BOSS DS-1
The photo above shows two switches. One is illustrated below, the other is not very good, so I didn’t include it in the illustration.
This page shows how to install a gated feedback effect. It’s a really great sounding effect. Sort of ringmod meets harmonic exciter of some sort.
What is feedback?
Basically feedback is where the audio signal from somewhere along the signal path is fed back into an amplifier stage somewhere EARLIER in the path. This creates a feedback tone and can result in some really nice sounding, rich tones when an incoming signal fights with the feedback tone.
The problem with feedback
is that when there is NO incoming audio signal, there is just steady, squealing tone.
Gated Feedback is the solution
I wanted to find a way to make the effect happen only when there was sound feeding into the pedal, so that when you aren’t playing into it, there’s no sound output.
A transistor configured as a gate is the answer. I experimented with some transistors configured different ways and found the 2N3904 NPN to be the most effective.
I encourage people to experiment with different types of transistors.
PLEASE READ!!!
In the drawing below, the yellow wires and purple and blue wires are the same mod! I photographed the circuit board after I had installed the mod switch. It’s impossible to see how the purple wires connect to the transistor and switch, so I drew yellow wires to illustrate how to wire everything. Ignore the purple and blue wires!
NOTES:
- The distortion knob controls the effect.
-I soldered the transistor to the component side of the board so that I could still close the back cover. The back cover presses right against the solder side of the board so there’s no room to add components.
joythief said:
September 18th, 2009 at 2:17pm #
hey! i am currently modifying and bending various FX pedals and was searching for what exactly you achieved, making the “bends” playable. however, i have doubts on how to hook up the transistor. sadly, my knowledge in electronics is basic at most and i am fairly new to bending and modifying, the bends i’ve found so far are due to the “connection” of two points in the board, but upon seeing your diagram i see that the middle pin of the transistor is making contact with a third point. should i connect this pin to a point within a path of one of the other points? can i connect it to just about any other point? does it make any difference?
casper said:
September 18th, 2009 at 2:46pm #
In the diagram you can see a yellow line coming from the center pin of the transistor. The yellow line connects the center pin to a point just left of the center of the board. Just follow the diagram:-)
jammastersticky said:
October 7th, 2009 at 1:24pm #
What a fantastic sound! As another just peeking into the world of mods and bends, this really is an inspiration. Thank you, Sticky
bosh dave said:
October 16th, 2009 at 10:04am #
was wondering whether you could use a trim pot rather than a transistor to offer just enough resistance to prevent constant feedback. also, is there much danger of me permanently destroying my ds-1 if i just start poking around trying bends? thanks
casper said:
October 19th, 2009 at 6:24pm #
Bosh:
I don’t think you’ll destroy your DS-1. My official answer is that anything is possible, so be careful and go slow.
A trim pot won’t work. Adjusting the pot will change the pitch/depth of the feedback. That’s why I used the transistor. It adjusts the current flow between the feedback loop without varying the pitch.
Garrett Weeks said:
November 30th, 2009 at 5:23pm #
Hi I just wanted to say that I really admire this website and was wondering if you know of any books that have a good beginners guide to circuit bending and such. The reason is I am sixteen so I don’t have very much experience with tweaking electronic devices.
Also I was wondering if you know of any mods for microkorgs? just wondering
Thanks:]
Eli B. said:
December 15th, 2009 at 4:50pm #
Just a quick question before I start, I have the parts here, but in the diagram, the purple wires are from a separate mod, correct? I’m only soldering the four yellow wires shown? Thanks in advance!
Noise_ToyMan_BR said:
January 11th, 2010 at 10:40am #
man i’ve start bending 2 weeks ago and i maked a toy keyboard into a noise machine the toy have a potentiometer for regulating the pitch some switche to new drum machine like sounds and two adjustable (did i speak adjustable right? im brazilian sometimes my english fail hehe but not always) tractor and “alien cat” sounds and i plan more for this keyboard and for two quitars and a drum machine….
please pete if you can recommend me some eletronics books or more content or sites like this i will thank you and i like alot your sound you rock man!!!
greetings from brazil!!
J. said:
February 10th, 2010 at 8:44pm #
this looks easy enough, but as another person asked, are the blue and purple wires from another mod? can i achieve the sounds posted here by just doing the mod diagramed with the yellow wires? thanks in advance!
casper said:
February 15th, 2010 at 3:52am #
@Eli B- The Yellow wires and the purple are the same mod. I just re-drew the wiring so that it is more clear where to wire the switch.
@Noise_ToyMan_BR. I would recommend anything by forrest Mimms. His book “getting started in electronics” is a good first electronics book. http://www.amazon.com/Getting-Started-Electronics-Forrest-Mims/dp/0945053282
I’ve heard Nic Collins Hand Made Electronic Music book is really good too.
http://www.amazon.com/Handmade-Electronic-Music-Hardware-Hacking/dp/0415975921
@Garret. I would check out the books listed above. I’ve never worked on a micro Korg. I would advise against “bending” it unless you really know what you’re doing. The MicroKorg is a very cool and relatively inexpensive synth. I imagine they had to cut lots of corners to keep the price down. I imagine the construction and circuitry are fairly delicate. There may be some interesting bends or mods in there, but I bet it’s minimal.
casper said:
February 16th, 2010 at 1:47am #
@J- Please read the revised text for this page. The yellow and purple wires are for the same mod.