Buzzy Overtones with OD Pedals?

[pedalpusher]

Over the years I've noticed that about 60% or more of the OD pedals I've tried have this buzzy sound that I hear as the note is decaying. I've been through numerous guitars, amps, speakers, pickups etc. I don't hear the sound with tube pre-amp distortion. Just most of the op-amp based ODs I've tried. I'm talking about store bought pedals. It's got me thinking about getting a channel switching amp just to get away from it. I play mostly strats btw. What gives?

[earthtonesaudio]

Tube Screamer-type OD pedals?

[Mark Hammer]

Keep in mind that whenever one is using diodes to provide clipping, the tonal quality of the clipping will be a function of whether there are signal components that meet the forward voltage (clipping threshold) requirements, and how often.  The best quality tone will normally arise at the beginning of the note/chord, when one has picked hard and the signal remains supra-threshold in consistent fashion for a while.  As the signal dies away, though, you can expect the moments when the signal peaks swing above the clipping threshold to be more intermittent.  I guess the best way to think of it is as if there was a random ultrafast speed tremolo adding in those little extra harmonic components.

This is one of the reasons why the venerable Big Muff has been as popular over the years as it is.  It boosts and clips twice, which means that the clipping is extended over a longer portion of the note's/chord's life, but most particularly it safely sees you through that period when the input signal is riding juuuuuuuuust around the threshold.  Even though "all it is" is the same diode clipper found in many of the OD pedals that irritate you, the duplication of clipping sidesteps the buzz.

At least that's how I see it.

[Caferacernoc]

Yeah, op amps and diodes are very hard to tune so that they decay gracefully compared to tubes.      Or jfets. 

[CynicalMan]

This buzzy decay also probably comes from opamp distortion, which has an ugly decay, like you described. Distortion circuits often have the opamp clipping a lot. For example, in a distortion+, the gain of the opamp goes from 1 to about 214. So, at maximum gain and given a 1V PP input, the opamp would be trying to put out up to 107 volts with a 9V battery. This is obviously going to cause a lot of ugly clipping.

[Mark Hammer]

This buzzy decay also probably comes from opamp distortion, which has an ugly decay, like you described. Distortion circuits often have the opamp clipping a lot. For example, in a distortion+, the gain of the opamp goes from 1 to about 214. So, at maximum gain and given a 1V PP input, the opamp would be trying to put out up to 107 volts with a 9V battery. This is obviously going to cause a lot of ugly clipping.

Maybe so, but my own point is that there is a certain point in the signal's decay when the amplitude is going to hover above and below the point where it produces that distortion.  And whether it is the circuit inside the chip or the circuit around the chip, THAT's what's producing the buzzy sound.  It's the inconsistency of the signal in a circuit that demands consistency to produce a certain sound that is the central issue, and guitar signals are about as inconsistent as you can get....unfortunately.

[pedalpusher]

So can a different opamp change things or am I stuck with the problem. I hate to have to avoid opamp pedals all together.

[John Lyons]

As a reference point, which pedals have you tried?
I know what you are talking about but there are a few different
diode/transistor/op amp configurations and they all are a little
different sounding.

Marks point about clipping proximity is at the heart of this
thread. Where your signal starts clipping as well as how long the
signal stays in the clipping threshold and how much into that
area it goes is where all the fun is in tuning in what where
talking about here.

John

[pedalpusher]

The current problem is with a Radial Bones Texas OD. I retubed My amp and that took some of the buzzing away but it still buzzes. It also buzzes when I play into a Crate VC50. I've had this problem with a lot of the modded TS types. Can't remember all of them but The Texas Two Step was one. I had a Proanalog Dual Drive that did it really bad. I sent it to Scotty and He sent it back with the problem completely gone. I had a Boss GT10 that exaggerated the problem. Hope that helps make it easier to figure out.

[aziltz]

The current problem is with a Radial Bones Texas OD. I retubed My amp and that took some of the buzzing away but it still buzzes. It also buzzes when I play into a Crate VC50. I've had this problem with a lot of the modded TS types. Can't remember all of them but The Texas Two Step was one. I had a Proanalog Dual Drive that did it really bad. I sent it to Scotty and He sent it back with the problem completely gone. I had a Boss GT10 that exaggerated the problem. Hope that helps make it easier to figure out.

are we talking buzzy like hum or noise, or buzzy like the clipping just doesn't sound good?

