True Bypass with trails

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Shadoweclipse13
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True Bypass with trails

Post by Shadoweclipse13 » Sat Sep 26, 2015 5:17 pm

I am building a couple true bypass loop boxes for my pedalboard 2.0 (one for gain, one for delay) and I had an idea awhile back that someone on here suggested (from DIY thread?) about having one for delays that would just cut the input signal, but leave the output jack open (allowing the delays to trail essentially even through they would still be on).

I've been googling schematics and a few people have some with trails but it's a decent size circuit. I keep thinking that there's GOT to be a way to do that mechanically with one footswitch and maybe a toggle switch, but I'm a bit stumped.

Anyone have any ideas?
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Re: True Bypass with trails

Post by jorri » Mon Sep 28, 2015 4:42 am

Problem is that leaving the output still connected to the effect is not true bypass, and actually might benefit from being buffered as it blends two signals. The only way I'd think is to have the output switch back to true bypass after the trails somehow. No reason not to just have two switches I suppose, one for input and output? could open up some other possibilities perhaps too.

I guess you'd really want to switch between true bypass and trails with a toggle?

Maybe just wire up a normal true bypass looper, but then wire a toggle that connects the out and return together which would short anything that part of the switch is doing. And in a slightly more complex way add a buffer if needed on that switch connection?.

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Re: True Bypass with trails

Post by Shadoweclipse13 » Mon Sep 28, 2015 10:11 am

jorri wrote:Problem is that leaving the output still connected to the effect is not true bypass, and actually might benefit from being buffered as it blends two signals. The only way I'd think is to have the output switch back to true bypass after the trails somehow. No reason not to just have two switches I suppose, one for input and output? could open up some other possibilities perhaps too.

I guess you'd really want to switch between true bypass and trails with a toggle?

Maybe just wire up a normal true bypass looper, but then wire a toggle that connects the out and return together which would short anything that part of the switch is doing. And in a slightly more complex way add a buffer if needed on that switch connection?.
That's exactly what I want to do: toggle between a true bypass mode and trails mode. I thought I almost had it at 3am this morning, but then I realized that what I had done WAS to leave the output open to the jack, but made it so no input signal at all went in to the send jack in "trails" mode :fp: Haha. The thing is, I want to do it mechanically. I KNOW it's possible to figure it out. I'm trying to avoid having another pedal that needs power on my board...

I have a buffer board laying around I could use for that if I need to, so that's not a problem. The problem is, having signal go through the send and return jacks and then cut off the send jack when the on/off footswitch is pressed. I can figure out how to do the switching, but so far, getting it to be changed with the footswitch is eluding me. I'm gonna keep messing around with it... Thanks man!!
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Re: True Bypass with trails

Post by Shadoweclipse13 » Mon Sep 28, 2015 8:40 pm

I'm gonna breadboard this one in the next couple days to see if it works, but at least in theory, it makes sense...

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Re: True Bypass with trails

Post by Shadoweclipse13 » Wed Sep 30, 2015 7:34 pm

Changed plans! I couldn't quite seem to figure out how to do a mechanical trails mode, but I found something interested and decided to go a different route. I was reading a bit about my looper (TC Ditto X2) and a couple things I wasn't sure it could do and found out that with the stereo inputs and outputs, it can be routed to two separate amps (don't know if the grounding would be an issue, but I've read reviews of people who have done it with no problems, and isolated outputs could be added post looper later anywho).

After watching a video by Dan from thegigrig.com, I got an idea to do sterero outputs and to have delays go to a second amp. I basically just added a second output jack post-bypass loop with a toggle switch to choose which output the signal goes to. It will be true bypass either way, and I may try to figure out a way to use both output jacks at the same time, but for now, this is what I drew up.

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Re: True Bypass with trails

Post by Shadoweclipse13 » Wed Sep 30, 2015 8:54 pm

Is there any reason that how I drew up the A-B switch wouldn't work compared with this one?

Image

Would the way I drew mine create an issue with the grounds?
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Re: True Bypass with trails

Post by Shadoweclipse13 » Wed May 11, 2016 9:55 am

I don't know if anyone is interested in doing this, but my new pedalboard is gonna be arranged as a wet-dry rig (two outputs: delay and reverb going to one amp, and all my gain and funky effects going to both) and I keep coming back to thinking that a mechanical trails mode would be SO cool to do.

