first act chorrus mods

[mikebike]

got working on bending/modding my chorus today.

its kinda neat. im getting some synthy organ kina sounds from my guitar.
i think im shorting the lfo(?) to ground.
theres 2 differant "distortions", ones just synthy, then the other has  extra lo end.

also, i think im running the lfo into the signal path, and its couasing some interesting gateing. but i can here the thud of the lfo, any ideas on controlling that?

i can get the lfo to modulate the chorus a little to.

thing is i can ac6ually find the lfo source except on the "speed" pot

this thing seems like its gonna be fun when its finished, ill share pics if anyone is interested in the mods

[expanoncolin]

Take a look at the small stone chorus trem tutorial for ideas on using the LFO to gate the signal (eg, through use of a vactrol).

-Colin

[mikebike]

cool tutorial!

my chourus uses differant chips than the SS but i traced the lfo to a tl072.

theres 2 of these chips on board, as well as bl3102, bl3207 an tc4013bp.

so right next to the first tl072 is a 100n between  pins 1 and 2, is this the obne i should toy with to get  differant speeds?

where should i look for the gain resister?

[expanoncolin]

cool tutorial!

my chourus uses differant chips than the SS but i traced the lfo to a tl072.

theres 2 of these chips on board, as well as bl3102, bl3207 an tc4013bp.

so right next to the first tl072 is a 100n between  pins 1 and 2, is this the obne i should toy with to get  differant speeds?

where should i look for the gain resister?

Yes, most likely that's the cap you need to futz with.  The other TL072 probably has some sort of output buffer/amplifier...  try to trace the output signal back from the output of the circuit until you find an op amp, and trace the op amp's configuration to determine if it's inverting or noninverting.  From there, you can find the appropriate resistor to replace.

-Colin

[mikebike]

allright, im about to do the cap switch,

in your mod your removing the 2.2 and adding a .1.

my pedal has a .1, so im gona add 2u in parellel, all i have is 1u's so im gonna put them in parrelel on the switch.

does this all make sence?

also, im replacing the feed back resister for the trem, right?

would this be going from pin 1 to 2?

EDIT: i tried the 2uf, it made the lfo go alot slower, i think i need it to go faste for tis mod right?

[expanoncolin]

Yes, bigger cap = slower LFO.  It's up to you whether you want to make it go slower or faster!  Yes, feedback resistor will control output gain, so you want to find that for the tremolo mod.

-Colin

[mikebike]

do i need a resister  for the led in the "vactrol" ?

the only resistor i could find being used as feedback was a 47k between pins 6 and 7, im gonna try that one, should the photoresistor be on a switch with the original resistor so i can switch to normal chorus?

[expanoncolin]

do i need a resister  for the led in the "vactrol" ?

the only resistor i could find being used as feedback was a 47k between pins 6 and 7, im gonna try that one, should the photoresistor be on a switch with the original resistor so i can switch to normal chorus?

Yes to both - I think both are covered in the tutorial.

-Colin

[mikebike]

sorry, i checked the tutorial over again and it was there.

is there a vibrato mod for the chorus too?

as soon as i rewire the pots and com up with an enclosure ill post some pics and such

[expanoncolin]

is there a vibrato mod for the chorus too?

I think that's in there too

-Colin

[mikebike]

man, this pedal is making me feel dumb.

i did the lfo mod, but it says something about a clock too? is that another part of the circuit?

as i understand it, the chorus kind of vibratos and delays?

the way i have the "vactrol" wired, it tremelos(volume)

also how do i figure out witch ic is mixing the wet/dry?

[expanoncolin]

man, this pedal is making me feel dumb.

i did the lfo mod, but it says something about a clock too? is that another part of the circuit?

as i understand it, the chorus kind of vibratos and delays?

the way i have the "vactrol" wired, it tremelos(volume)

also how do i figure out witch ic is mixing the wet/dry?

The clock is a separate part of the circuit - the LFO drives the clock and makes it change in frequency, which makes the delay length change, causing the pitch to shift and a vibrato effect to result.  When combined with the dry signal, you have chorus.  Isn't that the vactrol result you want?  Try tracing the mix/dry pot - most likely on one side of it, there will be some vibrato signal.

-Colin

[mikebike]

right now im using the vactrol to control the volume, thus tremelo

the issue im having with it, is that the overal volume drops significantly when its engaged.

also id like a depth control for the trem to?

should  i add a resistor in parellel to the photoresistor to make the volume louder?
is there a way to control the minimum vaolume as well as the depth?

[expanoncolin]

right now im using the vactrol to control the volume, thus tremelo

the issue im having with it, is that the overal volume drops significantly when its engaged.

also id like a depth control for the trem to?

should  i add a resistor in parellel to the photoresistor to make the volume louder?
is there a way to control the minimum vaolume as well as the depth?

In an op amp circuit, the ratio of two resistors will determine the gain.  Try to figure out which resistor is the "input resistor" as it's normally called, and changing its value.  I can't be much more descriptive without seeing the circuit.  To add a depth control, I'm assuming you're wiring the LFO through a resistor to the + side of the LED, with the - side going to ground?  If so, wire a pot as a voltage divider with the LFO on one side lug, the center lug going to the LED's resistor, and +V on the other side.  You may need to add a resistor in series with the V+ side lug.  This is covered in the tutorial too.  You probably want a low-value pot, like 1 or 5k.

-Colin