So how can you model OD pedals?
- Thread starter Top Jimmy
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misterwhizzy
Well-known member
Re: So how can you model OD pedals?
Overdrive is achieved by clipping the sine waves going into the amp. As long as you can achieve this clipping, you can get an overdrive sound. There's more to it, of course, such as how you achieve the clipping and what exactly clipping is, but as I understand it, that's the basis of all overdrives.
Overdrive is achieved by clipping the sine waves going into the amp. As long as you can achieve this clipping, you can get an overdrive sound. There's more to it, of course, such as how you achieve the clipping and what exactly clipping is, but as I understand it, that's the basis of all overdrives.
ratherdashing
Kablamminator
Re: So how can you model OD pedals?
You model it the same way you do everything else: software.
No matter what people think they're hearing, an OD does not interact with the amp. It does what every other pedal does: takes an input signal, processes that signal, and outputs a processed signal. The OD doesn't even really "know" the amp is there.
Whether you're doing that with transistors and diodes or with software, it's the same idea. In -> Process -> Out.
Guitarists tend to romanticize OD/disto/fuzz pedals, but all they're really doing is amplifying and clipping a signal. There's no magic to it. A computer can (in theory) do exactly the same thing.
I've tried the OD and distortion models on my m13. They're not bad at all. I still prefer my analog pedals for that, but if I were in a bind I could probably replace my entire pedal board with the m13.
You model it the same way you do everything else: software.
No matter what people think they're hearing, an OD does not interact with the amp. It does what every other pedal does: takes an input signal, processes that signal, and outputs a processed signal. The OD doesn't even really "know" the amp is there.
Whether you're doing that with transistors and diodes or with software, it's the same idea. In -> Process -> Out.
Guitarists tend to romanticize OD/disto/fuzz pedals, but all they're really doing is amplifying and clipping a signal. There's no magic to it. A computer can (in theory) do exactly the same thing.
I've tried the OD and distortion models on my m13. They're not bad at all. I still prefer my analog pedals for that, but if I were in a bind I could probably replace my entire pedal board with the m13.
misterwhizzy
Well-known member
Re: So how can you model OD pedals?
RD, you've developed pedals, so you'll probably know the answer to this. How close is the peak-to-peak output voltage of an OD pedal to the peak-to-peak voltage of the guitar? In other words, if there is a higher voltage from the OD pedal, then the first input tubes WILL be driven harder, right?
RD, you've developed pedals, so you'll probably know the answer to this. How close is the peak-to-peak output voltage of an OD pedal to the peak-to-peak voltage of the guitar? In other words, if there is a higher voltage from the OD pedal, then the first input tubes WILL be driven harder, right?
GuitarStv
Sock Market Trader
Re: So how can you model OD pedals?
OD/Fuzz/Distortion are all basically the same thing. You have a sound wave and you are modifying the tips of the peaks and valleys, generally you're cutting them off (hence the term clipping).
Traditionally this was done by boosting signals past the ability of the amplifier to reproduce them, as shown in the diagram above. Where it gets complex is that you can hear a lot of different things going on in that dist/fuzz.
Modeling amount of distortion:
- After clipping a signal the sound is then boosted to close to previous levels. The more clipping/boost that's given, the more distorted the sound becomes. A fuzz is generally accepted to be a very drastically altered sine wave, an OD is a slightly altered one, and Distortion usually sits in the middle.
Modeling characteristics of distortion:
- Asymmetric clipping is achieved by clipping the peaks more or less than the valleys. There's a noticeably different sound when you do this. For example, the Boss SD-1 uses asymmetrical clipping, while a TS uses symmetrical clipping.
- Soft clipping can be achieved by slightly compressing the tips of the peaks and valleys before lopping off the top. (You get a similar effect to tube amplifier clipping by doing this).
- Frequency dependent clipping can be achieved by boosting or cutting certain frequencies before clipping. This way you can have effects like a relatively clean sounding bass and distorted highs (like using a treble booster before a distorted amp).
- EQ after distortion just boosts the frequencies that you like. It can be used to remove unwanted harmonics and drastically change the overall sound of the clipping.
- Mixing the original signal back with the distorted one can keep you from sounding too muddy and give remove some of the compressed feeling that distortion can give. (The TS does this for example).
OD/Fuzz/Distortion are all basically the same thing. You have a sound wave and you are modifying the tips of the peaks and valleys, generally you're cutting them off (hence the term clipping).
Traditionally this was done by boosting signals past the ability of the amplifier to reproduce them, as shown in the diagram above. Where it gets complex is that you can hear a lot of different things going on in that dist/fuzz.
Modeling amount of distortion:
- After clipping a signal the sound is then boosted to close to previous levels. The more clipping/boost that's given, the more distorted the sound becomes. A fuzz is generally accepted to be a very drastically altered sine wave, an OD is a slightly altered one, and Distortion usually sits in the middle.
