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Direct bass overloading/clipping

I'm recording a bass direct into my DAW and getting a lot of clipping/popping/overloading, and I can't quite figure out where the problem is. To get the particular sound I want from this bass part, I have to hit the strings quite hard--harder than I normally play. Going direct into my Focusrite 2i2's instrument input, I would get pops on the pick attack. I tried turning the volume on the bass down but still was overloading the input on the 2i2. I switched to using a Zoom B3 to go through, so I could turn the output volume down, but the clipping still occurs, even though the signal is way under 0db once it reaches the DAW. 

See audio sample below. This was just trimmed and converted to mp3. No other processing. The level of the audio is well below 0db, but you'll hear the clipping clearly.

Will a dedicated direct box with an input pad help with this, or is the bass circuitry overloading (Squier Affinity Jazz Bass)? Do I need to chill out on the strings, or modify my playing technique? For this specific piece I would really like to beat the hell out of the strings, but I can't get a clean signal. Would a higher quality bass or pickups solve the issue? I don't have one to test at the moment.

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Comments

Profile picture for user bouldersound

bouldersound Thu, 05/20/2021 - 23:00

My suspicion is that the input impedance of the 2i2 isn't high enough. I didn't see a spec for the instrument input, but the line input is 10kΩ. I found a spec for the neck pickup of a Squier Affinity Jazz Bass neck pickup, which is 4.6kΩ. I'm no electronics expert, but I'd want the input to be more than just a bit over double the pickup. It's possible that a good active DI would solve your problem. Even a decent passive DI could have twice the input impedance of the 2i2, but an active would be on the order of 100x that.

 

@boswell

Profile picture for user paulears

paulears Thu, 05/20/2021 - 23:14

It’s odd. Even with the input turned down down it peaks? The impedance issue usually loads the pickup which results in tonal differences, it would be interesting to see what the waveform looks like on the line input. It will be low, but that playing level is pretty hot. I think a cheap di would be a problem solver, or the DI out of an amp. The clipping indicates and over level issue, but surely this should be controllable? Something a bit odd is going on.

Profile picture for user Boswell

Boswell Fri, 05/21/2021 - 02:32

There's no evidence of amplitude overload, simply of too low an impedance. The 2i2 input impedance is 60K Ohm with the button out (line input mode) and 1.5M Ohm with the button in (instrument input mode). Check that you really have the INST button pushed in for the appropriate channel on the front panel.

Bass waveform

 

televator Fri, 05/21/2021 - 07:23

I agree, that this is very odd. I can confirm that I have the instrument switch selected on the combo input of the 2i2. The pop is not a digital clipping artifact from the DAW, as evidenced by Boswell's screenshot. Something is happening earlier in the signal chain. I did try using a Behringer GDI21, with the amp modeling turned off. Presumably in this scenario it acts as a basic DI box (correct me if I'm wrong) and the issue persists. That's a $30 pedal, so the next step may be a trying a higher quality DI. 

The Zoom B3 mentioned above has volume for the output but not the input, so I'd also like to try a DI with an input pad switch to see if that helps.

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Boswell Fri, 05/21/2021 - 09:21

It could be that the pre-amp is faithfully reproducing what it is actually seeing at its input. Can you confirm that the bass plays correctly into an amplifier, using the same lead?

The Squier Jazz Bass is a perfectly acceptable instrument, but it is manufactured down to a price, and I'm not being derogatory. I think the model you have is the single-pickup version. I've seen the magnets displace themselves or even fall off the underside of those Squier pickups, and that results in a mangled output. It's worth unscrewing the pickup plate to check.

 

televator Fri, 05/21/2021 - 12:36

The bass is very much a possible culprit. I don’t have an amp on hand to compare, so still trying to figure that out. I might take a peak inside, but when not slamming the strings, everything sounds as it should. If the magnets/pickups are not damaged/displaced, are the cheaper electronic components a possible source of the problem? I wouldn’t know where to even start with trying to inspect the wiring and pots. 

I have also considered that I’m just playing too damn hard for direct recording. If all components and parts of the signal chain are in working order, should this popping not be happening, no matter how hard I play? I’m working with a cheaper bass, DI and interface. But even with top of the line equipment, could this problem happen with poor picking technique? 

Profile picture for user paulears

paulears Fri, 05/21/2021 - 13:22

There is a possibility that it's a transient response issue - but if the pick edge plays mega loud, it should be possible to not overload the input stage. It sounds like clipping but that should be controllable? We have a mystery?

Profile picture for user Boswell

Boswell Fri, 05/21/2021 - 15:14

I don't think there's any mystery - just a fault to be found. Plugging the lead into an amplifier rather than into the 2i2 would establish whether the problem is in the Focusrite or in the instrument plus lead. We can see from the waveform that there is no overload problem, simply that the waveform is not correct.

I forgot to ask: you are using a standard guitar lead, aren't you? You could well get this sort of effect if you mistakenly used a TRS (dual conductor plus screen) lead instead of a TS (single conductor plus screen), given that the 2i2 input jack can double as a balanced line input..

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