I was wondering: if someone was to build a circuit to intentionally add heavy IMD, without clipping, what would you start with?
In other words, what kind of circuits are notoriously prone to IMD?
The closest possible answer is usin an analog multiplier. The transfer function is extremely linear but the output is pure IMD.I was wondering: if someone was to build a circuit to intentionally add heavy IMD, without clipping, what would you start with?
In other words, what kind of circuits are notoriously prone to IMD?
But it is unclear what to use as the two factors to multiply. SMPTE is specifically looking for 60Hz modulation of a 7kHz tone because back in the day movie projectors used incandescent bulbs and 60Hz routinely corrupted audio paths. I guess you could use a crude crossover to separate out a LF pass band, and multiply the full range by that LF content.The closest possible answer is usin an analog multiplier. The transfer function is extremely linear but the output is pure IMD.
yup... +1However I very much doubt it has anything in common with AM. As JR said, restricted BW and dynamics are key.
well, that sounds interesting!How technical do you want to get? A previous research field of mine was pre-distortion linearization, if you search for that you should get some info. Essentially it is an intentional generation of IMD that was then used to cancel out (linearize) the system IMD. The concepts could be adapted for audio once you understand the merchanisms, you just ignore the cancellation part.
I see that I have been beaten on time by @john12ax7Normally, to correct a non-linearity distortion, an equal and opposite one is inserted, a linearity corrector can therefore be defined as a non-linearity generator. Precorrectors are widely used to correct intermodulation distortions in RF amplifiers (usually larger than those in audio amplifiers)
Cheers
JM
Normally, to correct a non-linearity distortion, an equal and opposite one is inserted, a linearity corrector can therefore be defined as a non-linearity generator. Precorrectors are widely used to correct intermodulation distortions in RF amplifiers (usually larger than those in audio amplifiers)
The simplest way would be to use a diode which is a perfectly effective multiplier for this purpose. Using an analog multiplier IC would be considerably more involved but no doubt you could control things more. Also, as a practical point, analog multiplier ICs tend to be noisy.IMD is basically AM modulation where where a high frequency tone is modulated by a lower frequency one and thereby produces sidebands. The simplest way to deliberately create this would be by using a multiplier.
Well, the OP wanted something that doesn't clip. that's why I proposed a solution that has very linear paths.The simplest way would be to use a diode which is a perfectly effective multiplier for this purpose. Using an analog multiplier IC would be considerably more involved but no doubt you could control things more. Also, as a practical point, analog multiplier ICs tend to be noisy.
Enter your email address to join: