Reverb pedal causing distortion in sound card input

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AbridgedPause

AbridgedPause

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Hey everyone. This is my first post. Hoping to get some good feedback on an audio problem.

Here's my set up: Guitar > Boss Digital Reverb RV-5 > Focusrite Scarlett 2i2 (1st Gen) > Computer.

The problem: Whenever the pedal is on, the input sounds like a distortion pedal is on. It's not crackling from bad jacks, it really sounds like distortion. As soon as I turn off the pedal, the sound is crisp and clean. I've been using these for years but only recently encountered this problem.

I know that my gain input on my Focusrite is low enough, and I know that it's not my computer itself because the distortion also comes in through the headphone monitors plugged directly in my Focusrite.

Any idea what could be causing this?

input.webp
 
Try plugging in a different pedal, and see if it also has the same problem.
 
The only other pedal that I have is the Boss Metal Zone distortion pedal. So I don't have that option.
 
I borrowed another pedal from a friend and the same problem occurs. Any pedals going in cause distortion on my Focusrite input. Is this a known issue? Could there be something wrong with my Focusrite?
 
When you switch the rev on and off, does the volume ramp up? If it's distorting then there are only a few scenarios. If you turn down the reverb effect to zero, stomping on the button should not change the sound volume? Does it? if it doesn't, then when you gently add in the reverb, does the distorted sound gently get added? If it does, then the input of the electronics in the pedal is probably being overdriven, so it generates the distortion and then it's there on all programmes. if stomping makes the volume rise, then the distortion probably comes from overdriving the focusrite's input. Of course, it could just be faulty! has it ever worked as you expect? What's it like going into an amp, not the focusrite?
 
Hey Rob. Thanks for your lengthy response. I appreciate it.

I did some more troubleshooting and I'm actually rather confused. I'm trying to pinpoint where the distortion comes from. Is it from my guitar's pickups, my Boss reverb pedal, my Focusrite, the cables?

To begin with, I'm now able to hear the distortion even when the pedal is off. I hadn't noticed that so much before because when the reverb pedal is on, it makes the distortion so much more obvious and sustained. But it's definitely there even when the pedal is off.

I then tried to plug my guitar directly in the Focusrite and I still hear some distortion. Not as much as when the signal goes through the Reverb pedal, but that's mainly because the input volume is lower. But there is definitely a distortion.

So I decided to plug my Guitar > Boss Reverb > Amp (I use a bass amp so it has no distortion). The distortion was still clear and present whether the pedal was on or off. I then plugged my guitar direct into my amp and I still hear distortion.

I tried to use another guitar and then a bass, I still hear distortion.
I changed the wires, I still hear distortion.

I then went as basic as possible: Bass > amp. I still hear distortion! I swaped the cable, but that also didn't help.

I just can't seem to figure out how to get a clean sound nor isolate where the problem is coming from since it's just always there.
 
We're getting somewhere - if bass direct to amp has distortion then the bass is the only thing it can be. The problem is now a different one. Is it a passive bass? I hope it isn't because the only physical problems with a passive bass is level, impedance changes and perhaps susceptibility to external fields when turns in pickups short - things like that. In all my years, I've had low level faults, I've had open and short circuit pickups and loads of dry joints - but none caused distortion because that requires some form of action. Traditional distortion involves adding harmonics and turning sine(ish) waveforms to more angular ones. The only fault I can think of is that maybe you have a fault that is creating a tuned circuit - it needs capacitance, inductance and resistance, and although I've never come across it, it needs energy to excite it and maybe, just maybe this comes from twanging a string. I can see the physics, but have never heard of it. This suggests your bass might be active, and then distortion generation is a much more common and simple fault.

The guitar into the focusrite and the amp, suggests the common item, the guitar, is the key. If it's active, there's a possibility that the jack socket could be the problem. The 6 or 9V preamp supply is often fed via the jack socket using the sleeve and ring contacts to short on the jack to turn power on, and remove it when the jack is removed. Is it possible the DC supply is being fed down the cable which is causing the distortion in the preamp/interface and the amp?

These are the two versions of fault I can come up with.

Never actually had either happen, but they're possible. I did have dodgy pickup once that picked up AM radio - SW stuff and a very feint Radio 1!

I guess swapping the guitar for anything would again rule it in or out. Weird this!
 
If it is an active guitar, distortion can also arise from the battery getting low, so try swapping that.
 
Hey guys, I will record some samples later tonight so that you can hear the distortion.
For now though, all of my instruments have passive pickups, in fact I've made it a point to only buy passive-pickup instruments because I don't want the trouble having to change batteries.
 
Last edited:
Alright I recorded a sample so that you may all hear the distortion in my clean reverb setting.



[MP3]http://www.abridgedpause.com/wp-content/uploads/2019/07/distortion-sample.mp3][/MP3]

Here is my exact set up:
This is the same set up that I posted a picture of in my earlier post.

-Jackson Kelly electric guitar with DiMarzio X2N bridge pickup and DiMarzio Tone Zone neck pickup.
>10 ft Monster cable
>Boss Digital Reverb RV-5 pedal with power adapter. Guitar comes into the Input A (Mono).
>Two 1.5 ft patch cables leaving the Boss pedal in Stereo mode
>into Focusrite Scarlett 2i2 (1st Generation). Both inputs set to Line (setting it to Instrument would make it clip). My headphones are connected to the Focusrite
>USB 2.0 into computer.

Just to clarify, there is no visual clipping at any point. All the knobs are green on the Focusrite and my DAW is well bellow any clipping levels.
Yet the recording clearly sounds like it's clipping into distortion constantly!
 
Is it a very early Mk1 2i2. I ask becuase these were known to have very low instrument input headroom. Does the distrotion clean up if you back the volume off on the bass? You could try that and record well down at -30dBfs then boost digitally to prove the matter.

Quite why the problem has only just surface now I could not say but I suspect a fault in the AI's input circuit, a leaky/short input coupling capacitor* or a faulty op amp. Both faults are however incredibly rare these days.

I will try to find a specification for the early 2i2 but in the meantime. You don't need a high Z input if using a reverb pedal (does the HZ bit for you) so try the pedal into the LINE input. Failng that, get a cheap passive DI box and go intp the XLR mic input. If that solve the problem (I assume the mic circuit is clean?) you have a choice? Better active DI or new interface!

Passive guitars/bases you see are "DC coupled" and thus provide a resitance to ground. Unless the input amp is DC isolated the working point can be shifted causing distrotion.

Dave.
 
Just had a harken...Geeez! Giving it some there lad. The signal is peaking to -4/-5 dB fs and whilst that would be fine on a decent modern AI I think an early 2i2 WILL distort.

Leave the front panel gain as was then back off the bass volume to get -20dBfs on the DAW meters.

Dave.
 
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