Ring mod question

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jeepo
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Post by jeepo » Fri Dec 18, 2009 5:11 pm

Bryan T wrote: Does it act the same as when you us the internal carrier? With my old ring mod I found that the shape of the tremolo effect changed based on where the mix knob was set. Mix on 10 was triangle shaped, mix on 5 was the same except it was half the speed, mix on 6 had a slight hiccup to the sound, as did mix on 4.

It is a behavior of the mix knob that never made much sense to me.

Thanks!
I think that the differing shape of the tremolo may be caused by wave interference of the input, and output waveforms, which results in beating, which, if slow enough will sound like tremolo. I don't exactly understand how the ringmod works, as i am not an electrical engineer, but I don know that the modulated signal consists the input frequency + & - the carrier frequnecy. With a low carrier freq, 5Hz, and an input of 262 Hz (middle C) the output would be 257 Hz, and 267 Hz. The two output signals would then beat at 10 Hz (beat frequency = [f2 - f1]), thus a 10 Hz tremolo would be heard, mixing in the input would result in two 5 Hz beat frequencies, which may then interfere with the original 10 Hz beat frequency, producing yet another 5 Hz beat. Which would then mean that with the mix set to ten the tremolo frequency should be twice that of the mix at five, which, based on my experimentation i find not to be so, thus i conclude at low frequencies I do not know how ringmodulation works, any other interpretations will be much appreciated
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Bryan T
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Post by Bryan T » Fri Dec 18, 2009 6:37 pm

jeepo wrote:I think that the differing shape of the tremolo may be caused by wave interference of the input, and output waveforms, which results in beating, which, if slow enough will sound like tremolo. I don't exactly understand how the ringmod works, as i am not an electrical engineer, but I don know that the modulated signal consists the input frequency + & - the carrier frequnecy. With a low carrier freq, 5Hz, and an input of 262 Hz (middle C) the output would be 257 Hz, and 267 Hz. The two output signals would then beat at 10 Hz (beat frequency = [f2 - f1]), thus a 10 Hz tremolo would be heard, mixing in the input would result in two 5 Hz beat frequencies, which may then interfere with the original 10 Hz beat frequency, producing yet another 5 Hz beat. Which would then mean that with the mix set to ten the tremolo frequency should be twice that of the mix at five, which, based on my experimentation i find not to be so, thus i conclude at low frequencies I do not know how ringmodulation works, any other interpretations will be much appreciated
The mix control with an LFO carrier has never made sense to me. When I got my ring mod I expected it to work like the depth knob on a tremolo pedal, but it definitely doesn't do that. I need to sit down and work through the math to better understand it.

Ex. Audio is 440 Hz. Carrier is 5 Hz. The sum is 445 Hz and the difference is 435 Hz. If I had three oscillators, one tuned to 440, one to 445, and one to 435 would it sound like tremolo? I guess, though at first glance it looks like it would just sound out of tune. Hmm.

Thinking a bit more. If the mix is on 10, then you'd hear 445 Hz and 435 Hz. If the mix is on 5 (it probably depends on the taper of the pot), then you'd hear an equal mix of 445, 430, and 435. Since the mix knob both increases the wet signal and decreases the dry signal, you can get any combination of 445/435 and 440.

It actually makes sense to me.


So, back to my original question, the mix knob should work the same for a square wave carrier frequency.

Clarity.

Lux_Seeker
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Post by Lux_Seeker » Fri Dec 18, 2009 8:23 pm

Perhaps clarity for you but I will have to think about this some more. Not to complicate matters, but also realize the difference formula for ring modulation is simple with sine waves which but when the carrier becomes complex, things get more interesting. Saw waves especially are harmonically rich (or phat). But now the two diffeences become multiple differences. I think ring modulators work well with guitars because once the note begins to decay, the waveform becomes more sine wave like and therefore, the ring modulation less harsh to the ear.

If both the carrier and the modutor have many partials, then I am actually not sure what the math gives you at that poing but its probably not pretty. I also find this with sounds. Ring modulation works well with thinner sounds.

Bryan T
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Post by Bryan T » Fri Dec 18, 2009 8:33 pm

Lux_Seeker wrote:Perhaps clarity for you but I will have to think about this some more. Not to complicate matters, but also realize the difference formula for ring modulation is simple with sine waves which but when the carrier becomes complex, things get more interesting. Saw waves especially are harmonically rich (or phat). But now the two diffeences become multiple differences. I think ring modulators work well with guitars because once the note begins to decay, the waveform becomes more sine wave like and therefore, the ring modulation less harsh to the ear.

