Dumble Note flips

gabbenante said:
Hi LVC,
Did a little search and came up with what appears to be a "technical" explanation as well as a another audio clip, where in the post they refer to the Phenomenon as "Swirl". Perhaps Cliff could validate the explanation as it seems to be a characteristic of the amp design and not a players skillset.
Just trying to help, don't know if its factual as its over my head :encouragement:
Greg

Telecaster Guitar Forum - View Single Post - Note-flipping
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This is way over my head as well.

"..."The Phenomenon is known as Swirl

Described as a dynamically-changing, slightly "phasey" sound as a note or chord decays, which is common to some tube amps. Typically, "swirl" is caused by a midrange "dip" or varying duty-cycle change in a clipped square wave that changes position as the note decays, giving a sort of mild phase shifter effect.


What happens is that first the phase inverter or output stage clips and produces a flat square wave. As the note decays, the signal level decreases, and the midrange frequencies start getting "unclipped" (either by the fact that their frequency band level is lower, or by phase cancellations due to the unequal phase shift with respect to frequency caused by tone controls and other RC phase shifts that occur in a gain stage) and show up as a "dip" in the top of the square wave, which will move back and forth along the top as the fundamental and other harmonics shift the operating point. Even if the clipping ratio isn't extreme enough to show the "dip" on the scope, the duty-cycle of the square wave will usually be dynamically changing as well.


Since the preamp stages are all AC-coupled to each other, the operating point shifts as the signal gets smaller, due to slight "blocking" distortion, where the gain stage clamps the top peak to a point slightly above it's cathode voltage, while allowing the wave to still increase in the negative direction. As the signal decays, it shifts upward and changes the duty-cycle of the clipping. It is this ever-changing shifting of the operating point that causes the "swirl" effect. The trick to good "swirl" is in the correct staging of the gain and frequency breakpoints of each gain stage in the amp, particularly in the phase inverter and output stage.


A similar effect can be caused by too much drive from the phase inverter to the output tubes. As the note decays, a riding "buzz" can be heard coming in and out. This is crossover distortion aggravated by too much signal swing to the output tube grids. Reducing the signal levels at the output of the phase inverter will cure this.


Another cause of a "swirly" sound is a parasitic oscillation that is riding on the output signal, causing intermodulation distortion. "
 
Swirl we should have already...

Cliff said:
One of the characteristics of a good tube amp is "swirl". It took me a long time to figure out what causes this and to reproduce it digitally.
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Single waveshaper approaches cannot capture the complex interactions of multiple distorting stages and the concomitant duty-cycle modulation, EQ modulation (which produces note bloom and swirl) and the vagaries of feel.
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Scott Peterson said:
I'll ask him. I don't understand what you are describing
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...but I do ;) It's called "bloomy notes", not related with loudness and/or feedback - it's a very subtile dynamic effect. I know this best from older fender amps, when playing them clean, not overdriven.....
Years back (1998 - 2001) we had a Fender 75 amp in a guitar shop were I worked as their amp repair guy - this was a 1980s early "Rivera-Fender" which had this special quality - the notes were very bloomy & chimey - almost singing! Sadly this amp is sold long time ago
 
I had a PM discussion with Scott Lerner last night; his term for this phenomenon is 'harmonic feedback'. I am no expert on the Dumble mystique at all, but due to client requests have had to make a quick study of all the Dumble magic and Lerner is a well known resource and experienced guy with the whole Dumble 'thing'.

Here is my own version of that sort of thing, preset too. Though I tend to go more for the Marshall roar and kerrang personally, this is what I do with the Dumble. Note the gain structure and 'even-ness' across the harmonic range that allows for that sort of natural sustain and 'bloom' when you hold a note. Going for that sustain, even, note chirp and bloom with the Dumble. Note I use two Own Hammer user cabs; the Mashall CB Mix versions of the EV-S T1 Studio Modern in User 13 and EV-L T1 Live Vintage in User 12. You can use the stock versions of those cabs if you do not own the Own Hammer versions. This isn't a direct attempt to ape any particular tone, just my version of a Dumble type of tone using a humbucker. I generally roll the guitar's volume off to about 8 and ride it to create some sustain and harmonic feedback when necessary



Clip:

Preset: Axe-Change - Download Preset - Dumble ODS SP - by ScottPeterson
 
Previously in older modelers "ODS" type tones have been a generic "overdrive type 2" with the highs cut off. Now we have Axe, and we can discuss this sort of nuances with wine terms. <3
 
aziz said:
Previously in older modelers "ODS" type tones have been a generic "overdrive type 2" with the highs cut off. Now we have Axe, and we can discuss this sort of nuances with wine terms. <3
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Yep!

I like mine smooth, with a hint of smokiness to it!
 
I usually tend to think of that sound as all about the speaker and the guitar interacting, but I've gotten the same sound or something very very close while monitoring through headphones.

