How does overdrive work?

[megadan]

So I just picked up an old bass amp off ebay for a good (I think) deal, it's a Guild Thunderbass, I got it for $140 plus shipping.

From what I understand, this is a fairly low wattage amp, which will be fine by me, because I plan to use it as the top end of a biamp rig.

 

Anyway, my real question is about overdrive. What does real tube overdrive soundlike? Does it sound good? Is it like a distortion/OD pedal, or is it more like clipping, but nicer sounding?

When we're talking about something that isn't meant to be overdriven, how exacly does one achieve a good sound? Just crank everything to 10? Is there a proper balance between pre and power amp tube overdriving? And anything else you can share about tubes and their hopefully lovely sound.

 

 

Ox, I'm looking at you, tell me about your overdriving adventures

[the_big_geez]

It's difficult to explain, while being ridiculously simle all at once.

 

In an amp (tube or solid state notwithstanding), the first thing that happens is the 'preamp' which boostst the guitar's signal enough for its tone to be modified (which throws PART of that gain away) and drives it to a higher voltage that the power amp section can make exponentially lopuder still.

 

All an overdrive does (again, irrespective to being tube or SS, or stomp-box or anything else)) is to add another stage of gain (or more!) BEFORE anything else happens.

 

What the results are is purely subjective.

 

Personally, I find that most amps overdrive too easily as it is, and all that is needed to get some grit to the tone is a simple knob-twiddle. Others prefer the ease of toggling on/off with a footswitch, stompbox-wise. Some amps have those features built in. For me, I'm always trying to get RID of it, for it is easier to put it in than it is to take it away.

 

BUT! One man's ceiling is another man's floor. You just have to find what YOU like...

[oldivor]

Tube distortion = sex

 

 

Grindy smooth hot melting distortion

 

The sound of the gods.

[illidian]

Overdrive is the clipping of the signal. I think it's in the FAQ's.

 

Anyway, the charts looked something like this:

 

Normal signal:

`````/

````/``

```/````

__/``````___

 

 

Overdriven signal:

`````_

````/``

```/````

__/``````____

 

Distortion'ed signal:

 

````__

```/```

__/`````__

 

Fuzz'ed signal:

 

 

```__

__/```___

 

 

Essentially it clips down the peaks.

 

Does this help at all?

[Benjamin]

I thought fuzz was more of a waveshape distortion rather than really clipping the peaks real nastily?

 

I don't know much other than knowing the audible difference between the two.

[illidian]

Originally posted by Benjamin I thought fuzz was more of a waveshape distortion rather than really clipping the peaks real nastily? I don't know much other than knowing the audible difference between the two.

 

You may be right, that was pulling from my rather horrid memory.

 

But yes, the audible difference between the two is definately apparent.

[T. Alan Smith]

Higher gear ratio?

[Rowka]

Originally posted by T. Alan Smith Higher gear ratio?

 

Yeah, my thoughts too.

Grearing such that one revolution of the engine produces more than one revolution of the axle.

[Benjamin]

 

Originally posted by Rowka Yeah, my thoughts too. Grearing such that one revolution of the engine produces more than one revolution of the axle.

 

 

As the ratio of overdrive increases, torque decreases proportionally. Sounds like the same principle applies to bottom end!

[der oxenrig]

Pure power tube overdrive

 

Note, when you overdrive an amp, especially when using a bass, to prevent farting, make sure you go easy on the low end. I dial it almost completely out on mine, because the overdrive on it's own has tons of low end already.

[der oxenrig]

bump

[Benjamin]

No, don't bump!

 

It will only serve to proliferate The Oxen's tube overdriven goodness and give us all a form of biamped GAS.

 

I just bumped, didn't I?