w3c
 
Welcome, Guest. Please login or register.
Did you miss your activation email?

 
   Home   Help Search Blog Login Register  
Pages: [1] 2 3 ... 37
  Print  
Author Topic: DIY True Bypass/Feedback Loop (aka KROK)  (Read 264687 times)
delorean
phpBB Junior Member
ian87sf
View Profile
« on: November 30, 2004, 05:21:59 PM »

Howdy, y'all. Here's a li'l ol' photoessay if'n you wanna build your own KROKlike object.

BYOB: Build Your Own Box.
A DIY feedback/true bypass box tutorial

What you gon' need:

A metal enclosure
A 3PDT stompswitch
A toggle switch
4 jacks, mono OK
A pot, pref 500k audio
Wire
Soldering iron
Solder
Patience

What you gon’ get:

1. A true bypass box. Bypass boxes are handy for a number of reasons: They can keep noisy pedals out of your signal chain; they allow you to turn on (or off) several effects at once; and they can essentially "add" an on/off stompswitch to effects that don't have one.

B. A feedback loop. A feedback loop takes the output of a pedal (or pedals) and sends it back to the input of that pedal (pedals), creating an unholy cacophony of noise. Put effects in the loop, turn the knobs, be amazed.


PART 1: The Switch

First thing I do is solder up the switch. After assembling a helluva lot of
these pedals, I've arrived at the process below as a fairly hassle-free way to hold the switch steady while soldering. While a third hand isn't required, it sure makes life easier for many projects. The clamp holds the switch better than the third hand alone, and makes it easier to manipulate.



Step 1. There are a couple of tricky connections to make on the switch — here's the first. Solder two wires (same color) to lug 9 of your switch, and connect the end of one to lug 4. Leave the other loose for now.



Step 2. Here's your other tricky connection. Pay attention now. You need to connect lugs 1, 2, and 5. I do this by stripping an inch or so off the wire I’m using, tinning it, bending it, and guiding it through all 3 lugs with needle nose pliers, then soldering. It takes patience, but it's totally doable.

NOTE: I’ve drawn on this photo in orange to better illustrate exactly where the wire goes.



Step 3. Go ahead and make the rest of the connections as shown in the next photo. The colors of the wire aren't important, with the exception the black wire on lug 7. This is ground, and it's always a good idea to use black for ground.



PART 2: The Case

Step 1. The next step is mounting the components in the case as shown in the next few pics. A pic of the top side of the case is included for reference.








Step 2. Here's a semi-tricky connection: the blue wire from lug 8 goes to the middle lug of the pot, and then the tip of the Send jack.



Step 3: Make the between the toggle and the pot. This is what turns your bypass box into a feedback loop. In this case, I’ve used an SPST toggle, so it’s easy. Connect the “on” lug of the toggle to the first lug of the pot.



Step 4. Make the remaining connections from the switch.

Here's a map for all the connections from the switch.

Switch lug 1/2/5 to tip of Out jack
Switch lug 3 to center lug of toggle switch.
Switch lug 6 to tip of RTRN jack.
Switch lug 7 to ground
Switch lug 8 to middle lug of pot.
Switch lug 9 to tip of In jack

The ground wire from lug 7 can go to the sleeve of ANY jack. The enclosure acts
as common ground for all jacks. In this pic, it's connected to the sleeve of the
Out jack. You can also see the orange wire from lugs 1/2/5 going to the tip of
the Out jack.

You’re done! Test that bad boy.
« Last Edit: April 27, 2010, 10:11:09 AM by expanoncolin » Logged
expanoncolin
Administrator
phpBB Member


View Profile WWW
« Reply #1 on: November 30, 2004, 06:07:18 PM »

Awesome Ian.  Thanks for posting this.  I know there are a bunch of people out there with little building experience who want to build one of these guys...  sticky'd.

-Colin

EDIT: This schem uses DPDT switching instead, just for reference... so if you're up to it, you could try this as well... and add an LED too if you want...



