Clipping Diodes
So when choosing clipping diodes, what values on the datasheet are the one sto be looking at? Forward / Reverse voltages?
I have literally NO idea what I am doing.
- NickS
- Solder Soldier
Depends what voltage you want to clip to.
Forward voltages for small-signal diodes are typically 0.3V for Germanium and 0.6-0.7V for silicon. LEDs vary but can be around 2.5V If you want to clip to these levels, use them in parallel.
If you want to clip to higher levels you can use parallel chains of series diodes.
Alternatively, use the reverse voltage (Zener voltage) of Zener diodes or the breakdown voltage of transistors' B-E junctions. In this case the diodes need to be in series to avoid clipping at the forward voltage.
Forward voltages for small-signal diodes are typically 0.3V for Germanium and 0.6-0.7V for silicon. LEDs vary but can be around 2.5V If you want to clip to these levels, use them in parallel.
If you want to clip to higher levels you can use parallel chains of series diodes.
Alternatively, use the reverse voltage (Zener voltage) of Zener diodes or the breakdown voltage of transistors' B-E junctions. In this case the diodes need to be in series to avoid clipping at the forward voltage.
- JiM
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You can also have a low threshold with Schottky diodes.
These can even clip a passive guitar signal, as in the "Black Ice overdrive"
http://www.stewmac.com/shop/Electronics ... drive.html
http://www.projectguitar.com/tut/blackice.htm
And you can play with asymetrical clipping by having different type or number of diodes in each back-to-back branch, hence clipping positive and negative alternances at a different voltage, and generating more even harmonics ...
These can even clip a passive guitar signal, as in the "Black Ice overdrive"
http://www.stewmac.com/shop/Electronics ... drive.html
http://www.projectguitar.com/tut/blackice.htm
And you can play with asymetrical clipping by having different type or number of diodes in each back-to-back branch, hence clipping positive and negative alternances at a different voltage, and generating more even harmonics ...
I only give negative feedback.
- Greg
- Old Solderhand
Keep in mind that there's more to clipping diode choice than forward voltages.
Different types can have a fairly major effect on tone as well.
Different types can have a fairly major effect on tone as well.
culturejam wrote: We are equal opportunity exposure artists.
I completely agree Greg. The important characteristic is the forward current/forward voltage graph. Unfortunately, the graphs in data sheets for most popular diodes have a scale that is too large to provide any real detail in the 0-5mA forward current region. but silicon diodes such as 1N914 tend to have a larger non-linear region than Germanium or Schottky diodes. Non-linear conduction curves should create smoother sounding clipping than linear curves. I've found that series combinations of silicon and Schottky diodes sound better than silicon alone, even though you would expect the curve of the silicon diode to dominate.Greg_G wrote:Keep in mind that there's more to clipping diode choice than forward voltages.
Different types can have a fairly major effect on tone as well.
Peter.
- Spazzmatazz
- Breadboard Brother
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soo... better silicon??
wich one??
what improvements you've done?
I'm thinking to make a passive box with a rotary swicht for testing diode combination and diferent guitars.
wich one??
what improvements you've done?
I'm thinking to make a passive box with a rotary swicht for testing diode combination and diferent guitars.
- Electron Tornado
- Breadboard Brother
Spazzmatazz wrote: I'm thinking to make a passive box with a rotary swicht for testing diode combination and diferent guitars.
I don't worry much about the specs on the data sheet as the real test is your ears. I have enough diodes around to be able to try different combinations as well. For experimenting with clipping diodes I use a couple of wires with alligator clips for quick changing. This also allows me to quickly test diodes in both hard and soft clipping settings.
- Spazzmatazz
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which diodes work? which doesn't?
schottky only?
schottky only?
Agreed - Ears are the best test instrument for guitar effects. Because I've been trained to use data sheets, I still like to try to correlate the specs with tone, but you don't always get what you expect.Electron Tornado wrote: I don't worry much about the specs on the data sheet as the real test is your ears.
I like the tones I've heard with a 100mA Schottky in series with a normal silicon diode that is similar to a 1N914, in the feedback path of a TS type circuit. These were SMT dual diode packages and I used only one diode from each package. The Schottky was a BAT754S and the other was a BAV99.Spazzmatazz wrote:which diodes work? which doesn't?
schottky only?
The bottom line is that you should try as many different combinations of power or signal diodes, LEDs etc. as you can think of. You can also use one junction of a transistor as a diode, or connect the base to the collector and use the emitter and collector leads as a diode.
Peter.
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I've always thought germaniums produced clipping with a rounder knee at the conduction point, leading to a softer clipping, albeit at a much lower output.clinchfx wrote:I completely agree Greg. The important characteristic is the forward current/forward voltage graph. Unfortunately, the graphs in data sheets for most popular diodes have a scale that is too large to provide any real detail in the 0-5mA forward current region. but silicon diodes such as 1N914 tend to have a larger non-linear region than Germanium or Schottky diodes. Non-linear conduction curves should create smoother sounding clipping than linear curves. I've found that series combinations of silicon and Schottky diodes sound better than silicon alone, even though you would expect the curve of the silicon diode to dominate.Greg_G wrote:Keep in mind that there's more to clipping diode choice than forward voltages.
Different types can have a fairly major effect on tone as well.
Peter.
Don't silicons like 1N914s pretty much chop off the tops of the waveform like a razor blade, leading to a harder clipping, with more high frequency content and higher output? Aren't they originally designed for fast switching applications?
I've always had to use caps to sort of "tame them down" a bit.
- Electron Tornado
- Breadboard Brother
clinchfx wrote:Agreed - Ears are the best test instrument for guitar effects. Because I've been trained to use data sheets, I still like to try to correlate the specs with tone, but you don't always get what you expect.Electron Tornado wrote: I don't worry much about the specs on the data sheet as the real test is your ears.
The bottom line is that you should try as many different combinations of power or signal diodes, LEDs etc. as you can think of. You can also use one junction of a transistor as a diode, or connect the base to the collector and use the emitter and collector leads as a diode.
Peter.
It would be interesting to see a table with specs for various diodes to do a comparison.
I agree about trying different combinations. To some extent, you don't always know what's going to sound best in a particular application. That's part of the fun of DIY, IMO. To my ears there are only a handful of combinations that sound appreciably different, however there are quite a few more where the differences are subtle. In the end, it really depends on what appeals to the builder's ears.
What would be great is if we could some up with a standardized set of descriptive terms for different sounds of distortion.