[pedalpusher]

are we talking buzzy like hum or noise, or buzzy like the clipping just doesn't sound good?

It's a buzzy sound that seems to ride on top of the note. Not buzzy as in 60 cycle hum. Check out the demo video at proguitarshop.com. If You all say You don't hear the buzzy overtones then I'll go have my ears checked. LOL It's a lot less noticable in the vid but I can still hear it.

[petemoore]

  In my experience with active devices: "Components sound like themselves".
  Choose the components you like the sound of.
  Not really that simple though, tweeking the circuit [which includes a speaker and...everything else] liberally can make a component I thought was uselessly cold, sterile or lifeless [terms I've seen associated with opamps], either had their operational position changed [anything...higher supply voltage, different diodes or voicing caps, etc.] or something integral to their operation changed [such as TC dialing on the amp] to make them 'lively, warm and have character'.
  The only opamp [I now regularly use] associated with distortion is in a Distortion+, but it has a LP filter knob [cap>VR>Gnd.], a Mu Amp [second bit of re-distorting and really warms things up] and 2 knob tone control, generally used with something beefing up the input [booster or compressor].

[aziltz]

are we talking buzzy like hum or noise, or buzzy like the clipping just doesn't sound good?

It's a buzzy sound that seems to ride on top of the note. Not buzzy as in 60 cycle hum. Check out the demo video at proguitarshop.com. If You all say You don't hear the buzzy overtones then I'll go have my ears checked. LOL It's a lot less noticable in the vid but I can still hear it.

I've been messing around with single op-amp clippers where the op-amp clips to the rails without diodes.  trying out some discrete op-amp designs as well as different IC's like TL072, TLC2262/2272, etc.  I've been trying to turn a popular classic compressor into half compressor, half VERY low gain overdrive by using the unused IC side, and I'll get sweet tones, but when I hit the strings hard or even just solidly enough, I still get some of that buzzing sound you've described, and I can't seem to dial it out.  It also happens a bit with the discrete op-amp I built out of 2n5087/2n5089's. 

Then I found this OLD OLD posting from RG, from the first stompbox forum. http://www.diystompboxes.com/smfforum/index.php?topic=14915.0

In it he explains some ideas about soft clipping and how to best implement it.  The made idea is multiple stages set in their soft clipping region instead of one big stage.

I'm not really sure if this is the answer to the buzzing question, but its where I'm at for the moment.

[aziltz]

i just realized that the buzzing I'm hearing could be my strings hitting the frets.  I'm going to restring and check it between my breadboarded circuits and my boxed stuff and see if its still happening.

[pedalpusher]

i just realized that the buzzing I'm hearing could be my strings hitting the frets.  I'm going to restring and check it between my breadboarded circuits and my boxed stuff and see if its still happening.

I get that too LOL. However I have been able to eliminate that as the cause of the buzz I'm referring to here.

[aron]

I bet you play with lots of highs. If so, then you need to filter... a LOT. They will all be buzzy if you use a lot of highs on the amp. There are many ways to cut down on the buzz. Almost all involving capacitors to ground to shunt the highs.

[aziltz]

i fiddled a bit.  i don't think its my guitar buzzing.  it might be that i'm trying to get such low gain/soft clipping out of a single op-amp stage with no clipping diodes.  not sure.


i think it has alot to do with the knee of clipping, like RG discusses in that old post.  It seems like i get nice tones, but if i push it too far, it buzzes.  Problem is, I want more soft clipping than I can get to.

[pedalpusher]

I bet you play with lots of highs. If so, then you need to filter... a LOT. They will all be buzzy if you use a lot of highs on the amp. There are many ways to cut down on the buzz. Almost all involving capacitors to ground to shunt the highs.

Actually my hearing is starting to fade at higher frequencies. I seem to hear a lot of guitar gear as dark sounding. The Texas OD is a much brighter pedal than everything else I'm using at the moment. 

[aron]

The truth is that when you have a bright sounding amp when clean, there is way more chance that your pedals will sound buzzy. That's why you need to compensate with low pass filters. You would be amazed at how much highs you might need to cut to make a pedal sound smoother.

[Mark Hammer]

The truth is that when you have a bright sounding amp when clean, there is way more chance that your pedals will sound buzzy. That's why you need to compensate with low pass filters. You would be amazed at how much highs you might need to cut to make a pedal sound smoother.

Quite true.  And we're not talking silly little 1-pole filters either.  You need some serious multi-pole lowpass filtering to keep the fizz out.