MegaDrumWiki - User contributions [en]

File:Megadrum-manager128.png

2014-12-28T11:12:26Z

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Sampling

2014-12-07T22:47:13Z

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The purpose of the sampling block is to transform analog
inputs into an event stream with the following characteristics:

*accurately represents the strength of each hit

*does not produce false trigger events

*emits the event as soon as possible after it occurs
MD has four parameters that allow you to control this
process:

*Gain

*Threshold

*High Level

*MinScan

To explain how these work, let’s consider a simple piezo input. Consider the following (very simplified) output from a sensor that has been struck four times:

[[File:Hits_1.svg|center|frame|Multiple Hits]]

MD uses digital sampling to start the process; this is actually just like sampling an audio signal to turn it into a digital wave.
==Gain==
The first sampling parameter is Gain. Gain can be thought of as a volume knob. Just as a volume knob makes the music louder or quitter, the gain setting will make the signal from the piezo stronger or weaker.

Why would you do this?

When MD samples it expects the voltage of the signal to be in a specific voltage range. If the signal is too weak it will be difficult to detect that something of significance has happened, and if it is too strong, MD will be unable to distinguish between softer and harder hits.

If your piezo is ‘hot’, this means that it is more sensitive and that the electrical signal is already strong and needs a lower gain setting to avoid clipping the input. If your piezo is cool, this means that it is less sensitive and that a higher gain setting will be appropriate.

Gain helps you match what your piezo produces to what MD wants to consume.

Gain is the only parameter that affects the analog signal. The other three are working with the output of the A/D converter.

After sampling, the block has a digital representation of the analog signal with values in the range from 0-1023.

==Threshold==
Any real world analog system has some degree of noise present. This noise is sampled along with legitimate strike signals. For a piezo input, threshold is the level, below which, the signal is considered noise. When the signal rises above the threshold, the sampling block will generate an event.

Consider the following:

[[File:Sampling_hits.svg|frame||center|Threshold]]

With the lower line for threshold, it should be clear that the sampling block is going to generate a large number of events for activity that isn’t actually there. The sampled noise looks like very quiet strikes. A threshold that is too low can demonstrate the following symptoms:

* Repeated notes when nothing is actually happening on an input
* Random notes when nothing is actually happening on an input<ref>Not to be confused with notes that are caused by vibrations between pads that are mechanically connected (we’ll discuss configuring those tools later in the filtering section)</ref>

Of course, the threshold can also be set too high. This will cause MD miss softer notes. Consider the second strike: with the ‘too high’ threshold value, MD will not detect it as a hit.

This is a crucial performance parameter and it may take a bit of experimentation to find a value that works best. Please note that the threshold will be different for different pieces of gear in your set.

==High Level==
The sampling block does not pass the actual sampled level (0-1023) with the strike events. That would make setting the parameters in the other blocks unnecessarily difficult. Instead it normalizes the sampled level to a 0-255 scale, where 0 is the Threshold and 255 is the pad being struck as hard as possible.

High Level is simply the sampling level that corresponds to strength 255 for the event. Any sample levels higher than this will be transmitted as 255. Levels lower than this will be scaled on a straight line to the threshold level.

Tips for setting HighLevel:
* The auto-High level setting will allow the input block to automatically adjust the high level to the strength of the strongest hit it has seen. Briefly turning this on and then hitting the pad as hard as you can, a number of times, will produce a very good first estimate for HighLevel
* Reducing the HighLevel allows a sort of brick wall limiting function. If your sensor occasionally emits a very strong signal, it is OK to reduce the MaxLevel so that these are squashed into the top end of the musically useful strengths.
*Reducing HighLevel too far will reduce the smoothness of your velocity response.
*Raising HighLevel high above the actual levels generated by the sample will also degrade the velocity response, generally limiting the final MIDI notes to lower velocity values, no matter how hard the pad is struck.

==Min Scan==
MinScan controls how long after the input signal crosses the threshold MD will continue to sample the input. Consider:

[[File:Min_scan_time.svg|frame|center|Min Scan Time]]

Remember, that once the input signal crosses the threshold, the sampling block is going to generate an event. The next question is what strength should that event have?

If MinScan is too short, then MD will stop looking while the input is still rising. This will result in a trigger that does not accurately record its potential dynamic range.

However, MinScan represents a delay (latency) between the physical strike and a note being generated. Setting MinScan too long will result in longer latency.
Typically, rubber cymbals and pads are able to use a setting of 20 (2 msec) while mesh heads may require 30-50 (3-5msec). The bigger the pad, the longer MinScan will need to be to properly detect signal level.

<references />

Input Types

2014-12-07T22:36:10Z

Airflamesred: /* Piezo Sensor */

== Piezo Sensor ==
A piezo is an electronic component that (among other remarkable properties) will generate a voltage when struck. The voltage is proportional to the energy (velocity) in the strike. If there is a positional sensing board attached to your MegaDrum this will also measure the distance, from the piezo, that the drum head is struck.
Piezos are used when we need to know how hard something is being hit.

