Almost all my 4049 based stompboxes sounds horrible...

[gigimarga]

Thx Frank for your words!

I like very much the sound of 4049 distorsions and i am very angry because they don't work ok.
I'd built a Red Llama some time ago and i like very much how it sounds.
Can you post some clips of Hot Harmonics here (on your site the links are broken)?

[earthtonesaudio]

For figuring out the output Z, stick a variable resistor to ground on the output of an inverter, and turn it down until you hear a noticeable drop in volume.  Then measure the resistance of the pot, and that should get you in the ballpark.

I did some breadboarding and used a 10k variable resistor (like a voltage "sag" knob) from +9V to the V+ pin, and there are good ranges of tones in there, in my opinion.  That's one way to get the voltage down at the chip, but a better way would be to first figure out what voltage sounds good to your ears, then use either a simple JFET current source or a voltage regulator IC to make that voltage from the 9V supply.  Both will give better noise performance when using a wall wart adapter, and they're relatively low-current devices, so you wouldn't be sacrificing too much battery life if you choose to go that route.

Also, in my experience the buffered versions are not that bad.  You just need to keep in mind they have higher output currents and more gain, and alter the distortion stages accordingly.

[gigimarga]

I replaced all the HCFs with CDs and it's a HUGE difference, mainly on hiss and squealing (both are almost gone...)...the only problem still remains the farty/muffled sound, but i will make more tries with the caps.

Thx a lot all!

[dschwartz]

hey! great it´s better now..

now..the farts issue..
if it is a hot harmonics, change the fet coupling cap to 3.3nF or around that, put a socket and try different values..

i did that in mine and took out most of the farts..like a "peptobismol"..great smooth distortion is done by cutting a lot of bass in the early stages, and cutting a lot of highs at the end..

[gigimarga]

Thx dschwartz
I will try to adjust the caps...i hope i will make it to sound as i want...

[Brian Marshall]

One of the problems i see with using inverters is that the output impedance is relatively high near centervoltage, and very low.  This means that any filtering following each stage could be adversely affected by really strong signals. 

Try buffering the output and then filter.  Example (of non-clipping buffer due to different voltage for the FET) here:

http://www.diystompboxes.com/smfforum/index.php?topic=64846.0

Personally, I don't bother filtering after each inverter.  I add a multi-pole filter after the buffered output.

the problem is buffering requires more parts.  It sort of loses the advantage of these circuits by only having one IC... unless of course you reduce the signal by quite a bit, and run it in to another inverter stage.  the best luck i've had in this regard is to make the last stage sort of like an integrator, and make sure that stage doesnt have anymore than a 2 volt swing.  Still these circuits always sound a bit gated, or splattery to me.

[gez]

Still these circuits always sound a bit gated, or splattery to me.

I think a lot depends on what PUs your guitar has.  Do you mainly play humbuckers?

Re the extra parts, a single resistor and a JFET is no big deal, but even without a final buffer you can get a great sounding circuit.  Personally, I've never experienced any gating, but then all my guitars are low-output.

[zencafe]

thx a lot zencafe!
your advice sounds right to me.
Today i will receive some CD4049UBE and after i will replace the HCF's that i used i will insert a high pass filter.

You're welcome, and sorry, I meant lowpass...

About buffering: I've designed about 3 medium and high gain distortions/preamps with 4049.
I've tried buffering between de gain stages and a tone control and lowpass... And there was just a slight difference... to my surprise, I think it sounded better without the Source Follower, from the 4049 to the tone control (The one I used on that experiment was de BPM) and from the tone ctrl the 2 lowpass filter cutting from 10Khz.
With the source follower I noted a slight tone sucking and volume drop (wired isn't it!?).
What I'll try soon is to add buffers between the gain stages, so that I can reduce the output impedance seen from the next stage, and therefor have more control about the gain of every stage, this could allow me to "model" more types of sound by knowing exactly how much gain there is in everystage. Right now, the limit of a CMOS stage is limited by the output impedance of the stage before, even though it should be measurable, I think is easier (and cheaper) just to buffer the outputs in order to ease the calculation and therefor the design, just as in discrete and OpAmps circuits. A Source follower is my favorite candidate, due to simplicity and parts required.

Has someone experimented already with addng buffers between stages?

Regards from Chile!

[zencafe]

hey! great it´s better now..

now..the farts issue..
if it is a hot harmonics, change the fet coupling cap to 3.3nF or around that, put a socket and try different values..

i did that in mine and took out most of the farts..like a "peptobismol"..great smooth distortion is done by cutting a lot of bass in the early stages, and cutting a lot of highs at the end..

Exactly Daniel!

Thats what I did with my Microtube distortion (schems to come!)

Saludos

[Xavier]

I always thought the red llama is one of the most amp-sounding overdrives I've ever built. It's just that I can't stand the fuzzy edge it has, but I still think 4049 circuits can indeed sound very good............

[dschwartz]

hey! great it´s better now..

now..the farts issue..
if it is a hot harmonics, change the fet coupling cap to 3.3nF or around that, put a socket and try different values..

i did that in mine and took out most of the farts..like a "peptobismol"..great smooth distortion is done by cutting a lot of bass in the early stages, and cutting a lot of highs at the end..

Exactly Daniel!

Thats what I did with my Microtube distortion (schems to come!)

Saludos

Douglas?
jajaja
By the way.. your microtubes kick ass to every other cmos distortion mentioned here..by far..

[Mark Hammer]

I always thought the red llama is one of the most amp-sounding overdrives I've ever built. It's just that I can't stand the fuzzy edge it has, but I still think 4049 circuits can indeed sound very good............