Well, I found a thread from the I Love Fuzz forum where someone had actually done it. It seems that they actually tested it with a basic AB pedal with a receiving box that recombined the two signals (dry through and the delays after they stopped receiving an input signal). Here's the link:
http://ilovefuzz.com/viewtopic.php?f=151&t=41964

I don't know if I'd need a buffer, but knowing it can actually work has spurred my mind into gear in figuring it out and I think I've got it: since most AB circuits can be made with a DPDT (if you don't need indicator LEDs), I could use a 4PDT as essentially two AB's: one that splits input into two outputs and the other side that splits two inputs back into one input.

Instead of 2 send jacks and 2 return jacks, one of the send and returns would be internal from one half of the switch to the other.

Basically it would still work like a true bypass pedal in that the delay pedals in the send and return loop would be out of the circuit when it's in the other mode.

I'll breadboard this in a day or so and see if it works!
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Re: True Bypass with trails

Post by Shadoweclipse13 » Wed May 11, 2016 11:37 am

I'm still gonna try it, but I have a feeling this will still cut off the trails after the input into the delay(s) is off. I may have to solder the return jack directly to the output jack. but here's what I've got so far:
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Re: True Bypass with trails

Post by FightingPlankton » Wed May 11, 2016 12:02 pm

there's actually a simple way to do this. I suck at drawin in MS paint so i'll try to explain it.
3pdt(or dpdt if u dont want leds)
guitar input to center lug(right side row)
amp output to center lug(center row)
pedal send to top lug(right side row)
pedal return to top lug(center row) AND bottom lug(center row)

done.
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Re: True Bypass with trails

Post by Shadoweclipse13 » Wed May 11, 2016 12:18 pm

Dude! I've been after that simple of an explanation for months! Haha. Have you actually tried it before? My only question (past the wire routing itself) is whether I need a buffer for the blending of the two signals...
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Re: True Bypass with trails

Post by FightingPlankton » Wed May 11, 2016 12:44 pm

Shadoweclipse13 wrote:Dude! I've been after that simple of an explanation for months! Haha. Have you actually tried it before? My only question (past the wire routing itself) is whether I need a buffer for the blending of the two signals...
I havent tried it, but in theory it SHOULD work. Most people like to ground out the unused jack when its switched, but my DIY ab/y just switches the positives.
as for the buffer, i wouldnt think so... normally buffers are used when you split signal since it lowers impedance.
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Re: True Bypass with trails

Post by Shadoweclipse13 » Wed May 11, 2016 12:47 pm

Then I'll just have to hope that my incoming signal before the switcher is low impedance then :P

Yeah, it definitely makes sense as far as the actual switching goes, but I've also made some switches that do switch the ground wires as well with no problems. I'll try it out and see how it works. Thanks Plank!
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Re: True Bypass with trails

Post by FightingPlankton » Wed May 11, 2016 12:49 pm

Saul Goodman
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Re: True Bypass with trails

Post by gibs » Sat May 21, 2016 8:51 am

This is something I've been researching, ( your original post that is, not the wet/ dry) anytime you combine to input sources passively (the output from the delay, and the incoming signal from everything before it in this case) you need to have a mixer in order to avoid any noise and signal loading issues. Think of all the ABY boxes that people complained about noise or weakened signal strength when they combined there amps in Y mode, this is the reason why. In order to accomplish what you want without signal loading, you'll need a line mixer, essentially a buffer with multiple inputs, and volume controls for each input in order to balance everything out.

Nose pedal.com sells true bypass loopers with trails toggles that are passive, and in their faq section have a disclaimer about this, they basically tell you to adjust your amps treble and output accomadate this issue.

So if nothing else, it doesn't hurt to try it out passively first, then if you need to add a mixer, you can always do that later. General guitar gadgets.com sells diy mixers that you can use for this.

The way I'm going to be trying, is to build a standard true bypass loop, then between the return jack, and where the footswitch connect, place the toggle switch, so that in the up position, it acts like a normal TBL. But in the down position, the switch would connect directly to output lug on the footswitch. So in theory it should work, I just haven't gotten around to it yet.

Here's my old post on thegearpage where I asked about this same thing:http://www.thegearpage.net/board/index. ... h.1501824/

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Re: True Bypass with trails

Post by Shadoweclipse13 » Mon May 23, 2016 2:51 pm

Dude, that's so cool to hear! Thanks for chiming in!! I think I posted earlier, but it didn't quite work after I actually soldered the pedal together (though it did work when I breadboarded it, which is weird). The mixer thing makes a lot of sense, but I may also try using a buffer circuit (since I have one already made and on hand already). Please post anything that happens when you do yours! I'll report back after I try it with the buffer.

To be honest though, unless adding the buffer kicks some major ass (and I mean MAJOR ass), I'll probably just rebuild it like it originally was with no trails. The trails is super cool, but I definitely need a full signal when I stop wanting a delayed signal, you know?
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