What causes amps to 'warble' on single notes?

[simon_d]

So I just bought a boutique amp and the standout thing was how single notes clearly rang out and decayed without, for want of a better description, note warble. I had to I swap back to my other amps to double check it wasn't just the honeymoon effect of new gear, and the difference was obvious.

It's like there are overtones, hash and other garbage in the signal that interfere with the note causing slight beating and other sustain-killing effects, particularly as it decays. I'm interested to know if the amp was designed that way or just a fluke.

Amp designers, can you set out to specifically reduce these effects on the signal even if the tone is very distorted and if so what parts of the circuit contribute to it? Is it the initial DC filtering or more complex than that?

 

[LP Freak]

Might be a bad filter cap. What’s the amp?

 

[simon_d]

Might be a bad filter cap. What’s the amp?

I wish I had a better word than warble, that's overstating it, it's not a major ghost note thing, it's subtle like the note is interfering with itself and wavering. Other amp was a Jet City 100, checked it on my JVM and that has more warble too. I'm sure all my other amps are like that to some degree. I only noticed it as amp-related when I tried this new head. It's not gone completely but noticeably less. I was like, ah so that's what I've been missing.

 

[homespun]

I had a microphonic tube in my Marshall Vintage Modern that would ring with certain notes. When I would tap on the the faceplate it would also go “BOING”. I tapped each tube with a chopstick and found the offending tube and replaced it.

See if you have any of those symptoms.

 

[simon_d]

I had a microphonic tube in my Marshall Vintage Modern that would ring with certain notes. When I would tap on the the faceplate it would also go “BOING”. I tapped each tube with a chopstick and found the offending tube and replaced it.

See if you have any of those symptoms.

Could be tubes, I could check that by swapping the tubes from the new amp into the jca. If the warble is less, then it's the tubes.

 

[311boogieman]

an overly hot bias can do that too

 

[simon_d]

an overly hot bias can do that too

Interesting. I had rebiased the JCA to about 60% dissipation. It was biased super cold from the factory. JVM does it too, so I'll rule out bias for now.

I recorded two amps back to back same everything else... and it's far more complicated than I expected. All sorts of stuff going on, from phasey volume drops to beating, to low mid thumps and crackles. And it's not on the sustain as I thought its right at the front of the note. Weird how perception works. This was JVM ch 3 orange. Channel 2 red however is totally different, much less junk going on. This could take some unraveling...

 

[midnightlaundry]

Ghost notes??

3.30..

 

[midnightlaundry]

The Young Bros are little dudes.. That Guitar Mal is playing is bigger than him.. LOL
Legends come in all sizes..

 

[simon_d]

The Young Bros are little dudes.. That Guitar Mal is playing is bigger than him.. LOL
Legends come in all sizes..

They're awesome aren't they! Never seen Malcom play anything other than the solid gretsch. Is that a white falcon?

Don't think its as strong an effect as a full-on ghost note... well spotted example of one in that clip though. It might simply be down to the kind of distortion and the harmonics produced. OD1 on the JVM is quite aggressive with a lot of attack. I like it for big chords but always find single notes to have the 'ick factor'. It'd be interesting to see if that goes away at high volume next rehearsal as I think I only really notice it at home.

 

[midnightlaundry]

 

[Dan Gleesak]

Which amp was it? Lots of vintage amps and boutique copies of them that were meant to be played at stage volume have all kinds of crap noises that go along with them. At volume with a band you don’t notice them but under the microscope of the bedroom, they can be unbearable. Especially know that IR loaders and all that let you crank an amp but keep it at useable volumes

 

[simon_d]

Which amp was it? Lots of vintage amps and boutique copies of them that were meant to be played at stage volume have all kinds of crap noises that go along with them. At volume with a band you don’t notice them but under the microscope of the bedroom, they can be unbearable. Especially know that IR loaders and all that let you crank an amp but keep it at useable volumes

Yeah, I'm thinking this may be the case. It was all of them lol! All except for a new hand made amp I just got (Marshall type), which is what prompted me to ask as notes seemed noticeably less crappy. Could just be the fact that they guy making it took the time to do a good job? The others are all mass produced. Under the microscope its not quite as clear cut as how it feels under fingers, and guitars can produce warbles too so it's difficult to isolate the cause, or even if it's really as big a difference as you first thought.

Distorted amps probably all do it to some degree, crackles and warbles, phasines etc. The JVM OD1 channel was just particularly objectionable in that regard despite it being my favourite, and the new amp particularly good, at bedroom volume anyway.

 

[311boogieman]

Wait, so this is happening with all your amps? A Jet City JCA100_and a Marshall JVM? Can you possibly be more specific as what amps you are talking about and the signal chain and power feeds of these? Also, are they connected together at all with an ABY box of some sort? The stuff you are describing is not normal IMO.

 

[skoora]

Wait, so this is happening with all your amps? A Jet City JCA100_and a Marshall JVM? Can you possibly be more specific as what amps you are talking about and the signal chain and power feeds of these? Also, are they connected together at all with an ABY box of some sort? The stuff you are describing is not normal IMO.

Yeah, I have a feeling it may not be the amps.

 

[simon_d]

Wait, so this is happening with all your amps? A Jet City JCA100_and a Marshall JVM? Can you possibly be more specific as what amps you are talking about and the signal chain and power feeds of these? Also, are they connected together at all with an ABY box of some sort? The stuff you are describing is not normal IMO.

Sure. Amps are JVM, JCA100h, JCA20h, Recto 2 channel (haven't checked that one yet). New amp is a hand wired marshall type 50w by a small UK builder called Stoneham. Nothing unusual about connections, guitar straight in, but they all go through a two notes captor into an Engl 4x12 with v30 and T75 speakers one at a time. So the amps can open up a bit, master on 4 rather than like 1. I also have an AX8, and I blame that on me becoming hyper sensitive to hash and other crap. You know what it's like, when you notice something you can't help lasering in on it until that's all you hear.

These are subtle effects, but noticeable. I can't unhear it once I do, it's annoying really and I try to ignore it. The fractal wrecked me, lol. I might have to post a clip as ppl might imagine something much worse than it is.

 

[311boogieman]

^ So you have an original Two Notes Captor? I'm not an exert on these but the descriptions you are giving:

"from phasey volume drops to beating, to low mid thumps and crackles" - on at least 3 of your 5 amps

Leads me to believe that this is more of an issue with your signal chain or power. I had similar issues after "installing" a simple ABY pedal for 2 amps and spent a lot of time troubleshooting tubes and cables only to figure out it was a grounding issue. If it were me, I try the Recto as well and then remove the Two Notes from the equation and just run one amp at a time with as little amount of stuff between the strings and the speakers and see what the results are. Obviously swap some cables/guitar around and maybe hit all of your connections with some Dioxit contact cleaner (do not spray directly into holes, spray the jack and work it in and out.

But yeah "phasey" and "warbly" sounds more like tubes or caps but I think that would be ruled out considering it is doing this with 3 amps

Good luck

 

[JackBootedThug]

Every time I turn on my tremoverb my balls grow exponentially bigger…then the sound waves from my speakers bounce off of them causing something similar to happen. Could this be the issue bro?

 

[311boogieman]

Every time I turn on my tremoverb my balls grow exponentially bigger…then the sound waves from my speakers bounce off of them causing something similar to happen. Could this be the issue bro?

Depends on how far apart you two live

 

[JackBootedThug]

Depends on how far apart you two live

Griff’s Chiron cured my erectile dysfunction.