Bass Amp clipping or Pickups clipping amp?

[Colin Thomas Nichols]

Hey guys. This is my first post! And I've been trolling the forums for about a month now.

Figured I'd post this here. Here's my issue -

My bass (any active bass I've tried) is clipping my amplifier and it sounds like poop. It's only on the lower notes, though.

After pulling my hair out and trying several things, I finally found a temporary fix. I say temporary because I'm trying to record a little "demo" album and my girlfriend bought me a Douglas NBC2 bass as a present. I have new strings on it and I'm trying to finish the recording before they loose their attack. My fix is to lower the volume pot on the bass to almost nothing - and the clipping stops.

Here's my question. This amp as clipped with every active bass that I put through it - is it an amp issue or an electronics issue? Judging by the "fix," it seems the pickups are overdriving the amp. I find it hard to believe that everyone's active bass over drives their amp unless the volume is nearly off.

Here's the specs in case anyone wants to know -

Two humbucker bass. Basswood, rosewood fingerboard. Active electronics.

Going into a Digitech BP355 for further EQ.

Going into an Acoustic B15 amp.

Going from the headphone out into a Behringer Xynex 802 mixer.

Using Cobalt Slinky Strings, 50-105.

Type of music is very Tool or Nine Inch Nails.

I've tried bass into amp, bass into mixer, bass into mixer with amp in the effects loop of the mixer, blah blah blah. The only thing that remedies the clipping is turning the bass's volume control down to almost nothing.

The other basses I tried were an Ibanez sound gear I believe and a Cort 4 string humbucker.

 

[espace]

It seems like the output of that bass is too much for your amp. Looking at that Acoustic amp, there is only one input. Most amps, that aren't low wattage practice amps, have one input for passive and one for active (or at least button for a 15 dB cut of input signal). Try setting gain or overdrive to low or off? Make sure the output volume on the effects pedal is not too high, if you're going through that before the amp.

 

[lundborg]

Check the 9v battery.

 

[Colin Thomas Nichols]

The battery is newly replaced.

So if I'm understanding correctly, it's probably because the amp is a low wattage practice amp? If it had a -db pad it wouldn't do this?

 

[T-Bird]

Hi.

Welcome to TalkBass Colin Thomas Nichols.

And I've been trolling the forums for about a month now.

The word You're looking for is most likely lurking, not trolling .

My bass (any active bass I've tried) is clipping my amplifier and it sounds like poop. It's only on the lower notes, though.

I've tried bass into amp, bass into mixer, bass into mixer with amp in the effects loop of the mixer, blah blah blah. The only thing that remedies the clipping is turning the bass's volume control down to almost nothing.

The other basses I tried were an Ibanez sound gear I believe and a Cort 4 string humbucker.

Correctly working active electronics are usually not all that hot compared with passives, hence the only 10-20 dB pad on the equipment, so it's somewhat unlikely that Yours is any different.
Since the same thing happens with the mixer, the most likely cause is a malfunctioning pre-amp.

If You have (or are able to make) an adapter that has a mono* plug in one end and either stereo or mono jack on the other -1/8" or 1/4" depending on your headphones- you can plug that straight to the bass and use headphones to find out if the pre-amp in the bass is indeed faulty and distorting the signal.

*A stereo adapter WILL NOT WORK, and may ruin Your headphones.​

Regards
Sam

 

[espace]

Not because it's low wattage, but because smaller practice amps usually don't have an input for an active bass (dB pad), or a gain knob to lower the input signal. The output of the pickups is too much for the amp. When you turn down the volume on the bass it solves the problem because it lowers the signal going into the amp.

 

[espace]

You said 3 active basses all caused clipping, have you tried a passive bass through the amp?

 

[cheapbasslovin]

Are you going bass > Digitech > amp with everything you're doing? If so, the Digitech has an output setting that is too hot. Or you're overdriving the Digitech input.

 

[Rich Terry]

Do you understand what EQ does to a square wave in the amp? Try taking the effects out of the system and try it. What usually happens is that you're EQ muddy up the signal and overdrives the amp section. It's like trying to go 150 mph in VW bus. The engine just won't get there.

 

[JimmyM]

Do you understand what EQ does to a square wave in the amp? Try taking the effects out of the system and try it. What usually happens is that you're EQ muddy up the signal and overdrives the amp section. It's like trying to go 150 mph in VW bus. The engine just won't get there.

