Echo Base - a new PT2399 delay

[slacker]

Yeah just put the diodes from lug 2 of the repeats pot to the outer lug that is connected to ground. I originally did this as a mod to my Rebote 2.5 and it works fine.

[gutsofgold]

Awesome! Do the diodes need to be anti-parallel ? One facing one way and the other facing the opposite way?

[slacker]

yeah anti parallel, basically they're just clipping diodes like you get in distortion pedals.

[Valoosj]

After some hours of soldering ( it's 1AM overhere...) I can say that this pedal rocks!
I added the extra time mod (see pics below for layout and mod to motherboard) and it works. The only thing is that my feedback started oscillating very soon. Since the pedal isn't finished yet I cannot say if this is my fault or not. The oscillation started even when the pedal was off. But no true bypass so...
I'll flip the switch to turn the extra time off so I can see if this is causing it. Otherwise I'll flip the feedback pot back to a 5-10K.

Slacker, any chance of getting some nice settings you use?

[Berger]

what is the above echo base add on for? and how does it connect to the main board?

-Aaron

edit: Is it this mod?
http://www.aronnelson.com/gallery/main.php/v/slackers-stuff/album170/echobasemod.png.html?g2_imageViewsIndex=1

[slacker]

Yeah it's the extra delay time mod.

Yorick does the mod work Ok, how clean are the longer delays?

The reason it's oscillating very easily is probably because the mod will add a lot of extra volume to the delayed signal. I didn't think about this when I drew it up. To solve this you could try making the 47k resistors on pins 14 and 15 of the original PT2399 smaller that will reduce the volume in that stage. Or you could just make the 20k resistor after the feedback pot bigger, making the feedback pot smaller won't do very much.

Sorry but I can't give you any example settings at the moment because I don't have the original pedal and I haven't had time to build another one 

[Valoosj]

I'll try that 20K thingie. Today I had rehearsal so I just took the pedal in it's current state, with the knob for extra time on the inside. The speed pot wired backwards, and the feedback pot causing oscillation after turning the knob from 0-2. I hope the increase in resistance after the pot will cure it, since I can't really dial in the ammount of feedbacks. Either 1, 2 or 500000

The delay is reasonably clean, but I really need to test it a bit more.

As for adding it to the original echo base with the above layout, check the schematic and the original pnp. I have added some holes, and you need to leave out one jumper (top left). The notes on the add on board show you where to add it. If it works the way it should I'll make notes on the motherboard for the echo base so it's easy to know how to add it.

[omarvolta]

Finished mine about a week ago and the only thing I did to it was the waveshape mod which is really cool(I'll do more to the next one!). Could this(waveshape pot) be done to a Deluxe Memory Man?? and maybe add a speed control to the lfo also??

[Valoosj]

I just fired it up again. Increased the 20 up to 100. Turning the feedback pot up to half makes it go crazy with feedback, which is cool. I do wish I could just get 1 delay sound when turning the pot to zero. I always hear some quieter delays.

When bypassed I also keep hearing a delayed sound albeit very quiet. Is this normal?
The delayed sound get some OD when you add the extra delay time. If I could get the sound during bypass out of the pedal and be able to tune in just 1 delay sound then it will be a keeper on my board.

[slacker]

Are these problems with the extra board attached? If they are try removing it and making the pedal stock, if the problems go away then it's probably the increase in delay volume added by the extra board that's the problem.

Try changing the 47k resistors attached to pins 14 and 15 of both PT2399s to 27k that should give the double version about the same gain as the single version which will hopefully solve the problems.

[Valoosj]

I'll give it a try.

[mth5044]

I joined this forum just for this. Guess I'm a little late to this party but this is very cool 

Quick question - how does it switch between the modulation types? I'm pretty unfimiliar with some of thhe chips in there, so it could be a stupid question. I have every intention of building this in a month or two 

[slacker]

Welcome aboard

The way the modulation works is like this, the delay time of the PT2399 is set by the resistance between pin 6 of the chip and ground, the greater the resistance the longer the delay. The BC560 transistor is used as a variable resistor and this is driven by a triangular wave the speed and voltage of which are controlled by the Speed and Depth pots. As the voltage driving it goes up and down the resistance of the transistor goes up and down and so the length of the delay goes up and down. It's basically like getting any delay and turning the delay time pot backwards and forwards whilst you're playing, only you don't need 3 hands to do it

The different modulation sounds are made with different settings of the Speed, Depth and Time controls there's no switching between different sounds.
Basically if you want the chorus type sounds you set the Time to a very short delay, set the Speed to what ever you like and keep the Depth quite low, increasing the depth gets you the vibe sounds and increasing it further gives you the pitch bending.
The modulated echo sounds are made in the same way but with the Time set to a longer setting.

[mth5044]

Hey thanks a lot   

I'm not going to lie, it could be the coolest, most useful effect that ever happened. Even before an overdrive 

It was definitly the clip of Shine On You Crazy Diamond that sold me. Thanks again for teh awesomeness.

[Drake120]

Can I use BC550 instead of 2N5089? Well, I know I can, but will it make any difference? It's in the bypass section, so I don't think it makes a big difference...

Thanks

(JD)^S

[slacker]

That should be fine, the transistor is being used as a switch so any NPN transistor should work.

[Gila_Crisis]

i think i'm going to build this one, but instead of the common Level control I wanna add a Mix/Blend pot (think like the deluxe memory man).
do you think this way is gonna work???


of coarse i'm gonna build it with out the boss/tails switching system, but with a normal true bypass

[slacker]

That should work. Personally I would put caps between the opamps and the mix pot so that there is no DC on the pot and then connect the wiper of the pot straight the 100k resistor. You might also need to experiment with the pot value, because using a 100k you might get a volume drop in the centre position, maybe try a 20k instead.
You might also need to reduce the volume of the delayed signal so it is about the same level as the dry signal in the 50/50 mix position. To do this you can increase the value of the 10k resistor connected to pin 6 of the opamp.

The only other slight concern is that the delayed signal can possibly travel through the pot and back into the effect. I don't know if this is actually an issue and the DMM seems to mix the 2 signals in the same way so it's probably fine.
You could put a buffer between the input opamp and the mix pot, that will make sure this isn't an issue, but I would build it without first and see what happens.

Good luck with it

[Gila_Crisis]

thank you a lot!
i'll let you know when i got some results

[Boogdish]

I've set tommorow aside to try and build this thing.  I was going through all my parts just now and I realized that I accidentally ordered an electrolytic for C25 (the 1UF between the LFO oscillator's output and inverted input) and I'd like to know if this is still usable, and if so, how should I orient it?