Open Source Digitally controlled Analog Project...

[Juanpcdiy]

the idea is to make an Open Source Hardware & Software,
to control Analog Audio Hardware with Digital signals, like a dummy plugin that has Total Recall in VST, AAX & AU.

WesAudio already has a similar project, but is Not designed to retrofit older vintage equipment, its designed for New HW.
by USB
but the principle is similar / same..

to modify existing hardware and clones from any manufacturer...
and be able to control it
like mixanalog.com
by Ethernet
but open source.

Digitally controlled Analog.

Relays, VCA, AD, & DA are basically the building blocks for the HW,
the hard part is the Software, because it also needs to download the Steiberg & Avid developer SDK.

maybe a Stand alone version would be enough, for version 1.0
Requirements:
Must Be OSX, Windows & Linux/FreeBSD compatible... "Multi Platform",x86_64 & RISC.  "future proof."
Must be OSX Maverics compatible 10.9.5 minimum.. "backward compatible" compiled with older version of Xcode.
preferably OSX 10.6.8 SnowLeopard compatible...
must be as compatible as possible.
must be as low latency as possible, RealTime if possible.
must have common parts, time proven, time tested, Not obscure or very obsolete.

i think this is the future...
McDSP the plugin company is also making a Digitally Controlled Analog HW.
Waldorf had a 16 channel DCA Low Pass Filter Box,
Summit Audio also has a DCA EQ.

like the movie, Back to the Future, where there is a billboard in the future, to convert any vehicle to a flying car... for $49.999

Not MIDI because it has 7-Bits, and thats too little for some things, maybe having an offset to fine tune could work too...
if CC has 156 steps per Hz.
a EQ that can swept from 0Hz to 20050Hz,
at CC 64 would be 10025Hz
at CC 32 would be 5012.5Hz
at CC 63 =9868 Hz
at CC 65 = 10181Hz
at CC 33 = 4855Hz
at CC 31 = 5169Hz

i feel MIDI is too coarse.
Yamaha DSP Factory volume control had a mathematical formula to change the volume smooth between MIDI jumps...
like Lag circuit.

 

 

[gyraf]

Good idea - would be great to have an open standard supporting this.

Maybe base it on some common hardware like a simple serial port under USB? That way you can circumvent some of the driver problems.

Would be great to interface to likeminded people like https://mixanalog.com/ and https://accessanalog.com/

Jakob E.

 

[zamproject]

Hello

Midi is a good protocol and can be used with NRPN for extended 14bit data
USB or ethernet (RTP-midi)
About no driver issue...

Have a look at http://ucapps.de/ for the HW and embedded SW.
almost everything is possible, I use this platform for my fader automation, work great.

Best
Zam

 

[mhelin]

Not MIDI because it has 7-Bits, and thats too little for some things, maybe having an offset to fine tune could work too...
...
i feel MIDI is too coarse.
Yamaha DSP Factory volume control had a mathematical formula to change the volume smooth between MIDI jumps...
like Lag circuit.

MIDI 1.0 is 7-bit.

Maybe it's time to move to MIDI 2.0.

Or maybe not in this case as OSC could be a better protocol than MIDI 1.0/2.0.

It's also used on Behringer X32, so you could just borrow X32 control messages.

https://behringerwiki.musictribe.com/index.php?title=OSC_Remote_Protocol

Better documentation here:
https://www.academia.edu/9709659/UNOFFICIAL_X32_OSC_REMOTE_PROTOCOL

Effect parameters starting from page 85.

More reading:
Introduction:
http://opensoundcontrol.org/introduction-osc

File area, various projects:
http://opensoundcontrol.org/files

 

[zamproject]

MIDI 1.0 is 7-bit.

No...

RPN/NRPN do 14bit...
sysex can even do more...

