Echo Base - a new PT2399 delay

[Slade]

Hello,
I just wanted to say thanks for this wonderful proyect. I have made mine with a chorus on/off switch, by just sending to ground lug 3 of time pot (Chorus Off).
Congratulations, again for this beautiful effect 

You can watch a demo (loooong demo...) of mine here: http://www.youtube.com/watch?v=QGRhp4bn6CI

Bye!

[slacker]

Nice demo, thanks for posting that

What is the extra knob for?

[Slade]

That's the waveshape mod... I just named it "Shaper". I forgot to show the sounds that knob gets 
Suddenly i'll be recording another [planned and shorter] demo and i will show more of the capabilities of the "Echo Waves"

Bye.

[mth5044]

~ Charlie

Hey Charlie, any more updates on this? Sounds like a great idea. Do you have a layout by chance?

Also.. is it possible to put this into the circuit without doing the blend pot mod? I'd prefer the delay level, but I want to give your Envelope Detector a try! Thanks!

[Radamus]

I'm trying to decide on which digital delay to build. I've read all the pages before this pretty well. I skipped a lot of the debug, but I tried to pay attention to the thoery and the schematics. So far, the benefits of all of the pedals I've read about come to this:
Echobase- allows for delay tails to continue after bypass, has a lot of really cool modulation effects and is really variable. All of the modulation is digital.
Rebote 2.5: Simple build, allows for infinite delay, straight forward.
PT-80: uses extensive filtering to make the angular "square" parts of digital signals to become more rounded, providing a more analog sound.

These details do not seem exclusive to me. I'm a little confused about how the rebote's infinite delay can be reset (or stopped), but I haven't heard an argument why the other two can't have it as well. Is it also impossible to alter the digital signal slope of the echobase to make it more "analog"? I know that Slacker's intent was not to make an analog-sounding pedal, but is it possible?

What I want from my delay is much less extensive than the echobase, but I'd like a little more than the others. Also, the time is really limited. I know that these are not meant to be  looper pedals, but I think it could have some limited use in that regard. I play bass, and it might be nice to have one note repeat somewhat rhythmically while the notes played over do not change. I think this can be easily achieved by altering the tails just slightly. The input to circuit can be switched off, allowing infinite repeats to continue being heard, but not added to. Another switch, possibly momentary, will reset the chip so that it stops the infinite repeat. In this regard, depending on how many chips can be used together, it seems like this project is not that far from being a looper. I do not necessarily want a DIY looper, but the thought occurred to me while reading.

I think some of the modulation is really cool, but I'd rather make an analog chorus/flanger/phaser setup (for my personal neuroses). I would, however, find the note sculpting (if there's a better verb, let me know) of the PT-80 to be very useful, but do the lengths to be "analog" go too far?

Also, I like the idea of the longer delay times, but I don't think I've read about a completely confirmed use of multiple chips to make that happen. If anyone can show me, that would be cool. I know earlier in this article there was mention of using two chips, but there were some unresolved problems.

I don't think any of these builds are too far out of my comfort zone (I haven't had a pedal yet that didn't need some diagnosing), but I want to make sure I make the right one.  It's a pain in the ass when you know what you want but have none of the skills (except soldering) to make it happen.

Any feedback (pun intended) will be helpful. You guys are making some great stuff. Slacker, your echobase is really an impressive unit.

Thanks,
Conrad

[mth5044]

Somebody should make a PDF file of this excellent build. I've got no idea how to or I'd give it a whack. The valvecaster PDF was a total life saver and possibly a PDF could help people get a bit more organized for their build.

Just a thought 

[andrew_k]

Somebody should make a PDF file of this excellent build. I've got no idea how to or I'd give it a whack. The valvecaster PDF was a total life saver and possibly a PDF could help people get a bit more organized for their build.

Just a thought 

Agreed!

On that note, if anyone can find which page the Blend mod is on, I'd be very grateful. I'm in the process of building an echo base and can't find the details in this thread..

