4049 distortion + opamp

[dachshund]

I've read that there's a circuit like, or based on, Anderton's 4049 "tube sound fuzz", that adds an opamp section. I've searched the forum and haven't hit on it (although I've found many posts discussing it.) 

Is this available in schematic form?

Thanks in advance.

[nelson]

Do you mean the VINTAGE EH hot tubes?


Do a search for that one. It runs off 9v like all others. I believe Jack Ormans site hosts the schematic.

[twabelljr]

Mark Hammer's "Forty-Niner" adds an op-amp:

http://hammer.ampage.org/

[dachshund]

Thanks for the link to the Forty-Niner circuit!
The switch for the frequency booster - is that a DPDT?

[Mark Hammer]

No.  It only needs to be an SPST.  That's the beauty of the Anderton Frequency booster.  If you don't feel like using the freq

[jmusser]

Mark, are you partial to the 1458 op amp, or is this just one you happen to have on hand when you put this together? I don't believe I've heard of a 1458 to tell you the truth. I've wanted to build this one to compare with the 3 Legged Dog, and the CMOS Drive, but didn't know about that chip.

[dachshund]

Mark, sorry - I meant the switch between the caps. It looks like it selects either the .1uF or .027uF caps. Is that one a DPDT?

[aron]

Well this one pretty much is awesome!

http://web.archive.org/web/20010615041932/members.home.net/fclarke/fx/Distortion-14.htm

[gez]

http://www.muzique.com/schem/tubesnd.gif

I think this is what started it all off...

[Mark Hammer]

To answer a bunch of questions and respond to Gez...

1) The 1458 is just a dual op-amp.  I suspect you can use any one you want: 4558, 5532, TL072, etc.  I'm not at all sure why I used that one, but since that was what was in the one I made and I was giving the schem to the person I made it for, I figured I'd label the chip correctly.  Nothing mysterious there.

2) The Frequency booster needs only an SPST switch.  The rest of my post was probably lopped off in the rush to catch a bus.  It should have said that if you didn't feel like using the frequency booster section, there should be a DC blocking cap between the output pin of the first op-amp and the Drive control (points A and B).  Anything between 2.2uf and 10uf is fine.

3) The switch that selects between caps for the frequency booster can be a lot of things, but it needs to be able to switch two contacts at once.  I have a fondness for 3-position toggles with a centre off position.  The way the switch should work is that in the middle position the 5k6 resistor goes to each side of the 10k resistor via a .027uf and .01uf cap in series.  That gives you an effective capacitance of about 7300pf.  Flick the switch in one direction and it should shunt/bypass the .027uf caps, giving a value of .01uf, flick it the other way and it shunts the .01uf caps giving a capacitance .027uf.  That yields one boost in the lower midrange/upper bass and two others in the upper midrange.  They were my choices but they don't have to be yours.  See the schem for the frequency booster over at AMZ and you can figure out "ideal" cap values from that.

4) Yeah the TSF that appeared in the Jim Messina cover (I think) issue of GP in 1977 was, to my mind a far superior sound to the one that eventually showed up in EPFM and became modded to be the Red Llama.  But that's my taste and not everyone's.  After making the EPFM one, I decid3ed that I liked having a medium-high gain stage before the invertors and using more modest feedback resistances for the invertors.  There were still a bunch of things I didn't like about the GP '77 one so I tinkered.  That turned into this thing: http://www.geofex.com/FX_images/mhtsf.gif which sounded better than the Anderton unit to my ears but was unnecessarily complicated (and an incomplete drawing, too).  The 49-er (minus the booster stage) is what has become one of my go-to pedals.  The feedback caps in the op-amp and the invertors are a big part of what does it for me.  They help to spool out the high end just a bit at a time, so that you don't end up with harmonics of harmonics of harmonics, and are a big part of what needed improving from the original Anderton '77 design.  The SWTC control, labelled Filter, also helps to tame the fizzies and warm the pedal up nicely....again, to MY ears.

5) Frank Clarke's assorted Hot Harmonics designs, the 3-Legged Dog, and Stellan Lehrberg's Slowfinger ( http://www.fortunecity.com/tinpan/humperdinck/223/slowfing.gif ) pick up from where Anderton left off.  I was happy with mine so I never built Frank's designs but on paper they look good and are substantially simpler than the mhtsf or 49-er, while retaining the essential ingredients, which is a nice high-impedance input, some decent gain up front *before* the invertors, and a pair of invertors with fizz-taming caps.

6) I will still put in a word for the EM Fuzz posted over at GGG.  I still haven't built it and I don't recall anyone here building it yet either, which is a damn shame.  It uses a single invertor whose functioning is moderated by a current regulator.  Clever, different, and worth exploring.  http://www.generalguitargadgets.com/index.php?option=content&task=view&id=174&Itemid=200

[lovric]

thanks for pointing to lost fclarke's site. i'll try to find 'midwest analog'.

[brett]

Hi.
There's a few "fiddles" with the 4049.
First, the gain of the inverters goes UP as the supply voltage goes DOWN.  Yes, there's no mistake there. Voltage down for gain up.
According to the HEF4049UB datasheet, gain =50 at 5V and 25 at 9V.

Like many people, I use a series resistor in the supply line to reduce power consumption and lift the gain a bit.  A 220 ohm resistor works well.

My experience with the 4049 suggests that a small feedback cap around each inverter takes the harsh "edge" off.  Anything from 10 (hard)to 100pF (soft) works for me.  Also a 220k or 470k feedback resistor makes each stage more "tube-like" than the 1M feedback resistors seen in some schematics.  But, as always, tone is subjective and many master builders have used big feedback resistors.

Soft vintage jazzy tone can be got from a 10x op-amp, a 220 ohm supply resistor, 2 x 220k inverter stages with 220pF caps.

[Mark Hammer]

We're on the same wavelength.  I'm partial to 100k and 220pf-330pf myself, but it's the same general idea: small resistors and "softening" caps.

[Steben]

Hi.
There's a few "fiddles" with the 4049.
First, the gain of the inverters goes UP as the supply voltage goes DOWN.  Yes, there's no mistake there. Voltage down for gain up.
According to the HEF4049UB datasheet, gain =50 at 5V and 25 at 9V.

Looking at the chip's graphs, one can figure out that a variable supply voltage can cause harder/softer clipping.... no?
One disadvantage would be the constant needed volume compensation (twiggling the level knob)

[Mark Hammer]

That's why the EM article intrigues me.  It uses regulated variation in the supply current to the 4049 to accomplish distortion flavour.

[twabelljr]

I built a "Hot Harmonics" that is amazing. I used 200 ohms in the power supply. How would something like a 1k pot wired as a variable resistor in the power supply of a 4049 circuit act? Have it on the front panel as a sort of gain adjustment. Anyone ever try it? I think I will this weekend. I,ve also read about using zener diodes to create the voltage drop, but with noise issues?

[WGTP]

http://aronnelson.com/gallery/WGTP/KubotaCMOS

This is an interesting variation that Mr. Kubota did that I redrew.  I think it my be in Schematics II.  I did it from memory, so I hope I got it correct.  It lacks an op amp, but one could easily be added.

[jmusser]

Thanks Mark (and everyone else) for the information. I figured that op amp wasn't cast in stone, but, if I hadn't asked, there would have been some sort of mojo that only it could have provided.  The couple circuits I have built (especially the 3 Legged Dog) are amazing. When you kick them in through a SS amp, it's just like you're playing through a whole other amp. I couldn't believe the difference it made! When you build other effects, you're expecting a whole different sound, but it's basically a distorted version of the amp your using. With these emmulators,the tone is as different as night and day, and if you turned your back, you'd believe that it was a whole other (and more expensive) amp.

[Mark Hammer]

Exactly!

For fun, try sticking a bypass cap in the drive pot so that there is more treble drive when its turned down a bit (come to think of it, that might be a cool BMP mod to try).  It may be my guitar/amp, but my first reaction to it was "Holy Cow, where'd that Rickenbacker come from!?".

[markm]

My experience with the 4049 suggests that a small feedback cap around each inverter takes the harsh "edge" off.  Anything from 10 (hard)to 100pF (soft) works for me.  Also a 220k or 470k feedback resistor makes each stage more "tube-like" than the 1M feedback resistors seen in some schematics.  But, as always, tone is subjective and many master builders have used big feedback resistors.

Soft vintage jazzy tone can be got from a 10x op-amp, a 220 ohm supply resistor, 2 x 220k inverter stages with 220pF caps.

So, if i change the 1M in this schem http://gaussmarkov.net/images/redllama-schem.png
It will provide less gain in the output of the circuit?
Maybe, make the drive less "aggressive" perhaps?