Hello OscillatorSync here and welcome to another video where we are building patches from scratch on the wonderful Arturia MiniBrute 2. So pretty much ever since I posted my first video on this I've had people on the channel asking whether I was going to do some videos or digging into the sequencer a bit more because the sequencer on this thing is just fantastic. But I wanted to spend some time really really learning it. I feel like I've got to know it a little bit better now and I'm ready to talk about it. And in this first video we're going to be focusing a little bit more on the sequencer and quite a lot on the patch bay. We're going to do something quite special because we are going to build a true polyphonic patch. We're basically going to turn the MiniBrute into two completely separate mono synths that you can sequence and use completely independently. Let's check out how that's going to work. So on the way to our true polyphonic patch we're going to make our way through a duophonic patch because that's kind of a good starting point on our way there. So it's maybe worth just quickly talking about what the difference between a duophonic and polyphonic would be in this context. So duophonic would be where you have two oscillators which can be tuned independently of one another. So we have our two VCOs here but that then share the rest of the architecture. So what would happen is we have these two oscillators which are going to be moving independently but they're going to meet at the start of our filter and go through our VCA and output. So what that means is that you can have two notes playing but they are being articulated through a common path. So you can't have one note being plucky and the other note being long because they are sharing the rest of the architecture. But that's a good place for us to start so let's take a look at how we can do that. So if we talk about how the synth is set up to begin with, if we have oscillator 1 and 2 turned up by default the pitch will follow each other. And you can actually kind of see this on the patch bay here. Here on the pitch of VCO2 it says pitch 1. So it's basically saying that at the moment VCO1 and VCO2 are kind of coupled. You can tune them independently but they will move together. So that's the first thing we need to do, we need to decouple those two things. Now it's a decouple that is really really easy. If I just stick a patch cable into the pitch 2 input of VCO2 you can hear now that VCO2 is not moving with VCO1 anymore. So we've kind of got a geophonic synth now, it's just that at the moment we have no control over the second pitch. We want to give ourselves some control over that second pitch. So what I'm going to do is I'm going to make use of one of the mod tracks here. So if we go through our four tracks here, track 1 is always doing pitch and track 2 is always doing gate. And those two are sort of coupled together. If I go into record mode and I put a step on pitch that we want on at gate as well. Now by default our two mod tracks here are recording the velocity and the pressure as we play but that's not all they can do. They can do a bunch of different things and we can change their modes by holding down the track and we can use the scroll wheel to pick something else. So I'm going to roll that back so that this track is also doing pitch. So that means now if we look on here on our knobs for mod 1 we're getting pitches. Great, that's a good starting point and you will be unsurprised to know now that we are going to control the pitch of VCO 2 with this mod track here. Now the first thing we want to do is get it so that these two tracks are going to be scaling together. So I'm going to go into our pitch track here which is now only controlling VCO 1 remember. I'm going to stick a step here, I'm going to set it to C3 and I'm going to set the last step to just this step here. So this track is just going to go just play C over and over again and I'm going to do exactly the same thing on the third track here on mod 1 track which is now controlling VCO 1. I'm going to stick a note there make sure it's playing C3 which it is. I'm going to set its last step here and this is going to be cacophonous and I'm going to set, I've got it already set onto all here and I'm just going to make sure that the two oscillators are now tuned together. That's probably close enough. So if we remove this last step here and on this one as well, this now means that we can. So maybe if I just put that sequence there but we can now put completely different pitches here. So this one can go down to that one there. Why do I have them? This one can be going down to A. I'm just trying to remember what I put in the other one. This one here can be going down to A. And now we can hear we've got two notes which are now moving independently. Which is quite cool. However, if I change the filter here it's changing the filter for both of them. So I can't have one bright and one dark. And more importantly if I stick another note say here on. Can you hear how it's just barely coming through? The reason for that is that this note isn't triggering the gate in the same way that these notes are on this one. As I said, the pitch and the gate are coupled here. So that means that on this note here the AD envelope is already pretty much closed because it's not firing out another gate. So we've got a duophonic situation here but not a polyphonic situation. So we've decoupled our pitches of our two VCOs. Now I want to decouple oscillator 2 from the rest of the synth architecture. I want it to basically skip all of the rest of the