Mark Hammers Chaos Clips

[tungngruv]

Here are two clips of Mark Hammers Chaos pedal. Both are recorded w/no effects so you can hear the pedal only. I lowered the volume a bit so they recorded better than the Jack Orman OD Pro I did a day ago.(sorry Jack!!, I'll re record yours). Both clips are original material and the first has the basic guitar tone, then the pedal kicks in and the tone knob is swept to both extremes. Second is a solo example. Once again, I recorded directly into the computer, gain is all from the pedal ( and I cannot stress enough how much better this one and the OD Pro sound through an amp rather than a sound card!!!!!). My fingers aren't really warmed up either, it's about 20 degrees here in Peoria. :lol:  Anyway, I love the pedal and hope this helps anyone who's interested in it. 5mm red leds instead of 1n914's


http://home.grics.net/~tungngruv/mywebs/MHammerChaos1.mp3

http://home.grics.net/~tungngruv/mywebs/MHammerChaos2.mp3

[panasonic_youth]

thanks

[Marcos - Munky]

Sounds cool!!! Thanks a lot.

[MartyB]

Sounds like Randy Rhodes / Crazy Train.

Very unique.

[radio]

The second sample qualifies the Chaos for unofficial

Vai/Halen pedal. I ll build it and I ll use it!

Thanks for this decision helpers!

JME

[tungngruv]

Thanks guys. And thanks again to the"mad scientists" Mark Hammer and Jack Orman.  

[jrc4558]

Ok, you convinced me. Chaos is next...

[Paul Marossy]

Yep, I built the Chaos almost immediately after Mark introduced it. Love the way the tone control works, too.  

[RDV]

I just built one but mine doesn't sound like the clips, it's very bass heavy. Very bass heavy. I used green bright LEDs.

RDV

[Paul Marossy]

Hmm... that's interesting. Mine seems to be pretty well rounded, not too much bass, mids or treble (depending on how the tone control is set, of course). I used 1N4148s in mine.

[RDV]

Update: I had a severely malfunctioning gain pot, which seemed to have a capacitive effect as well. I replaced it and now it sounds much more like the clips above. I would strongly suggest a volume recovery stage at the end if you're gonna use it onstage however.

RDV

[Mark Hammer]

Thanks, fella.  I'm looking forward to hearing them tomorrow when I go back to work (not inclined to wait for large file downloads over a modem line).

Ricky Don makes a good point about a gain recovery stage.  On the other hand, there is still considerable room for adding gain to the second stage, and if one is using LEDs as the clipping element, that permits enough signal to hit the tone control that it may still leave enough signal to do damage.  If you already have one built, it may simply be less nuisance to put a 220k or 270k feedback resistor in place of the 100k one shown in the schematic.  If you're starting from scratch and don't mind a perfboard build, a simple op-amp or transistor gain recovery stage (e.g., just clone the one-transistor stage after the tone control on a big muff) may provide suitable boost.

Here's a mod I started thinking about while waiting on the highway this afternoon (lots of black ice between Toronto and Ottawa, and lots of folks whose assumptions about how much speed their vehicle could *safely* handle took them straight into the centre median barrier or another vehicle; bad, bad day   ).....

On several occasions I have fielded complaints from people about how little bottom there was in their Distortion+ with the gain cranked.  The rteason is that when the gain of a non-inverting op-amp is set by changing the resistance from the non-inverting pin to ground, that resistance, and whatever capacitance is in series with it, form a high-pass filter of sorts.  The rolloff point is given by the usual formula: F = 1/(2*pi*R*C).  As R gets smaller, F gets higher (i.e., less bottom).  In this way low end is yoked or tied to gain.  

In the case of the Chaos pedal, at maximum gain in the first stage, the rolloff starts around 160hz.  In the Distortion+, it is unfortunately much higher, about 720hz.  In a sense, that provides an interesting combination of both gain and tone control, but not everybody wants their bottom end to disappear when they crank it.  Typically, what I suggest to folks with the complaint I mentioned to simply increase the level of the cap to ground from .047uf to about .33uf or higher.  For example, with a .33uf cap, the bass rolls off around 103hz at max gain.

What you will see in some pedals, such as the Proco Rat, are dual paths to ground from the non inverting pin, through separate resistors and caps.  What this does is set different gain levels for different ranges, but in an interesting way.  If you have a low resistance path through a small capacitor value, you'll have high gain, but only for stuff above that rolloff, which may well be only upper mids and above, and everything below that point will be at successively lower and lower gain/amplitudes.  Of course if you have a parallel path to ground, through a higher value resistor and higher value cap, then content below the rolloff set by the smaller value cap still has a relatively low impedance path to ground, and gain can  be made flat till the lowest frequencies through that path.  It won't enjoy the additional gain provided to high-end content, but it will still be there, and be audible.  In essence what it does is allow a frequency response that mimics a treble-shelving control on steroids turned up full.

It occurred to me while watching the cars edge ahead slowly, that one could put this to work for you in an interesting way, and could do so with this pedal or virtually any design using a non-inverting gain/clipping stage, including the Chaos, Tube Screamer, Distortion+, etc etc.

