A/B/Y pedal... any suggestions?

[otokomae]

I'm planning on building an A/B/Y box, and was wondering if anyone had any suggestions for a good design.  I've got a Japanese guitar magazine with a project build for one, but it's only A/B, and the "Y" part is what I'll be using the most!  I thought I could probably sort out how to add the "Y" part to it, but was hoping somebody might know of a good design already setup for what I need.  Just let me know where to find a schematic/layout, the simpler the better I suppose.  Thanks!!!

[nelson]

If you are using it to run two amps hum can be a problem. There is a design at www.geofex.com that uses transformers to isolate the grounds. Not a simple design. If you require a simpler design and are not worried about hum look in the layouts gallery of this site. There are 2 or 3 ABY designs.

[SolderBoy]

I built an active one recently that combines signals in the "Y" setting- ie. two guitars into one amp.  Its basically a simple two channel mixer with fet buffered inputs and outputs.  I can post a diagram if you want.

[R.G.]

A/B/Y boxes come in two main flavors - passive and active. The passive ones are done with metal switching contacts. Metal switch contacts don't care which direction the signal is flowing. Active ones use semiconductor buffers which *do* care which direction signal is flowing, and only work one direction.

If you want to do two guitars into one amp, and want to use an active box, you need one that has the A and B as INPUTs.

If you want to do one guitar to two amps, and want to use an active box, you need one that has the A and B as OUTPUTs.

Passive is both more flexible and simpler to make - which would by itself make passive the only way to go except for hum problems with two amps. For two-amp versions, you need to have some kind of ground isolation unless you're very lucky every time you set up.

[bioroids]

There's no need to isolate the grounds on the active box?
Would a ground lift button help on the ground loop situation?

Luck!

Miguel

[otokomae]

Hmmm...  that's a lot to think about.  Can anybody point me to a site somewhere with a good description of how to get "ground isolation?"  Thanks!!!

[bwanasonic]

Hmmm...  that's a lot to think about.  Can anybody point me to a site somewhere with a good description of how to get "ground isolation?"  Thanks!!!

http://www.ebtechaudio.com/he-2des.html

Kerry M

[R.G.]

Can anybody point me to a site somewhere with a good description of how to get "ground isolation?"

Yep. Read GEO. In this instance, read "the Spyder" for what ground loops are and what isolation is, and then the "Hum Free Splitter" articles on one way to get ground isolation. I believe that the Ebtech stuff is really good transformers. The GEO transformer isolators is good performance from cheap transformers.