Weird tremolo sound at higher frets w/distortion

I'll take a stab, though I'm a newb.

You mentioned your noticing it on your Fender now too. Two different guitars. Something in your equipment? Pedal going bad, battery dying, your amp?

You have another amp other effects you could try and see if you get the same issue?

Is it happening when you play a single string alone, or with a "double stop" (two strings) or chord? If it's double strings, slight tuning errors are magnified up the fretboard, and shared harmonic frequencies between the two strings will "beat" together making a sound that seems to pulsate at the difference frequency.

If you're playing a single string but there's another one tuned to the same note, like the low and high Es of standard tuning, the same will happen as playing one excites the other to vibrate sympathetically, and if they're not tuned exactly together there will be a beat frequency heard. Same with a fretted note that matches the tuning of another string, like playing a G on the D string for example, which makes the open G string ring as well.

Ricochet, wow. Reason I come here..

I'll totally take your word for it, but slight tuning errors are magnified up the fretboard? Never read anything about it and not really noticed before - when I'm slightly out of tune it's usually everywhere. But now that you mention it, maybe it is a little more apparent higher up..why is that?

Another possibility:

Sounds like it might be what's known as trem gargle. This is not an intonation effect, but a result of the floating trem mechanics. Happens on single notes (as well as multiples) with floating trems (really the vibrola) if one picks hard -- harder the picking, the worse the problem. May be worse on high notes due to the force geometry. What happens is the pull on the string during the picking displaces the floating trem, which then vibrates back and forth until it settles back into position. So it's really a small vibrato (dynamic frequency) effect -- which is indistinguishable from a small, true trem (volume) effect to the ear.

If it's trem gargle, you can make it really obvious by popping (pulling and releasing) the string instead of picking.

To improve it: you need to add more springs to the trem -- as many as you can and still tune properly, with the bridge still held in correct resting position. This will increase the effective spring constant and reduce the motion of the trem while you pick. If you cannot add springs, you may want to look into one of the damping spring accessories that's aavailable for floating trem bridges.

Why are tuning errors magnified up the fretboard? Simple. If two strings that are supposed to both be tuned to Es, for instance, are mistuned enough to make a 5 Hz. beat frequency on the open strings, when fretted to the 12th fret they're both an octave higher and their frequencies are doubled. The difference between them now is 10 Hz. The beat will be faster and more noticeable.

Intonation problems tend to get worse as you go up the higher frets, too.

I tend to forget about the problems of playing with trem bridges. I stick to hardtails. :D

Why are tuning errors magnified up the fretboard? Simple. If two strings that are supposed to both be tuned to Es, for instance, are mistuned enough to make a 5 Hz. beat frequency on the open strings, when fretted to the 12th fret they're both an octave higher and their frequencies are doubled. The difference between them now is 10 Hz. The beat will be faster and more noticeable.

I've noticed this same problem is worse when there is more bass in the mix, such as when playing with the neck pickup. Seems to clean up nicely with the bridge pup. This makes me think it's not a tuning issue exclusively. Thoughts?

Why are tuning errors magnified up the fretboard? Simple. If two strings that are supposed to both be tuned to Es, for instance, are mistuned enough to make a 5 Hz. beat frequency on the open strings, when fretted to the 12th fret they're both an octave higher and their frequencies are doubled. The difference between them now is 10 Hz. The beat will be faster and more noticeable.

Intonation problems tend to get worse as you go up the higher frets, too.

I tend to forget about the problems of playing with trem bridges. I stick to hardtails. :D

All true because beating is detected by the ear/brain as an absolute difference, not a percentage effect.

But I still think this problem is likely trem gargle, because it happens on a single note -- no strong reference for tuning delta beat notes. Trem gargle is not a subtle effect for aggressive players. One of my favorite guitars has a floating bridge trem. It's hard to avoid this problem with the basic "Fender" floating design, whose geometry also is the basis for FR and other trems. Bigsby -- not so much, as the mechanical advantage of the spring (and its constant) is probably multiplied many more times by the design. Now I'm curious about the design differences. Gonna have to go check the dimensions of each.

Why are tuning errors magnified up the fretboard? Simple. If two strings that are supposed to both be tuned to Es, for instance, are mistuned enough to make a 5 Hz. beat frequency on the open strings, when fretted to the 12th fret they're both an octave higher and their frequencies are doubled. The difference between them now is 10 Hz. The beat will be faster and more noticeable.

