Showing posts with label Eurorack. Show all posts
Showing posts with label Eurorack. Show all posts

Wednesday, 31 August 2016

Malekko - Wiard - Xmix


The  Malekko Wiard XMIX is a mixing/crossfading utility module.
I understand it's different from the 300 series Mixolator which used a  CA3280 transconductance amplifier.

 The XMIX is 8hp wide, 25mm deep, and consumes approximately 45mA power.

There are two inputs (X and Y). 

The Y input can be inverted via a switch.
Z controls the balance of X Vs. Y. 
Z has a CV input, along with an attenuator for CV amount. 
Positive and negative outputs are provided, as well as an Expand input which provides a unity input to chain the output of other modules (such as another XMIX).


Some uses for the XMIX (Manufacturer's manual):
– A 2 > 1 Mixer
– CV crossfading
– A signal inverter
– Audio rate amplitude/crossfading modulation
– With a single input, you can use the XMIX as a linear VCA
– Input different waveforms to create new wave shapes
– The X input normals into the Y input when nothing is plugged into Y. Invert the Y input with the switch, and crossfade the X signal VS the inverted version of itself
 
 
 
 
 
 
 
 
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There is a three pin connector on the back of the PCB that goes hot-ground-cold.

Connect this to an XLR or TRS and you have a low impedance balanced send.

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mAKING  a  ADSR Envelope.
You will need two Envelators. 
 

1. Set 1st to AD mode, and 2nd to AR mode.
2. send a trigger to the 1st Envelator.
3. send a gate to the second envelator .
4. take outputs of each Envelator into the inputs of the xMix
    AD Envelator plus output to X input of XMIX (X control set to max)
    AR Envelator plus output to Y input of XMIX (set Y polarity to plus and Y control to max).
5. The ADSR envelope is available at the XMIX plus output 
6.  The XMIX "Z" control acts like a "Sustain" control.  
     The "ZMOD" input can be used as voltage controlled sustain level input.   
 
Take the output of the xMix and input into a VCA 

The Wiard Xmix can be used as a mixer & as a VCA.
I find there is a little bit of audio bleed when I use the Xmix as a VCA.
I prefer to use a dedicated VCA for this task.
 
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Balanced (ring) modulation. 
  • 1. Make sure the X & Y knobs are at full.
    2. Connect your carrier sine wave (or whatever) to the X input.
    3. The Y input is normalled to the X input so the carrier is going to X + Y.
    4. Switch the Y input polarity to negative (minus).
    5. Monitor the plus output.
    6. Adjust the Z control to get the best carrier null.
    7. Now run anything into the Z control input (modulator), Z Control is the volume for the modulation input.
 Thanks to "shady smiles" for the ring mod patch.
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Unbalanced modulation (VCA)
 

 X in = Audio in
+ out = Audio out.
Zero both Y & Z pots.
Z control pot is set to Max
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
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Links:

Wednesday, 17 August 2016

Compressors for Audio

 This is an attempt to demystify audio compressors.
They are useful both in the music studio and when performing live.
It's all about reducing & smoothing the audio peaks and troughs.

I have a few different types, ranging from small modules to rack units.
They all however have similar controls.
There are also quite a few eurorack compressors.
My favourites are the WMD MSCL and the L-1micro compressor 


You can actually build a compressor with a envelope follower, a an inverter and a VCA. A modular compressor is essentially a voltage controlled envelope follower tied to a VCA.
 
+ Modular Compressor -using eurorack modules
 
 
The MSCL is unusual in that it doesn't have the usual controls.It's inspired by the classic 
DBX "over easy"style compressor . The threshold, gain & output are all controlled with one
knob and two switches. 
 
This is an excellent stereo compressor for a small modular system. It packs in a lot for just 4HP
 
The Limit Switch limits the make-up gain allowing the MSCL to act like a peak limiter. 
The Threshold Switch helps compress signals of different amplitudes. Both modular & line level.


Both switches have 3 settings:left (off), middle(half on),right (full on).
The side chain input helps create your ducking sounds.
 
To turn on the compressor, I like to turn the LIMIT to the left & 
THLD (Threshold) slide switch to the middle to start with.
 
The Limit is your final volume. 
The Threshold is the volume the audio has to reach before compression begins.
 
I usually end up with both switches in the middle or maybe one of them 
to the right (usually the threshold).
Often I'm mixing Line Level audio with Modular audio and these have 
huge volume differences.
 
