Another stupid idea - using echo --

[woody alien]

I've been kicking around the idea of using an echo device, not as an echo, but more like the element whose input is (optionally)controlled by
some sort of pick filter. The output section of an echo should then follow the input signal's decay rate.

That thing might enhance guitar's tone..or not. Long delay.. not sure would it work as well as an echo. 

I have no idea, if that thing is even feasible, but if it is, how to achieve it?

So far, I have ordered few pt 2399's to build a base effect, Small Time.

[FiveseveN]

You mean something like gated reverb?

[woody alien]

FiveseveN, thanks for the link. Gated reverb is rather close to what I'm after. There seems to be several commercial delay/echo stompboxes for guitar, which include gated reverb,
but only with limited controls.

I'm actually looking more of a lo-fi contraption of that, being a lot cheaper and easier to modify.

As mentioned earlier, pt2399-based device forms the base effect, and when I find out, what kind of circuits to use as an input and output stages, it could be time to throw them all together. 

[woody alien]

Well, after some wrestling with that Small Time(delay/echo effect), I finally managed to persuade it to work. After all, what a delightful little device. For the price, it is far beyond my expectations.

So, the base effect is now completed, and it's time to take the next step.

I did some background snooping on the net, but the phrase 'pick filter' didn't give any usable results. To make a long story short, I found the phrase 'envelope follower', which is, again closer, to what I'm after. Especially reversed version of that, to form this 'pick filter'. I have heard, and recognized that effect, but the correct name still escapes from me.

Basically it is a guitar player, who turns the guitar's volume way down to mute the sharp picking sounds, and then, turns the volume on, to get the 'tone'o'tails'.

Two, simple enough candidates for envelope handling might be: Dr.Quack and Graig Anderton's Envelope follower.

I think I'll build Quack first, as it doesn't include any exotic optical components. Plan B would be to build Anderton's EF, and also make the optoisolators for that purpose.

[Kipper4]

Bringing up the volume after playing the note is called a swell. Sometime violinist.

[woody alien]

Well thanks, Kipper !!  Swell is the term. Again I did some net searching, and finally ended... here, to this very forum.

There is already a great thread about the subject at: http://www.diystompboxes.com/smfforum/index.php?topic=76457.0

It seems to be very problematic to achieve even decent, automated swell effect. At least on analog(which I prefer) side.
Simple ideas turn easily to complicated, technically (almost)impossible things.

Problems ahead, but I'm still going to give it a shot, and use my 'caveman analogy' to keep that thing as simple as I can.
Just to provide, if nothing else, at least hundreds one or two ways, which doesn't work.

But, in the meantime, I ordered parts for the Quack, and Anderton Envelope Follower.

[Kipper4]

I cant think of its name but isnt there a boss pedal that does swells?
Was it the slow rider or something??

[Kipper4]

I stand corrected its called the slow gear. You tube time for you my friend.
I like to do swells with traditional finger on the pot plus occasionally with a foot pedal which leaves my hand free to play. Also sounds great with a delay for ambiant type stuff..

[stallik]

You might also try this one.
http://www.diystompboxes.com/smfforum/index.php?topic=103938.msg928632#msg928632
It's a noisegate but does the swell thing rather well

[midwayfair]

Trying to determine what exactly you're looking for. Does this describe it:

Wet/dry signal: The dry signal is like in a delay, where you hear the note, and then the delay is mixed in with it.
Envelope controlled Delay signal: You want the delay to come in when the guitar signal is less present. So it's only there on quiet notes.

There are a handful of ways this can be done, but one of the easiest is to use an envelope to turn off an LED while playing, hook the LED up to a light dependent resistor in series with the mix pot on the delay, and now the volume will fade in as the LED turns on and lowers the LDR's resistance.

Or you can do it another way: put the LDR in series with the INPUT of the delay, and it will block your signal going into the delay. Now you just get the tails of the note echoed. That's more like what happens when you use your guitar volume. A PT2399 is still going to have some ping on the front of the notes regardless of how the signal gets into it, but it'll sound pretty good regardless.

If you really do just want the slow gear type effect, then the Boss pedal is the way to go. BYOC has/had a clone, I know.

[Vallhagen]

the Boss pedal is the way to go. BYOC has/had a clone, I know.

They call it the Lazy Sprocket.

It was a while ago i had a look at that effect, because i like it too. I ended up building the fairly ambitious MFOS Subcommander instead. It does "some sort of swell" and a lot more:)

Cheers

[ch1naski]

Vallhagen, calling the sub commander "fairly ambitious" is like calling Mt Everest "a hill".

[SmoothAction]

^ +1 to that. The MFOS sub-commander is pretty much the coolest thing I've ever seen as far as DIY guitar projects go. My only hang-up is the PCB is $45.00US plus shipping, plus everything else. The other option is to do a very complex 2 layer etched board (they provide the design for free, it's pretty awesome) which to me is only for psychopaths/seriously good etchers and at that point I would just spend money on the PCB because Im just not that good at etching.

Using a MFOS SC into an effect-loop style pt2399-based effect would be the bee's knees. Spitballin'...

