Ultimate CS-3 Mod Question

[Mumphrey]

Hi everyone,

I just finished this mod today (see below my post), and I have a question about the IC chip portion. Which way do I place the chip on the conversion board? I know the direction of the little 'dot' on the chip is critical. Also, which way should the chip face when I install it? Lastly, do the experienced members (11 Gauge and wnorcott) see any real value, tonally speaking, to do the the chip portion of this mod? I've done the rest, and the improvement is remarkable. The CS-3 sounds quite good now, whereas before, the pedal really kinda' blew. I only have one 4558 and one OPA2134PA and one conversion board. Which chip should I use, and which SIP chip should I replace?

Thanks!

C4, C6, C14, C17----1mF tantalum
C1, C2, C10, C16----0.1mF
C9, C13----0.047mF
R5----1.2K
D2, D3, D6----1N34A

IC1, IC2
To really lower noise the cheap stock op-amps have to go. I replace both IC1 and IC2 SIP op-amps with two stacked DIP sockets. To do this you will need to make a little conversion board. You can buy fancy little PCB from Monte Allums which makes things super easy. I stack a RC4558P and a Burr-Brown OPA2134PA. This really increases the clarity and brings the noise level way down.

[Mumphrey]

Seriously, no one has a clue about this?

Thanks anyway.

[JohnnyCrash]

Give em a few days... it could be a Halloween hangover, busy work week, or they might be soldering some projects away from their computers :)

I've gotta a CS-3 I've been wanting to mod too, so I am also very interested.

As far as the improvement, without messing with IC's (just swapping the resistors, caps, and diodes) how does it sound? Would it be hard to make a conversion board? I'd rather save money and time and do it myself... unless its a pain.

[Ormond]

Yea....I ordered the CS 3 Opto Plus Mod but it is beyond my ability to do. Just too many pieces and I have never used a soldering iron before. I am going to have to find someone to do it.
Do I have to replace everything? Or can i just do some to cut down on assembly cost. I have Resistors, capacitors, LED, and diodes, chips? I really do not know what the "improvement" is supposed to improve.

[Mumphrey]

As far as the improvement, without messing with IC's (just swapping the resistors, caps, and diodes) how does it sound? Would it be hard to make a conversion board? I'd rather save money and time and do it myself... unless its a pain.

To answer your question, it is a massive improvement in sound and performance.
The attack and sustain are significantly better, and the tone control works differently. I'm not exactly sure what it is doing, but it's not just a treble boost\cut as it was before. You still can't turn the sustain up past one without heavy 'squash'. If you're into that sound, the attack control will at least compensate and keep the guitars attack intact.

I like it a lot, not having done the IC chip change yet. I pulled my MXR Super Compressor off the board, and replaced it with the CS-3.

Very impressed. It's almost an entirely new compressor compared to the stock version.

As to the conversion board, I don't know. That's beyond my skill level. I would hazard to guess that if you're skilled at it, then why not? I just happen to have one from a Monte Allums mod that I did, hated, then uninstalled. I'm waiting to see a response to my questions before making a move though. I only have one of each chip and one board. As the chips are stacked, that means only one IC can get replaced.

I'm still wondering what those 1N34A diodes are doing though...

[11 Gauge]

Originally Posted by Mumphrey

Lastly, do the experienced members see any real value, tonally speaking, to do the the chip portion of this mod? I've done the rest, and the improvement is remarkable.

If it sounds to your liking now, I personally wouldn't bother with the chip replacement.

That said, most modders replace chips to reduce noise. For a dirt pedal, that is a NO-NO for me, but it does make sense for comps, EQ's, and other types of pedals that aren't supposed to be racket makers...

Basically all that's being done is that the stock op amp is being stacked, which means that you will have two amplifiers in parallel, which reduces noise. And if you mismatch them, it reduces even more noise, because it cancels out some portions of the frequency spectrum.

On the PCB, there should be a square with a dot in it that signifies "pin 1" of the stock SIP8. All that you have to do is trace where pin 1 will be on the DIP8 adapter, and that will tell you how to orient it in the SIP8 holes.

I have to be honest, though. The stock chips are NOT crappy, IMO. You could actually get another SIP8 dual op amp - just about any one (NJM makes SIP8 equivalents of the 4558, 4559, TL072, etc.) and solder it parallel to your existing one (you bend the pins on one chip 90 degrees and solder them to the existing chip). And since they are 40 cents a piece, you can order a pile and mix and match. It takes some precision to solder two together (and still have room to drop it back in the pcb), but it's not impossible.

The proof is in the 4558 specs - it's NOT a low noise chip, yet it is part of the mod that is supposed to lower noise.

[11 Gauge]

Originally Posted by Mumphrey

I'm still wondering what those 1N34A diodes are doing though...

They allow for significantly more signal limiting, which is what a comp does.

Almost all of the CS-3 mods do the same basic thing - reduce noise. It simply allows you to hear better what the effect is supposed to do.

[Mumphrey]

Thank you very much for taking the time to respond.

I'll pass on the chip replacement I suppose then. The pedal
isn't that noisy as it is now. The rest of the mod may or may not have affected the noise floor, but it did improve the performance.

So if the the ge diodes allow for more limiting, I'm guessing that 1N400X diodes would allow for less? Would I likely hear or feel any difference in the way the pedal behaves?

Thanks again.

[11 Gauge]

Originally Posted by Mumphrey

So if the the ge diodes allow for more limiting, I'm guessing that 1N400X diodes would allow for less? Would I likely hear or feel any difference in the way the pedal behaves?

You should hear a difference, but it may be slight. And in a loud or live setting, it may be negligible. If you find yourself constantly hunting for a sweet spot with the knobs, it might be worth it to sub them in. Otherwise, I wouldn't bother, personally.

[Mumphrey]

Well, the mod is really quite good. I actually like the CS-3 now. Before it shrill and sterile sound. Very thin too. The only beef is that the attack time is a bit too fast.

If I could marry the sound of the modded CS-3 to the attack time of a Dynacomp, it would be perfect.

Again, thanks for your help.