Simple Tails mod for delays.

[LaceSensor]

fixed below

[madbean]

I have a couple technical questions:
-What keeps the delay line seeing 4.5v so that there isn't a DC offset when it's switched on? Or alternatively, why isn't that an issue in this setup? (This was a problem I ran into when I did tails on the Multiplex.)

For number 1) I'd say it is because of the bias output of the first PT2399 (which is about 2.6v, IIRC). So, while there may be some offset it isn't large enough to impact the switching on and off. It just seems to work. Granted, I have not done a full battery of tests across multiple delay builds. Since I'm doing the build tutorial on the SDX this week, I'll give it another shot to say definitively if there are any issues. So far, none that I have found.

2) I made it 100n only to save space on the layout. I have not found much difference at all using 100n vs. 1uF (for guitar) in that spot. If you were using it for bass, it might be better to go up to 470n. I can always adjust the layout if desired...just not sure that it is necessary.

[matropiero]

But I have a question: this can be done in a true bypass pedal? And is it possible to change between bypass (with trails mod) and true bypass in the same pedal?
Thanks!

All this does is block signal by shunting the connection from the dry path at the input of the delay line -- it can't "bypass" anything. If you want something similar, check out the millennium bypass.

Sorry...I thought it was the trail mod, like other delays (Diamond memory lane 2, Visual Sound tap delay...), where the repeats continue when the effect is turned off. In this delays, there are a switch to change between trails mode (the repeats continue when the effect is turned off) but buffered bypass, and true bypass mode (the repeats stop when the effect is turned off). That was my question but my english is not good!

Thanks!

[madbean]

You could probably do an additional mod via a switch to go between tails and true bypass. However, the downside to that is you would not be able to use the SPDT for bypass which is the big advantage here (i.e. much more silent switching). But, I think a combo of a DPDT and 3PDT would get you there.

[matropiero]

fixed,  I trust...
plus a smaller one with standup resistors/diode

Sorry but I think the vero is still wrong. The drain goes to point A, now you have gate to point A. Turn the transistor 180º.

I don't know how to make a mod to have trails when bypassed and switch when I want to true bypass.
But anyway thanks for the reply!

[LaceSensor]

harumpf

Right, last try.
If this isnt right, im  sure people can socket the transistor...

[midwayfair]

I don't know how to make a mod to have trails when bypassed and switch when I want to true bypass.
But anyway thanks for the reply!

Here's one way.

UNTESTED

You'll need a 2PDT toggle and a 3PDT stomp.

Toggle
1 4
2 5
3 6

1: Input jack
2: Effect input
3: Footswitch lug 4
4: Output jack
5: Effect Output
6: Footswitch lug 7

This switches the effect input and output between the jacks and the footswitch. In true bypass mode, the effect is connected through the footswitch, and switched as normal. In tails mode, the effect input and output are connected to the jacks all the time.


Footswitch
1 4 7
2 5 8
3 6 9

1-3: Tails switching as shown in the schematic above. Note that this also controls the LED, and we needed

4: Input Jack
5: Toggle lug 3
6: Ground
7: Toggle lug 6
8: Ouput jack
9: Input jack

Standard TB wiring with grounded input. The effect input and output are only connected when the toggle is in TB mode, so those two columns have no effect in "tails" mode. The LED is controlled by the tails switching, so nothing special needs to happen to make it work in a different mode.

Edit: See new wiring description below.

[LaceSensor]

fixed,  I trust...
plus a smaller one with standup resistors/diode

I don't know how to make a mod to have trails when bypassed and switch when I want to true bypass.
But anyway thanks for the reply!

rawr

[matropiero]

Wow!!
Thanks for the time!! I try it and I reply if is verified.

[midwayfair]

Actually, looking at this again, I made one mistake. You need something that disconnects the output jack connection from the stomp switch in tails mode, otherwise they'll connect in bypass regardless of where the tails switch is set.

This is the corrected 2PDT toggle:
Toggle
1 4 7
2 5 8
3 6 9

1: Input jack
2: Effect input
3: Footswitch lug 5
4: Effect Output
5: Output jack
6: Footswitch lug 8

And on the footswitch:
4: Input Jack
5: Toggle lug 3
6: Ground
7: Effect output
8: Toggle lug 6
9: Input jack

Now in tails mode, the output jack is not connected to the footswitch, so it never connects to the input jack. In true bypass mode, the input jack connects to the footswitch, and the board output is no longer connected to the jack unless the footswitch is "on." The input side works as before: The switch toggles between connecting the board input directly to the input jack and to the footswitch.

[LaceSensor]

Wow!!
Thanks for the time!! I try it and I reply if is verified.

all mine are wrong, LOLZ

at least I am learning a bit, I hope...

[LaceSensor]

I think this is what John wrote, in picture form.

Make up for posting rubbish before!

[matropiero]

Hi!

Verified, it works fine! There is only a problem. When turn the effect on there is a pop noise that go into the audio circuit and sounds pop-pop-pop-pop with repeats. But only when the effect is turned on. I have a pull down resistor but the noise continues there.

Everything else works fine. Now I can switch between both modes without any problem.

Thanks!!

[midwayfair]

Verified, it works fine! There is only a problem. When turn the effect on there is a pop noise that go into the audio circuit and sounds pop-pop-pop-pop with repeats. But only when the effect is turned on.

Do you mean when you first power up the pedal, or is this every time you press the bypass footswitch? Is it happening in true bypass or tails mode or both?

We can debug this ...

[matropiero]

Is every time I press the bypass footswitch (on/off). In both modes (tails and true bypass) I hear the noise and the noise repeated. Is not loud but with repeats is annoying.

Thanks!