Imagine the following.  You have a standard non-inverting op-amp, with diodes either in the feedback loop or after the op-amp output.  Let's say, just for discussion's sake, we have a 1meg feedback resistor, and a 470k pot configured as variable resistance to ground, in series with a 10k fixed resistor and, oh say, a .47uf cap.  At max pot resistance, the gain is equal to (1meg+470k+10k)/(470k+10k) or just over 3.  With the components listed, the low-end rolloff will be just under 1hz.  When the pot is reduced to minimum resistance, the gain shoots up to 148, and the rolloff changes to about 34hz.  Still not bad.

Let's change that pot, though, and make it a 100k linear pot.  The 10k fixed resistor goes to the inverting pin, and the other end of the fixed resistor goes to the wiper of the pot.  One of the pot's outside lugs goes to ground through a .01uf cap and the other outside lug goes to to ground through a .22uf cap.

When the pot is centred, there are two equivalent paths to ground.  One will "prefer" high end because of the .01uf cap, but since the resistance is the same on each side, there are negligible difference in how much gain is produced across the spectrum.  With a 100k pot divided in half, that gets us 60k (10k plus half of 100k) to ground (in theory, in practice the pot will likely be a bit less).  With a 1meg feedback resistor, that yields a gain of  17.7.

What happens as the pot goes off-centre, though?  If you rotate it towards the smaller cap value, there is now a lower impedance path to ground for high-end content, and a higher-impedance path to ground for anything below the low-end rolloff created by the small cap.  For example, if we rotate the pot so that the pot's resistance is divided up as 25k and 75k, 25k (plus the fixed 10k resistor) and a .01uf cap gets you a gain of 29.6 for content over 454hz.  With a 75k+10k combined resistance path to ground, whatever finds its way through the larger-value cap will have a gain of 12.8.  A boost, to be sure, but not as much as the higher stuff.

Rotate that gain pot a little more, so that you divide the pot's resistance up as 10k and 90k, and you end up with a gain of 51 for content over 795hz, and a gain of 11 for content below that.

Rotate the pot in the OTHER direction, and you start to get more consistent gain across the entire spectrum, including the bass.  See how this starts to get interesting?  It lets you get the full bottom end at higher gains if you want it, OR get a more selective mids-and-up boost at highest gains if you want that.

There are, of course, numerous parameters to play with here, such as:
1) the fixed resistor (in tandem with the feedback resistor, it will determine maximum gain)
2) the value of the pot (it will determine the minimum gain achievable and the tonal contrast between pot extremes)
3) the value and spacing of the caps (C and the fixed resistor will set where the maximum boost starts in the audio spectrum for one side, and how low the boost can be applied on the other side)

One of the neat things about the Chaos approach to double clipping is that  it lets you change the kind of harmonic content the second stage sees.  If you combine that with a variable gain control on the second stage, there is no end to the kinds of tonal textures and types of harmonic content achievable.

I'm intrigued by this and hope you will be too.  LOVE those one-knob-changes-everything controls!!

[Fret Wire]

Good food for thought Mark.

[tungngruv]

Hey Mark, when I was first building your Chaos pedal and asking you daily questions, you wrote:

Well, it's hard to say no to someone with such dogged persistence at making something work, and hard to turn your back on such enthusiasm. Rock on my friend, rock on

I recorded those clips with that in mind :lol:
I've been playing your Chaos and Jack's OD Pro quite a bit lately and I have to admit, in my limited building experience, both pedals are worthy of being mass produced. They sound as good (or better) than about anything I've ever purchased from a music dealer. Also, in my opinion, the gain recovery is not needed using LED's. I play original hard rock music fairly loud and this pedal, on about 12:00 acheives a slight boost with not much hiss considering the ridiculous :lol: amount of gain. Jack posted one of my clips on his site for the AMZ Overdrive Pro. If you like what you hear tomorrow, by all means you have my permission to use either or both on any link you'd like also.(it's about all an idiot like myself can contribute here!). I tried to make the clips short and sweet but I was having way too much fun. Thanks again for the design Mark.

[RDV]

Doesn't hurt to have someone who can play their ass off making clips for you.

Sigh

RDV

[tungngruv]

Thanks Ricky!! I'm 43 years old and have owned a guitar for 25 of them, I hope I can do something!! Seriously, I listened to your clips and I'm ready to sign up for lessons  You and I seem to like the Old School stuff!!! I've read your post's and I hope everything is working out for you and your spouse. Prayers are with you.

[RDV]

I have to agree with Tongue, this circuit doesn't need a volume recovery circuit. I tried one and it screwed up the good tone I was getting. With LEDs as diodes, you don't need a recovery circuit IMO.

Ricky "Flip-Flop" Vance

[WGTP]

Mark, I have to agree that the one Magic Knob deal is appealing.

So, need to figure out how to use a dual ganged pot.  One for this new idea and the other for the RosieRay circuit.  

[RDV]

It's funny y'know. I tried unhooking the vol rec circuit on the HMP to see if it was screwing up the signal like it did on Mark's pedal, but it was no different at all, other than not being as loud. I gotta have it too, as that rat style tone control will otherwise eat the signal down to a knub.

In mad scientist al a mode

RDV

[irakliszs]

hello everybody!

i was trying to find some clips of mark hammers chaos but no luck till now...
these links on top of page are not working anymore.
is it possible someone upload them again?

thanks a lot!