Best
Zam

 

[abbey road d enfer]

Not MIDI because it has 7-Bits, and thats too little for some things, maybe having an offset to fine tune could work too...
if CC has 156 steps per Hz.
a EQ that can swept from 0Hz to 20050Hz,
at CC 64 would be 10025Hz
at CC 32 would be 5012.5Hz
at CC 63 =9868 Hz
at CC 65 = 10181Hz
at CC 33 = 4855Hz
at CC 31 = 5169Hz

i feel MIDI is too coarse.

Do you want 1 Hz resolution all the way?
Think different; you have 127 steps over a range of 10 octaves; each step would be 1/12th of an octave, which is not bad. At 5k, the next step would be 5.3k.
It would not be enough for surgical EQ, but for tone control, I could work with it.

 

[zamproject]

Do you want 1 Hz resolution all the way?
Think different; you have 127 steps over a range of 10 octaves; each step would be 1/12th of an octave, which is not bad. At 5k, the next step would be 5.3k.
It would not be enough for surgical EQ, but for tone control, I could work with it.

I totally agree...
then again, if you want more use RPN/NRPN up to 16384 steps...

But after that be ready to design a HW that properly convert a more than 7bit data to analogue function.
Good DAC design practice, digital pot (over 1024 steps 10bits ?) etc...

Best
Zam

 

[abbey road d enfer]

I totally agree...
then again, if you want more use RPN/NRPN up to 16384 steps...

But after that be ready to design a HW that properly convert a more than 7bit data to analogue function.
Good DAC design practice, digital pot (over 1024 steps 10bits ?) etc...

Best
Zam

When digitally-controlled analog mixers were considered a viable option, several techniques were considered, including digipots and photoresistive optocouplers; only two remained: DC-driven VCA's and MDAC's. Although more expensive, the VCA solution was preferred by several designers because of the absence of the dreaded zipper noise. The lack of resolution of digipots was an unanimous no-go.
Of course, the appearance of decent digital mixer put a stop to hybrid mixers.
For the subject at hand, I would say that digipots are an adequate answer since they don't require modification of the analog circuitry. There are some possibilities regarding the issue of resolution:

• Either accept the limited resolution and live with it; after all, I don't know any HW EQ that has a range of 20Hz to 20kHz in a single range
• Use range switching; if the HW is not ready for that, it can be implemented as an add-on
• Cascade digipots; an 8-bit 100k in series with a 5k provide a 5000 points resolution (12-bit)

Now if the idea is to build a dedicated HW, without any reference to an existing one, I would follow the path of those who've treaded it successfully before and go for MDAC's.

 

[JohnRoberts]

When digitally-controlled analog mixers were considered a viable option, several techniques were considered, including digipots and photoresistive optocouplers; only two remained: DC-driven VCA's and MDAC's. Although more expensive, the VCA solution was preferred by several designers because of the absence of the dreaded zipper noise. The lack of resolution of digipots was an unanimous no-go.
Of course, the appearance of decent digital mixer put a stop to hybrid mixers.
For the subject at hand, I would say that digipots are an adequate answer since they don't require modification of the analog circuitry. There are some possibilities regarding the issue of resolution:

• Either accept the limited resolution and live with it; after all, I don't know any HW EQ that has a range of 20Hz to 20kHz in a single range
• Use range switching; if the HW is not ready for that, it can be implemented as an add-on
• Cascade digipots; an 8-bit 100k in series with a 5k provide a 5000 points resolution (12-bit)

Now if the idea is to build a dedicated HW, without any reference to an existing one, I would follow the path of those who've treaded it successfully before and go for MDAC's.

Digitally controlled analog mixers have been around for decades but failed in the market as prohibitively expensive. The huge cost/benefit and massive feature set increase offered by modern digital mixer platforms put the final nail in digitally controlled analog coffin.

BTW zipper noise can be managed by coordinating digital pot gain changes with signal zero crossings. The gain change times zero, equals zero.

I would vote for DPOTs to retrofit into existing designs, but this will not be trivial, and market may not support NRE.

JR

 

[abbey road d enfer]

BTW zipper noise can be managed by coordinating digital pot gain changes with signal zero crossings. The gain change times zero, equals zero.