[andrew_k]

Found it!!
Blend mod - http://www.diystompboxes.com/smfforum/index.php?topic=60662.msg556933#msg556933

[chilecocula]

I'm trying to decide on which digital delay to build. I've read all the pages before this pretty well. I skipped a lot of the debug, but I tried to pay attention to the thoery and the schematics. So far, the benefits of all of the pedals I've read about come to this:
Echobase- allows for delay tails to continue after bypass, has a lot of really cool modulation effects and is really variable. All of the modulation is digital.
Rebote 2.5: Simple build, allows for infinite delay, straight forward.
PT-80: uses extensive filtering to make the angular "square" parts of digital signals to become more rounded, providing a more analog sound.
Thanks,
Conrad

As far as i know the modulation of the Echobase is analog,the repat filtering trick can be implemented in any digital delay in order to make it sound "analog", and the infinite repeats of the rebote it's not really infinite; i´ve built two of them one with a switchable infinite mode, and the other with the infinite repeats resistor stock. The delay is nearly infinite only with longer delay times, with shorter you get self oscillation wich is also cool, but i think you can add a trimpot or full sized pot in series with the infinite repeats resistor in order to adjust infinite repeats with shorter delay times.

[Radamus]

Then is there a mod someone can recommend me for (near) infinite repeats on the Echo Base? And from what I understand the modulation has to do with the delay, or am I mistaken? And how would I go about rounding the edges of the digital signal on this pedal, if that's what I wanted? I find this sort of thing really fascinating as I had no idea that a digital delay pedal was even possible for DIY. These projects are really creative.

Thanks for your response, chilecocula.

[sovtek50]

If You have built the veroboard version you can exchange R17 (20K) with a 100k trimpot. Solder the trimpot to an extra space on the board, connect it to where R17 went and don't forget to cut the traces, so the trimpot doesn't interfere with the rest of the circuit. Then, with the feedback pot set to max, You can dial in the wished for infinite repeats with the trimpot.

If You have used a PCB (with no space for a trimpot), exchange R17 with an ordinary 100k pot (or higher), dial in the infinite repeats again, then measure the resistance of the setting and replace the pot again with a resistor of that value.

done!

[sovtek50]

Ah yes, I also have a minor problem with this wonderful circuit...

The status LED function is reversed, means it's off when the effect is on and vice versa.
Anybody got an idea what that could be?

Slacker, again muchos gracias for this little wonder.

[slacker]

Then is there a mod someone can recommend me for (near) infinite repeats on the Echo Base?

The echo base will do near infinite repeats already, no mods are needed. This doesn't sound like the hold mode on something like a Boss DD3 though, the delayed signal loses clarity over time and will eventually become distorted. The Rebote does the same, you can't get infinite clean repeats with a PT2399.

And from what I understand the modulation has to do with the delay, or am I mistaken?

The modulation signal is analogue, there's no digital chips used to generate it, but the sound you hear is coming from the PT2399 so I suppose you could say it was digital as well.

And how would I go about rounding the edges of the digital signal on this pedal, if that's what I wanted?

I'm not sure what you mean by this, there's no digital edges to round off, the sound that comes out of the PT2399 is analogue, the chip is only digital internally. If you want to make it more "analogue" sounding compare the values of the components around pins 16,15,14 and 13  of the PT2399 with those of the rebote, that should give you an idea where to start.

[slacker]

The status LED function is reversed, means it's off when the effect is on and vice versa.
Anybody got an idea what that could be?

That's strange, which layout have you used?

[slacker]

Somebody should make a PDF file of this excellent build. I've got no idea how to or I'd give it a whack. The valvecaster PDF was a total life saver and possibly a PDF could help people get a bit more organized for their build.

Just a thought 

Cool idea I'll see if I can do something over the Christmas break.

[~arph]

Somebody should make a PDF file of this excellent build. I've got no idea how to or I'd give it a whack.

Here is how: Toss MS Office, download openoffice for free (openoffice.org)  type it up and just save it as pdf. Btw. openoffice also supports saving/opening MS Office files, so no problems there.

[Radamus]

Then is there a mod someone can recommend me for (near) infinite repeats on the Echo Base?

The echo base will do near infinite repeats already, no mods are needed. This doesn't sound like the hold mode on something like a Boss DD3 though, the delayed signal loses clarity over time and will eventually become distorted. The Rebote does the same, you can't get infinite clean repeats with a PT2399.

And from what I understand the modulation has to do with the delay, or am I mistaken?

The modulation signal is analogue, there's no digital chips used to generate it, but the sound you hear is coming from the PT2399 so I suppose you could say it was digital as well.