[woody alien]

Thanks to everyone for replies and suggestions ! I might consider of building that Maplin Noise gate also. But time will tell.
...And perhaps Slow Gear clone, if things start to go to that direction.

Midwayfair, using the Led/Ldr combination to control the guitar's volume and/or delay's settings, has also crossed my mind.
In fact, that Anderton envelope follower seems to be a simple enough device to start the testings for that purpose.

I'm still waiting the ordered parts to arrive.

But, the video demo at http://www.youtube.com/watch?v=hLcBYbXS7ng  shows how the first stage, before the delay/echo should sound.
Especially at slow, and medium swell settings. There is also a compressor involved, but I'll leave it out for now.

[woody alien]

Well, here we go.. plan B came first, so I built that Anderton envelope follover. But lo and behold, the bugger required bipolar power supply, of which I have very limited understanding.
Using two 9V batteries could be ultimately the simplest way to accomplish that task, but as far as the testing process goes, the more 'rigid' power source is preferable.

Again, I did some net searching, and finally found the GGG(General Guitar Gadgets) bipolar power supply, which doesn't need a 'center tapped' AC- transformer.
I breadboarded it, although with much smaller capacitors, but it provides the -8, +8, and the ground nonetheless. Definitely one of the 'side effects' of this project, which I need to build, with proper components. Transformer, that is in use, is a cheapo 9Vac/1000mA.   

Anyways, back to the original subject. I tweaked the EF(as suggested in Electronic projects for musicians, project 25) to make the test-Leds to respond better for the guitar's signal.
Visual approach had enough success, and I rolled two Led/Ldr -optocomponents for the device. Leds are white, clear ones, and Ldrs.. small ones, about the same diameter, as 5mm Leds.

I'm just eagerly waiting for the moment, when I could, at last, get there to apply the jolly EF for that Small Time.

Some Y-boxes, possibly buffered ones, might also be on order, if needed.

Anyone else familiar with 'side effects'?

[woody alien]

So, I have tested that Anderton EF, to control the volume of guitar, and it gives rather unstable results, no matter what the settings are. Breathing effect being most noticeable.
Also, as might be expected, variations of the response time through the fretboard.
Number one, that doesn't work, as it is.

Conclusion, after using my infamous caveman analogy, would be to mod an EF device(perhaps including the one, that I've tested), to have an adjustable, fixed release time.
If that could be done, there shouldn't be need to convert incoming guitar signal from AC to DC.

[woody alien]

After a bit of studying about a one-shot, and/or monostable circuits, I still haven't found one, that would work the way, that is needed in this project.

Tested 555(Timer IC)- and 393(Comparator IC) -based one-shots, but no luck, as they both wanted to stay on the 'on' -state, after trigger pulse(plucking a note on a guitar).
Especially the 555 seems to need a shorter input pulse, than the output one is, to work. This assumption came after reading some more about 555. Might as well be the connecting matter
of one-shots/monostables, though.

What I'm after is the opposite effect, meaning, that the input pulse could be as long, as the envelope follower provides, after plucking a note on guitar, but the following stage would register only the leading edge on the envelope. Therefore the guitar's 'pluck' could become much shorter, adjustable length 'tick', for triggering various.. analog devices?

No doubt, that aforementioned effect is already a part of many, more complex devices. Logically, I should isolate/extract only that part of the countless, EF-related schematics.
Problem is.. that I'm not capable of doing that. Drives me almost sane.

How swell could it be to have a discrete box, labelled something like "trigger happy".

BTW, there is also Maarten's thread about the subject, looks simple, sounds fairly good at http://www.diystompboxes.com/smfforum/index.php?topic=91640.0
Breadboard awaits...

[~arph]

I'm kinda working on something like this.. Still a work in progress but here is what I have:

https://dl.dropboxusercontent.com/u/1849818/published_images/envmix.png

Not simple no, but it could be modified to do linear swell triggered by the envelope. The interesting bit is the window comparator triggering and resetting the linear ramp generator.
The ramp is driving a dual VCA ( NE571 in this case)

[woody alien]

Thanks for sharing that circuit, arph. Although I don't fully understand every part of that schematic, I assume, that IC2c and IC2d together form the window comparator.

I've used plain comparators for several tests, but never a window comparators, as they seem to have way too many variables for me to handle.
That 'trigger and reset' -sequence is the factor, of which I wish to know more about.

Anyways, arph, keep up the good work! Looking forward to see, how that circuit developes.

[woody alien]

So, I breadboarded Maarten's Autoswell circuit, and found some sweet spots on the response time/swell effect during the testings.
After all, I found it to be very difficult to get stable 'effects' out of it. 
Additionally, no clean effect, no. Actually a very raw fuzz sound was present. I don't mean to underrate that circuit. It just isn't the one, that is needed in this project.

Before I take the final step, and build that Slow gear clone, I'll go to the very basic level.


The circuit above shows the simplest form of the 'one shot' -circuit, that I'm aware of. Meaning, when the voltage source is connected to that circuit, Led flashes only once, no matter, how long time the voltage is applied.  Question is, how to reset that bugger?