Echo Base - a new PT2399 delay

Started by slacker, August 27, 2007, 04:33:19 PM

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Quote from: slacker on January 04, 2009, 09:24:24 AM
Quote from: bent on December 21, 2008, 11:56:26 AM
i have a little problem....

there's a little "tic...tic...tic" in the sound that goes faster or slower when i turn the speed pot....

only mod made is the wave pot 25kb....

anyone have a clue?


Is this ticking all the time, in bypass as well as when the delay is on?
What happens if you remove the wave shape pot?
always there, even in by-pass...
even when wave shape pot is remove...

Long live the music.....


I'm not interrested to get auto-oscillations, so how i can to extend the scale of the feedback pot (to get a more usable length of it)?


if you raise the resistor that leads to it (as mentioned earlier in the thread), you can eliminate oscillations altogether if that's your aim. You have to be careful though because if you raise it too much, it will stop the delay completely. try putting a trimpot in that resistor's place and adjust to get the most useable pot swing.


Thx a lot Barecode80!
Can you tell me which is exactly the resistor involved?


This one:

Increasing this you will have less feedback (auto oscillation).




I have a question to anyone who knows...

What are the 1N4148 diodes for? What is their function?


They are there to clip the feedback signal when you make the pedal self oscillate, without them it gets much too loud for my liking. With them I can mess about with extreme setting without having to turn the level down.

They might also clip the signal a bit if you run a really loud signal into the delay, this will probably sound better than the PT2399 distorting.


Thanks for your soon answer, slacker, i imagined that but i was not sure.. much clearer now ;)
Was that your idea?


Slacker, thank you for a great project. Which enclosure is pictured on your very first post? And can you provide the dimensions of the perfboard as well?



I build the echobase with a pcb from John Lyon. (great pcb although you really need some good eyes :icon_wink:)

It is a very nice echo and the modulation works great. (Slacker thanks for the project)

I have build a PT80 as well and so I can compare both:
I do like the fexibility that the modulation gives but the echobase does not sound as clean as the PT 80.

The PT80 has a very nice analogue like sound that only gets darker in the multiple repeats.
The echobase I build sounds already darker and a bit distorted on the first repeat.

I am using a guitar with humbuckers so the signal is a little hotter than with single coils of course.
Does this have to do with the compander that is in the PT80 design, that might deal better with a hotter signal?



Hi all

Dumb question but I can't find the transistor substition charts that I used to use.  So does anyone know what I could substitute the 2n5089 for, having difficulty finding them in my usual haunts.  I'm guessing a 2n2222 will do it, just a general purpose NPN?

And does anyone know where I might find one of those transistor equivalence charts?  I'm sure I used to have a couple bookmarked but my google-fu has lost it's mojo.


Ian M
(not that one)


Welcome to the forum, Ian :)

Any general purpose NPN transistor will do, it's just being used as a switch so specs aren't important.


Ow yeah, a big thanks, yet again for this project Ian.

Here are the Echo Bases I've built so far, and I have 2 more coming up. My friends just love them.

(bottom right)

[Image] (yet to be painted ;D)
Quote from: frequencycentral
You squeezed it into a 1590A - you insane fool!  :icon_mrgreen:
Quote from: Scruffie
Well this... this is just silly... this can't fit in a 1590B... can it? And you're not even using SMD you mad man!



Has anyone tried to modify the echo base schematic to make it work with a pt-2395? I think that the sound quality would be far better compared to the double delay time mod that uses two pt2399´s ?

This circuit looks interesting:



Quote from: Valoosj on January 13, 2009, 02:33:42 PM

niice! I've always wanted to use bubble chamber art for something...
{DIY blog}


what's the difference when putting an effect loop before pin 16 or putting it after pin 14?
I guess you'll get the same results, right? the dry stays dry, the wet is processed by the effect in the loop, even the first repeat, and then every repeat get always more effected.. this is what I want  ;D
where is the correct place to achieve this? I guess before pin16


If you do either of those the first repeat will be effected by the loop and every repeat will go through it and get more effected. They will probably sound different though because of where the loop is.

If you put the effects loop before where the 10k and 47k resistor join before pin 16 then the input signal will be processed by what ever is in the loop before it gets to the PT2399 so the first repeat get the effect. Then the feedback signal will get fed through the loop so every repeat will be effected.
The loop will be after the feedback pot so it will control the level going into the effect in the loop.
The loop is before the delay so you'll be hearing effect in the loop after it's gone through the PT2399.

If you put the loop after the 10k resistor from pin 14 but before where the two 100n and the 15n capacitors join then the input signal will go through the PT2399 and then through the loop so the first repeat will get the effect. The volume of the PT2399 is very loud at that point though so some effects might not like it. Then the effected signal from the loop will go through the feedback pot and get mixed with the input signal so all the repeats will be effected.
The feedback pot will be after the loop so it will control the level of the effected signal that gets mixed back into the delay.
The loop is after the delay so you'll hear the delayed sound processed by what ever is in the loop.

I don't know which would be better but it should be easy enough to try either option or even do both.


Quote from: roseblood11 on January 14, 2009, 10:20:13 PM
Has anyone tried to modify the echo base schematic to make it work with a pt-2395? I think that the sound quality would be far better compared to the double delay time mod that uses two pt2399´s ?

I don't think anyone has, it should be possible though.

You could keep the input and output buffers, the switching and the LFO and redesign the rest of the circuit around the PT2395. I don't know what the shortest delay times for the PT2395 are though so you might no be able to get the chorus effects, you could do the modulated delay effects though.