction"

It's something I'm keen on trying but need to know more about it
Yeah you can split the signal with it but you may have a few problems: if there is no buffer before the splitter, you may get signal loss; if you route the signal to two different signal paths, e.g., two amps, you may have phase issues or ground loop noise issues. A more foolproof approach would be a buffered splitter with phase switch and one of the output isolated with a transformer. Robert’s splitter does 2 out of those 3 things.
 
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