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

[earthtonesaudio]

Hey y'all.  The basic info on how to do this is floating around out there, but I thought it would be nice to have a pretty photoessay available for all.

This covers the mods for adjustable delay time, infinite repeats, and increased wet signal from the "Mix" knob.  Plus a solution to the extra pot placement.


The infinite repeats mod: a big ol' blob of solder between that SMD resistor and the leg of the cap sticking through from the other side.  Other DIY sites recommend shorting a different resistor (visible above and slightly left of the tip of the screwdriver/pointer) but I felt that one took too much travel out of the stock "repeat" knob.  This one still gives infinite repeats, but you get better control over them.


The maxed out wet signal mod: short the resistor between lug 2 of the "mix" knob and that big metal pad.  I used a piece of wire.


And the real point of all this mess, the adjustable delay time mod: remove the resistor between pin 6 and ground, and replace it with a pot to ground.  I soldered one lug (center lug I think) to pin 6 and the other to that big ground point below and to the left of the top left screw.  Like Dano says, put some strain relief on those wires, or they will snap off. Immediately. 


Here's where the other "how-to's" have been lacking: delay time pot placement.  I took my trusty Dremel with the 1/2inch sanding drum attachment and slowly ate away at the corner of the battery tray and the footswitch lever arm apparatus.  It took lots of grinding, then checking clearances, then grinding again, etc. until I was satisfied with the result.  Make sure you can depress the switch button and that it actually turns on and off.


Clearance issues: the pot pushed the footswitch lever too far down, so I put in a spacer to raise the switch board.  Cured the problem of "always on" or "always off."


Put it all back together...


Still works? Good!


Make your own knobs from fallen twigs and branches.  Never take from a live tree, because in the next life you might be a tree. 


Here's where I got the basic ideas:
http://experimentalistsanonymous.com/board/viewtopic.php?t=1094&highlight=fab+echo
http://www.beavisaudio.com/Projects/FABRack/

[12milluz]

Thank you so much! I'm going to try this!

BTW, I love that knob, what an original idea!

[widdly]

now you should go play some Bach...hahaha sorry I'll go stand in the corner now

[disarrayed]

Thanks a ton for these photos.  They really helped me along on my first mod.  I just did the 100% wet and infinite repeats mods tonight.....wow.  Some crazy sounds come out of that thing now.

I'm hoping to get to the store this weekend to grab some parts for the delay time mod and maybe a re-house.

[theundeadelvis]

Hey are you located in Bloomington? I've seen your pedals at Roadworthy!

[Processaurus]

I bet one could get one of the tiny 9mm Alpha pots Small bear sells (which I talk up a lot, I guess) in the vacant "gable" between the other two pots.  There are maybe one or two film caps in there, but they relocated to the bottom of that pcb.  Or I bet it could go on top, around the "B" in FAB.  I just feel bad hearing about all the dremeling going on.

[earthtonesaudio]

Hey are you located in Bloomington? I've seen your pedals at Roadworthy!

I sure am!  Yup, those are my pedals.  Have you played them?

I bet one could get one of the tiny 9mm Alpha pots Small bear sells (which I talk up a lot, I guess) in the vacant "gable" between the other two pots.  There are maybe one or two film caps in there, but they relocated to the bottom of that pcb.  Or I bet it could go on top, around the "B" in FAB.  I just feel bad hearing about all the dremeling going on.

I saw one like that.  If you relocate the caps to the other side of the board, there's room for a small pot to fit on top, with the knob coming out of the "A" right in the middle.  It looked pretty slick.  The one I saw used one of those small/thin pots like Crate uses in their amps.  Very low profile, but they have a fragile look to them.

[darwin_deathcat]

Hey, I did basically the same mod, but with a different pot mounting technique. I drilled a small hole (in the middle of the "A" in the "FAB" sticker") and pulled the pot wires through them. I had a small PCB mount pot (almost identical to the ones already in the FAB), and I hot glued it in the "center" pot location (you know how all the FAB chassis have three places for pots whether they have three or not). I basically covered all exposed wiring and solder joints with hot glue, and then used some nail polish on top of that to get a similar color match. I made a YouTube video, check it out: http://www.youtube.com/watch?v=It8WOGPxOoQ

Cheers!

