Is there a way to switch between trails and true bypass for a PT2399 delay?

[sherminator1995]

I've tried to think of many ways to google this, but nothing gives me what I want, so I guess the best bet is to ask you guys what to do, after being a longtime lurker.

The TL:DR is that I'd like to be able to switch between trails/spillover and true bypass. I would really like some help with this. Thanks.

So the background is that I'm going to make my own version of the Deep Blue Delay with trails/spillover using the vero schematic on TagboardEffects, along with the UK-Electronic.de tap tempo module. One thing I'd like to have is a way to switch between the spillover bypass and true bypass (like the Way Huge Supa Puss). I was thinking that if I used a relay for the true bypass and the spillover bypass, could I use something to switch between the functions of the momentary DPDT switch? For example, could I use a toggle switch that, in one position, sets the momentary switch to energise and de-energise the true bypass relay, while in the other position it does the same with the spillover bypass relay.

I'd quite like this feature because I use a loop station after my current delay as well, and I wouldn't like the spillover during loops, but at other times I would.

If what I'm saying is pure rubbish, then I apologise, I have only built a fuzz and modded an overdrive until now, and I'd really only like to build stuff that I'd actually use (money in somewhat short supply). In that case, would the regular spillover/trails bypass sound any worse when bypassed? I'm wondering because I use some digital pedals that aren't true bypass, but also add a huge amount of noise.

[R.G.]

First, no need to apologize, you're trying to learn.

I've tried to think of many ways to google this, but nothing gives me what I want, so I guess the best bet is to ask you guys what to do, after being a longtime lurker.

The TL:DR is that I'd like to be able to switch between trails/spillover and true bypass. I would really like some help with this. Thanks.

You're running into a fundamental problem. I think you're already at trailing echos cannot be made true bypass, because the trailing echos have to happen a variable and unpredictable time after the player tells the pedal to go bypassed.

...In that case, would the regular spillover/trails bypass sound any worse when bypassed? I'm wondering because I use some digital pedals that aren't true bypass, but also add a huge amount of noise.

I haven't delved into your issue, but a casual reading suggests you're going to do some version of an external true bypass with an internal "cancel" function. It's probably possible to make something like that work.

As a step sideways, I would add to your thinking that true bypass is the answer to a problem that guitar pedal technology hasn't really had to contend with for several decades now. It's hailed as a cure for quite a lot of things, some of which *is* pure rubbish. I'd encourage you to think about ways to not need true bypass, even if it means getting rid of the noisy digital pedals and putting pedals in their place that do much the same thing but are not noisy. It *can* be done - I've done it.

[induction]

Here's how I do it.

For the record, I tested this on the breadboard for both delay and reverb circuits, and it worked great. However, I never built it into a pedal because I found, like RG said, the true bypass option didn't add anything I needed. I compared the sound of buffered and true bypass on the breadboard and could not hear a difference at any setting of the controls. There were some circuits that I tested that were noticeably noisier with buffered bypass, so I mucked around with the circuits to figure out why that was (too much gain at certain points in the circuit, usually), and then corrected it in the circuits instead of working around the noise. This was a better option, IMO, because the noise afflicted the effected signal as much or more than the bypass signal.

However, the option of turning tails off and on could be useful to some people. If so, or if you really want the true bypass option, follow the link. I think there are other ideas in that thread if mine doesn't suit you. Typing 'tails' into the search function will yield even more.

[sherminator1995]

First, no need to apologize, you're trying to learn.

I've tried to think of many ways to google this, but nothing gives me what I want, so I guess the best bet is to ask you guys what to do, after being a longtime lurker.

The TL:DR is that I'd like to be able to switch between trails/spillover and true bypass. I would really like some help with this. Thanks.

You're running into a fundamental problem. I think you're already at trailing echos cannot be made true bypass, because the trailing echos have to happen a variable and unpredictable time after the player tells the pedal to go bypassed.

...In that case, would the regular spillover/trails bypass sound any worse when bypassed? I'm wondering because I use some digital pedals that aren't true bypass, but also add a huge amount of noise.

I haven't delved into your issue, but a casual reading suggests you're going to do some version of an external true bypass with an internal "cancel" function. It's probably possible to make something like that work.

As a step sideways, I would add to your thinking that true bypass is the answer to a problem that guitar pedal technology hasn't really had to contend with for several decades now. It's hailed as a cure for quite a lot of things, some of which *is* pure rubbish. I'd encourage you to think about ways to not need true bypass, even if it means getting rid of the noisy digital pedals and putting pedals in their place that do much the same thing but are not noisy. It *can* be done - I've done it.

Thanks for the advice. The reason I'm making this delay is exactly because of what you said! My Zoom G3 has a fantastic array of delays and effects, but I only really use a tape delay into an analog delay, then a reverb (but my amp has a great spring reverb anyway so that's not an issue). That's why I want this tap tempo delay. I was thinking that, because the dry signal passes through the PT2399 when with trails, I may get the digital noise that I'm currently getting with the Zoom. I would get an isolated PSU but there's nothing really cheap or small enough for me.

I have multiple boss pedals (buffered ofc) that have pretty much no downsides (although the CE5 does suck treble like hell when bypassed, but a lot of people have complained about that). I'd actually rather not have the mechanical switch due to the annoying pop.

Here's how I do it.

For the record, I tested this on the breadboard for both delay and reverb circuits, and it worked great. However, I never built it into a pedal because I found, like RG said, the true bypass option didn't add anything I needed. I compared the sound of buffered and true bypass on the breadboard and could not hear a difference at any setting of the controls. There were some circuits that I tested that were noticeably noisier with buffered bypass, so I mucked around with the circuits to figure out why that was (too much gain at certain points in the circuit, usually), and then corrected it in the circuits instead of working around the noise. This was a better option, IMO, because the noise afflicted the effected signal as much or more than the bypass signal.

However, the option of turning tails off and on could be useful to some people. If so, or if you really want the true bypass option, follow the link. I think there are other ideas in that thread if mine doesn't suit you. Typing 'tails' into the search function will yield even more.

Thanks for the link! When you tested the noise, was this on circuits with PT2399's? Also, would true bypassing help with noise from a daisy chain power supply (i.e. due to ground loops), or am I just totally mistaken?

[induction]

Thanks for the link! When you tested the noise, was this on circuits with PT2399's?

No. Well, not quite. It was a reverb with a Belton Brick (the BYOC 2-knob to be specific). The noise was related to the fact that the gain on one of the op-amps was cranked way up, which amplified noise and also made the reverb overwhelmingly strong. Reducing the gain got rid of the bypass noise and also reduced the reverb to a usable level. The Belton bricks do have 3 PT2399's inside them, but I don't think you can blame either the brick or its internal components for the noise. Any design that cranks the gain on a op-amp (even one with no input) and then mixes it with the dry signal is going to be noisy.

Also, would true bypassing help with noise from a daisy chain power supply (i.e. due to ground loops), or am I just totally mistaken?

I don't think that would help. Unless you are disconnecting the power ground in bypass (which I don't recommend on any build, but especially one with a digital chip), the ground loop won't be broken by using true bypass. The adapter ground will still be connected to the ground on the jacks. That being said, I have never had a problem with hum caused by ground loops in daisy chains, and I have lots of pedals daisy chained on my board. Not saying it couldn't happen, just that it hasn't happened to me so far.