If both the carrier and the modutor have many partials, then I am actually not sure what the math gives you at that poing but its probably not pretty. I also find this with sounds. Ring modulation works well with thinner sounds.
I think some experimentation with the MP-201 providing the carrier signal to the Ring Mod is in order.

Can you have the user-defined ADSR envelopes act as LFOs? (i.e., can you have them repeat without some sort of gate signal triggering them?) There are some very interesting tremolo sounds possible, I think.

Lux_Seeker
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Post by Lux_Seeker » Fri Dec 18, 2009 8:42 pm

I think your right. :D It's why I own Moog products. Digital stuff is frankly boring. I never program a digtal synth and say, I think. I pretty much know what I am going to get. Don't get me wrong, I like my digital synth but my Moog analogue gear, well, it turns me into the made scientist. A few days away from getting back to my studio but I will try this. In fact, I think I will print this thread and try a lot of stuff. Just learning to use the MP-201 awsome beast that it is.

DontBelievetheHype
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Post by DontBelievetheHype » Sat Dec 19, 2009 6:27 am

Bryan T wrote:
I think some experimentation with the MP-201 providing the carrier signal to the Ring Mod is in order.

Can you have the user-defined ADSR envelopes act as LFOs? (i.e., can you have them repeat without some sort of gate signal triggering them?) There are some very interesting tremolo sounds possible, I think.
Yep you can set the ADSR envelopes to One-shot, or to Loop; The Treadle, Footswitches, or MIDI notes can be chosen as the Gate 'Trigger', and they can be Latching or Non-latching; So when the HADSR envelope is set to 'Loop' and the Trigger to 'Latching', you can turn it on/off like an LFO, tweak the parameters in real time while looping, etc.

With the Ringmod, I've only been using short ADSR envelopes to make percussion, but have worked on some other looping envelopes with the filter successfully, though Im mostly interested in MIDI syncable modulation (for live use) so I haven't spent tooo much time with it. When using the Ringmod's Carrier In, I've found it to reach full amplitude at about +2.5v, and after that it drops back down to 0 volume (ie plug a 5v exp pedal In and from heel to toe you get a manual tremolo; cut the voltage in half and you instead get full volume at toe down.)

When I originally posted about using the MP201 as the Carrier with the Ringmod, I had noted that it worked great except for using the MP's squarewave, which resulted in a significant volume drop, but I've since rectified that by cutting the stock voltage setting in half. Now back to your original question:
Bryan T wrote: Right, a square wave as carrier gives an on/off envelope to the amplitude. However, at different settings of the Mix knob the behavior is (probably) different. With the internal carrier you can change the tremolo effect based on the Mix knob setting. I'm curious how the Mix knob affects the tremolo effect when you use a square wave as the carrier.

Sadly, I sold my ring mod before really exploring alternate LFO sources for the carrier signal.
I experimented with the Ringmod, and the MP201+Ringmod just now for 30min; First off, I noticed what you're talking about with the Mix knob, though this is only present when using the internal carrier: As you noted, when I get to 6 on the dial (Mix) the squarewave's pattern changes, adding a little rhythmic pulse to it, and at about 4 the speed of the trem seems to be cut in half. When using an External Square wave as the Carrier, there is no change with the Mix knob settings, other than the wet/dry mix.

BUT, when you lower the LFO offset about 40% (interesting percentage..) it has a similar effect as using the *internal carrier with mix at 6*, adding in an extra hump or whatever, giving it a more rhythmic fee similar to the Internal carrier behavior noted- there is more inherent noise and use of a lag processor is necessary. As you lower the offset more, it does not continue to act like the Internal carrier+mix knob, but it does make for a choppier tremolo.

Anyway, this thread is long and confusing, but I think I got the jist of it; If there's anything I missed let me know :)
Synth bass guitar rig including MS-20 filter clone, Paradox TZF, MF101, 102, 103, 107(x2), CP-251 and MP-201

Just Me
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Post by Just Me » Sat Dec 19, 2009 8:26 am

You want to SEE what is going on? Put an O'scope on the input and output and look at the wave form.
"Music expresses that which can not be said and on which it is impossible to be silent."

