Here's a tails mod that I've been playing with. It comes right from the Small Time delay posted on DIYSB, so credit goes to ValveWizard.
The pdf contains all the info you need to implement it on just about any PT2399 delay (you can use it on analog delays, too).
Thanks for making this available. Im tempted to give it a whirl soon not sure what on.
Can you comment on which of your pt2399 pedals to your knowledge change the dry signal so this set up would be undesirable?
anyone help me out where A and B go on a rebote 2.5 ?
http://tonepad.com/getFile.asp?id=98
Quote from: LaceSensor on January 25, 2013, 10:50:27 PM
anyone help me out where A and B go on a rebote 2.5 ?
http://tonepad.com/getFile.asp?id=98
The 1uF cap after pin 7 of IC1.
Thanks. I have one on vero I'm going to try the tails mod on.
Here is my vero. Hope using your images / information was ok?
Ive given what I feel is the appropriate credit.
Sure, sure...no problem :) Thanks for doing a vero!
Thanks for the vero
One thing I did not mention in the doc: I highly suggest using the SPDT over a 3PDT. Not only because you only need one set of switches, but also because the mechanical noise of toggling the SPDT is greatly reduced. It is a much quieter switch and that is quite important when toggling a delay on and off.
Hi!
Thanks for the schematic and the vero (in the vero I think the transistor is wrong placed).
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!
Quote from: matropiero on January 27, 2013, 07:07:59 PM
Hi!
(in the vero I think the transistor is wrong placed).
Hi
Can you explain why? It looks right to me...
Ian
Quote from: LaceSensor on January 28, 2013, 09:20:05 AM
Quote from: matropiero on January 27, 2013, 07:07:59 PM
Hi!
(in the vero I think the transistor is wrong placed).
Hi
Can you explain why? It looks right to me...
Ian
In the schematic the "source" leg of the transistor is connected to C2, but in the vero C2 is connected to the "gate" leg.
Yup, he's right. Gate is the the bottom lead, not the middle. The pinout is DSG with the transistor facing left.
Quote from: matropiero on January 27, 2013, 07:07:59 PMBut 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.
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.)
-Why is the decoupling cap with tails 1/10 the size of the original?
Quote from: madbean on January 28, 2013, 01:01:08 PM
Yup, he's right. Gate is the the bottom lead, not the middle. The pinout is DSG with the transistor facing left.
ok ill fix it
fixed below
Quote from: midwayfair on January 28, 2013, 02:27:46 PM
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.
Quote from: midwayfair on January 28, 2013, 02:27:46 PM
Quote from: matropiero on January 27, 2013, 07:07:59 PMBut 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!
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.
Quote from: LaceSensor on January 28, 2013, 02:57:55 PM
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 180ยบ.
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!
harumpf
Right, last try.
If this isnt right, im sure people can socket the transistor...
Quote from: matropiero on January 28, 2013, 03:29:10 PM
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.
UNTESTEDYou'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.
Quote from: matropiero on January 28, 2013, 03:29:10 PM
Quote from: LaceSensor on January 28, 2013, 02:57:55 PM
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
Wow!! :o
Thanks for the time!! I try it and I reply if is verified.
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.
Quote from: matropiero on January 28, 2013, 09:31:42 PM
Wow!! :o
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...
I think this is what John wrote, in picture form.
Make up for posting rubbish before!
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!!
Quote from: matropiero on January 30, 2013, 10:40:16 AM
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 ... :)
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!
As I mentioned before, the mechanical noise of the 3PDT is at fault here. If using an SPDT just for the tails, I found no switching noise at all. For the tails/TB mod, this pop may not be able to be removed.
One possible idea is to place a huge resistor between 9v and the "Tails" lug on the 3PDT. Like 10 or 20 meg. Can't say for sure :(
....
bugger. >:(
I know how to do the tails so that it won't pop (and doesn't use the FET), but it won't light the LED at the same time. Not enough lugs.
Yeah, you could probably do just an SPST in place of the decoupling cap if you don't care about the LED.
Hmm--maybe the SPDT with some kind of millenium bypass?
You need to reference the delay side to Vb to avoid DC offset (the delay is 2.4v, the op amp is 4.5v) when simply shunting the connection to the decoupling cap. Otherwise it'll still pop. I actually suspect that's part of what's going on here, rather than mechanical noise. The voltage to the delay line is jumping pretty suddenly.
Maybe there's some solution there I'm not thinking of. Do we have enough poles between a SPDT and 3PDT (toggle) to go between millenium and tails? I can't wrap my head around it.
A 4PDT stomp would have enough poles to do the simple tails bypass + LED ... Tayda has them.