[earthtonesaudio]

Cool!

[theehman]

Hey are you located in Bloomington? I've seen your pedals at Roadworthy!

I sure am!  Yup, those are my pedals.  Have you played them?

You're in Bloomington?  I'm in Bloomington!  I don't sell any RonSound stuff in town, though.  A lot of my sales are international.

[earthtonesaudio]

Another Bloomingtonian, cool!  PM sent.

[Rawkgod]

Thanks EarthsTone I actually just got a FAB echo and am  excited to do this.

[earthtonesaudio]

Cool!  Good luck.


By the way, these are so cheap that I got 2, and so of course I had to mod the second one as well.



This one has adjustable delay time, infinite repeats (but not the other mod for increasing repeat volume), and a LED/photocell in parallel with the delay time pot, brought out to a 1/8" jack for external LFO or manual delay time.  Oh yeah.
I had to relocate the through-hole caps to the other side of the board, but it was still a tight fit.  Worth it though!

[darwin_deathcat]

I like how you place the pot... I wish I'd thought of that! I keep having my delay time wiring connection break. It's so hard to get a good solder connection to thos SMD pads. I'm actually thinking of rehousing the thing in a roomier box so I can make sure that I can get proper "strain relief" on that connection! Cool job man!

[jacobyjd]

All of these crazy Indiana people....sheesh...it's an epidemic

[earthtonesaudio]

I like how you place the pot... I wish I'd thought of that! I keep having my delay time wiring connection break. It's so hard to get a good solder connection to thos SMD pads. I'm actually thinking of rehousing the thing in a roomier box so I can make sure that I can get proper "strain relief" on that connection! Cool job man!

Yeah, I actually drilled a couple extra holes in the PCB to allow placement of a wire tie which I used for strain relief for the connecting wires.  I might rehouse mine eventually because I find the footswitch a bit awkward.

I think if you use one of those 9mm pots like Zvex uses, you could put the pot on top without other modifications, but if you use a full size one, you really have no choice but to relocate the components to the other side of the board.

All of these crazy Indiana people....sheesh...it's an epidemic

Haha, yep!

[drewl]

That's great, how long a delay time does it have?
I've been thinking of doing something similiar to my $20 Arion delay....maybe even mounting it in a metal case if I like the sound.

[earthtonesaudio]

I used a 100k pot for the delay time and I'd say the usable time tops out a little under 1 second, but it probably will go up to maybe 1.5 seconds.

The longer delay times are increasingly distorted, sort of low-fi sounding.

[edit]
And I should point out that while longer delay times won't hurt the chip, decreasing the resistance from pin 6 to ground to zero is not a good idea, because it can potentially harm the chip.

[moertz]

hey, i did my first mods with the help of your description so thank you very much for your encouragement! everything worked out great apart from the infinite repeats mod. i only got it to make a few repeats that blend out very quickly. so i also shorted the other resistor as described in the experimentalists anonymous forum's post but nothing changed. it has both resistors shorted now and still just a few repeats. i also tried random bends with a nice result so i'm already very happy with it but i really would like to hear more of the lofi repeats.
do you have any ideas why mine dind't work out the same? i alredy re-tried it multiple times and think i'll just buy another one to see if i get it working on that..

[earthtonesaudio]

I'm not sure why that isn't working for you.  If you could post a high-resolution, very close-up photo that might help. 
Also the answer to a couple more questions may be helpful for de-bugging:

-Aside from the obvious fact that you can't get the infinite repeats, does the "repeats" knob work as usual?  Meaning, can you turn it down to get just one repeat, and then turn it  up to get a few more repeats?  Or, has its function been entirely compromised?

-Is the solder bridge contacting anything else that it should not touch?  Look very closely.  It's easy to slip with a big soldering iron tip, especially when working around surface mount components.


Hopefully you can get this working 100%.