Maskin
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Post by Maskin » Sat Dec 19, 2009 8:58 am

Just Me wrote:You want to SEE what is going on? Put an O'scope on the input and output and look at the wave form.
That's a great idea! Will try that soon.
[size=75]"I like to play with electronic noise makers. I hope someone wants to listen, and if not, I'll still be up at 3 am making sequences in the dark, drinking coffee, and burning expensive incense." [i]Rod Modell[/i][/size]

Lux_Seeker
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Post by Lux_Seeker » Sat Dec 19, 2009 10:06 am

Just Me wrote:You want to SEE what is going on? Put an O'scope on the input and output and look at the wave form.
I have thought about getting one actually because I think this does make things easier to figure out.

Bryan T
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Post by Bryan T » Sat Dec 19, 2009 12:07 pm

DontBelievetheHype wrote:Anyway, this thread is long and confusing, but I think I got the jist of it; If there's anything I missed let me know :)
Thanks! That was a great response.

Maskin
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Post by Maskin » Sat Dec 19, 2009 1:10 pm

Lux_Seeker wrote:
Just Me wrote:You want to SEE what is going on? Put an O'scope on the input and output and look at the wave form.
I have thought about getting one actually because I think this does make things easier to figure out.
I bought one from work earlier this year but I rarely use it, I'm glad I still have it.
[size=75]"I like to play with electronic noise makers. I hope someone wants to listen, and if not, I'll still be up at 3 am making sequences in the dark, drinking coffee, and burning expensive incense." [i]Rod Modell[/i][/size]

Bryan T
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Post by Bryan T » Sat Dec 19, 2009 1:37 pm

DontBelievetheHype wrote:BUT, when you lower the LFO offset about 40% (interesting percentage..) it has a similar effect as using the *internal carrier with mix at 6*, adding in an extra hump or whatever, giving it a more rhythmic fee similar to the Internal carrier behavior noted- there is more inherent noise and use of a lag processor is necessary. As you lower the offset more, it does not continue to act like the Internal carrier+mix knob, but it does make for a choppier tremolo.
I was thinking about your comments in the shower (I'm a dork!). The Ring Mod's internal carrier is designed to be at the same intensity as the audio signal. The LFO that you are feeding it from the MP-201 might not be at the same intensity. Thus, the mix knob can change in behavior (affecting the sound of the tremolo) because it isn't necessarily mixing signals of similar amplitude. That would be consistent with your findings when changing the LFO's offset, though the offset is going to change both the max and min value of the LFO.

I need to get a ring mod, an MP-201 (I sold mine before the major update), a Voyager Old School, a Moog guitar, and the rest of the MoogerFoogers. Sounds like a fun shopping spree for when I win the lottery.

Bryan

moremagic
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Post by moremagic » Sat Dec 19, 2009 2:52 pm

Bryan T wrote:The Ring Mod's internal carrier is designed to be at the same intensity as the audio signal.
I'm not so sure about this; I think the carrier is just line-level all the time. I know the ring mod sounds weak when using an external instrument-level carrier with the mix at ten, which is mildly disappointing since its a pain to make enough space in my gear to get a non-audio (at least in use) signal boosted up to line level

jeepo
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Post by jeepo » Sat Dec 19, 2009 5:37 pm

Maskin wrote:
Just Me wrote:You want to SEE what is going on? Put an O'scope on the input and output and look at the wave form.
That's a great idea! Will try that soon.
Please share your findings, I would love to solve the mystery of the ringmod's function, but my school just went on break, so I don't have access to a scope for about a month.
Stage II, MF-102, MF-105m, MF-107, paia theremin, akai s2000, yamaha pss 680, yamaha cp 25, and other stuff

Bryan T
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Post by Bryan T » Sat Dec 19, 2009 10:05 pm

moremagic wrote:
Bryan T wrote:The Ring Mod's internal carrier is designed to be at the same intensity as the audio signal.
I'm not so sure about this; I think the carrier is just line-level all the time. I know the ring mod sounds weak when using an external instrument-level carrier with the mix at ten, which is mildly disappointing since its a pain to make enough space in my gear to get a non-audio (at least in use) signal boosted up to line level
I misspoke. My point was that an external carrier in is potentially not at the same level as the internal carrier in, which means that the mix knob would function differently with the different signals.

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