howling sound with high gain string bends

[jjrt2]

I have stumbled across an issue, that quite annoys me. Playing with high gain sounds i notice an artificial, howling sound when i do bends on neigboring strings (12th fret or higher). I wonder what is the reason for this and in particular, how can i avoid it. I also get this howl with different daw-plugins. I have attached a short example click (4 takes:  (1) dry signal, (2) helix, (3) Amplitube, (4) archetype nolly). Any hints how to deal with this?

modelerHowl.mp3

[Rattlehed]

that sounds like two notes together, i think the problem is with your guitar.

[kduck]

Sounds like intermodulation (IM) distortion and it's somewhat normal with distortion/high gain.  Check out the very end of Working Man by Rush--sound familiar?  

 

Basically, when you play 2 notes,  you will end up with the sum and difference frequencies of the notes, PLUS their harmonics.  For guitars and guitar amps, this tends to be more pronounced on the higher frets.  Some dirt pedals & amps (both real and modeled) are more prone to it than others.   With octaves and 5ths, IM can sound great--i.e. power chords.  With other intervals, not so much.  In the case of your string bend, a variable interval is creating moving sums/differences and harmonics all at the same time.  A trem (esp. floating) can make bending technique tougher because as you bend one string, the tension (and thus the pitch) on the "static" string will naturally decrease. 

 

So, what can you do? 

• You can try a bass EQ cut before the distortion or between gain stages (might help, but probably not in your specific case)
• Try a different pedal/amp combination
• Reduce the gain and/or check your gain staging.  A lot of gain early in the chain is going to throw not only the sum/difference freqs, but also a ton of harmonics (both good and bad) to everything after.
• Work on your bending technique so that you move through the dissonant interval(s) quickly and finish on a  "desired" interval
• On the helix, you might try reducing the ripple on the amp.  I've built/played/service tube amps for years and ripple can definitely contribute to IM.

Hope this helps.

[jjrt2]

Thanks for your very knowledgeable response. Intermodulation seems to be just what i  was  suspecting - basically a problem of frequency overlap.  I am wodering wether this is caused by digital modelling. I only have a fender blackface analog amp,  not the right device for testing this.  Your argument sounds very convincing that it happens in analog devices as well. 

I know i can somewhat work around with my playing technique,  just as you suggest. I have tried different amps and dirt pedals,  even different vst plugins , which made a difference,  but helped only so much.  

Your suggestion concerning ripple sounds interesting - have not looked for that so far and will give it a try. 

[kduck]

21 hours ago, jjrt2 said:

Thanks for your very knowledgeable response. Intermodulation seems to be just what i  was  suspecting - basically a problem of frequency overlap. 

 

Kinda...you have your 2 fundamental frequencies plus 2 new freqs (and the associated harmonics) also being created as the sum and difference.  For example, if you play a power chord at the 5th fret, you are playing A110hz and E165hz (a 5th interval), you will get a sum of 275 hz (within a 2 cents of C#, which is the major 3rd of the A chord) and a difference freq of 55hz (exactly 1 octave below A110).  Those 4 freqs--A55, A110, E165, and C#275--happen to be an A major chord.  You also get even- and odd-order harmonics of those freqs, to varying degrees, depending on the circuit, EQ, etc. This is why power chords sound so "good" with distortion, esp. with tube distortion, which tends to be even-order (5ths and octaves).

22 hours ago, jjrt2 said:

I am wodering wether this is caused by digital modelling.

 

Nope, it's just the nature of the beast, whether analog or modeled.  Sure, there may be some digital artifacts or other weirdness caused by a particular modeling algorithm, but that dissonance in your sound clip can and does happen on analog devices as well.  You can test this yourself on your Fender, then on your Helix with a similar amp model (Princess, Deluxe, etc):  play a D (2nd string 15th fret), while bending an A (3rd string 14th fret) up to B. You should hear a lower "ghost note" going downward while you're bending up.  Now throw some dirt on top of it...

 

22 hours ago, jjrt2 said:

I only have a fender blackface analog amp,  not the right device for testing this. 

 

It will be much less prominent on a clean tube amp like the Fender BFs.  That being said, my #1 is a Vibroverb 2x10, and I can still hear some IM, especially once I start to push the volume up above 5 or so.  It's the tubes doing what they do. 

 

[amsdenj]

Turning down the hum and ripple in the amp model might clean it up a little. Also try using less gain, i.e., the minimum amount of gain required for the song.