I am agreeing with this, I think. I have never played any active bass that has overdriven any amp to an unusable level in the passive input, even very low wattage practice amps. I think the Digitech thingy is probably set way hotter than your signal without it, right? Pull it out and see if you still overdrive the amp. If it cleans up, then you need to set your effects at what they call "unity gain" to keep from overdriving your amp so much.

 

[Rich Terry]

Thanks JimmyM, I used to own 7 Audio Stores when Audio was cool and had to explain to customers all day that the reason they blew their speakers was that they didn't have enough power. They'd say "My speakers are rated at 100 watts and I only have 50 watts." Just because something has "10" on the volume knob doesn't mean that 10 with bass and treble both at 10 it won't clip. Clipping is distortion...distortion kills speakers. Every time you change your EQ up you add more gain and bend the square wave of the amp chasing the amp to clip very quickly. This happen very quickly in solid state amps. Tubes clip in a very subtle way. You can run a speaker rated at 50 watts all day with a 200 watt amp because the volume you are trying to get out of it will be clean power not clipping power. VW vs Corvette.

To notice the slightest change in volume you've only increased the volume by 3 dbs and for each 3dbs you double the power used. It's a logarithmic progression. 2 wts, 4 wts, 8 wts, 16wts, 32wts, 64wts, 128wts and so on. You run out of power quickly trying to reach a volume you don't have the power to produce. That's when the speakers blow, burn the voice coil. Game over.

I found that musicians as a whole have no understanding of this. I was talking to a very good bass player last night that told me that he kept blowing speakers in his cabs. He kept buying high wattage cabs and couldn't figure out why that wasn't working. I explained to him that he needed a "bigger" "engine" not larger tires. He didn't understand how a 4 ohm cab vs an 8 ohm effected his wattage output on the amp or how resistance effected current. Look up "Ohms Law" and that should help.

Like JimmyM said, you have the digitech to hot and adding to much color ie. bending the square wave and clipping the amp.

Keep this up and you'll be replacing the speaker soon.

 

[okcrum]

What?

 

[Rich Terry]

What is your question okcrum? I know that was a bit lengthy.

 

[okcrum]

It wasn't a question.

Speakers blow from being overpowered, not underpowered. Square waves blow crossovers and tweeters in cabinets which are rated for sine waves. They are still being overpowered, regardless what the rating for the cab says.

To get back on topic, we still don't know where in the signal chain the clipping starts, do we? I had a Roland that looked similar to this once, speaker simply could not do low notes. That's what it sounds like from OP's description. 20W, the darned thing farted like a whoopie cushion below A.

 

[Rich Terry]

As you know any time you bend a square wave it changes the output and as the amp reaches it max output you are cutting the top of the sine wave off which is clipping. Burned voice coil due to lack speaker of movement caused by distortion.

Junk in Junk out

 

[okcrum]

Seriously, no, just no. "Bend" a square wave? Lack of speaker movement? That might have worked for selling your customers amps, but that's simply not how it works. An underengineered driver in a crappy cab so it has a wicked secondary resonance? I might buy that.

 

[T-Bird]

Hi.

As you know any time you bend a square wave it changes the output and as the amp reaches it max output you are cutting the top of the sine wave off which is clipping. Burned voice coil due to lack speaker of movement caused by distortion.

And to think of it, the last time folks who still held that belief were shot down HARD here was....






...last week .


It's people like that who keep the misdemeanor of underpowering very much alive .


Regards
Sam

 

[okcrum]

It isn't as if there's a section of the amp FAQ (stickied) about this, either.

 

[T-Bird]

Hi.

It isn't as if there's a section of the amp FAQ (stickied) about this, either.

I've said it before and I'll say it again: "Folks don't read no stinking stickies".

OTOH if they did, internet forums would be really boring places I guess...

Regards
Sam

 

[teemuk]

I've said it before and I'll say it again: "Folks don't read no stinking stickies".

Damn right. Half of forum "discussion" are really questions that would be instantly answered by...
a) devoting few seconds to a simple experiment
b) devoting few seconds to read the user manual
c) devoting few seconds to read stickies and FAQ's

OTOH if they did, internet forums would be really boring places I guess...

Or way more interesting.