stuff here, the filter and the VCA. That's pretty straight forward to do. So I'm going to take the output of VCO2 and if I plug it into master there. You can hear that VCO2 is just ringing through and it's like that for a second. And indeed, now if I put another note in here, you'll hear that we do actually hear that note change. But of course, we don't want this oscillator just droning the whole time. Oh, also note that I've turned down oscillator 2 now. We don't need to have this turned up to hear it because we are skipping literally everything. Plugging something into the master input literally puts it just before the master volume here. So I mean we are skipping everything else. Now the downside of that is that we don't have any controller for its volume anymore. Just want to have to keep unplugging it. We want to have some control over its volume. What do we have in our synth architecture here which allows us to have control over the volume or to put it another way, amplitude, we have our voltage controlled amplifier. So rather than going straight into the master, we're going to go via the VCA. And then we're going to take another patch out of the VCA and into the master. Now that's still going to be ringing out the whole time at the moment and that's because we're not controlling the CV of the VCA. So it's just fully open at the moment. We've basically achieved nothing except for the fact that we now have CV control over this VCA. Now what are we going to use to control the CV here? Now we have two quite capable envelopes here. However, let's take our main sound on the pitch sequence here. We probably want to control its filter cut off a little bit so maybe something a bit plucky like this. That's great. Except I've now used up both of our envelopes and I can't use one of these envelopes to control the envelope for our VCA because if I do that we've lost our polyphony straight away. We've recovered the architecture in a way. Now you might be thinking, well, there's our two envelopes. What else could we do? Could we hack the LFOs to kind of work it? Maybe not keen on that. Get this. One of the modes for our mod tracks is, if I just scroll through here, where is it? Env. This is incredible. I can't get over how cool this is. What the Env track allows us to do is literally put an envelope, an AD envelope, so attack, decay, envelope and sequence it. We can sequence the attack and we can sequence the decay of this envelope. That's mad. Just incredible. I'm going to take the CV output of our second mod track, pop it into the CV of our VCA and I'm going to stick that into the master output. Now you can hear that we haven't got anything happening because the track at the moment is set to zero. It's closed essentially. When you're trying to get this sort of polyphony patch working, just a little caveat. As I said before, the pitch and gate here on our pitch and gate tracks, they're coupled. Step down on one, you get a step on the other. That's not the case for all our mod tracks. What we do have to go through and do, if we want each of these steps to play a note essentially, perhaps we'll put another, another female or something, is just go through and just copy across where we have those steps. I'm just going to copy that one, I've got two there, and I've got one there, like that. Now if I hit play, you can hear that we've got two separately articulated notes. We can start to sequence this envelope track. By default, if I turn the knob here, I'm changing the decay. If I want a long note here, maybe one there as well. We can also do the attack by holding down shift and turning the knob instead. Say I want a bit of an onset here, be longer, that's cool, go and attack there. The other nice thing is that we don't have to have a note playing on the pitch to put another envelope, so if we want to do doubles, we don't have to put another one here. Two entirely separate tracks going on together that we have pretty much full control over. I say pretty much full control over, because this is pretty good, but our first oscillator, which is going through the filter and stuff, we have control over its timbre, so we can do all this stuff. We kind of can't currently do that with our VCO2 because it's skipping the rest of the architecture. So the question is, can we get some timbre change happening with this other voice as well? I reckon so. It's going to take a little bit of repatching and one sort of special gift, if you like. So one of the really cool things about the VCO1 section, or rather the VCO1 section here on the patch bay, is that the metalizer on our triangle wave, which allows us to do stuff like this, that's basically a wave folding circuit. The nice thing is that we can put anything into that because we actually have a metal in here, and if you put something into the metal in and then take the triangle out, you'll get wave folding applied to whatever came in here. So what that means is this, rather than taking our output of our VCO, which is controlling VCO2 and putting it straight into master, let's go via metal in and then from the triangle out, which is now our output of the metalizer, rather than our triangle, we go into the master here instead. We could do it the other way around instead, actually. Perhaps we should do it the other way around. We should, yes, let's change that a little bit. So I'm going to change my mind in here and then go from the output of our VCO2 into the metal in and then from the output of our triangle, our metalizer into the VCO in there and then come into the master there. The reason being that the amplitude is