The lower toggle switch needs to be in the centre position.
I usually set the COMP knob to around 75% and GAIN to 50%
As you turn up the COMP knob you will see the LED change from red to green.
Red is your gain reduction. Green is gain addition.
(The GAIN knob is your Makeup... so use it at the end of the audio chain). 

Play around with the envelope. Turning up the attack will let the
beginning of your kick drum through. These envelop knobs are a great
performance feature

The bottom 3 throw toggle switch has side chain, in, out.
IN = wet compressed signal
OUT = dry uncompressed signal.
Switching between these two is a great way to compare.
As WMD say in their video .. "don't be afraid to use your ears"
Just listen to how each sounds and make your adjustments accordingly.






Threshold

 This sets the volume the audio has to reach before compression begins.
It acts like a gate. 
Adjusting this control sets the level at which the gate will open and allow the signal 
at the input to pass through to the output.

Ratio

This is the amount the audio is reduced (over the threshold).
It's as the name suggests a ratio.

When an input signal is above the THRESHOLD reference level, the setting of this control determines the number of decibels (dB) by which the input signal must change in level to produce a 1dB increase in the signal level at the output
 
Common ratios you will see are:
1:1
1.3:1
2:1
3:1
4:1
Infinity :1
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1:1 is no compression
Infinity :1 , Here the compressor acts as a limiter as audio will never exceed the threshold.
 3:1 here the audio above the threshold is compressed a third.
So if the sound peaks 15dB over the threshold, it will be attenuated to 5dB over the threshold.
 
I tend to set the ratio between 3:1 to 10:1
Above this, it tends to clip the audio.
 

Attack

The ATTACK control is an envelope. Just like a ADSR. It sets the amount of time it takes the module to begin compressing a signal once the threshold is breached. The ATTACK range is from FAST (for a tighter and more noticeable compression effect) to SLOW (for more delayed, gradual compression). 
 

Release

The RELEASE control sets how fast the compression circuit returns the input to its original level. 
Again this is very similar to the ADSR envelopes you are used to with modular synths. The RELEASE rate is from FAST (where the compression slope is steep) to SLOW (for very smooth, gradual compression). 
 
There is no absolute right way to set the ATTACK and RELEASE controls.


MakeUp / Output Gain

The OUT-PUT GAIN control  is also known as MAKE-UP.
It does not interact with the threshold of compression.
Use it to compensate or Makeup for any drops in the final volume which may have occurred during compression 
 

Knee

While discussing the MSCL compressor above, I mentioned the DBX "over easy" style.
This is where Hard vs Soft knees curves come into the discussion. 
"Over easy" seems to be dbx's way to describe a "soft knee".
A soft knee will yield a generally "softer" more subtle compression effect. 
 

It is, in effect, a variable threshold since there is no distinct point at which processing begins.
The compression ratio will start climbing gradually before you approach the threshold as opposed to suddenly "kicking in" all at once at the threshold. 
 
Some compressors have an adjustable knee. I haven't seen many of these in the eurorack format
 

Multi-Band Compression.

There aren't many of these in Eurorack.
Here, the sound from your modulars is split into multiple frequency bands using modules like
EQs. Three bands is the most common number. 
Each frequency band is then compressed separately after which the audio streams are
mixed back together.


I particularly like the Endorphin.es golden master.
It's a 3 band equaliser with a compressor for each band.
Just 6HP
What it lacks in compressor controls it makes up for in size and ease of use.
Sounds great too.


















2HP also make a compressor.
It might be fun to have a few of these chained to an EQ to make a multi-band compressor  with lots of control

 

Peak vs. RMS

Peak value is the highest voltage that the waveform will ever reach, like the peak is the highest point on a mountain. The RMS (Root-Mean-Square) value is the effective value of the total waveform.
When it comes to compressors, these two settings refer to response times.
Peak compression is great for things like drums.The compressor's changes occur much quicker.
RMS changes are slower and good for slower sounds like strings or pads. 
 
 

Sidechain

This effect was first developed in radio studios. The background audio could
be dropped automatically when the announcer spoke. 
Thus, the volume level on one instrument is controlled by the volume 
level of another instrument. A common example would be making the 
compression level on a bass controlled by the output volume of the 
kick drum.  This is called Ducking.
 
I really like the endorphin.es Cockpit. 
Though it's not marketed as a compressor, it's ducking is great for getting
that pumping sound. 
It's really a mixer with a VCA.  
 