== Switch ==
Typically a film switch, this doesn’t convey information about how hard something was struck, but it can convey information about ''where'' it was struck.

== Potentiometer ==
A ‘volume knob’. This is used to indicate continuous positions (i.e. 10%, 40%, 100%, etc.). This is used for the Hi Hat controller.

== Hall Effect Sensor ==
This is a sensor that works with a magnet to provide continuous positions. It is similar in effect to a potentiometer.

[[Theory of Operation]]

Theory of Operation

2014-12-07T22:24:28Z

Airflamesred: /* Note Selection and Velocity Scaling */

Connecting a Yamaha or Roland drum brain to the corresponding pads is usually pretty simple. However, if you want to use a Roland pad with your Yamaha brain you may end up having to do some tweaking if you can even get it to work at all.

MegaDrum is agnostic with regards to the pad vendor and even supports a wide variety of DIY triggers. In order to do this, it needs to expose many more configuration options than the vendor specific units do. Unfortunately, having this large number of parameters available can make it difficult to understand just what parameter you should adjust when something is not behaving correctly. It can be hard to see the forest for the trees.

'''The purpose of this document is to explain the forest and where each tree fits.'''

(I have pictures that I will add when the wiki allows me to)

== Block Diagram ==
Consider the following (very simplified) block diagram:
[[File:Simple_block_diagram.svg|frame|Simple Block Diagram|none|800x800px]]

=== Sampling ===
The inputs from your pads are presenting some sort of analog signal. The purpose of sampling is to convert this signal into discrete events that can be dealt with more simply.

=== Filtering ===
Filtering is used to remove unwanted events from the event stream. A good example of this would be if a strike on one drum pad caused a faint strike to register on another pad that was connected to the same rack. MD allows a filter to be created that can reduce or eliminate this problem.

=== Note Selection and Velocity Scaling ===
This is the final step before transmitting a note. Based upon the input, a MIDI note and MIDI channel are selected and, based upon how hard the input was hit, a velocity is selected. MD provides some very nice tools for transforming input strike strength into a note velocity.

[[Input Types]]

[[Sampling]]

Main Page

2014-12-07T22:17:32Z

Airflamesred: /* Why MegaDrum */

'''Welcome to the MegaDrum wiki!''' This site is under construction, but eventually we hope that it will be the best place for current information about MegaDrum, as well as a wealth of guides, tutorials, troubleshooting tips and much more!

== About MegaDrum ==
{{Main|MegaDrum}}
MegaDrum is a [[MIDI drum trigger]] module publically released as a [[wikipedia:do-it-yourself|do-it-yourself]] project by [[Dmitri Skachkov]]. It is used as an [[wikipedia:electronic_drum_module|electronic drum module]] without built-in sounds. It is cheap and relatively easy to build for an average DIY-enthusiast.The ability to solder and read a simple wiring diagram is all that is required. For those not so good at soldering, a fully working module in a 1 unit 19" rackmount case is available to order from the MegaDrum site.
== Why MegaDrum ==
The current processor, ARM STM32F205RCT6 chip (November 2014) is running at a clock frequency of - 120MHz, which is the fastest on the market. The speed at which both the original analogue signal and the sound are processed are crucial to an authentic playing experience. This is, overall, the time it takes from striking the drum pad/cymbal to the sound being heard. This is known as latency. The lower the latency the better, a few milliseconds is desirable.

The MegaDrum has 56 input channels which can be configured to how the user requires, and thus, can be used on a variety of projects from standard drumkits to electronic mallets or whatever your imagination can conjure.

To better understand what you can do with a MegaDrum read Zourman's [http://powerhell.wordpress.com/about/zourman/poor-mans-td-20/ poor man's Roland TD-20 article].

=== Links ===
[http://www.megadrum.info/ Main MegaDrum Site] 
[http://www.megadrum.info/forums/index.php MegaDrum Forums]

== Deep Discussions ==
'''[[Hardware]]''' 
'''[[MegaDrum Configuration]]''' 
'''[[VSTi Configuration Guides]]''' 

== How can you help improve this wiki? ==
[[Contributor Guidelines | Glad you asked...]]

Main Page

2014-11-23T20:15:29Z

Airflamesred: /* Why MegaDrum */

'''Welcome to the MegaDrum wiki!''' This site is under construction, but eventually we hope that it will be the best place for current information about MegaDrum, as well as a wealth of guides, tutorials, troubleshooting tips and much more!