I've noticed this same problem is worse when there is more bass in the mix, such as when playing with the neck pickup. Seems to clean up nicely with the bridge pup. This makes me think it's not a tuning issue exclusively. Thoughts?

There is another effect on "perceptably" single notes that is related to high gain and saturation of gain stages in either an FX box or the amp: intermodulation. The occurs if a bass string is vibrating slightly, but almost unmoticeably. It can modulate the "obvious" higher note. The effect will occur at either the frequency or double the frequency of the base note. This definitely requires either a large level of non-linearity or high volume level out of the amp.

One more: At high volume levels, the power supply can "sag" at the rate related to that of the phantom bass string's vibration and that will moduled a higher "single" notes or chords or everything else.

In either case, cutting back on bass out of the guitar -- using a bass cut tone control (usually active) or switching to the bridge pup would help.

Could it also be do to with the compression effects of distortion - quiet sounds, that would, normally, be more or less background noise, are being amplified disproportionately to the louder sounds (due to the clipping)?

Why are tuning errors magnified up the fretboard? Simple. If two strings that are supposed to both be tuned to Es, for instance, are mistuned enough to make a 5 Hz. beat frequency on the open strings, when fretted to the 12th fret they're both an octave higher and their frequencies are doubled. The difference between them now is 10 Hz. The beat will be faster and more noticeable.

I've noticed this same problem is worse when there is more bass in the mix, such as when playing with the neck pickup. Seems to clean up nicely with the bridge pup. This makes me think it's not a tuning issue exclusively. Thoughts?

There is another effect on "perceptably" single notes that is related to high gain and saturation of gain stages in either an FX box or the amp: intermodulation. The occurs if a bass string is vibrating slightly, but almost unmoticeably. It can modulate the "obvious" higher note. The effect will occur at either the frequency or double the frequency of the base note. This definitely requires either a large level of non-linearity or high volume level out of the amp.

One more: At high volume levels, the power supply can "sag" at the rate related to that of the phantom bass string's vibration and that will moduled a higher "single" notes or chords or everything else.

In either case, cutting back on bass out of the guitar -- using a bass cut tone control (usually active) or switching to the bridge pup would help.
Oh thanks gnease, I should have specified that I get it with chords up the neck, rather than single notes. Even at lower volumes, but with moderate distortion; and I have a hard-tail bridge. Like when doing Brian May's We Will Rock You solo, starting on the A chord at the 14th fret and going from there; the single notes in the solo sound fine with the neck pickup or bridge+neck, but the chords get that muddy oscillating sound. I thought it was just poor intonation on my part, but like I said, switching to bridge-only seems to clean it up.

Anyway, I thought of it when I read the original post, but now I'm thinking it's something unrelated (surely not trem gargle on mine.)

Yet another thing that's amp specific is "blocking distortion." In a tube amp with resistance-capacitance coupling, a strong positive signal peak applied to the grid of a tube pulls current out of the electron stream that flows from the grid back to the coupling capacitor, discharging it and reducing the positive peak. But when the signal goes back to a negative peak, now it's a lot more negative than it would've been. That cuts down on or cuts off the stream of electrons from the cathode to the plate, dropping the output volume. The effect lasts until the added negative charge can bleed off to ground from the coupling capacitor through the grid resistor, with a "time constant" determined by the product of the values of those two parts. That's what makes that "buzz saw" sound from many Marshall amps. It sounds that way because the time constant's short. Choose too large coupling capacitors and grid resistors, and you get a long time constant that will cause the sound to cut in and out most disturbingly.

It's not entirely limited to tube amps, either. My Danelectro Honeytone does it when the gain's up and I hit a chord.

:arrow: Wow Doc. is there anything in there that we can use to create energy to power my 87 buick ?

It's not entirely limited to tube amps, either. My Danelectro Honeytone does it when the gain's up and I hit a chord.

My assupmtion has been power supply capacity issues (small caps/large resistance and/or low charging current) on the Honeytone. Rarely use mine because this, as it breaks up way too soon for usable volume and this "feature" annoys the crap out of me.

Thanks a lot for the tips guys. I was thinking it might be the trem too and maybe I'll try adding more springs. I also tried the following two ideas:

Turning bass way down: didn't seem to have any effect
Making sure no other strings were vibrating: I muted every string very well and picked a note and it still "warbled". It's only at higher frets and on different strings in different places, but all on frets 11+, none below that.

Gnease: What do you mean by pulling the string instead of picking it?