going to affect how metalized things get. I'm going to switch over to the sine wave for our second oscillator now because that's going to metalize better. So I'm going to turn down everything from the first VCO here and just hit that beautiful sine wave. First we now metalize it, get all these cool additive new harmonics, super cool sounding. But I can't be sat here twiddling that knob constantly. Do you know what? I'm just going to transpose that down an octave, so I think it's going to sound better. Cool, yeah, sorry. Anyway, I can't be sat here twiddling this knob. I want to be able to control it and that's what the metal mod input is for. Now, even with our envelope tracks, we've now run out of envelopes, so we could have this being done by an LFO and have it sweeping. I kind of want it to work with the envelope. I kind of want it to almost be like a West Coast synthesizer where you've got that wave folding thing that's being controlled by an envelope. It's a really cool sound, so let's try and emulate it. Now, what I really want to be able to do here is take the output of our envelope and send it both to the CV and to the metal mod input here. We can't do that because we don't have a malt, essentially on this patch bay. But as recommended to me by Div Kid, I have picked up some stack cables from Tip Top. What these allow you to do is patch something in, but also tap that patch to go somewhere else as well. Neat. So I'm going to unplug my CV control there, so it's going to start ringing out. I'm going to repatch it with my stack cable here. So this is now working exactly as it was before. Perfect. And then I'm going to take the top of the stack cable, so I'm copying that signal and I'm going to stick it into the metal mod input here, which now means that if I turn up the metal mod, I haven't actually patched it in. There we go. There it is. Barsing. There we go. I was wondering why that wasn't working. Now here that we're getting that timbrel change along with our volume envelope happening. That's really, really cool. It's kind of like working backwards with a filter. This is additive rather than subtractive. It's got a really cool sort of metal, as the title would suggest, great with plucky sounds. Let's bring that other VCO. Two entirely separate sequences. Let's see if we can drop the octave again. Really cool. The cool thing here is that we can now change the last step of one of the sequences to get them rolling over each other because they're working entirely independently so perhaps we'll come in here and we'll do some repeats.  So what we've got here now is rather than having a mono synth, we've got kind of two mono synths and it's all possible because these mod tracks can fire up their own sequenceable envelopes. I can't overemphasize how mad that is. Just so much fun. So that's some reverb. I could sit and mess with this. This just needs a kick drum. All right, amazing. Where's a drum machine where I need it? Anyway, that's enough of that. Anyway, I hope you found that interesting and that it might have opened your eyes some of the power that the mod tracks on the sequencer have. I'm going to do at least another two videos that I have planned digging into some more of the alternate modes on the mod tracks because I really think that the sequencer on this synth is incredibly generous and incredibly powerful. You know, if they released Artoria, please do release Beatstep Pro 2 that has some of these alternate modes, has the ratcheting. Man, it would be an instant buy for me and I suspect for a lot of people out there, especially people with modular setups because some of the stuff being able to sequence envelopes, just really, really powerful, really, really interesting. So if you enjoyed that, if you found it interesting, please do hit the thumbs up button. It does help me out. Make sure you subscribe if you're interested in seeing some more stuff like this because, as I say, I've got a bunch more videos planned to talk about some of the more interesting features on the MiniBrute 2S. Until next time, take care. Bye-bye, see you soon.


Hello all, in this video I am going to deal about basics of sample size calculation. Our ultimate aim is to select a sample size from the population. We cannot do our study in all of our population because it involves more cost, time and personal. It is neither feasible nor ethical also. So we are taking a few sample from the study population and we are doing our research. While doing so we should ensure the representativeness of the sample to the population so that the results from the sample will be generalizable to the population. We have five major steps in sample size calculation. First is we need to identify the major study variable and its type whether it is a number or a percentage. After identifying the major study variable and its type the step two is doing a thorough review of literature and identifying the expected frequency from a similar study. Step three is understanding the parameters used for sample size calculation followed by calculating the sample size which can be done by formula or online calculators, apps and software. Formulas are going to be the more complicated method to calculate the sample size which I am going to demonstrate and online calculators are the most easiest which also will be demonstrated in the end. Step five is the adjustments. There are three adjustments here. Adjustments for population size, design effect and response rate. So now we are going to deal with each steps in detail. Step one is identifying the major study variable and its type. For example