Modeling characteristics of distortion:
- Asymmetric clipping is achieved by clipping the peaks more or less than the valleys. There's a noticeably different sound when you do this. For example, the Boss SD-1 uses asymmetrical clipping, while a TS uses symmetrical clipping.
- Soft clipping can be achieved by slightly compressing the tips of the peaks and valleys before lopping off the top. (You get a similar effect to tube amplifier clipping by doing this).
- Frequency dependent clipping can be achieved by boosting or cutting certain frequencies before clipping. This way you can have effects like a relatively clean sounding bass and distorted highs (like using a treble booster before a distorted amp).
- EQ after distortion just boosts the frequencies that you like. It can be used to remove unwanted harmonics and drastically change the overall sound of the clipping.
- Mixing the original signal back with the distorted one can keep you from sounding too muddy and give remove some of the compressed feeling that distortion can give. (The TS does this for example).
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ratherdashing
Kablamminator
Re: So how can you model OD pedals?
I don't know what the typical peak-to-peak voltage of a passive guitar is, so I can't really comment on that part. I'm sure it's very low.
The theoretical maximum of an overdrive with a 9V power source will be 9V. In practice, that never happens. You'd need a very efficient op amp or transistor with no volume or tone controls to get close to that. The answer varies a great deal from pedal to pedal.
You also have to consider the output impedance of the guitar vs. the output impedance of the pedal, and the input impedance of the amp. Most amps have a 1Meg Ohm input impedance. Output impedance of pedals varies a lot, but they are all significantly less than 1Meg (usually around 10k). The lower the output impedance, the greater the pedal's ability to drive the amp harder.
This is a pretty complicated subject, and I'm probably not the best person to explain it.
I don't know what the typical peak-to-peak voltage of a passive guitar is, so I can't really comment on that part. I'm sure it's very low.
The theoretical maximum of an overdrive with a 9V power source will be 9V. In practice, that never happens. You'd need a very efficient op amp or transistor with no volume or tone controls to get close to that. The answer varies a great deal from pedal to pedal.
You also have to consider the output impedance of the guitar vs. the output impedance of the pedal, and the input impedance of the amp. Most amps have a 1Meg Ohm input impedance. Output impedance of pedals varies a lot, but they are all significantly less than 1Meg (usually around 10k). The lower the output impedance, the greater the pedal's ability to drive the amp harder.
This is a pretty complicated subject, and I'm probably not the best person to explain it.
ratherdashing
Kablamminator
Re: So how can you model OD pedals?
Excellent post.
OD/Fuzz/Distortion are all basically the same thing. You have a sound wave and you are modifying the tips of the peaks and valleys, generally you're cutting them off (hence the term clipping).
Traditionally this was done by boosting signals past the ability of the amplifier to reproduce them, as shown in the diagram above. Where it gets complex is that you can hear a lot of different things going on in that dist/fuzz.
Modeling amount of distortion:
- After clipping a signal the sound is then boosted to close to previous levels. The more clipping/boost that's given, the more distorted the sound becomes. Setting the point where the clipping
Modeling characteristics of distortion:
- Asymmetric clipping is achieved by clipping the peaks more or less than the valleys. There's a noticeably different sound when you do this.
- Soft clipping can be achieved by slightly compressing the tips of the peaks and valleys before lopping off the top. (You get a similar effect to tube amplifier clipping by doing this).
- Frequency dependent clipping can be achieved by boosting or cutting certain frequencies before clipping. This way you can have effects like a relatively clean sounding bass and distorted highs (like using a treble booster before a distorted amp).
- EQ after distortion just boosts the frequencies that you like. It can be used to remove unwanted harmonics and drastically change the overall sound of the clipping.
Excellent post.
Top Jimmy
New member
Re: So how can you model OD pedals?
I just thought an OD "overdrives" the amp. I guess I consider a distortion pedal and OD different beast, but I could be wrong. I know they modify the signal but I though an OD pushed the amp in some way. Do the modelers push the amp in the same way?
I just thought an OD "overdrives" the amp. I guess I consider a distortion pedal and OD different beast, but I could be wrong. I know they modify the signal but I though an OD pushed the amp in some way. Do the modelers push the amp in the same way?
ratherdashing
Kablamminator
Re: So how can you model OD pedals?
OD and Distortion are really just two names for what boils down to the same thing: a circuit that amplifies and clips the signal. Every OD/disto has the same fundamental features: an amplifier, a clipping circuit, and most of the time a tone stack.
Usually a pedal will be called "distortion" if it has harder clipping, and OD if it has softer clipping. It's just a name, really.
Fuzz and boost pedals are doing more or less the same thing too, but most fuzz circuits are very, very simple (the Fuzz Face is just two transistors slamming each other's inputs). Boosts have an amplifier, but no clipping.
