...
The Erica's website link to the compressor is here.
I think I'll probably need to go down this rabbit hole sooner or later.
The builds are easy and very educational.
500 euro for the basic kit
JonDent - Explorations in Electronics, Electronic Music, Coffee, Sci Fi, Art & Travel (but mostly electronic music)
Showing posts with label compression. Show all posts
Showing posts with label compression. Show all posts
Sunday, 9 April 2023
Saturday, 16 April 2022
Mutant Hot Glue - part 2 - build notes
Finally getting the parts together which I need to finish this project.
Covid, the war in Ukraine, etc are really slowing down my builds.
Part 1 of the build is here:
Finally have a 576k resistor.
The THAT 4301p is super rare.
So is the THAT 2180. This is a VCA
Finally there.
Part 1 of the build is here:
links
+ Modular Compressor -using eurorack modules
Wednesday, 2 March 2022
Mutant Hot Glue - buildnotes - part 1
Mutant Hot Glue
The upper PCB has the jacks, pots etc that fit into the front panel
...The
Hexinverter Hot Glue was once available as a DIY product, in PCB+panel format, as
well as full eurorack kits.
It might still be available. Anyway, here's the DIY project information for
building it.
DIY RESOURCES
Resistors & IC sockets
The THAT4301 Dynamics Engine & THAT 2180 VCA are rare.
Almost impossible to find.
Purchased The 4301on ebay - about $70AUD
THAT2180 Blackmer VCA
THAT 2180-series pre-trimmed Blackmer
voltage controlled amplifiers (VCAs) ICs are high-performance
current-in/current-out devices with two opposing-polarity,
voltage-sensitive control ports. They offer wide-range exponential
control of gain and attenuation with low signal distortion. The parts
are trimmed during wafer processing to minimize THD and control-voltage
feedthrough. After packaging, the parts are tested and graded based on
the degree to which the trim survived packaging. No further adjustment
is required to achieve the guaranteed distortion and feedthrough
performance
Out of stock on synthcube.
Ordered on Mouser. 887-2180CL08-U
38 weeks lead time??
Some words of warning about DIY builders :-)
I needed to drill some holes into the panel as some of the pots had thick shafts.
I decided to try soldering some pots and a few jacks just to test the height.
The electro caps esp the 10UF need to fit under the panel.
The build notes suggest they be less than 12mm height.
These are the headers that join the two PCBs
100nf caps monolithic ceramic x18
22pf ceramic caps
47nf polyester
--
Took 38 weeks :-) I'm sure it will be worth it.
purple LED - ordered from ebay
finally arrived
------------
TL072 op amps
IC3, IC5, IC10, IC11, IC12, IC15, IC4, IC16, IC17, IC19
-----------------------------
The rest are 071 opamps
We are almost there.
To be continued...
Mutant Hot Glue - part 2 - build notes
Wednesday, 17 January 2018
Modular Eurorack Compressor
There are plenty of off the shelf compressors you can buy.
However by building one yourself, you'll learn the principles of how they work.
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.
The 4 basic components:
1. Mult
2. VCA (linear preferably but a exp VCA will work too)
3. Inverter / attenuverter
4. envelope follower
First split the signal into two.
a. the original signal (A) to be compressed.
b. the side chain detector signal (B)
Signal A --> envelope follower ----> inverter ------> CV input of VCA
Signal B --------> audio input of VCA
The fun thing about building your own compressor is varying the components.
The VCA for example could be vactrol based LPGs
You could use a Make Noise Maths. It could perform the envelope follower & voltage inverter tasks.
A serge DUSG could do this as well, as could the Doepfer VCS( A-171-2).
This is a patch for compressing a bass drum
In this example channel 4 is acting like a slew limiter.
It's output is plugged into the input of channel 3. It's in inverter mode.... creating an inverted
version of channel 4.
Chanel 2 of the maths is simply amplifying the straight audio of the bass drum.
It's then going into the second audio input of the VCA.
I'm using the HP filter to remove some of the lower frequencies. I could also use an EQ.
The delay has lots of CV inputs which could be modulated with LFOs, the Maths, sequencers, or EGs.
The Doepfer A-119 envelope follower has a voltage comparator with a gate output that can be used to trigger envelopes.
Of course the signal processed in the VCA doesn't have to be the same signal that is being analysed by the envelope follower. The open architecture of a modular synthesizer allows you to design any kind of side-chain compression scenario your heart desires.
Another interesting module is the Bastl Dynamo.
Its just 5HP and contains two Envelope Followers with inverted and non-inverted
Envelope Follower Output. There is also a Compressor CV Output with indication LED
(only negative voltage when envelope is greater than the threshold.
When the Compressor CV is plugged into CV input of a VCA with offset and attenuator knobs you get an Compressor!
Extra modules that would come in handy
5. mixer
6. Slew Limiter
7. EQ
8. filters
9. comparator
Links
Thursday, 1 September 2016
sidechain compression - eurorack modular
Sidechain compressors.
Compressors are essentially devices used to make loud sounds softer.
They enable a producer to boost the level of a track, thus narrowing the dynamic range.
This type of compression is evenly applied to the tack
Side Chaining is a more active type of compression.
It's sometimes referred to as "ducking".
It is a type of compression where the volume level of one instrument is controlled by the volume level of another instrument.
That is, the compressor is only triggered when certain sounds appear.
This is the pumping effect you often hear in electronic dance music.
Here, the compression level on a bass track is controlled by the output volume of a kick or snare drum.
The Bass line volume drops every time the kick is heard.
Another example of its use is when a song suddenly drops in volume when a radio announcer speaks.
Daft Punk - Indo Silver Club (Official Audio)
Thus for side chaining, we need an external signal to act as the trigger.
To build your own side chain compressor using a eurorack system
we need a
1. drum source
2. Baseline
3. VCA
4. EG with an inverted output
The EG could be replaced with a Envelope follower & an inverter.
In this case, the VCAs gain needs to be turned up.
The baseline is passed through the "open" VCA.
Everytime the kick sounds, it triggers the envelope generator.
The inverted CV lowers the volume of the VCA
These two videos are really good to watch.
They use the MATHs module
This second video is esp good
This is my usual setup.
I'm using the the Make Noise Function instead of a Maths.
I like to set Rise to full anti clockwise & Fall to about 11 0'Clock to get a ducking effect.
A fast attack & a slower decay.
Play around with these settings to adjust the amt of ducking.
The bubblesound VCA is set to expo and CV in to around 3 0'Clock
The Doepfer A-171-2 VC slew Processor works very much like Maths and Function
It's mostly a licensed copy of Ken Stone's vcs (voltage controlled slope)
which is in turn based on the Serge
vcs.
The VCS is a really useful module. Quite versitile.
In this instance it's being use as a voltage controlled envelope generator with an inverted output.
The top and bottom pot are the most important parameters to adjust.
The top and bottom pot are the most important parameters to adjust.
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
---------------
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
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
Links
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