Bode ring-mod vs. modern VCA (functioning as a ring-mod)?

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Sir Ruff
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Bode ring-mod vs. modern VCA (functioning as a ring-mod)?

Post by Sir Ruff » Tue Oct 22, 2019 4:35 pm

In my ongoing quest of maximum 5U/MU efficiency, I'm looking for any way to reduce module count while maintaining certain sounds.

In this case I'm wondering how much I lose when replacing a S-W 640 Bode ring-mod with a standard modern VCA (an STG triple VCA in this case).

Obviously, my ears are the best arbiter, and there certainly is a sound difference, though not a vast one, and I'm not sure if there are any other less obvious differences that I might be overlooking.

The benefit of the STG module of course is that I could dedicate one VCA to being a ring-mod and then still have two others for more VCA dedicated jobs.

syncretism
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Post by syncretism » Tue Oct 22, 2019 8:44 pm

You'll get amplitude modulation with just a VCA, but not ring modulation. You'll need a mixer and one or more inverters (or an attenuverting mixer) to phase the carrier sound out out of the mix, keeping only the sidebands as best as you can. Practically speaking, that's not always easy, but I reckon you can get close enough.

If you're not hearing a major difference, that may be a reflection of how you use amplitude modulation or the sounds you're working with; I can't say! When I want RM, I find I get the best results with a dedicated module. I have an old outboard RM/Frequency Shifter that's pretty good at suppressing the original signal.

Sir Ruff
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Post by Sir Ruff » Wed Oct 23, 2019 2:22 pm

syncretism wrote:You'll get amplitude modulation with just a VCA, but not ring modulation. You'll need a mixer and one or more inverters (or an attenuverting mixer) to phase the carrier sound out out of the mix, keeping only the sidebands as best as you can. Practically speaking, that's not always easy, but I reckon you can get close enough.

If you're not hearing a major difference, that may be a reflection of how you use amplitude modulation or the sounds you're working with; I can't say! When I want RM, I find I get the best results with a dedicated module. I have an old outboard RM/Frequency Shifter that's pretty good at suppressing the original signal.
yeah, I realize this is kind of subjective (and also the difference between AM/RM). Probably that is where the different tones are primarily coming from. the Bode ring-mod has that classic, very mid-rangey tone that I really love, so I've decided it's probably not going anywhere. I also like that sound enough that it's nice to have the option of either AM with a regular VCA or pure RM. And I've decided I can make this all work by getting rid of my 902 VCA (sacrificing "purity" for utility) :banana:

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