Tremelo

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BRSHiFi

Previously known as kingden
Joined 2008
#1
Should the waveform of a tremolo look like a modulated AM signal, with the low frequency oscillator behaving as the carrier?

The waveform I get in spice looks like this (see attached) when I attempt a bias adjustment configuration. It looks like more of a summation rather than multiplication.
 

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#2
Waveform of what? Tremelo is a low frequency oscillator modulating the amplitude of the signal. So the waveform of the LFO is one thing, the waveform of the modulated signal is another.

Your image appears to be as you describe, but the amplitude is steady.

Perhaps if you shared the schematic you were running in Spice...
 
#4
No, tremolo is not just mixing a low frequency signal to the audio wave form, as Enzo said, it's amplitude modulation of the original signal. Typically a cadmium sulfide type opto-coupler driven by a LFO is used to accomplish that. If you Google "tremolo circuits" I'm sure you'll find many exampls to check out.

Mike
 
#6
Neither is "hard" on the tubes. VArying the bias has the effect of also changing the signal level through the tube. It doesn't misbias the tubes. Think about your breathing. YOu need to have air for oxygen, yet half the time you are exhaling. Just so your bias swinging tremolo. It changes the bias level several times a second, but the average bias doesn't change.
 
#8
My old bassman I,m trying to restore has tremolo on it, the bios method makes a nice visual effect when the 6l6's pulse. but I'm not convinced its worth wasting a valve for, not really a fan of the audio effect itself.
the tremolo in mine hasn't worked for years, only trying to fix as I'm going to sell the amp.

give me a spring reverb anyday lol
 
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