"Pushing the amp" is a pretty meaningless term. I think most people are talking about the gain/volume boost an overdrive has when they say this. Like I said, the pedal is not aware of the amp and vise versa. It is itself just a tiny amp.
OD and Distortion are really just two names for what boils down to the same thing: a circuit that amplifies and clips the signal. Every OD/disto has the same fundamental features: an amplifier, a clipping circuit, and most of the time a tone stack.
Usually a pedal will be called "distortion" if it has harder clipping, and OD if it has softer clipping. It's just a name, really.
Fuzz and boost pedals are doing more or less the same thing too, but most fuzz circuits are very, very simple (the Fuzz Face is just two transistors slamming each other's inputs). Boosts have an amplifier, but no clipping.
"Pushing the amp" is a pretty meaningless term. I think most people are talking about the gain/volume boost an overdrive has when they say this. Like I said, the pedal is not aware of the amp and vise versa. It is itself just a tiny amp.
Top Jimmy
New member
DrNewcenstein
He Did the Monster Mash
Re: So how can you model OD pedals?
Typically you'd want an Overdrive if you want to push the amp's built-in distortion a little more (like a Fender RocPro1000 which doesn't have very high gain). You'd want a Distortion pedal if the amp being used doesn't have built-in distortion (power amp, older amps built when distortion was not wanted, etc).
Note that doesn't include good-old-fashioned "turn everything all the way up so it overdrives the speakers" (overdrive meaning literally to over-drive - drive more/harder than the speaker or poweramp is designed to handle).
Even then, as has been stated, the pedals work on the signal coming from the guitar more than the signal going to the amp.
Typically you'd want an Overdrive if you want to push the amp's built-in distortion a little more (like a Fender RocPro1000 which doesn't have very high gain). You'd want a Distortion pedal if the amp being used doesn't have built-in distortion (power amp, older amps built when distortion was not wanted, etc).
Note that doesn't include good-old-fashioned "turn everything all the way up so it overdrives the speakers" (overdrive meaning literally to over-drive - drive more/harder than the speaker or poweramp is designed to handle).
Even then, as has been stated, the pedals work on the signal coming from the guitar more than the signal going to the amp.
thespricket
New member
Re: So how can you model OD pedals?
Great explanation RD! It's just like any other "Effect". It simulates the sound an amp is supposed to make when it's getting driven. Fuzz and distortion pedals are doing the same thing. Think of all dirt boxes the same. They're just meant to sound different. With the right tweaking and EQ, you can make a fuzz or distortion pedal sound like an OD. Look at the MXR distortion III. It's technically a Distortion pedal, but really too me, it sounds like a really fat and heavy overdrive. Like comparing a Chorus pedal to a Delay pedal. They do the same thing, just differently.
Great explanation RD! It's just like any other "Effect". It simulates the sound an amp is supposed to make when it's getting driven. Fuzz and distortion pedals are doing the same thing. Think of all dirt boxes the same. They're just meant to sound different. With the right tweaking and EQ, you can make a fuzz or distortion pedal sound like an OD. Look at the MXR distortion III. It's technically a Distortion pedal, but really too me, it sounds like a really fat and heavy overdrive. Like comparing a Chorus pedal to a Delay pedal. They do the same thing, just differently.
DrNewcenstein
He Did the Monster Mash
Re: So how can you model OD pedals?
Actually a Chorus creates a detuned copy and introduces an oscillation to the copy, whereas a Delay merely copies.
A Chorus and Flanger would be closer to each other, or a Chorus and Detuner.
Actually a Chorus creates a detuned copy and introduces an oscillation to the copy, whereas a Delay merely copies.
A Chorus and Flanger would be closer to each other, or a Chorus and Detuner.
thespricket
New member
Re: So how can you model OD pedals?
that's what I meant when I said they do the same thing, it does what a delay does but differently. That's just how I think of it. :friday:
that's what I meant when I said they do the same thing, it does what a delay does but differently. That's just how I think of it. :friday:
Sporky McGuffin
New member
Re: So how can you model OD pedals?
Depends how you set the volume knob on the overdrive.
Most will let you go below unity gain - ie the output level is quieter than the bypassed level. Almost all will let you go way over - ie the output level is louder than the guitar level.
In a 9v pedal you can typically output up to 10 times the input level (or thereabouts). An 18v pedal (assuming good design) can go to around 20 times - but there are a lot of factors.
Depends how you set the volume knob on the overdrive.
Most will let you go below unity gain - ie the output level is quieter than the bypassed level. Almost all will let you go way over - ie the output level is louder than the guitar level.
In a 9v pedal you can typically output up to 10 times the input level (or thereabouts). An 18v pedal (assuming good design) can go to around 20 times - but there are a lot of factors.
