Why is clipping such a concern w/ bass amps & not guitar amps?

[jdfarrell81]

While pondering that age-old forum question--"Will I fry my guitar head by playing bass through it?"--I began to wonder why almost all modern bass amps have a clipping indicator whereas I've never seen a comparable indicator on a guitar head.

Would one of you fine folks mind explaining the disparity to me?

Thanks and cheers!

[Soundmasterg]

Basses tend to have more output than guitars, and bass players like clean and punchy sounds often, so those would be two reasons.

greg

[MusicFox]

Also not to be overlooked is the "Bells and whistles" factor as technology creeps in.... just try and buy a plain vanilla "cell phone only" these days. Soundmasterg is quite right though about the main reasons...... after 37 years as a bassist I find the clipping indicator only slightly less useful than my ear for detecting clipping as I'm usually at the microphone singing and not staring at me amp. Usually if I think I hear clipping and look, I'll see the clip light wink and I'll drop pre volume and turn up master more. Lowering pickups help to reduce clipping if running bass guitar's volume wide open and playing aggressively. Something about Bass frequency's make it hard for circuits to keep from clipping. Aggressively played clacking strings AND clipping, Mmmmmmm theres a sound we can all live without.

Now I have a question or 2. Clipping indicator on a tube amp anyone seen one? Tube clipping by nature would be nicer sounding like tube distortion is.... right or wrong? That's also what the whole Hi Lo inputs were all about weren't they? Coping with varied instrument outputs and things like clipping? I think if you check a Bass input in a double duty amp like a Bassman there might be some sort of "Padding" on the bass channel input.

[jdfarrell81]

MusicFox, you really got to the heart of my question.

I have a 300T, which is all-tube, and it has a clipping indicator. This confused me because, like you, I assumed overdriving the amp would result in tube distortion, which I like for certain situations. I'm concerned that the clipping indicator is warning of distortion more than true clipping, but I'm relatively new to tube amps, so I'm not sure how far I can push it before I damage something. Hence, I'm a bit leery to test this theory.

Also, I often play guitar through the 300T, and I think the clipping indicator is psyching me out. Even if it's not the case with bass, wouldn't "clipping" essentially amount to harmless tube-driven distortion when running a guitar through the 300T?

[EdBass]

I think tubes generally clip "nice" and transistors clip "nasty". Also, while a bass may or may not have more output than a guitar, they certainly are lower frequency, and low frequencies take more power to reproduce accurately, putting more strain on the amp.

And... as Greg points out; most bass players like clean tones. Don't tell Tom Petersson or John Entwistle (RIP)!

Also, I often play guitar through the 300T, and I think the clipping indicator is psyching me out. Even if it's not the case with bass, wouldn't "clipping" essentially amount to harmless tube-driven distortion when running a guitar through the 300T?

I'd have to agree with that, I think your best bet is to use your ears rather than a light.

[scotzoid]

I'm concerned that the clipping indicator is warning of distortion more than true clipping, but I'm relatively new to tube amps, so I'm not sure how far I can push it before I damage something. Hence, I'm a bit leery to test this theory.

Clipping is to distortion kinda like phase-shifting is to flanging; different words to describe the same thing. "Clipping" refers to the way the tops & bottoms of the waveform are "clipped" off on an oscilloscope display, producing a more or less square wave pattern; tube amps show more rounded corners, SS amps produce a really square pattern, which to the ear creates a harsher sound. And when clipping occurs, it simply means that the amp's dB limit has been reached, & it won't do no more! Pushing it harder will only produce more clipping, & it won't damage the amp, other than working the tubes harder & possibly shortening their lifespan some, but nothing's likely to blow up because the amp will only put out what it'll put out. Now, there's another issue I've heard that presenting the speaker(s) with square waves will eventually lead to a recone job, but we'll live to fight that battle another day. Long & short, a little clipping won't blow up your amp; relax & enjoy the blinking lights

[EdBass]

Clipping occurs when an amplifier is driven beyond it's design specification, when a device just physically can't produce the peaks of the sine wave and they get "clipped off", and as scotzoid posted, forming a trapezoidish waveform on a 'scope.
When a tube clips, it can be a desirable "effect", but generally nothing good comes from a clipping transistor.
Well, nothing good sonically, a hard clipping power amp can put out enough thermal energy to grill a cheese sandwich. 

[jdfarrell81]

Thanks for sharing the knowledge, folks. It's much appreciated.

[Soundmasterg]

When you hard clip an amp, whether tube or solid state, the signal from both pretty much looks the same at some point on the scope. However, a tube amp has a soft clip range where it starts to clip the signal as you drive it more, yet it sounds musical and vibrant because mostly even harmonics in the preamp, and mostly odd harmonics (but sonically pleasing ones) are generated in the pwoer amp if the amp is push-pull that reinforce the fundamental note, and they also have a compression effect which makes it sound louder to our ears. They are generally more touch responsive as a result. If you want to clip with a tube amp you just hit the strings harder. Tube stuff gradually clips as it is driven harder. Solid state stuff has a threshold that has to be met, then it is very clean until it clips, and when it clips, it clips hard and has bad sounding harmonics being generated.

Drive the tube amp all you want....you won't damage anything. I'm not sure what the clip meter is all about though.....

greg