Has anyone done this? and Chaos build report

[jimbob]

I been trying to figure out why my "Chaos" wasnt working right. I perfed it as i do everything and chked everything twice and still no sound. But, i noticed tonight that i had looked at the layout from Paul Marossey wrong. What i did was put it togather as though looking at the bottome when its really looking down at it. Though it would still generally work this backward way it ic is backward as well--you would have to place it on the solder side of the board to be oriented correctly--and youd have to do this VERY carefully as the original leads on the board would have to be soldered to the legs of the 8 pin ic socket.. But, after trying to figure it out for so long--i did just that..I placed my ic on the solder side of the board--sure it looks silly as i should have just started all over--but i got it and it sounds great!

Anyway,

Mr Mark Hammer--Awsome pedal-- lots of distortion and gain! There are a lot of effects out there that claim to have a lot of distortion--this one really does! In fact, this is one of the best ones for this out there! And i know--having built most of the distortions from GGG, Tonepad, ROG, Joe Davisson, ect...Ive been on a "find the best distortion sound mission"

[petemoore]

Kool, never really had to think about it. Did one that way for a while though...repeated it the 'other'

way.
 Sounds like a tricky soldering job, I think I'd have tried to tack a socket there, I've overheated IC's before 'piggybacking' them and other ways too....they don't like much heat...
 Congrats, seems like you figured that one out good!!!
 I haven't found any use for non-working boards...glad to hear you got it going!!!

[Mark Hammer]

:oops:  :oops:  :oops:   Heh, heh.  I did that particular goofup once or twice myself.  If memory serves, I suggested on a thread in the "old" stompbox forum (pre-php) that people make a point of putting something in text on their PC layouts so that users could keep track of whether it was a PnP or "traditional" layout (letters will look backwards if its a PnP layout).  This was met with a round of nodding heads and people were thoughtful and considerate enough to do so, at which point it started to become standard practice.  I think the fact that some folks started churning out layout after layout and wished to identify which layouts were their work also resulted in text appearing on the posted layouts.  Given the emergence of many cheapo alternatives to PnP (e.g., glossy photpaper), more and more people are using that transfer method, such that layout designers assume you'll use PnP and so only make a point of telling you it ISN'T a PnP layout.

In any event, it is generally (though not always, as you found out!) easier these days to avoid accidental layout reversals, and I thank all for that courtesy.

My own problems arose when I made a Dr Quack from RG Keen's layout but did not use PnP (drew it on).  I tired for weeks to get that sucker working and I felt like a complete tool when I discovered that all my components were stuck in wrong.  Did the same damn thing with a Small Stone layout too.  Had to gently bend the pins of the IC's over and insert them into the sockets upside down to get them to work (and flip all trannies around too).  Go easy, though, if you need to use that fix; pins can break and while you don't mind losing a pin on a 4558, you don't want to lose a single CA3094!

Glad you like the Chaos.  Given all the fabulous things you seem to find at rock bottom prices on a regular basis, and the excellent DIY designs you list, I consider it high praise to have it be compared so favourably.  While I like the sound, the passive tone control eats up a fair amount of signal.  Feel free to up the value of the feedback resistor in the second stage a bit (e.g., 150-180k), and consider upping the value of the 390pf cap in the tone control circuit to 470pf or even 560pf for a bit more midrange bite.  Upping that cap will also tend to even out the volume differences between the two extremes of the tone control a bit better.

Enjoy, and keep your eyes on the copper!  :wink:

[Paul Marossy]

Glad to hear that you got it working.  
Of course, I like the tone of the pedal, but I also like the way the tone control works on that circuit, too. You can get a pretty wide range of tones out of that thing...

FWIW, I have designed a few PCB layouts and then mirrored the copper part in my drawing only to find out that I etched it mirrored...  :oops:  :evil:
In other words, I didn't need to mirror the copper part. I did find a way to make the circuits work in spite of that, though. Live and learn as they say.

[jimbob]

Paul- Ive done that a few times as well. But, it only seems to be a problem when theres an ic involved. When its transistors there doesnt seem to be a problem. I wish i could upload the pic of this thing--it looks sooo silly..But man, i really like the way it sounds..I didnt have a 1m so i used a 250kb and it goes from no gain to full gain. I run outta parts very quick as im always building... Im also using the tl072..think ill try the 4558rc and the jrc4558, ect..and see if theres a big difference.

[Paul Marossy]

Yes, let us know if you hear any differences between opamp types. I don't I fooled around with different opamps on that one...

[Mark Hammer]

My instinct says that chip type will make no audible difference unless one's ears have beens afeguarded from fuzz and other loud noises since birth.  The use of two clipping stages, and the amount of lowpass filtering in the feedback loop of each stage make it unlikely that bandwidth or transient-handling will reveal themselves.  Maybe the voltage swing of the particular chip might have some impact, but I doubt it.  The diodes in the second stage declare "Thou shalt not pass"  around 2200mv P-to-P or so, which is well below the voltage swing of even the worst dual op-amps operating on a battery that has dwindled down to 7.5v.

On the other hand, less hiss is always nicer, and and low current consumption is a good thing too, so chip changes are not entirely fruitless.