The $20 delay (Fab Echo mods photoessay) 56K warning!

[mueller]

Is there a simple way to add an FX loop to this pedal?

Not worrying about fitting in the jacks,etc. I would put it in a different casing.

[earthtonesaudio]

Any suggestions to get the knobs off?

I just used pliers.  It's fast, but it will scuff up the knobs (I didn't care).  If you want to keep them "pretty," you could put something (like rubber) between the pliers and knob.

Is there a simple way to add an FX loop to this pedal?

This would be possible, but tricky.  The schematic is very similar to the echo base, so you could take a look there for inspiration.  But the hard part is that the Fab Echo board is very compact and mostly surface mount, so it's very difficult to attach extra components. 

[AM]

Resurrecting an old thread but I was playing with my Fab Echo today and I was wondering about the following:
Is the dry signal kept without A/D and D/A conversion or it also goes through the A/D and D/A conversion?
Just curious.

[Processaurus]

These Princeton chip based designs are implemented much like an analog delay, so that means not only an analog dry path, but analog regeneration as well.

This is an interesting chip because it uses 1 bit sigma delta A/D/A conversion, which a totally different process from regular digital audio.  Rather than a pixelated, stairstep the audio looks more like a connect the dots, vector image.  Ironically an analog delay with its slow sampling rate would resemble a typical digital audio output closer than this type of conversion.

http://www.diystompboxes.com/smfforum/index.php?topic=31886.msg219966#msg219966

[The Tone God]

Is the dry signal kept without A/D and D/A conversion or it also goes through the A/D and D/A conversion?

The dry signal gets passed through the buffer/mixer opamp and mixed with the delay signal so there is no A/D/A action. To switch the effect off they just disconnect the delay signal so the dry signal is always going through the opamp. Its not true bypass.

Andrew

[E-mol]

Hey.

I have tried to do the mod of the delay time, but now there isn't any effect at all. Sounds like pass through. I have followed the guide in the beginning of this thread, plus the ideas about cold soldering, and missing connections. Nothing had worked. A possibility could be that number 5 and 6 (on the photo) have more ohms than my meter can measure.

I have tried anything I can think of, but I'm pretty new to this modding stuff, so that's no guarantee 

I have addet a photo of my circuit board as it looks now. Hope it can help


Bigger picture here:
http://emilharder.dk/print.jpg

I hope there is light at the end of this tunnel
Thanks
E-mol

[Mark Hammer]

In situations like this, I often suggest the person get an old toothbrush and some methyl hydrate and scrub the solder flux off the board.  When the traces run close to each other, sometimes the flux reflects the light in a way that makes it hard to say if there is an accidental solder bridge or if the solder joint is a good one.

The problem may well NOT be any of the above, but at least you can scratch "solder bridge" off your list with confidence because you had a good and unobstructed look.

[E-mol]

Thank you hammer
But after I had assembled the pedal it all works

I don't know what the problem was but.. the tunnel wasn't that long..

Cool mod - maybe I get addicted to this stuff

Thanks
E-mol

[Top Top]

Did  this mod last night. I almost didn't do it because the fab echo actually sounds kind of cool even though it is very limited. I figured $15, I will go for it. I am really glad I did.

I re-housed the pedal into a new enclosure to make room for the knob and because I plan to add an LFO possibly for modulation eventually. Clipped the switch wires and hooked them up to a momentary spst pushbutton (any will do).

It actually sounds pretty sweet. I used a 100K pot. You do start to hear some clock noise at the longer settings, but the delay itself still sounds ok - a little grungy, but ok... It sounds really good, smooth, up to that point. Each repeat is colored in a nice way. Very dub sounding.

You have to really watch out with those SMD resistors. If you touch one with your soldering iron, you can pretty much kiss it goodbye. I don't know if you were supposed to remove the resistor (by the cap leg) for the infinite repeats mod, but as soon as I touched it, the tiny thing stuck to my soldering iron - so small I almost  couldn't see it on there. I just bridged it with a solder blob, and it works... so... no complaints but a close call maybe... wouldn't want to touch any that you weren't sure about... I used some hot glue in a couple places for the stress relief on the wire for the delay time mod pot... that's that...