It was a few years ago and I can't remember what I was playing through an AxeFx, a 2101 or something else. It was a sound with more gain than Robben or Larry had so its not an exact match, but I was definitely isolated from any speakers. When it happened I was quite surprised. It almost seemed like there was a real fast change in the eq as if certain frequencies were increased and others were muted in the moments after the note was struck.

It didn't last a long time. I couldn't hold a note Santana style, but for a few seconds the harmonic of the note just rang out, and no it wasn't pick harmonics. There was the fundamental for a brief moment and then harmonics.

Sorry I can't offer an explanation for how it happened and I don't mean to muddy the waters but that was my experience.
 
I had a Fender 75 years ago (God, why did I sell off my old gear?!). It was Fender's answer to the first Boogie combos, and it was the first amp I owned that produced the flip. I never knew there was a name for it until I saw this post. It comes pretty easily with my Lonestar Special as well. To me it's as much a guitar thing as it is an amp thing. Large frets and a lively guitar (ie hollow-body with humbuckers) are key, now that I think about it, as glissing across nice, fat frets excites the string in a unique way. It happens easily with my Epiphone Sheraton, but not so much with my LP, Tele, Strat, etc. It's always *felt* like a touch thing to me, enhanced by the right tone, the right guitar, and a bit of volume.

Alas, I'm now using the AFX direct with IEMs (and absolutely loving it!) but, especially being a semi-hollow player, I'm missing the interaction between guitar and amp a bit. Perhaps a guitar output on a future Axe-Fx that's wired to a contact transducer affixed to the guitar body would lively things up a bit? Lol.
 
There was a thread a good while back where Cliff talked about trying to explore the in-the-room feel notion and the role of the interaction between speaker and guitar in tone. I think he said they measured as much as a 10 db difference in the frequency response of certain frequencies when there was interaction between speaker and guitar (rather than a headphone or speaker isolated situation). Just from experience, most people probably know that feeling of the guitar vibrating in your hand from the amp being played at the guitar. It's a beautiful thing.

The transducer idea seems crazy on the one hand, but not that crazy. Makes me think of the Fernandes Sustainer. I might need something to isolate me from my CLR and headphones, too. I know the Axe sounds great not so loud, but something about FW 11 sounds so great that it makes me want to crank it and immerse myself in the sound. My ears have had a tinge of "that's too loud for too long dude" the last couple of days, cause I've played the Axe a ton.
 
hillbilly said:
To me it's as much a guitar thing as it is an amp thing. Large frets and a lively guitar (ie hollow-body with humbuckers) are key, now that I think about it, as glissing across nice, fat frets excites the string in a unique way.
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This.
 
aziz said:
we can discuss this sort of nuances with wine terms. <3
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LVC said:
I like mine smooth, with a hint of smokiness to it!
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You guys on that side of the pond have access to Palmina and Brewer Clifton wines from Santa Ynez Valley, CA... I was hugely honoured to get a full on tour of everything they do there recently and their stuff is simply fantastic
icon_cheers.gif


Apologies for the drift ;)
 
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MikeyB59 said:
There was a thread a good while back where Cliff talked about trying to explore the in-the-room feel notion and the role of the interaction between speaker and guitar in tone.
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That being said, during shows I'm constantly distracted by the realization that the beautiful tones I'm hearing are from a digital processor plugged directly into my skull. It's almost a problem. :)
 
I've got it!! A line of Fractal guitars, each with an *input* jack, and a "Guitar Exciter" block in the Axe-Fx! Lol!
 
I always thought note bloom is due to the change in frequency content of the note as it decays. If you strike a string not too hard (say the B string mid way up) - not hard enough to get fret buzz - the beginning of the note contains more of the fundamental frequency than harmonic frequencies. Then as it decays the ratio changes so there is more mid and upper frequency energy present. This causes the right amp, set the right way, to compress a bit more at first, with the fundamental frequency being the dominant tone. Then as that lower frequency dies out the amp compresses less and "sings out" the mid and upper frequencies. Or, maybe it doesn't have anything to do with frequency, just amplitude causing the same phenomenon. My $0.02.
 
jakel said:
I always thought note bloom is due to the change in frequency content of the note as it decays. If you strike a string not too hard (say the B string mid way up) - not hard enough to get fret buzz - the beginning of the note contains more of the fundamental frequency than harmonic frequencies. Then as it decays the ratio changes so there is more mid and upper frequency energy present. This causes the right amp, set the right way, to compress a bit more at first, with the fundamental frequency being the dominant tone. Then as that lower frequency dies out the amp compresses less and "sings out" the mid and upper frequencies. Or, maybe it doesn't have anything to do with frequency, just amplitude causing the same phenomenon. My $0.02.
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don't know the theory behind it or what the hell to really call it ... all I know is that Dumbles do it the best (IMO of course)
 
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