if the study variable is exam result then we need to decide whether we are going to measure the average or mean marks of the study population or we are going to measure the mere pass or fail status from the study population. If your study interest is on anemia we need to fix whether we are going to measure the hemoglobin level of the population or we are going to check the status of anemia present or not. After fixing the study variable and its type we need to do a thorough review of literature, identify prevalence from the similar study. If we are not able to get a similar study then we are supposed to do a pilot study or we need to go with the maximum prevalence for proportion as 50% which will yield the maximum sample size. In the third step we need to understand the parameters involved in calculation of sample size. For sample size calculation we need to be clear about the types of errors. We have two types of errors that is type one or alpha error and type two or beta error. The null hypothesis which says that there is no significant difference may be true or false. Our study result may accept it or reject it. If we correctly accept a true null hypothesis then that is the right decision. If we correctly reject a false null hypothesis then that is also a right decision. If we falsely reject a true null hypothesis then that is called as type one error or alpha error and if we falsely accept a false null hypothesis then it is called as type two error or beta error. The 100 minus beta will yield you the power of the study. The probability of committing an alpha error is called as p-value. After fixing the level of these errors which is most commonly going to be 0.05 or 0.20 we need to look at this z-table corresponding to the alpha and beta error values which we fixed before calculating the sample size. We have the liberty to allow this alpha error and beta error before calculating the sample size. As we are stingent in allowing this alpha error and beta error then your z-value is going to increase and increase your sample size because z-value is directly proportional to the sample size. The step four is going to calculate the sample size. There are various ways to calculate sample size that is you can calculate directly by applying the formula or online calculators, absence software. In this presentation I am going to show you calculating the sample size through formulas and online calculators. When proportion is the parameter of our study then the formula is going to be n is equal to z-square p-q by d-square where z is the standard normal dv8 or the z-value p is the proportion or prevalence of the interest from the similar study which we got through the review of literature and q is 100 minus p, q is 100 minus p, d is clinically expected variation or precision. This can be either absolute or relative precision. This precision is the value which will be altered by the researcher in order to adjust the sample size. Here is one example. From a pilot study it was reported that 28% had anemia, it was decided to have 95% confidence interval and 10% variability in the estimated 28%. How many patients are necessary to conduct the study? So what is given here is the prevalence, 28% through a pilot study. This can be through a pilot study or through review of literature from the similar study. So q is 100 minus p which will yield 72%, z-alpha is 1.96 for alpha at 0.05, d is 10% of 28%, that is 2.8% because it is given as 10% variability in the estimated 28%. So it is going to be the relative precision of 10%. So the formula given here is n is equal to z-square pq by d-square. So substituting the values 987.8 as the required sample size. Now how to write up this in our protocol or the research article? So a sample size of 988 would be sufficient to observe 28% prevalence of anemia with 10% relative precision and 95% confidence interval. Now when mean is the parameter of our study, how to calculate the sample size? So the sample size, the formula is z-square instead of pq we have this standard deviation square divided by d-square. d is the difference between the mean or the clinically expected variation. So z is same standard normal deviation at the z value, s is sample standard deviation, d is clinically expected variation or the precision between the means. Here is the example for calculation of sample size for estimation of mean. In a health survey of school children it is found that the mean hemoglobin level of 55 boys is 10.2 per 100 ml, a standard deviation of 2.1, consider the precision as 0.8. So mean is given as 10.2, standard deviation is 2.1, z value is going to be 1.96, d is going to be 0.8, the formula is n is equal to z-square, standard deviation square divided by precision square, so substituting the values you will get 26 as the sample size. Now we are moving on to the next two scenarios that is when we are going to compare two groups for proportion and means. So when the proportion is the parameter of our study, the formula is n is equal to z-alpha and z-beta whole square into p into q into 2 divided by d-square, p is equal to average percentage between two groups, q is equal to 100 minus p, whereas d is the precision, here it is clinically meaningful difference between two groups. So here is one more example, prevalence or the combined prevalence of is given as 10.4 percentage, so q will become 100 minus p, so 89.6 percentage, z-alpha is 1.96, z-beta is 1.282 for beta error at 0.10, so substituting these values will yield 125 in each arm. So when mean is our parameter of our study, the formula is n is equal to z-alpha plus z-beta