Distortion circuits without clipping diodes

[radio]

Over the years,when it comes to distortion circuits I happen to like them most without clipping diodes.

Whereas it s a Rat ,Tubescreamer even Big Muff I leave them without.

So I asked myself how come?Do I want less compression more volume what else?

Would be interesting to know for future projects!

Regards Jean-Marie

[John Lyons]

Compression isn't always because of the diodes.
Diodes obviously limit the volume but that's just how them work. Most of the time you can adjust the output volume after them.
You can always adjust the clipping diodes as well. Mosfets, LEDs, Germanium, zener, added resistance in line with diodes, adding s\diodes in series, feedback clipping vs diodes to ground clipping etc etc. all have an effect on what you get.

Key words:
Warp control (AMZ)
Proximity to clip
Clipping threshold
Check out the DIY FAQ above as well.


There have been some great threads recently about adjusting the clipping threshold and how clipping diodes in the feebback loop and diodes to ground actually work.

So many possibilities!

John

[foxfire]

in my short time building pedals i've found diode clipping to be often times just too buzzy or thin. though i do rather like the Red Fuzz and the BMP. i mostly chalk it up to my lack of knowledge due to my newness.

[radio]

Thank you for pointing me to the right direction!

Regards Jean-Marie

[frank_p]

Jean-Marie,

Study the effects where the load line is near saturation and cutoff of the transistors used in the effects.  There is a lot of old "vintage fuzz circuit" where the bias is adjusted to do so (correct me, and give me some advice too).  Check out the difference between the Rangemaster and the Apollo for simple circuit analysis (there is only one transistor in these circuits).  Then go for cascading  transistors stages.  After, go to the Fuzz Face variations to get a glimpse at " dual progressive" clipping-compression. Look at the operating point of these effects on the load line of each transistors.  Try to visualise the operating point on the I-V characteristic curves of these transistors and what are the effects on "compression" of the signal depending on the operating Q point (and the curves).  Try the standard bias and then move on your own.   It's the simplest way to enter the subject (correct me if I am wrong).  BJTs are a base component that must be studied and it will give you a good point to go further (there are many "flavours" of fuzzes on these effects).

Choose some circuits on "fuzzcentral" site and try to experiment with them.  Classic fuzzes circuits must be "observed" in visual and repetitive manners to get you to some questionments and so the basics bias configurations get sticked in your mind.   Don't worry about "yet an other fuzzface circuit" or (X effect).  Play with that and get good books of electronic basics using active components.  Then ask folks on this forum of what you don't understand so you can dig deeper.  Go for the simple maths equation and do some measurements "labs" so you can ask more questions. It will guide you to more complex questions (and addictions)  Undersand the basic equations of these simple circuits.  Don't get fooled by "sodid state is not good at doing any good tone".  Transistor fuzzes is the basics and eternal quest of many folks in the "dist. boxes" domain, and it  will open you many doors for "new" ideas that you might have questions about.  Then study the effects of "tone shaping in the frequency view" so you can "amplify" or "cut" some of the "aspects" that you don't like.  What is already invented is not a limitation but a seed for what you will get to in your understanding and creativity.  If there is something that you find by youself and you see it elsewhere, tell you that you are on the right way rather than "everything had been done before" frame of mind.  Dig what the "old folks" had done before, this IS NEVER lost time.  It's the basics of electronics on the ground (or underground if you like it most like this) of audio in the world of distorted TONE.

Reste accroché avec nous !
Frank P.       

[brett]

Hi
diode are used to avoid harsh, non-harmonic rail-slapping distortion.
Seems that you like that sound.  It would be boring if we were all the same.
Just my 2c.

[WGTP]

That is what I was thinking.  Seems you like pretty nasty distortions.  In general I think we consider things like Dist +, Rat, DS-1, etc. to create distortion with diodes, but in cases with the diodes to ground rather than in the feeback loop (i.e. Tube Screamer, SD-1, etc.) the op amp is usually contributing lots of distortion when the thing is maxed.  (I think op amps in these designs may contribute more to the tone than in feedback loop designs which limit the op amp output). 

Try using LED's for your clippers.  Since they clip at 1.8v rather than .7v like silicon diodes, there would be more op amp distortion in proportion to the clipping distortion.  On the other hand GE's are around .3v and sort of have that nasty fuzzy tone to them IMHO.   

[radio]

OK ,I was allways thinking of diodes as the "squarer of sinus". So they are used to tailor unpleasant waves.

I might also take contact with a doctor to verify my ears.

Because I was not aware this sound was more unruly.

Regards Jean-Marie

[John Lyons]

Diodes smooth out the large spikes. If the signal going though the diodes is large the diode will clip all the time and clip hard.
If the signal is smaller the diodes will clip less and not clamp down the level as much.
If you add diodes in series the clamping threshold will be higher and the diodes will not clamp down the signal as much. (Louder)
It's all a balance of how much and where in the signal path.

john

[WGTP]

Apparantly some op amps produce some really nasty harmonics when distorting.  The same is true of using silicon transistors like the BMP.  But if you like it, go for it.   You might check out the Black Cat.  It is an op amp distortion without clipping diodes. 

[WGTP]

http://www.diystompboxes.com/smfforum/index.php?topic=66266.0

Yeah, your a wild man.  Check out the above, it is supposed to be a good one with no clippers.