A-B/Y footswitch

[TD_Madden]

I'm looking for a diagram for how to build an A-B/Y pedal with true-bypass.... anyone make one?

[Amp Kat]

Try this and R.G. will be proud of you. http://www.geofex.com/fx_images/Oaspltr.gif

The splitter really needs those isolation transformers however you can also cut one of the shields on one end of your guitar cable to reduce hum but it all changes when you get to a two wire circuit. You may get hum and you might not. The trannys are a plus in both situations.

There is also an explanation site and then transformer model at http://www.geofex.com

[TD_Madden]

how about a PASSIVE one.....?

[Amp Kat]

There is a passsive one on R.G.'s website.

[TD_Madden]

guess I'm blind....there are two listed, but both seem to have transistors.

[Amp Kat]

Oops sorry bout that TD. They are both active and I'm sure I've ever seen a passive one. The Whirlwind is an excellent A/B/Y box but uses a battery also.

[Ray Ivers]

TD,

I know in this day and age of many, many schematics available on-line, DIY Web sites, etc., what I'm going to suggest will sound almost archaic, but seriously... I'd grab a piece of paper and a pencil, and draw five objects on it:

1) Three guitar jacks, in a row - Output A, Input, and Output B - and

2) Two DPDT switches directly below them - one for A/B switching, and one that overrides the A/B switch for Y'ed operation.

You may be surprised at how quickly you can draw up your own schematic, even with ground-and-hot switching (the reason I suggested DPDT's). Or you could continue looking for a print... but designing an A/B/Y box is less difficult IMO than wiring up a Strat. You could even use the commonly-available 3PDT switches and include LED's w/resistors and a 9V battery for mode indicators, but no sense in making things complicated if you don't have to.

Ray

[TD_Madden]

yes, it's that ground-switching I'm interested-in.....the a/b part isn't difficult at all, and even the y portion isn't... In fact, I have a commercial box (maker withheld) that does the switching with no problem, but it doesn't seem to ground-out the unused side and can be almost microphonic....while the "y" selection is quiet.

That's why I was interested in a design that does that properly.

[Regis]

Gooogle is your friend:

http://www.monkeyfx.co.uk/pictures/bestABY.jpg

http://www.threepoundsofbakon.com/guitarfx/buffer.htm

[TD_Madden]

Thanks.....I hadn't used ab in my google searches, just a-b, a/b, and a-b/y.

[TWANG]

try these

for a/b try this


Guitar A/B/Y AB-Y AB switches pedals

and with efx loop



and this

[TWANG]

and this

ABY guitar box

[Mark Hammer]

Hold up at 2nd base there for a bit.

While an A/B box can be easily and successfully built in all those manners described above, an A/B/Y box is a horse of a slightly different color (and a different kettle of fish too).

The problem arises with the Y part of the equation and what might occur if the inputs of two devices - and especially their input impedances - are placed in common. In these circumstances, you likely want to have some electronic isolation, and that turns into an active or transformer-based passive circuit of some kind. At the very least, you have to know something about what might be imposed on yur signal when the two output paths are linked directly.

[TWANG]

are you saying their info is incorrect?

[Mark Hammer]

The info is correct IF one is solely interested in connecting to two devices from the same source simultaneously without regard for tone.

Once two inputs are ganged, the question becomes one of whether the nature of the inputs you are feeding and the source you are feeding them from, will result in audible loading. In some instances it won't, but in most instances it will. Keep in mind that the very thing that true bypass switching was supposed to solve was exactly this problem/issue: having a signal tied to multiple inputs in parallel.

So, if you are the sort that strives to keep your clean signal sparkling clean, you probably don't want to parallel the inputs without isolating them.