Stick a SWTC just before the Volume pot to tame that.  Works wonders.

[zencafe]

hey! great it´s better now..

now..the farts issue..
if it is a hot harmonics, change the fet coupling cap to 3.3nF or around that, put a socket and try different values..

i did that in mine and took out most of the farts..like a "peptobismol"..great smooth distortion is done by cutting a lot of bass in the early stages, and cutting a lot of highs at the end..

Exactly Daniel!

Thats what I did with my Microtube distortion (schems to come!)

Saludos

Douglas?
jajaja
By the way.. your microtubes kick ass to every other cmos distortion mentioned here..by far..

Thanks Daniel!

Heres's the Schem of my Distortion:


For simplicity's sake, I'll post this one here... I'm now working on a extended version based on this same circuit, but this one incluse active 3 Band EQ, and some other improvments.
One very curious thing about this circuit is the range of dynamics it has; With a dual coil DiMazrio, tI got a very heavy and thigh high gain distortion. Very 5150 or Engl like.
But with a Strat, the sound was very creamy and soft overdrive. I'd dare to say that it didn't have more gain than a Tube Screamer. That intrigued me, and I spent a lto of time thinking how I could solve this "issue"... but many people (dschwartz among of them) convinced me that this would be a desirable thing, since the distortion is so transparent, that it adjusts to your guitar.
I encourage you to try it... Any improvments, mods and constructive critics are more than welcome!

Saludos.

[Xavier]

I always thought the red llama is one of the most amp-sounding overdrives I've ever built. It's just that I can't stand the fuzzy edge it has, but I still think 4049 circuits can indeed sound very good............

Stick a SWTC just before the Volume pot to tame that.  Works wonders.

Thanks for the suggestion Mark. Nevertheless, I think I'm not explaining correctly. The Llama has a nice freq response and to me it doesn't sound harsh or brittle at all. When I say "fuzzy edge" I mean there's inherent "fuzz" to the sound no matter the eq. I guess the only way to adress this is by tweaking the filtering in between gain stages. I once tried but lost my patience.............I guess I need to clean the dust off my breadboard.............

[gez]

Right now, the limit of a CMOS stage is limited by the output impedance of the stage before, even though it should be measurable, I think is easier (and cheaper) just to buffer the outputs in order to ease the calculation and therefor the design, just as in discrete and OpAmps circuits.

Coincidentally, I've been doing some measurements with the scope recently.  I've only tested one chip so don't take this as gospel, but output impedance seems to be a lot lower than many were originally anticipating (inclucing myself!)  As you'd expect, when closed-loop gain is low then output impedance is lower, but not by that much.  Running a single inverter at full pelt from a 9V supply I measured zout at around 500 Ohms with a 1kHz sine.  This is in contrast with a zout of 220 Ohms with a closed-loop gain of 2.  Using a 5V supply the figures were 620 Ohms max and around 470 Ohms with the gain of 2.  Surprisingly, amplitude of the output signal made no difference - you'd think zout would lower with increased amplitude, but if this is happening it's only a tiny reduction.

I dare say there'll be variance from chip-to-chip (and between manufacturers?), but probably not that much.

[dschwartz]

Thanks Daniel!

Heres's the Schem of my Distortion:


For simplicity's sake, I'll post this one here... I'm now working on a extended version based on this same circuit, but this one incluse active 3 Band EQ, and some other improvments.
One very curious thing about this circuit is the range of dynamics it has; With a dual coil DiMazrio, tI got a very heavy and thigh high gain distortion. Very 5150 or Engl like.
But with a Strat, the sound was very creamy and soft overdrive. I'd dare to say that it didn't have more gain than a Tube Screamer. That intrigued me, and I spent a lto of time thinking how I could solve this "issue"... but many people (dschwartz among of them) convinced me that this would be a desirable thing, since the distortion is so transparent, that it adjusts to your guitar.
I encourage you to try it... Any improvments, mods and constructive critics are more than welcome!

Saludos.

i can´t see the schem..
BTW, the gain was higher than a TS with a strat..is just that you were expecting death metal destroyer sound from a strat...

[zencafe]

Thanks Daniel!

Heres's the Schem of my Distortion:


For simplicity's sake, I'll post this one here... I'm now working on a extended version based on this same circuit, but this one incluse active 3 Band EQ, and some other improvments.
One very curious thing about this circuit is the range of dynamics it has; With a dual coil DiMazrio, tI got a very heavy and thigh high gain distortion. Very 5150 or Engl like.
But with a Strat, the sound was very creamy and soft overdrive. I'd dare to say that it didn't have more gain than a Tube Screamer. That intrigued me, and I spent a lto of time thinking how I could solve this "issue"... but many people (dschwartz among of them) convinced me that this would be a desirable thing, since the distortion is so transparent, that it adjusts to your guitar.
I encourage you to try it... Any improvments, mods and constructive critics are more than welcome!

Saludos.

i can´t see the schem..
BTW, the gain was higher than a TS with a strat..is just that you were expecting death metal destroyer sound from a strat...

hahahaha yeah, that's very very likely!


Sorry for the schem, I thought it was better to just open a new thread with more details: http://www.diystompboxes.com/smfforum/index.php?topic=69335.msg555496#msg555496

[gigimarga]

Where i can find some sounclips of Microtubes?

[zencafe]

I haven't recorded anything yet sorry... actually I haven't even built it, the Beta PCB is designed and everything... but haven't had time to build it properly...  Is just on breadboard right now...
As soon as I record something I'll let you know.

[gigimarga]

Thx!