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Mod to lessen distortion 5-knob (old layout)



Just put 62k instead of the stock 47k resistors in these two spots. You may have to experiment with higher values until you are happy with the result.

Also, if possible, try running the pedal at 18v to increase the headroom.



Those resistors have already been changed to 56k (R26 and R33 - scroll down a couple of posts for the layout pic) in the new layout. If you still want to raise their value, they are the only 56k resistors on the right side of the board (right of the footswitch looking at the board where you can see the values). If you already have your board filled just look at the instructions to see which resistors are the 56k http://www.buildyourownclone.com/compinstructions.pdf

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Math illiteracy affects seven out of every five people.

I can't get enough minimalism.

Possible Mods to increase bass for 5-knob

Here are some of the "filters" in the signal path that you may want to experiment with:

C4 - larger value or pull it completely
C13/R17 - Try a larger cap/smaller resistor
C14/R18 - Try a larger cap/smaller resistor
C11/C12(part of the tone knob) - maybe try pulling C11 completely

C6 - increase size, possibly .001uf, .0022uf, .047uF
R8 - increase if C6 increase is causing clipping or if active bass has too much output.

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Math illiteracy affects seven out of every five people.

I can't get enough minimalism.

Opticomp Mods: 3-way attack switch & release pot mod

3-way switch mod: You will need and 0n-off-on switch and an additional 1uf and 100uf caps.

The two positions would put caps in parallel with the "off" position cap. So the off position cap would be 1uf which would be your fast attack. 33uf would be your medium attack. and 100uf would be your slow attack. The true values would be 1uf, 34uf, and 101uf.

Put the switch in the empty holes in the PCB. Put the 1uf cap in the space marked for the 33uf cap. The 33uf and 100uf caps go in the empty spaces below the switch.

This is from a build by Stephen
This is a shot of the assembled PCB. Take note of the positioning of the Attack mod capacitors. A member recently submitted some photos of this mod but the 33uf and 1uf caps were in the wrong positions. The 4.7K position on the PCB was left empty so that the Release pot and series 1K resistor could be attached from below.


Adding Release Pot: Remove R10 (4k7) and replace with a 1k resistor and a 50k pot in series to be able to adjust the release time.

Connect one leg of the 1k resistor to one of the empty spaces from the 4k7 resistor. Now connect the other leg of the 1k resistor to lug 1 of the 50k pot. Lastly, connect lug 2 of the pot to the other empty hole from the 4k7 resistor.

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Math illiteracy affects seven out of every five people.

I can't get enough minimalism.

Opticomp adding LED to indicate compression:

I have figured out a way to add the compression indicator LED to the design. This is an additional LED and not the bypass/on LED. To add it you will need to drill another hole in your enclosure. The bypass LED still functions the same but the new LED will indicate when the pedal is compressing your signal.

It is pretty simple, on the new board all you have to do is connect the positive side of the LED to bottom leg (closest to the footswitch) of the octocoupler on the side with 3 leads. (on the old board - the rightmost leg on the side of the octocoupler with 3 leads). This lead has no connection to anything else on the board. It is only connected internally in the octocoupler. I then attached the other leg of the LED to ground on the outlet jack or anywhere that is grounded.

When you strum a string the light lights up completely but it fades as the compression fades. The more the compression is turned up the longer it stays fully lit up before it starts to fade. Notes that are picked gently don't fully light up but the indicator works just like it is supposed to.

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Math illiteracy affects seven out of every five people.

I can't get enough minimalism.

THis is really cool stuff! I'm going to do these mods this weekend and report back...

hey coolhand, how does this work with the new 5 knob layout?
caps and resistors aren't labeled as "C4, C13, R17, R18" etc.
they are listed by value.

i'd love to try swapping these out, but can't pinpoint your suggestions...

thaaaaaaaaaaaaaanks!!!!!!!!!!!!!

Any idea if these mods can be done on the old Opticomp layout? I build one of the original ones (I think), with the jacks on the side of the unit, and the PCB that doesnt wrap around the switch. I can post pics if that'll help. Thanks!

These mods can both be done to the old layout. The attack mod will take some off board wiring since it isn't pre-made to do the mod. The release mod is already on the schematic of the old style comp instructions, along with a few other mod ideas.

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Math illiteracy affects seven out of every five people.

I can't get enough minimalism.

Check the original post again. I have mapped out the PCB and labeled all the components.

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Math illiteracy affects seven out of every five people.

I can't get enough minimalism.

woo! you rule.

i'm gonna put in a few sockets and try out a bunch of different stuff.

i'll let you know how it goes!

thanks, again!!!

Hi all,

Just a question regarding the tone knob. When it's all the way down I experience bass roll off. I want to maintain the use of the tone knob... but I wish that when it was all the way down... I could maintain my guitar's natural bass response.... which of the mods would give me a neutral setting?

Sean Meredith-Jones
http://www.seanmeredithjones.com

the Tone knob is a variable high pass filter. It doesn't adjust treble, it only rolls off bass.

Are you finding that it still rolls off bass at its lowest (fullest) setting?

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Coldcraft Effects - Forum -Fabricated PCB Projects

That is precisely what I'm saying.... it still rolls off too much bass at its lowest setting. I would like the option of having it bypassed completely... or switched on when I want bass roll off... but I will settle for out of the chain completely... because I really don't care for it in general.

Sean Meredith-Jones
http://www.seanmeredithjones.com

With the pot at the lowest setting pedal is at stock ross compressor specs. The ross is known for it's "jangle" tone. If you still don't like the loss of bass then maybe you should try some of the mods listed above to increase bass.

You can omit the tone control by replacing the pot with a 7.5k resistor but I don't think that will solve your problem.

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Math illiteracy affects seven out of every five people.

I can't get enough minimalism.

But that's the thing... which mods will restore the natural bottom end without altering the top end? From what you're telling me... the tone control is not the only source of bottom roll off... but it's occuring in other parts of the circuit as well?

Sean Meredith-Jones
http://www.seanmeredithjones.com

It seems as though you aren't happy with the stock Ross tone. I think you should try to socket C6 and experiment with different sizes there to increase bass response.

Try this:

C6 - increase size, possibly .001uf, .0022uf, .047uF
R8 - increase if C6 increase is causing clipping or if active bass has too much output.

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Math illiteracy affects seven out of every five people.

I can't get enough minimalism.

Can I permanently convert to a faster attack speed for my Opti-comp by just replacing the 33uf cap with a 1uf cap and no other mods?

Yes, just like using a cap larger than 33uf would give you a slower attack. You and experiment with different values to get the attack that you want.

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Math illiteracy affects seven out of every five people.

I can't get enough minimalism.

Thanks for the response. I'll insall a socket and try some different value caps. Can I experiment with the release time the same way by trying different resistor values in place of the 4.7k? Would larger values increase or decrease the release time?

Hi,
I want to use the 5 knob comp for my bass (also). I see usefull tips, thnx!
Can anybody post some results?

I want to remove the complete tone section c12, c13, r37 and Vr1.
Would this result in full bass response in the comp section?

I guess the downside of this, is the threshold is reached earlier through the sub frequenties (louder), but a slow attack would fix this...

Looking forward for some replies. What works for bass?
tnx

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THX!!!

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Yep 18V, bass, can't do without...
But I need those low freq's. I found in the old version 1 of the 5 knob comp, there where more 1uF C's and they where changed to 0.1uF right in the signal path so, I'll change them...

Don't be afraid to go bigger than that. Let your ears be the judge. And get on your gig rig. The headphones lie.

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