Echo Base - a new PT2399 delay

[Taylor]

Yo fellas, I've added several mods including the "humbucker-friendly" resistors to the Echo Base PDF:

http://www.aronnelson.com/gallery/main.php/v/Taylor/

[arjespen]

Hey.
Just built this thing using a layout I tried making myself.
It seems to work alright - meaning I can get delays and modulation.
However, I get some pretty bad hum...even with the input grounded.
I'm in the proces of comparing it to the schematic, and haven't found any errors yet.
Also, the voltages seem ok, in relation to what's written at the start of the thread.
When poking around in it, I found that the first two 2M2 resistors by the input is very sensitive - when I put a finger close to them, I get a very audible noise.
Is this normal or?

Regards.

[beatnik]

I was thinking about adding an expression pedal jack to my echo base, o control feedback.

Can you help me?

[dmc777]

Is there an updated thread or sticky on this pedal that shows the newest version mods, etc, only? There's just too many pages and thread on this. Thanks alot!

[Taylor]

As far as I know, the closest thing to that is my PDF:

http://www.aronnelson.com/gallery/main.php/v/Taylor/

But it's aimed at my PCB so if you're using another layout or perfing/vero-ing it's not of much help.

[ashaxx]

Hey, was wondering if anyone might be able to offer any advice. Built my echobase sometime ago, it all worked fine then the feedback pot stopped working, tried a new pot, No good. Anyway left it, tested it out again and now everything except the speed and feedback knobs work, could it be ive blown one of the tl072s while messing with it?thanks for any advice x

[slacker]

When you say the feedback pot doesn't work, what does the pedal do?
If you just get one repeat then the problem has to be with the feedback pot or a bad connection to one of the components connected to it.
To figure out what the problem is with the speed pot measure the voltage on the pin of the opamp that connects to the 240k resistor before the speed pot. The voltage should go up and down between about 3 and 7 volts and the speed it changes at should be controlled by the speed pot. If it doesn't do this then you have a problem with that opamp or with one of the components connected to it or a bad connection to one or more of the components.
If you get a changing voltage then measure the voltage at the lug of the speed pot that connect to the 240k resistor and the wiper of the pot, also measure at the base of the PNP transistor, you should get a changing voltage at all those points.
If you don't then the point the voltage disapears is where the problem is.
If you get a changing voltage at all those places then check all the connections to the PNP transistor and pin 6 of the PT2399.

[ashaxx]

Ah thanks that sounds like some really good suggestions i'll try them all out when i get a bit of time, thanks a lot x

[phector2004]

I was thinking about adding an expression pedal jack to my echo base, o control feedback.

Can you help me?

1. Get two stereo jacks
2. Get a stereo cable
3. Connect each lug, both from PCB and from the pot in your expression pedal to the respective lug on the jack (i.e. if you connect the wiper to the tip in the pedal, connect the tip to where the wiper would go on the PCB.)
4. Make sure your grounds are connected to the sleeve**

[ashaxx]

so i just started noodling around to try and resolve the problem and the feedback pot works if i hook up the other side of the resistor,  (R17 on the vero layout) is it safe to just wire it to that point instead or shall i actually find out why it isnt working?many thanks

[slacker]

Does it go into self oscillation really easily with it connected there? 
If you wire it to the other side of R17 and it works then all that can really be wrong is that R17 is the wrong value or is broken or you've got a short across D2 and D3. I'd fix it properly

[ashaxx]

I thought it would be one of the 2 problems you mentioned, either resistor or the diodes, im pretty sure it worked at one stage so is it possible to have blown a diode or somehting?thanks again for the help

[DLC86]

Yo fellas, I've added several mods including the "humbucker-friendly" resistors to the Echo Base PDF:

http://www.aronnelson.com/gallery/main.php/v/Taylor/

Hi, why can't I see the pdf on that link? Could you attach it here?

[davent]

Hello,

After clicking on the link you provided, clicked on no thumbnail above Echo Base build PDF updated 051810 . On the page that takes you to look for Download document , (second column upper left) click on that and you should get to the necessary document. You can't attach pdf's in a post here so you need to provide a link to any pdf's you'd like to show. Hope that works for you!

dave

[Taylor]

Thanks for helping with that Dave. Yeah, the gallery does do its best to hide the PDFs on those pages. I may start hosting them myself, but I do like the idea of having them hosted externally so if I get hit by a bus, people can still get the PDFs.

[DLC86]

thank you!  I couldn't see "download document"
I'm getting blind... and I'm an optician too!  

[DLC86]

So, I've read almost every post of this topic, this pdf but I can't find an answer so i have to do a question: for the extra time mod with 2 pt2399 should I use a stereo pot for the delay time (if so: where do I have to solder its lugs?) or I can use a mono pot to drive both ICs?
Thank you in advance

[davent]

thank you!  I couldn't see "download document"
I'm getting blind... and I'm an optician too!  

I lose things under my nose all the time, have to get a second pair of eyes to help me flush out the missing item even though it may be sitting right there out in the open, aging sucks!

dave

[DLC86]

Ok, so I've studied it a bit and thought a stereo pot (or the 2nd one) should substitute R2 in the add-on board, and the 39k resistor near the time pot in the main board should have the same value of R1 in the daughter board to have the same delay in the two chips, please correct me if I'm wrong  
But now I have another doubt: how the feedback works? I mean, if I put these 2 ICs in series (e.g: having the same delay time) won't I have the repeats with half time after the first one?
Example: den -  -  - den - den - den - den
               ^             [                              ]
          dry note                 repeats

I think to prevent this there should be a sort of "shared" feedback (I don't know how to explain it better), is this the case?
Example: den - - - den - - - den - - -

Please clarify me how it works, thanks

[Leftwing73]

Hey gang,

i just built mine from the board that Taylor did and I love this pedal. I have a few general questions, sorry if some of it may have been covered before:

1) What are you guys doing to combat the clock noise? Can I swap out the "level" pot with a different value to maybe restrict the overall level? The noise only gets bad when the level pot is at 75%+

2) Is there a way to clean up the repeats, or is it a limitation of the PT2399? I know it's intended to be a low-fi effect but wondering oif that's a result of the circuit or chip.

3) anyone experience this: pedal will pass dry signal in both modes (bypass and on) but I get no repeats until i unplug/re-plug the power?

Thanks!