 
 
 
 
 
 
 
 
 
 
 

Feedback (feed forward) compression.

Here, the input signal is split into two. One goes into the compressor itself.
The other goes into the sidechain. The sidechain is then fed by the output of the compressor.
This type of compressor was made famous by the Universal Audio 1176.
 


LIMITING

This is where you set the max volume your signal will reach.
It provides overload protection.  
 
 
The Audio Damage ADM10 Kompressor is DSP based.
Just 6HP. Nice 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Other eurorack compressor modules
+ Autodyne - SSF
+  Dynamo - Bastl
+ Mutant Hot Glue - Hexinverter
+ Mutable Instruments Streams 
 
An example of a compressor in a pedal format.

Links

Wednesday, 3 August 2016

NLC Bong0 - Drum - Build notes

These are my build notes for the Bong0.
Its a Eurorack module from Non-Linear Circuits

"The bong0 is a twin-T based drum module with a LED acting as a nonlinear resistor to give it some interesting characteristics. 
 
Twin-T Oscillators
(sometimes known as parallel-T oscillators) are another type of RC (resistor-capacitor) oscillator which produces a sinewave output . They require an Op-Amp, some resistors & capacitors.
They are very similar to the Wein-bridge oscillator

The two "Tee" shaped RC networks are part of the OP-amp's feedback loop
between the output and input of the op-amps inverting amplifier.
Note that each of the the resistor & capacitor elements are in an opposing formation
but are connected in parallel.

Because the inverting input is used there is a phase shift of the oscillator by 180 degrees.
Note the "Ladder Network" of resistors & capacitors that form this feedback loop.
This is pretty common with RC Phase-shift Oscillators.

The trigger input acts as a normal input to get your drum sound. The input marked ‘in’ can also be used, or you can jam a CV in there, or a gate or audio. You can just use the ‘in’ input without anything into the trigger.


Bong0 can also be used for basslines, drones and as a crude but useful VCO. It has about 20 passive components which are 0805 smd and 1 thru-hole TL072, meaning it is a good circuit for learning to solder smd parts and delivers way more fun than such a simple module should." (Andrew F).


More Links:
1. Muffs
2. Build notes (NLC)
3. Panel art
4. NLC Blog

 
"Not a smoking implement" - NLC words of wisdom.






The pots are linear 100K






As you can see in these pics I used a green LED.
The LED acts as a nonlinear resistor so i think the type of LED you choose is important.
I couldnt remember the specific specifications of the green LED that I used , but I found that the volume was very low if used as a drum.

I decided to bump it up by swapping the 470K resistor with a 1M.
 If you check the schematics this is the second -ve feedback loop of the 072 op amp.
Andrew reckons it wont hurt anything....except my speakers if I crank it to self-oscillate.

I'll try building this with a blue LED next and see if there is any difference.
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05/05/2018
Yes, the blue LED made a huge difference.
I kept the 470K resistor.


 


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A side note regarding TT  or twin T oscillators.
Instead of using  a operational amplifier , someting like a logic gate could be substituted to provide the oscillations.
Ive seen a 4011 ic used as a tone generator.
 
The CD 4011 is cheap and includes 4 positive logic NAND gates on a single chip.
The NAND gate is a logic gate that gives a LOW output only when all inputs are HIGH
 

 
 See the RC network below.
The circuit is of a drum machine from the magazine "Practical Electronics", 1978.


NLC 1006 filter

This is based on the ARP 1006 filter.... from the ARP 2500.
The ARP1006 is called the Filtramp.... the NLC version doesn't have the Amp bit.
It's just a prototype - the panel is an extra Andrew had left over for the NLC Serious Filter.

The world doesn't have enough ladder filters. I really love this version and can't wait to compare it to a vintage 1006. The NLC 1006 contains a two input audio mixer & a voltage controlled 24db/oct low pass filter. The cutoff frequency may be varied with control voltages or by the front panel Fc control.

Guitar Fool have schematics and a BOM of the 1006.
http://www.guitarfool.com/ARP2500/1006.html


This is a scan of an old ARP-2500 manual of mine.

.



For more info:


More NLC words of wisdom

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Sunday, 31 July 2016

Wiard - Malekko Envelator - quick start notes


The Envelator is a 10hp envelope generator (Function Generator).
This eurorack version was based around the Wiard 300 series of modules
developed by Grant Richter.