Yes, I see you point. Perhaps a 1M resistor from the source to VB would be the way to go? That way both sides of the transistor are referenced to the same voltage, then it's decoupled and referenced to the bias output of the PT2399. Or, do you think it should be after the decoupling cap and then the bias point of the PT input would just be higher. I don't know what effect that has since it is awfully close to the supply voltage in value.
I found the problem: led popping. Without led works perfect.
Sorry...thats not the problem :-\
Has anyone found a solution yet? I would like to have tails on my Zero Point SDX
On the Zero Point, this works just fine for tails:
Remove R8
solder in two wires where R8 used to be.
Solder a 10K to one of the wires. (This is R8, which we still need.)
Solder the termini of the 10K and the other side of "R8" to lugs 1 and 2 of a foot switch.
Add the LED as normal.
On mine, there's no popping and no need to reference Vb as in the Multiplex. I assume it's because it's decoupled from the audio path, unlike the set up in the Multiplex. It's still in the testing rig, but I've tried a couple different switches and it's not popping. Fingers crossed.
If something changes, I'll let everyone know in my build report.
dredging up an old post here but has anyone successfully implemented tails on the Zeropoint SDX or the Multiplex?
Quote from: timbo_93631 on August 22, 2013, 09:42:58 PM
dredging up an old post here but has anyone successfully implemented tails on the Zeropoint SDX or the Multiplex?
I used the shunt bypass I talked about in my ZPSDX.
http://www.madbeanpedals.com/forum/index.php?topic=9314.0
Jon, can you go over again? There is nothing in the link that I could see explaining it, and I'd like to know specifically how to implement it in a Multiplex.
Quote from: timbo_93631 on September 02, 2013, 02:25:12 PM
Jon, can you go over again? There is nothing in the link that I could see explaining it, and I'd like to know specifically how to implement it in a Multiplex.
You have to cut a trace to do it in the Multiplex. Check the schematic and find the connection to pin 1 to the rotary. Then use two lugs to make the connection and the third 'off' lug should be connected to Vb to prevent DC offset into the delay line.
Thanks for the great mod.
I added this mod to my Deep Blue Delay and works really good.
But this mod introduced white noise which the pedal didn't have before the mod.
Can anyone give me some advice?
Thanks in advance.
I am not sure I understand. If you get a minute can you make a diagram/snippet of schematic? Thanks.
Quote from: timbo_93631 on September 13, 2013, 01:10:45 PM
I am not sure I understand. If you get a minute can you make a diagram/snippet of schematic? Thanks.
Foot switch:
1 4
2 5
3 6
4 = LED
5 = Ground
3 = VB
The VB connection is necessary because the Multiplex doesn't have a coupling cap at the PT2399 input and there's significant DC offset (~2v)
1 = IC1 pin 1
2 = Rotary A
6 is either not used, or you could use a 2-color LED to flip between bypass and delay
Cut the trace between IC1 pin 1 and rotary A. I'm pretty sure the trace is under the PCB.
In designs where there is a coupling cap before the PT2399s, you can use the simple shunt bypass I used in the Hamlet if you don't want to use Merlin's bypass scheme. That's what I did in my ZPSDX.
Quote from: midwayfair on September 13, 2013, 06:32:45 PM
Quote from: timbo_93631 on September 13, 2013, 01:10:45 PM
I am not sure I understand. If you get a minute can you make a diagram/snippet of schematic? Thanks.
Foot switch:
1 4
2 5
3 6
4 = LED
5 = Ground
3 = VB
The VB connection is necessary because the Multiplex doesn't have a coupling cap at the PT2399 input and there's significant DC offset (~2v)
1 = IC1 pin 1
2 = Rotary A
6 is either not used, or you could use a 2-color LED to flip between bypass and delay
Cut the trace between IC1 pin 1 and rotary A. I'm pretty sure the trace is under the PCB.
In designs where there is a coupling cap before the PT2399s, you can use the simple shunt bypass I used in the Hamlet if you don't want to use Merlin's bypass scheme. That's what I did in my ZPSDX.
sweet, thanks
can confirm this works. Cut the track on the bottom of the PCB coming off IC1pin 1 connecting to Central pin A of the Rotary
a nice VB connection is the positive side of C3. Tack a bit of wire onto that, its got some space next to it on the underside of the PCB too.
With this you'd just wire the board in/outs direct to the jacks because you'd be switching between the sending the signal through the delay line or a path from the input direct to the output? Could you use an optotron with this?
Opto tron unrequired, just a dpdt switch as suggested.
Thanks guys, brilliant mod. My build is now in the 1776 build report sub-forum.