== About MegaDrum ==
{{Main|MegaDrum}}
MegaDrum is a [[MIDI drum trigger]] module publically released as a [[wikipedia:do-it-yourself|do-it-yourself]] project by [[Dmitri Skachkov]]. It is used as an [[wikipedia:electronic_drum_module|electronic drum module]] without built-in sounds. It is cheap and relatively easy to build for an average DIY-enthusiast.The ability to solder and read a simple wiring diagram is all that is required. For those not so good at soldering, a fully working module in a 1 unit 19" rackmount case is available to order from the MegaDrum site.
== Why MegaDrum ==
The current processor, ARM STM32F205RCT6 chip (November 2014) is running at a clock frequency of - 120MHz, which is the fastest on the market. The speed at which both the original analogue signal and the sound are processed are crucial to an authentic playing experience. This is, overall, the time it takes from striking the drum pad/cymbal to the sound being heard. This is known as latency. The lower the latency the better.The MegaDrum has 56 input channels which can be configured to how the user requires.

To better understand what you can do with a MegaDrum read Zourman's [http://powerhell.wordpress.com/about/zourman/poor-mans-td-20/ poor man's Roland TD-20 article].

=== Links ===
[http://www.megadrum.info/ Main MegaDrum Site] 
[http://www.megadrum.info/forums/index.php MegaDrum Forums]

== Deep Discussions ==
'''[[Hardware]]''' 
'''[[Theory of Operation]]''' 
'''[[MegaDrum Configuration]]''' 
'''[[VSTi Configuration Guides]]''' 

== How can you help improve this wiki? ==
[[Contributor Guidelines | Glad you asked...]]

MegaDrum Manager

2014-11-22T22:07:03Z

Airflamesred: Created page with "The display on the MegaDrum is rather small and awkward to work with so a PC interface is available. With Megadrum Manager running you can access all the features of MegaDrum,..."

The display on the MegaDrum is rather small and awkward to work with so a PC interface is available. With Megadrum Manager running you can access all the features of MegaDrum, from you PC, far quicker an easier.

MegaDrum Configuration

2014-11-21T19:20:15Z

Airflamesred:

[[Updating MegaDrum firmware]] 
[[MegaDrum Manager]] 
[[Megadrum Commander]]

MegaDrum Configuration

2014-11-21T19:18:46Z

Airflamesred:

[[Updating MegaDrum firmware]] 
[[MegaDrum Manager]]

Main Page

2014-11-21T19:16:26Z

Airflamesred:

'''Welcome to the MegaDrum wiki!''' This site is under construction, but eventually we hope that it will be the best place for current information about MegaDrum, as well as a wealth of guides, tutorials, troubleshooting tips and much more!

== About MegaDrum ==
{{Main|MegaDrum}}
MegaDrum is a [[MIDI drum trigger]] module publically released as a [[wikipedia:do-it-yourself|do-it-yourself]] project by [[Dmitri Skachkov]]. It is used as an [[wikipedia:electronic_drum_module|electronic drum module]] without built-in sounds. It is cheap and relatively easy to build for an average DIY-enthusiast.The ability to solder and read a simple wiring diagram is all that is required. For those not so good at soldering, a fully working module in a 1 unit 19" rackmount case is available to order from the MegaDrum site.
== Why MegaDrum ==
The current processor, ARM STM32F205RCT6 chip is running at a clock frequency of - 120MHz, which is the fastest on the market. The speed at which both the original analogue signal and the sound are processed are crucial to an authentic playing experience. This is, overall, the time it takes from striking the drum pad/cymbal to the sound being heard. This is known as latency. The lower the latency the better.The MegaDrum has 56 input channels which can be configured to how the user requires.

To better understand what you can do with a MegaDrum read Zourman's [http://powerhell.wordpress.com/about/zourman/poor-mans-td-20/ poor man's Roland TD-20 article].

=== Links ===
[http://www.megadrum.info/ Main MegaDrum Site] 
[http://www.megadrum.info/forums/index.php MegaDrum Forums]

== Deep Discussions ==
'''[[Hardware]]''' 
'''[[Theory of Operation]]''' 
'''[[MegaDrum Configuration]]''' 
'''[[VSTi Configuration Guides]]''' 

== How can you help improve this wiki? ==
[[Contributor Guidelines | Glad you asked...]]

MIDI drum trigger

2014-11-21T12:06:11Z

Airflamesred:

'''MIDI drum trigger''' refers to an [[wikipedia:Electronic_drum_module|electronic drum module]] without built-in sounds. The module is only used to convert signals from electronic drum pads into [[wikipedia:MIDI|MIDI]] messages which are then used to trigger sounds on MIDI capable devices such as drum machines, samplers etc. Also known by the acronym 'TMI' (Trigger MIDI Interface).

Examples of MIDI drum triggers include:
* [[MegaDrum]]
* [http://www.edrum.info/ eDrum] which gave an initial inspiration for the MegaDrum project
* [[Alesis Trigger IO]]
among others.

There exists a multitude of PC based drum sampler applications (usually running as [[VST]] instruments) which can be effectively used with a MIDI drum trigger module. Examples of commercial samplers:
* [[Addictive drums]]
* [[BFD]]
* [[EZDrummer]]
* [[SuperiorDrummer2]]
* [[Kontakt]]