Where does distortion come from?

[Rogue]

Ok, I'm learning about tube amps when I get some time to do so. Probably a question I should understand the answer to. I get that tubes clipping the signal gives a nice musical overdrive/distortion. The more it's clipped, the more distorted (although maybe not as musical ). Correct, right?

Now, most amps I've played have an inherent distortion to it. Even with the gain real low, it never really gets "clean". The closest I had to getting clean by turning down the gain was my 1959x (turned down the volume in this case), but it still had an inherent distorted sound.

So where is this distortion generated? Particularly in amps that gets its distortion from the preamp (for instance, my DSL). Do the tubes always clip, regardless of your gain settings? Is it a function of bias that keeps clipping asymmetrically and at a point that something will always be clipped? Or is it just the signal being generated by all the tonal elements that produces a distorted signal that the tubes then merely amplify? Or something else? Or all the above?

Any thoughts are appreciated.

 

[MajorNut1967]

Distortion comes from Heaven!

 

[TwinACStacks]

Distortion comes from Heaven!

Unless you are into Death and Black Metal then it comes from the OTHER place.

TWIN

 

[MajorNut1967]

Unless you are into Death and Black Metal then it comes from the OTHER place.

TWIN

We're some cheeky bastards huh Bro!

 

[shredless]

good distortion comes from ball sweat of slash, clapton, rhoads, etc

bad distortion comes from hall & oates

 

[Rogue]

Yeah, I'd say some distortion comes from heaven. Others? Not so much.

 

[Ronnie_Speedbag]

I can't speak for everyone on here....but my distortion comes from a little riff wizard that lives in my amp

 

[TwinACStacks]

We're some cheeky bastards huh Bro!

Yes, but it's an endearing quality....

TWIN

 

[MajorNut1967]

okay somebody better answer this straight.

Distortion occurs when an amplifier is overdriven and attempts to deliver an output voltage or current beyond its maximum capability. Driving an amplifier into clipping may cause it to output power in excess of its designed ratings.

 

[diesect20022000]

mine's from my marshall

 

[Rogue]

Distortion occurs when an amplifier is overdriven and attempts to deliver an output voltage or current beyond its maximum capability. Driving an amplifier into clipping may cause it to output power in excess of its designed ratings.[/COLOR]

Thanks majornut.

But what about a preamp with the gain turned way down...say like a JCM800. I had a 2203x and I thought when I bought it that if I turned the gain way down, I could get a good clean tone. Made sense, right? Or so I thought it made sense. In any case, I could turn the gain all the way down to where the amp wasn't making a whole lot of sound and it still had a distorted tone. This has been the case with any of the rock type or modern type amps I've had.

I mean, is the gain way down like that still making the preamp tubes clip?

I thought it was just an inherent preamp design. Now that I'm kind of learning what makes an amp tick, I'm fairly curious where that distortion comes from.

 

[diesect20022000]

you get a touch of overdrive in all tube circuits. it's what fattens your sound. if you want truly clean acurate rep run your guitar stright into a hi power classd stereo.....sounds horrid and that's clean. I still don't know how to nswer the other part though with regard to your minute distortion regardless of settings....cold bias could be a factor.

 

[chuckharmonjr]

Distortion is all in the hands!

 

[demonufo]

Thanks majornut.

But what about a preamp with the gain turned way down...say like a JCM800. I had a 2203x and I thought when I bought it that if I turned the gain way down, I could get a good clean tone. Made sense, right? Or so I thought it made sense. In any case, I could turn the gain all the way down to where the amp wasn't making a whole lot of sound and it still had a distorted tone. This has been the case with any of the rock type or modern type amps I've had.

I mean, is the gain way down like that still making the preamp tubes clip?

I thought it was just an inherent preamp design. Now that I'm kind of learning what makes an amp tick, I'm fairly curious where that distortion comes from.

The bright cap makes it a bit thin, and allows higher frequencies pass at lower volumes, which will clip. It's not full bandwidth distortion like with higher volumes though.
The best way to making a 2203/2204 clean up is to plug into the LO input. You won't even have to turn the gain pot down. It will dirty up when you get loud on the master volume though (in fact, some players use 2203/2204's exclusively like this)

The main difference between the lo and the hi input on these amps is one more gain stage. The hi input uses three stages of gain all fed into each other before going on through the rest of the circuit, whilst the lo input only uses two.


However, that said, none of the early marshall circuits clean up that well, there's always a bit of hair to them. Blame Leo Fender.

 

[TwinACStacks]

I've been called distorted and twisted.

TWIN

 

[chuckharmonjr]

Im Dazed and Confused

 

[Moose Coghill]

Distortion is in the eye of the beholder... especially after a few favorite beverages.

 

[MajorNut1967]

Thanks majornut.

But what about a preamp with the gain turned way down...say like a JCM800. I had a 2203x and I thought when I bought it that if I turned the gain way down, I could get a good clean tone. Made sense, right? Or so I thought it made sense. In any case, I could turn the gain all the way down to where the amp wasn't making a whole lot of sound and it still had a distorted tone. This has been the case with any of the rock type or modern type amps I've had.

I mean, is the gain way down like that still making the preamp tubes clip?

I thought it was just an inherent preamp design. Now that I'm kind of learning what makes an amp tick, I'm fairly curious where that distortion comes from.

well you have to remember that the JCM 800 has generous amounts of gain and even turned down it's going to clip a little. And with the treble peaking circuits it makes it sound like it's even clipping more. The only way you can do it without modding the amp is to turn the master volume all the way up and barely cracked the preamp gain open. I will warn you this can be quite bright on the stock amplifier, but turn down the treble and the presence and try it. now my version of the JCM 800 is modded so you can play clean and still have the full tone of your guitar come through without the brain shearing treble.

 

[RickyLee]

You also have to take into account the very beginning/upstream part of the equation: Your guitar and it's pickups.

You should notice that when using a hot humbucker that you will get a bit more distortion on your 2203 even with the amps gain quite low. If you now switch your guitar over to a single coil, lower gain pickup or lower the guitar volume pot, you should have a "cleaner" sound.



From your amp's High input, you are hitting the first gain stage before the Gain pot - this first gain stage is getting all the signal you send from your guitar. From the Low input you are going directly to the second gain stage after the Gain pot.

Amplitude of Audio Signal . . .

 

[T-Bird]

Hi.

Jon will most likely explain it way better in a short while, but here's a brief explanation.



By definition distortion is the signal shape difference between the input and output of an amplifier stage, ie. the accuracy of the amplification.

Every amplifier stage generates distortion for various reasons, intentional or not.

Overdriving an amplifier stage may cause clipping, which is obviously distortion by definition, but the circuit topology determines whether that sounds good or not.

The majority of A/B PP magic comes from the OT though. It distorts the signal and always effectively reduces the even order harmonic distortion.

There's plenty of books written about distortion, and preventing it .

Regards
Sam