Hey guys, I was looking at adding tails to the cave dweller, but it looks different than the examples out there that this tails circuit has been used with. Any advice?
Bad news. Here's what happens in the Cave Dweller:
Input goes into the first op amp (pin 16) whose output (pin 15) is internally connected to the delay line.
This output is also used to mix it (via R3) with the delayed signal (via R7) at another opamp at pin 13.
So with this design you can't simply switch off the input of the delay line without losing the dry signal in the mix.
Yeah, I was afraid of something like that. Well it's no biggie, I will just use it in a regular way then, it's not a dealbreaker for me.
There is a simple circuit that I saw a while back where you could route the signal clean or through an effect. It has very few parts (an IC and a few resistors and caps) and might be able to be designed to fit around a footswitch. I will try and find what I am talking about when I get home. If you are trying to fit the thing in a 1590a, it probably wouldn't work though...
Cortexturizer, here is the schematic I was thinking of. I saw it somewhere on the web and copied it down by hand. Unfortunately, I can't give whoever created this any credit since I can't remember where I saw it. I just drew it up in Eagle for more clarity. In theory, it looks like it could work for your predicament.
(http://i.imgur.com/HdB7gM8.png)
Which cap would you replace in this layout?
http://2.bp.blogspot.com/-oPSs9IbXTPM/U_uPy7SeJAI/AAAAAAAAIg8/iUMKUKzsfrA/s1600/CultureJam%2BNeptune%2BDelay.png
Would it be the 1uf coming off of IC2 in the top left? Is that correct?
Not to derail, but there is another method for tails I've tried which works great. You can use this with a DPDT and make the other set of contacts switch an LED on and off. It doesn't pop. All you need to do is replace the coupling cap from the input stage to the delay stage with the little circuit shown. This will work on most PT2399 delays. If, however, you have another op-amp stage between the input and PT2399 (like a sallen-key filter) then you make the two resistors 1M and attach them to Vb instead of ground. In that case the circuit replaces the coupling cap and the biasing resistor of the second op-amp.
How would you go about making a toggle switch to choose between trails bypaths
Bypass and true bypass?
I see there's something similar on page 2 of this thread, but will rhatbwork with the updated trails mod you just posted above ?
this is what puzzles me, why would anybody prefer having that switch anyway? what is there to gain with cutting your delays off and "preserving" the tone. I am not trying to initiate a debate or something, it's just, if you put that switch do you really think you will turn off the tails occasionally, really? :D
Hi all,
As a novice, before I start to wrap my brains around this, is this mod also applicable in the Rebote3? (which I have already built, but not boxed)
Thanks :)
I am having trouble with this mod. I wired my delay for true bypass and placed the tails add-on on a separate switch (SPDT). When I turn the switch on, tails in engaged and seems to work fine. But when I turn the switch off, all delay repeats disappear.
Does turning the switch off kill the signal's ability to go into the PT2399? How can I fix this?
I noticed earlier a diagram about wiring the tails switch to a 3PDT switch, but on another site (Fuzzdog), there was nothing about this, and the implication was that wiring the add-on as I did would be sufficient and allow the delay to function normally when tails swas switched off. I'm quite confused.
Wait. I think I understand now. Turning off the tails add-on cuts the PT2399 from the signal entirely.
So -- I am going to try to hack together something with a DPDT switch that will allow for the PT2399 to stay in the circuit when the tails add-on is switched off.
If it works, I'll post a diagram of what I came up with.
I built this mod and added it to a wampler faux analog echo. It works fine initially but after about 10-15 seconds, I start getting distortion and the audio signal slowly fades until the pedal is completely silent. Unplugging the power adapter and plugging it back in brings back normally functioning but the same fade out/distortion happens each time.
I'm not super tech savvy with circuits yet, but could someone point me in the right direction in terms of troubleshooting? Thanks so much!
I am using 100nf for C2, although the cap it's "replacing" is 1uf, could this be the issue? Will try replacing it tonight.
Hi there. Sorry to resurrect an old thread, but is there a way of adapting this trails bypass to a circuit like the Total Recall (Deluxe Memory Man)? Would it be best across the 1n2 cap into the second half of the first 4558 (after the input preamp stage) or across the 220n into the NE570 compander input? Obviously, the biasing and voltages would be quite different, being that it's a -15V positive ground circuit. Is there a more elegant method? Or one with a lower parts count?
Let's see if anyone will still read this in 2018,
I want to modify my T-Rex Tonebug Reverb to have tails. It's based on the Spin FV-1 chip. Does anybody know if this mod would work with that pedal?