Also, NaBo made a layout of a slightly more complex feedback loop here:



-Colin
« Last Edit: May 03, 2011, 01:15:04 PM by expanoncolin » Logged

The best way to learn is to experiment.  Try it first, then learn from what went wrong.

http://www.eaced.com
http://www.experimentalistsanonymous.com
spivkurl
phpBB Member


View Profile WWW Email
« Reply #2 on: December 03, 2004, 10:33:46 PM »

This really is impressive!  So simple, yet it seems very useful.  Definitely on the long list of TO DO!
Logged

Byrd
phpBB Junior Member

View Profile
« Reply #3 on: March 23, 2005, 08:10:57 AM »

hi everyone

just discovered the forum tryin to get some info on the DBA Total Sonic Annihilation.

Now this post is just what I needed! Thanks so much. The TBA's a great idea but as a non-US resident I just cant afford it (Maybe I wudnt ..even if I was in the States)

Anyway, I'm building the one posted, just wanted to know if anyone's ever put a led in it.. and how I could do that

More input about the pot? a 1 MEG would be too much?

Thanks guys :]

Javi,
Spain.
Logged
expanoncolin
Administrator
phpBB Member


View Profile WWW
« Reply #4 on: March 23, 2005, 02:20:02 PM »

1meg would probably be too much, 500k is cool.  I'm not sure why Ian uses a 3pdt as such, but you can make a feedback loop with a DPDT stomp like this:
http://experimentalistsanonymous.com/di ... 20loop.gif

Just take the remaining column of lugs on the 3pdt and wire a 9v battery to the center lug and a 4k7 resistor to the longer (positive) end of an LED, with the shorter (negative) side to ground.  There is also a long post on feedback loops here:  

http://experimentalistsanonymous.com/bo ... 47&start=0

-Colin
Logged

The best way to learn is to experiment.  Try it first, then learn from what went wrong.

http://www.eaced.com
http://www.experimentalistsanonymous.com
alex
phpBB Junior Member

View Profile
« Reply #5 on: April 09, 2005, 12:17:58 AM »

ok. i attempted this project, with the following results.

i got a perfectly good TB box. but it doesn't operate as a feedback loop - nothing happens when the loop swsitch is activate.
i did make one modification to this design, by using a DPDT footswitch instead of the toggle switch...  connections were made to the bottom left and top middle lugs (if that makes sense)... any ideas where i went wrong?
Logged
expanoncolin
Administrator
phpBB Member


View Profile WWW
« Reply #6 on: April 09, 2005, 08:16:37 AM »

I'm guessing you are looking at the switch like this:
X X X
X X X
Where X are the lugs... and you wired to the Ys:
X Y X
Y X X

If so, you need to wire "bottom left, bottom middle" instead of the top.  The switch works by connecting the middle lug to one or the other of the side lugs, in the rows of 3.

-Colin
Logged

The best way to learn is to experiment.  Try it first, then learn from what went wrong.

http://www.eaced.com
http://www.experimentalistsanonymous.com
alex
phpBB Junior Member

View Profile
« Reply #7 on: April 10, 2005, 04:45:55 AM »

ah. why didnt i think of that for a diagram

ok so if i go

xxx
yyx

it should work properly?

EDIT: it works now, thanks colin
Logged
De Stijl
phpBB Junior Member

View Profile
« Reply #8 on: April 10, 2005, 03:39:36 PM »

Hi!

I'm from germany so I guess I'll have to apologize for my english, which may not be 100% correct.

I just built the feedbacklooper on this site, and now i got a problem:

I started playing around with it, with my Boss Chorus in the loop and the pot set to the left moving it slowly to the right, to see how it affects the sound. With the Pot somewhrere around 12o'clock, I had a really nice, spacy, flanger-type sound with a little bit of oszillation in the background, which I liked very much. As I turned the pot on, the oszillation suddenly started to get damn loud, somewhere around 2o'clock, so I turned it back to 12:30. This seemed to be a nice spot, and it was really interesting to play around with this thing... until I switched to the neck pu of my guitar, which means higher output level and a massive oszillation set in, so damned loud it even caused pain, which is quite impressive cause my amp was set really low (in germany it's 0:30am right now). If I imagine, this would have happen with my amp at practise-room-level, it would have been really dangerous for me and my bandmate's ears.

