Schottky diodes, good idea for clipping?

[QSQCaito]

Well.. the subjetc says it all... i have seen lots of different types of clipping, in for example the mods page.. using transistor, si or ge diodes..
But i think i have seen only once the idea  of using Schottky diodes.. are they too fast:P any problem with them, expensive?
Do you know which type of sound do they give?

Thanks a lot!!

Sorry for too much opsting

bye bye

dac

[aron]

Apparently they sound close to Si. I've never tried them for my diode clipping.

[bioroids]

I bought some of them by mistake (the seller thought they were germanium  ), and didn't like the sound at all.

Of course the circuit was an overdrive tuned to use Ge diodes, so maybe with tweaking they can sound good.

Luck

Miguel

[MartyMart]

Tried then several times and they sounded horrible !
RG has explained "why" somewhere ... if I remember correctly 

MM

[Peter Snowberg]

They're "different". The closest I can come is the character of a Si diode with the headroom of a Ge, only to me they sound a little more Si than regular Si signal diodes if that makes any sense? 

The lower Vf has to be taken into account and circuit parameters adjusted to provide any fair comparison.

[QSQCaito]

Ok.. so i see they're not much welcomed.. But as a friend of mine said.. a record isn't bad or good, YOU like or you don't...

Maybe the same case for these diodes??

bye bye, thanks

dac

[Peter Snowberg]

Try combining with a series resistor and a small cap in parallel.

[QSQCaito]

cap in pararlel to resistor?


thanks a lot

bye bye
dac

[Harry]

Schottky's work fine. Go ahead and try them if you want.

[Peter Snowberg]

----/\/\/\/\---+--->|--->|---+----
               |             |
               +---|<---|<---+
               |             |
               +-----| |-----+

This is one configuration. Use your imagination for others.

[QSQCaito]

----/\/\/\/\---+--->|--->|---+-GND
               |                  |
               +---|<---|<------+
               |                  |
               +-----|  |-----+


This is one configuration. Use your imagination for others.

I added gnd, is it okl, right?

[jmusser]

Tim Escobedo uses them in several of his circuits, and the ones I have built have worked fine. I have no idea of their clipping voltages though.

[R.G.]

A Schottky diode is by definition half of a PN junction. The junction is made by placing a metal layer on doped semiconductor. It has half the junction potential and half the forward voltage.

[Quackzed]

thats why they work good in opamp octave circuits... like the octup blender. they clip at a lower voltage so you get nice half wave rectification right?

[markm]

If they in fact clip at a lower voltage, that would perhaps give them performance characteristics of a GE diode but not the tonal quality?

[MartyMart]

If they in fact clip at a lower voltage, that would perhaps give them performance characteristics of a GE diode but not the tonal quality?

That kind of "nails" my problem with them , early clip but horrible "gnarly" tone !
I should try using perhaps 3-4 each way and not 1 - 2 of them ?
Am I right to remember they are "hard knee" and not "soft knee" also ?

MM.

[Rob Strand]

1) > Am I right to remember they are "hard knee" and not "soft knee" also ?

Yes thay are have a "hard knee", harder than silicon and much harder than Ge.

and

2) > If they in fact clip at a lower voltage, that would perhaps give them performance characteristics of a GE diode but not the tonal quality?

From (1) and (2) demonstrates softness has nothing to do with the diode voltage - many people here think the higher the diode voltage the harder the knee.  Often it turns out this way but it's not a magical "law" as such.

Ge is quite soft, softer than Si.

The body diodes of MOSFETs are actually quite hard knee'd, similar to Schottkys.  Some people say these sound fairly soft but that shows *in a practical 9V circuit* that the diode voltage drop itself can also be a factor in the sound  (there's other factors too).

Schottkys can be substituted for Ge in rectifier circuits without changing the sound too much.  In some compressors the hard knee changes the  compression characteristic changes but most people won't pick it up.

[Mark Hammer]

Schottky diodes are what is used in the in/famous "Black Ice" modules; the passive, no-batteries-required, add-ons for guitar that have been sold for several decades now.  They are able to function as fully passive clipping devices because the Vf is so low that power chords from a HB-equipped instrument will often exceed the Vf, without any additional boosting as one would find in "normal" diode clippers.

The thing about a low Vf is that it sets the ceiling on signal very very low.  That may not require much boost to bring it to clipping, but it sure as heck requires some post-clip gain to bring the level up to something approaching rock and roll boost.

I may be unique in this opinion but Schottky diodes are perhaps more useful or productive in contexts where they are in series with the signal,hence eating up less signal durng the rectification process, than a different type of diode would.  So, for instance, they may be very useful in envelope follower circuits like the Dr Q/Nurse Quacky/Dr. Quack or the Oraneg Squeezer.  Tim Escobedo uses them productively in phase-splitter-based octave-up units.  My guess is they might also improve the performance of something like the Green Ringer or other discrete phase-splitter-based octave-up devices.

[bioroids]

Or use them as protection diodes on the power supply (I use a 1N5817 in series with V+)

Luck

Miguel