And how would I go about rounding the edges of the digital signal on this pedal, if that's what I wanted?

I'm not sure what you mean by this, there's no digital edges to round off, the sound that comes out of the PT2399 is analogue, the chip is only digital internally. If you want to make it more "analogue" sounding compare the values of the components around pins 16,15,14 and 13  of the PT2399 with those of the rebote, that should give you an idea where to start.

Thank you for the in-depth reply. I'm still a little confused about the modulation. I probably do not understand how chorus, ect. work well enough to figure this out completely, but from what I can tell, there's no chorus circuit, it's just one method of using the delay to make the chorus sound. I know it's ultimately futile to argue analogue versus digital, but I like the analogue methods because they make more sense to me. If I'm wrong on this, please let me know. I don't mean to sound like I don't think what you've designed is great, because it really is amazing, I just want to make sure I understand it.

As for the analogue sound, I'm confused because it seems that the sampled sound comes out as a semi-square wave. I was also told that the square-ness could be rounded off. I'm curious how that works.

Thanks again for the excellent project.

Conrad

[slacker]

Thank you for the in-depth reply. I'm still a little confused about the modulation. I probably do not understand how chorus, ect. work well enough to figure this out completely, but from what I can tell, there's no chorus circuit,

The modulation works the same way as in an analogue chorus. If you look at a chorus schematic like this one http://www.hollis.co.uk/john/zombie.jpg the signal goes through the first opamp then splits, some goes through the MN3007 and the second opamp stage and some goes straight through the 10k resistor at the top of the schematic this "dry" signal is then mixed with the delayed sound.
To make the chorus effect the 2 opamps at the bottom of the schematic make an LFO and the CD4046 converts this signal into something that can drive the MN3007. The sound that goes through the MN3007 gets delayed and the delay time changes in time with the LFO speed. The changing delayed sound mixed with the clean sound give the chorus effect. All analogue choruses work basically the same even if they use different components.

The modulation in the Echo Base is exactly the same, if you look at the schematic on the first page of the thread the signal goes through the first opamp (U3A) then splits, some goes straight through the 10k resistor to pin 6 of U3B. The rest of the signal goes through the 4066 switches and the PT2399 to pin 6 of U3B where the delayed sound is mixed with the "dry". If you ignore the 4066 switches and the feedback and level controls that's basically the same as the analogue chorus with the PT2399 replacing the MN3007. U1A and U1B then make an LFO that creates the changing delay time.

Hope that makes sense and don't worry about asking questions it's great that people are still interested in this after over a year

As for the analogue sound, I'm confused because it seems that the sampled sound comes out as a semi-square wave. I was also told that the square-ness could be rounded off. I'm curious how that works.

This is just wrong, sounds like you've been talking to someone who hates digital delays

[Radamus]

I guess the difference is that the MN3007 is an analog BBD device, and the PT2399 is a digital echo device. I think that's where I was getting confused. So in typical analog choruses, the the chorus is created by an analog (though imperfect) device, whereas this one uses a digital.

As for the partially squared sound, I'm thinking back to the PT 80 pdf document that said something to that effect. The sampler takes a sample at every x interval, and when the sound comes out, it only has those x intervals to work with. So the ordinary "analog" sine wave isn't as round. It has edges where each sample leads into the next. But I understand that those can be rounded to look more like a sine wave again. Does the PT2399 do that internally or is that something that has to be done elsewhere?

And for the infinite delay, how does that work with the delay tails? It would need another switch to stop it from pulsing, wouldn't it?

Somebody should make a PDF file of this excellent build. I've got no idea how to or I'd give it a whack. The valvecaster PDF was a total life saver and possibly a PDF could help people get a bit more organized for their build.

Just a thought 

Cool idea I'll see if I can do something over the Christmas break.

I would also appreciate something like this. There's been so many modifications on this board, and also on the stereo delay board, that it would be a lot of work for someone like me to try to figure out where all the pieces are and how they fit together. I'm not sure it's your intent to put all of those together, but that would be really helpful. I guess this project could fill up a several gallon box if you wanted it to. Thanks again for the great work.

[Dimitree]

what is the "range" of the waveshaper mod? I'd like to add that..but..what kind of additional waveforms could I get with this mod?