I know that this thing is supposed to do crazy stuff, but I guess/hope this is not normal.

Hope somebody can help me, fixing that prob. I used 100k for the pot, instead of 500k, could this be the reason?

greetings!
Logged
expanoncolin
Administrator
phpBB Member


View Profile WWW
« Reply #9 on: April 10, 2005, 07:56:26 PM »

Your english is completely perfect.  I thought it was interesting that you said "now I got a problem"-it's actually right to say "now I have a problem", but most people in the us say "got" instead, it's just more normal.

I'm afraid to say that's really not a "problem"-thats the kind of thing people want when they use feedback loops.  However, it sounds like the oscillation was created by the change in pickup impedance-this could be fixed by putting a simple buffer between your guitar and the feeback loop, either buy ptuting a pedal with buffered bypass in front of it, or by building one in.  Could help, I guarantee nothing :)

-Colin
Logged

The best way to learn is to experiment.  Try it first, then learn from what went wrong.

http://www.eaced.com
http://www.experimentalistsanonymous.com
De Stijl
phpBB Junior Member

View Profile
« Reply #10 on: April 11, 2005, 05:12:13 AM »

Thx!

Hm... Now i'm a little bit scared... Like I said, I knew that this thing is kind of noisy and causes oszillation, but this noise was scaring :/
You know, I'm really afraid this could happen again, with my amp running at high volumes, cause it would be loud as hell and really really dangerous. Right now, I'm thinking about using an effective compressor right after the loop to decrease the amount of feedback-level, because I really liked the chorus in the loop...

So,...what kind of effects do you use in the loop, and how do they behave?
Logged
expanoncolin
Administrator
phpBB Member


View Profile WWW
« Reply #11 on: April 11, 2005, 10:42:20 AM »

Remember, try putting a buffered bypass pedal in front before you get too scared.

Gain pedals are usually pretty predictable in that they just make long tone noises.  Chorus and flanger, as you have heard, sort of makes the resonance go up, which can be nice, but if the gain get s too high it's bad news.  You might want to try an active feedback loop, which they actually usually use on phasers and flangers and choruses for their resonance controls, like the one found in the prophecysound infinitphase schematic.... which unfortunately is offline.  It basically just has buffers at either end.

-colin
Logged

The best way to learn is to experiment.  Try it first, then learn from what went wrong.

http://www.eaced.com
http://www.experimentalistsanonymous.com
De Stijl
phpBB Junior Member

View Profile
« Reply #12 on: April 11, 2005, 01:19:39 PM »

Which means the feedback I get is not going to blow my speakers?
Logged
expanoncolin
Administrator
phpBB Member


View Profile WWW
« Reply #13 on: April 11, 2005, 03:32:56 PM »

Quote from: "De Stijl"
Which means the feedback I get is not going to blow my speakers?

Well, if it's tweaked right... the sad thing is that it really depends on the circuit, the input and output impedance, the circuit's gain, etc...  so you really have to do it on a per-pedal basis.

-Colin
Logged

The best way to learn is to experiment.  Try it first, then learn from what went wrong.

http://www.eaced.com
http://www.experimentalistsanonymous.com
Liam
phpBB Junior Member

View Profile
« Reply #14 on: April 14, 2005, 10:52:16 AM »

CAn some please please post a diagram with it with a DPDT switch please  :/  im a newb to this electronics thing :S
Logged
Pages: [1] 2 3 ... 37
  Print  
 
Jump to:  

Powered by SMF 1.1.12 | SMF © 2006-2009, Simple Machines LLC