Using a passive A/B pedal switch in the middle of a pedal chain

[mlannoo]

hello fellas ...

Fulltone has a DIY Passive A/B Switcher under their Tech Tips page ....

if i were to build and use this A/B box, i was wondering if it could be used in this manner? (see attached drawing under "Ideal Setup")

I basically would like to A/B between two different pedals ... then route the OUT for both back into a single INPUT to continue on down the line.

i would need some sort of 1/4" mono splitter i guess ... so my question is: are there any drawbacks to running the signal this way or is there a better solution?

i basically want to toggle between the zvex fuzz and the fulltone OCD for my tone (without stomping one off, then the other on) .... the rest of the pedals in the chain are just color for either 'tone'. make sense?

i had this question up on Weber's FX forum and someone had suggested using a "looper device ... two loops that you could toggle between plus a global bypass". Does something like that exist? Has anyone built a box like this?

thanks
Matt

[cbarrow7625]

You can't just run the outputs of the two pedals together & expect everything to sound right & be happy. That being said, depending on the exact design of the output circuitry in each pedal, you could get lucky.


What you should be able to do is run the output of the BOSS pedal directly into both inputs of your two distortion pedals. Use the A/B box to select one output or the other of the two distortion pedals and pass that down the line.

As long as the output impedance of the boss pedal is low and the input impedance of the two distortion pedals is high, you should have absolutely no problems and no difference in tone.

Chris

[mlannoo]

i found several nice "looper" boxes out there but they only provide a situation like this - loop A: On or Off, loop B: On or Off. that doesn't solve my problem. i want a single stomp switch to either choose loop A or B.

i will try the method you suggested. thanks for the reply.

[Brad1]

Yes. To expand on CBarrow's suggestion, also make certain that you build an A/B box, and not an A/B/Y where the signals could inadvertently get mixed together. Never mix outputs on anything with a Y. A passive Y is meant to route only one of two input signals through to one out, or one signal out to two separate devices/amps, etc. And, be careful even doing any of that, depending on how the Y switches.

Just turn the A/B box around, use the Boss out with the mono Y cable to the two inputs of the two stompboxes, out of them into the two inputs of the A/B, and the one out of the A/B box now goes straight to the rest.

Since you will be switching out either pedal from the path, it should be close to the same as if you just inserted it by itself because it's directing all the signal to the active jack. Only if you tried to Y them after the A/B box to separate paths would you split the load to cause potential problems.

Edit: Now that I looked at this again, WOULD the non-used box still present a load from the Boss pedal out, even though it's not passing signal from it's out?

Brad1

[Don Moose]

WOULD the non-used box still present a load from the Boss pedal out, even though it's not passing signal from it's out?

Yes it would - but if the input impedances are adequately high, not enough to notice.

Would it be close to practical to build an double-A/B box? Two switches close enough together that, with a strip of something stuck to both buttons, you could guarantee hitting both at once?

Then you would isolate the two fuzzes from each other completely.

Hey, for that matter, could you do the close-together thing with the two fuzzes?

Hope this helps!

[diode breath]

I know you specifically stated "passive" A/B switchbox, but have you considered using the Morley A/B? It will accept two inputs and give one output, or vice-versa. I've used one with a guitar in and switched the outputs from a rhythm amp (Princeton Reverb) to a lead setup (Blues Jr with an TS-5), and it works very well -- no "pop" like ya get with a mechanical switch.....

There are two switches on the box, an "A or B" and "A and B". Just gotta make sure you hit the right switch. I'd set it up so that you split the output of the Boss TU-2 so it goes to the input of both fuzzboxes, and plug the outputs of the fuzzboxes into the A and B jacks. Hitting the "A or B" switch would toggle them, and isolate the unused device.

I just got a second unit at the Dallas Guitar Show about three weeks ago, and it was $50at one of the vendors' booth. I'll have to install a power jack, 'coz changin' the battery requires pulling off the underside. A small power jack tied into the battery connections eliminates removing the switch unit from the pedalboard.

[BackwardsBoB]

Here's one

ToneJones makes an AB looper, and he works at keeping the switches close together so that you can get them in one stomp:

http://www.tonejones.com/ABLooper.html

Once you have one loop running, stomping both switches will switch to the other loop, and you get the advantage that you can bypass both loops. As you can see from the site, it has lots of applications.

He makes replacement FS-36 footswitches for Carvins too, so you know he's a great guy.

[BritishSteel]

Your setup can be used just fine IF:

The A/B box is 2 input - 1 output. Simply put the box after the 2 OD's
A:is one OD and B:is the other

As suggested make sure it is an A/B not an A/B/Y