True Bypass in an A/B Switcher?

[Jerry Overstreet]

Interesting comments in some of the threads here recently and in the past concerning tone deterioration with A/B switch boxes.

I commented about the ones I've built not having any problems and when players asked if it was true bypass, I felt it wasn't possible with these.

Mine are just a twinkie sized enclosure with Switchcraft components. 3 jacks along with a 3 pos. switch and some 20-22 ga. wiring hooking that altogether. No LEDs or other circuitry.

Seems to me, that when the switch is in one or the other positions, it simply directs the signal to that instrument and should have no effect otherwise.

I do sort of understand how that can happen with certain stomp boxes circuitry that add effects but these devices do not add or change anything, just select one input or the other to a simple output jack.

I admit to being very basic in my knowledge of electronics, so perhaps I'm in the dark here. I'm just trying to learn something and advance my simple knowledge.

What would make some devices need true bypass and others not?

[Richard Sinkler]

It seems that your configuration would have no tone loss or need for true bypass. There's no circuitry for the signal to have to go through like an effects pedal. I'm anxious to see some technical replies.

I use 3 of these between my 2 pedal boards. They say true bypass. I'll have to open one up to see what's inside.

EDIT: I took mine apart and there is definitely a circuit board that the jacks and power jack mount to. I can see some resistors and I believe diodes on the board too (hard to see in there without completely disassembling). The ones by the power jack are probably for the LED. There are some down by the switch too and in the center of the board near all the 1/4" jacks.

https://www.amazon.com/lotmusic-Selecto ... r=8-1&th=1

[Jerry Overstreet]

Thanks Richard. Yes, that's what I'm thinking as well. Just want to have the correct information to pass along.

[Dennis Detweiler]

I built my own bypass as Jerry did (no electronic components) and find no pop when switching it in or out and no signal/tone loss.

[Jeff Highland]

Jerry you are true bypass with just a switch in the pedal and no circuity that the signal passas through. Indicator leds if fitted Are not in the signal path but are swiched separately.
Non true bypass pedals such as most Boss pass the signal through the circuit and the switch just engages the effect

[Cappone dAngelo]

Yours is true bypass if it's just switching between A and B with no active circuitry. But true bypass isn't necessarily inherently better - it depends on the application. If you are splitting the signal ("A + B"), if there are active electronics on either side that may cause a pop when switching (typically due to a DC offset being present), or if there is a long cable run that is adversely affecting tone, a buffered solution may be preferable. And if splitting the signal, there may be benefits to having transformer or other isolation built-in to interrupt ground loops, and a polarity inversion feature may be handy depending on the rest of the rig. So it really depends on the particular application.

[Cappone dAngelo]

It seems that your configuration would have no tone loss or need for true bypass. There's no circuitry for the signal to have to go through like an effects pedal. I'm anxious to see some technical replies.

I use 3 of these between my 2 pedal boards. They say true bypass. I'll have to open one up to see what's inside.

EDIT: I took mine apart and there is definitely a circuit board that the jacks and power jack mount to. I can see some resistors and I believe diodes on the board too (hard to see in there without completely disassembling). The ones by the power jack are probably for the LED. There are some down by the switch too and in the center of the board near all the 1/4" jacks.

https://www.amazon.com/lotmusic-Selecto ... r=8-1&th=1

It says "Due to true bypass circuit design, the A and B jacks will affect each other when used as inputs in A&B mode", which, if true, does suggest that it's true bypass (and is the reason I generally don't recommend true bypass for splitting passive guitar signals). That said, given that the circuit board photo shows what appears to be a completely different device (it has a 2399 digital delay chip ...) I don't know how much I'd trust the info they provide.

But if it sounds good ... does it matter?

[Jerry Overstreet]

Thanks for confirming my theory everybody. I feel more confident in my understanding and description thereof.

No splitting with my device. The switch only selects one or the other output jacks, no mixing.

I install a 3 pos. switch with a center off. My reasoning was to have a switch position with no output as a mute for tuning or whatever other situation one might want that.