The version on the left is a vintage gargoyles. 
These date from around 2009/10.
I love these "Celtic" designs.
 
It offers simultaneous output of positive and negative envelopes as well as voltage control of attack and decay functions.
There are 3 types of envelopes: 
AR (attack release), AD (attack decay) &  CY (cycle).
AR mode, outputs an AR envelope, maintaining full level until GATE [in] goes “low”. 
AD mode, outputs an AD envelope, and begins decay immediately when
the attack stage is complete.  
Cycle mode, the end pulse is fed back to the envelope input, and will force the envelope to re-trigger.(triangle LFO). The SQR output functions as a square wave LFO

The GATE socket is where you plug your gate or trigger.
This input is a comparator 
The threshold is 2V so any waveform above this will work


The SQR socket is an output.
It puts out a square +10V pulse during the attack phase.
and 0V during the decay/release phase.

The END socket is an output.
It outputs a a pulse at the end of the decay phase.
 
 

This is the modern Malekko version. 
As with the vintage version, the attack & delay have two settings
They are operated with the push buttons on the modern version
and pull switches on the gargoyles version. 

Attack : has a normal & 10X setting.
Delay :When the switch is "in" the delay control does nothing.
It is only when in cycle mode that activating the delay control has an effect.
The effect is to introduce delay before the envelope re-triggers.

You have CV control of the delay time. "DEL CV" on the modern version.
"Ext" on the Gargoyles version.


Both modules have CV inputs for Attack Modulation (AMOD) & Decay Modulation (DMOD).

There are 3 envelope outputs:
-out : inverted copy of the envelope.
+out : two positive copies of the envelope.



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Using the Envelator as a clock divider:

1. Clock signal into Gate socket
2. Use the SQR socket as the output of the divided clock.
    It puts out a square +10V pulse during the attack phase
    and 0V during the decay/release phase.
3. Use the Attack pot to set the clock division. 
4.  Works in AD and AR modes

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 Using the Envelator as a LFO:
 
You have both triangle & square waveform LFOs.
Put the module into Cycle mode.
Leave the decay control at max (fastest speed).
The end pulse is fed back to the envelope input, and will force the envelope to re-trigger. creating a triangle LFO.
The SQR output functions as a square wave LFO.
 
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Using the Envelator to change gate length.
 
1. mode switch to AD.
2. end your gate to the Envelator's gate input. 
3. Leave the decay control at max (fastest speed).
4. The attack control determines the length of the gate.  
 
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ADSR Patch
 
You will need two Envelators,  a mixer and a VCA.
1. Set 1st to AD mode, and 2nd to AR mode.
2. send the same gate to each envelator .
3. take outputs of each Envelator into the inputs of the mixer.
4. take the output of the mixer and input into a VCA 


The AD one acts as the attack and decay. The AR does the sustain and release.
The Wiard Xmix can be used as a mixer & as a VCA.
I find there is a little bit of audio bleed when I use the Xmix as a VCA.
I prefer to use a dedicated VCA for this task.
 
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The -OUT is normalled to the AMOD input 
but you can  patch it to the DMOD.
 
This makes the DEcay curve bend up.
 

Sunday, 24 July 2016

Segue - NLC - VC panner/crossfader

These are my build notes for the Nonlinearcircuits Segue.

Its a very versatile unit. a VC panner, VC cross-fader, VCA and VC attenuator, process CV and audio.
Plus should be a easy build.  Though there are plenty of SMDs, they are all passive.

Andrew describes this as a "kind of hybrid between a Buchla 207 panner and a Korg PS3200 VCA".

There are just two through hole 10R resistors to instal.
Then, caps, trannies, headers.
The trim pots are all 100k.They set the gain for each channel.

I'm using Silonex NSL 32 vactrols. The white dot marks the cathode. (K on the PCB).

NLC words of wisdom: (He'll never be) an old man river.
Mmmmmmmm ????

The reference to "Ol' Man River" isn't the song from the 1927 musical of showboat.
Rather it's refering to TISM ... the Australia band.


 
 OK, its time for the pots & jacks.

 The LED works.... so does the VC fader. Very cool.

"The LED provides offset to one side of the current mirror so they turn on/off at different voltages." Andrew F advised me to "drill the panel, or just drill/scrape off the soldermask on the back and the LED will make the panel glow".





Useful links:
1. Andrew's Blog
2. Youtube 1 - Wear Headphones
3. NLC build notes

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