Fun with crummy pedals

[Deep Blue]

I picked up a crappy old KMD flanger for $35 from a secondhand music shop the other day.  It's really thin and lame, but I figured I could do something to make it more interesting.  I tried playing with the trim pots, but the only thing it's good for is turning all the knobs down and using it as a treble booster, and even then it's pretty useless.

Anyways, I'd be fun to turn it into a sort of novelty effect.  I'm not concerned with making it a better flanger or anything like that.  I just want it to become interesting.

Any suggestions on where to start?  It's a KP-400, by the way.

[Hal]

as with all effects, larger input and output caps might boost the bass responce...

Have fun

[Travis]

Post the chips it uses.  Use the info to whack the clock speed all over the place.  It's the only reasonable thing to do to crappy sounding flanger.

[bwanasonic]

Sorry to hear that - I have a KMD Analog Delay that is really sweet.  The KMD line was made by Maxon for Ovation. They usually are variants of Boss pedals from what I've seen (which isn't much).

Kerry M

[Pedro Freitas]

See if you can play with the clock speed and/or feedback circuit.

[Brian Marshall]

yeah, feedback loop that is driven by the lfo.... woo hoo.

[Mark Hammer]

If you wish to "go wacky",here are a few simple but dramatic things you can do:

1) Make it sound like a ring modulator: Any modulation pedal can get that "rubber band" sound by makiing the LFO operate at speeds in the audio range.  Usually, flangers, phasers, and chorusses are set to sweep at maybe a maximum rate of about 8hz to mimic a fast Leslie.  If you can locate the cap/s that set/s the LFO range, and can drop the/ir value to 1/3 of the original or less, you will raise the maximum modulation speed well up into the audio range.  Speeds higher than 20hz or so will sound very much like ring modulation.  Often there is only one cap involved, but if the needed capacitance value is large enough, the designer might use a pair of electrolytics back-to-back to mimic a large value nonpolarized cap.  If you see, for example a pair of 2u2 or 4u7 caps, back to back beside a dual op-amp, that's your target.  Replacing a pair of 4u7's (series capacitance of 2u3) with a plastic  680 or 560nf cap will be perfect.

2)  Make it a vibrato: Lifting the "dry" path going to the mixer stage at the output will turn it into a vibrato pedal.

3) Alternate resonances:  There is often a resonance trimpot onboard to set the maximum amount of feedback before it howls into oscillation.  The setting is predicated on using full signal bandwidth in the feedback path.  If you lop the bass substantially (e.g., reducing, say, a .01uf cap in the feedback path down to 2n2 or even less) you can crank the resonance like there is no tomorrow and retain the peakiness without the boxiness.

[ExpAnonColin]

To add to mark's first suggestion specifically, it helps to lower the clock speed a bit when you're making the LFO higher speeds.  Then, the depth gets to be much bigger, so the ring mod effect sounds more interesting.  Also, if you're lucky, sometimes there are resistors on either side of the speed pot-if you change their values, you can make the range of the speed knob much wider.

You could also find the totally wet output and lower the clock speed a tad and use it as a vibrato.

Lowering the clock speed is probably a must, find the MN3102 or 3101 and the cap betweens pins 5 and 6, and just put something in parallel there.

-Colin

[Deep Blue]

I love the ring mod idea.  What do you mean when you say to just put something parallel in there?  I think I found the (small, ceramic) capacitor you're referring to.  What exactly am I supposed to do with it?

[Mark Hammer]

The value of that cap sets the range of clock speeds the MN3102/3101 can produce.  As the capacitance value is increased the range of clock rates goes lower, which results in proportionately longer delay times.  So, if a cap of 220pf gets you, say, 1msec to 12msec sweep, adding a second 220pf cap in parallel will increase capacitance to 440pf and shift the delay range from 2msec to 24msec.

You *could* remove the cap and replace it, but the fact of the matter is that caps in that range are so small and flat, that you can easily just solder one to the pads on the copper side in parallel without having to remove anything.  More importantly, once you have the pads identified, you can just plug into the box, play and touch the leads of parallel caps to the pads until you find a combo that serves up a tone you like.

Please note, however, that the filtering in a flanger assumes a much higher clock frequency, so it doesn't have to be too ambitious to keep clock signal out of the audio output.  If you drop the clock frequency by a factor of 2 or more, clock whine may be noticeably more audible.  Of course that would depend on whatever the filters are presently set to, and how immune to whine the unit preently is.

In general, a big part of what makes one chorus or flanger sound different from another is the range of delay times selected by the design.  In particular, longer delay times in chorusses can yield very rich sounds.  Think Pat Metheny.  Of course the corollary of what Colin notes is that if the delay time is extended, then sweep width will need to be adjusted.