[aleister]

I just did the 3 mods on my fab echo and all I can say is WOW!!! This pedal is a total beast now. Sure when you max out the pots you do get osscillation but there are so many great sounds to be coaxed out of this baby now.       Now when I went to do the second mod, wet mix, I also had the problem of the smd resistor come right off and stick to my iron. Then I tried a blob of solder with no success, then I clipped a short lead and tried to solder that on and it wouldnt take. Now this was my first time messing with smd components so I am thinking I am screwed but I sit back and take a second and realize that both ends where the smd resister was connected to thru hole components so I got a .47 ohm resistor and connected it to those joints. So with 30 minutes work and less than a buck in compnents I have a kick ass delay.  I got mine new off ebay  for 18 bucks shipped to boot!

[clamup1]

i thought i messed mine up with the ocillilation. but im glad i didnt. great mod

[Renegadrian]

So the wet signal comes out from the pin with that arrow. So I have to desolder the pot and take the wet from there, then take the clean fron the oter board and connect the wiper to that cap on the sw board. right?!

My goal is to make it true bypassable as a standard pedal - even get rid of the sw. board, in case I'd add the tl072 part with a daughter board! but keep the switching as usual!

To get the wet signal wire a connection to the wet side of the mix pot on effect board:



Note: Do not forget to turn down the pot attached to the board otherwise it will interfere with the mod.

Connect the clean signal to one end of a 100K linear pot. Connect the wet signal to the other end. Connect the wipe of the pot through a 1uF capacitor and a 33K resistor.

Go ASCII graphics:

Code: [Select]

Clean
   |
   |
   |
   P    1uF      33K
   O----|(----/\/\/\/\----Board
   T
   |
   |
   |
  Wet       

Connect the wiper to the orange capacitor at this spot on the board:



You now have a 100% wet / dry mix pot. If you want you can decrease the 33K for more output then put a volume pot on the final output of the effect as a level control.

Since the clean signal is disable the bypass function will not work anymore. If you want to force the pedal into effect mode all the time then perform this mod.

Always On Mod

Cut the trace at this point:



Connect a wire from the switch's board connection to the resistor:



The pedal will now always be on. You can install a true bypass switch.

Enjoy.

Andrew

[The Tone God]

So the wet signal comes out from the pin with that arrow. So I have to desolder the pot and take the wet from there, then take the clean fron the oter board and connect the wiper to that cap on the sw board. right?!

My goal is to make it true bypassable as a standard pedal - even get rid of the sw. board, in case I'd add the tl072 part with a daughter board! but keep the switching as usual!

I don't need to desolder the pot although you could. Just set the pot to zero so the wiper is grounded out. No soldering needed. Other then that just follow the diagrams and the solder points with the arrows and your good to go.

Andrew

[joelindsey]

Just as a heads up to you folks who might have a hard time placing the pot out of the way of the lever arm. I just bought a new one of these, and it looks like Danelectro got rid of that entirely with the newer models. Instead there are two springs directly under the actuator. That frees up a lot of space. 

[Renegadrian]

clever move - lever (re)move(d)

[The Tone God]

The batch I bought awhile back are like that. Simpler and cheaper I'm sure.

Andrew

[Renegadrian]

FINALLY REHOUSED

switch is a momentary dpdt - I had some work to do to make the boards fit the box, like sanding off excess pcb!
Added pot for the time, it it very similar to a rebote minus the feedback crazyness and the mix mod hasn't been made, so wet level isn't that high - good effect anyway, 20 euros shipped is ok!!! I had fun doin' this!!!

[ThunderShowers]

REVIVAL: Sorry guys

If I want to use a Roland ev-5 to control the feedback, I would use a Stereo jack across the pot, orrrr?

[steampunkistof]

Hi,

Great mod! But I have messed up the pcb pretty bad.
I have a question.


xcgsdfgd by steampunkistof, on Flickr
Are these points connected?
I have stripped the path running from the cable (right upper circle) to the zero resister so I have no way of knowing. I have a suspicion that it is connected under the white line around the cap (thats also gone on my pcb).
Can somebody check

PLeaase

BY the way ignore the red arrow ( it was already there). I dont mean that resitor haha

[muffinman]

Just wanted to add that I'd had one of these for years- came free with something (like a mag subscription?-can't remember) but never used it as that slapback is so - well I reckon everyone knows... did the infinite plus feedback , wet volume and put in a 250k for the delay time. MONSTER for glitch madness and catch and mutate loops. Many thanks for the info and great pictures.