whole square into standard deviation square into 2 divided by d-square, where s is standard deviation between the two groups, d is the clinically meaningful difference. So here is an example for calculation, so mean duration of ICU in hours for a low dose is 61.7 and high dose is 33.2, standard deviation is given here. We are fixing alpha level at 0.05, beta level at 0.10, so substituting the formula we will get n is equal to 210, if we are keeping the beta error as 0.10 and if we are keeping the beta error as 0.20, then we will get 157 as required sample size. Now the fifth step is adjustments after calculating sample size, which usually researches miss while calculating sample size. We have three adjustments, finite population correction, design effect, response rate. This design effect and response rate is going to increase your calculated sample size, but finite population correction will decrease your required sample size. What is finite population correction? If the population is small, then the sample size can be reduced slightly. This is because a given sample size provides proportionately more information for a small population than a large population. Here is a formula for finite population correction. The new sample size is equal to the calculated sample size divided by 1 plus calculated sample size minus 1 divided by the total population size. Now the two factors which may increase the sample size is response rate and the design effect. For non-response rate, the sample size can be modified using this formula. The required sample size is equal to calculated sample size divided by response rate. Remember, here we are not using the non-response rate. Instead, we are dividing the response rate with the calculated sample size to yield the required sample size. Now the third adjustment is for the cluster designs, we should inflate the sample size based on the design effect. Now how to calculate the design effect? So design effect is going to be 1 plus b minus 1 into rate of homogeneity, where b is equal to the cluster size and RoH is rate of homogeneity, otherwise called as intracluster correlation, which will be ranged as below. And we have to remember, for sample size calculation of case control studies, survival analysis, and validation studies are going to be different. Validation studies are diagnostic studies. The formula for validation studies or diagnostic studies is given here. Those who are interested can pause the video and can check. Now I am going to demonstrate how to calculate sample size using online calculators. So I am using here cleancalc.com for the sample size calculation. So here all our four scenarios will be given. So you need to select between this study group, whether you are using one group or two group. So if suppose let me start with one group, and whether if we are dealing with the categorical or a dichotomous variable, or we are dealing with proportion. So we will click like this. The calculation will appear here. So here they are asking for non-population in order to have this finite population correction. And the study group prevalence they are asking. And all followers we can adjust. And based on that, they will apply the z value and calculate the sample size. Same way we can use for one group continuous variable. The calculations will be here. Same way we can compare between two independent study groups. And means can be calculated. So group one anticipated mean and group two anticipated mean has to be substituted. And alpha and power will be here. Same way two group dichotomous variables can be calculated through this online sample size calculator. Here is one more tool for online sample size calculation that is select-statistics.co.uk, where you can have these calculators comparing two mean sample size, population mean sample size, comparing two proportion sample size, population proportion sample size. In this tool, you can get the information about, if you have any doubt about the information which you are feeding, you can check this info icon. After substituting these values, we will get a sample size, calculated sample size. And in alternative scenarios, when we are adjusting this alpha and beta error, how the sample size will change also will appear. So from this written example, we can get an idea on how to write this in research paper or your proposal. Basically, the sample size calculators is for estimation of a population proportion, population mean, and estimating an odds ratio, which we have not discussed. That also can be calculated using this online sample size calculator and comparing two proportions and comparing two means. This select statistics.co.uk and cleancalc.com are easy to use. To summarize, we have five steps in sample size calculation. Step one is to identify the major study variable and its type, whether we are going to estimate a mean or a proportion. Step two is, after deciding on the major study variable, we are going to do a thorough review of literature. We are going to get a similar study and the expected frequency of the variable. Then the third step is to understand the parameters used for sample size calculation. And fourth is to calculate the sample size either by formula or online calculators or apps or software. And the fifth is the adjustments. There are three types of adjustments. One is the finite population correction. Number two is the design effect adjustment. And number three is the adjustment for the response rate. Thanks for watching this video. If you like this video, please share it to your friends and subscribe to our channel. Thank you very much.