That's correct; but pioneer designers had so many things to struggle with in terms of software, adding the necessary hardware and code lines was overwhelming for many of them. In addition it turned out that performance was better with MDAC's.

 

[Juanpcdiy]

#1. i have an UPS from Forza FX-1500 & Fx-2200,
has Serial USB port,
but software is a nightmare...
needs Java+Flash,  sometimes eats 100% CPU of a G4400 doing nothing... or 1-core of a i7-970,
the port is locked to 1 USB port, if you move the USB cable to other port, software wont work unless you force it "hack it".

a friend also has an older UPS from same manufacturer, and the latest software is Not compatible...
i had Not good experiences with Serial-USB interfaces.
maybe is just bad luck.

i have my doubts about serial-USB, i think Ethernet is better...
Waves Soundgrid has Ethernet..
DANTE also has Ethernet,
Solid State Logic, Ethernet...
rptMIDI works great,
AVID / Euphonix control surfaces, Ethernet.

i had better experiences with Ethernet, than serial-usb, im biased towards Ethernet.

#2. MIDI 14-Bit is a nice idea, but is Not compatible, Not supported,
for example:
Peavey Cakewalk Studio Mix controller, it was revolutionary, 14-Bit MIDI controller...
what happened?
Died... Abandonware, Obsolete.
software developers never supported 14-Bit MIDI controllers...
someone did a custom firmware chip and a software,  to make it more compatible,
but also disappeared...
forgotten.
most Peavey Studio Mix owners never purchased the upgrade.
Abandonware,
and still is an amazing hardware, advanced for its time, but if software developers dont support it, its useless.

#3. MIDI has low bit rate, 32kbps, too low, its like Ethernet v0.5, has similar twisted pair technology.
DMX its a bit better, "MIDI 3.0", instead of 5-pin din, its 3-pin XLR, sometimes 5-pin XLR, more robust for live rental.
but still, Not convinced... i use it for disco dj mirror lamps but... does Not feel as powerful as Ethernet. XLR is better than RJ45, plastic tab breaks too easy, but repair is easy with a punch machine, and high quality connectors with longer blades..

but also Not as popular,
All computers have Ethernet,
None has DMX,.

#4. MIDI is very unstable, "stuck Notes", i use the MIDITest software v4.12 32-Bit to analyze many different OS & MIDI interfaces, OSX & Linux with Wine / PlayOnMac.

the best MIDI Interface was the True MPU-401 included in older Pentium4 boards, and some Athlon XP Joystick ports...
lowest jitter, lowest deviation, lowest latency.
+ WindowsXP,
also some SoundBlaster cards have a Nice MIDI... "Not all"
most USB Midi is crap, the ones ive tested.
except Focusrite 18i20 MK2,

i still have a P4 478, with rtpMIDI as a midi interface...
like a cheap  noisier RedBox rptMIDI interface.

#5. Digital Controlled Analog failed the market because Digital technology was born, was difficult, was expensive,
but those variables are gone now...
Digital technology is cheap & easy available Now.

#6. DPOTs are 8-Bits, "Better than MIDI, as good as DMX but still Not as good as VCA + 10 or 12-Bit DA."
smaller & cheaper, than VCA, Yes.

#7. Mastering analog equipment has steps, to recall settings, Not because having 12 steps is cool.
Digital Controlled Analog can have Total Recall Analog, with 10-bit or 12-Bit precision.
1024 to 4096 steps.

to have analog feel must be like MIDI Pitch Bend Wheel.
16,384 possible values. General MIDI specification recommends that the total range be ±2 semitones,
though this Pitch Wheel Range (or Sensitivity) can be adjusted using General Midi Registered Parameter Number 0, 0.

https://en.wikipedia.org/wiki/Pitch_wheel

10-Bit = 1024
11-Bit = 2048
12-Bit = 4096
13-Bit = 8192
14-Bit = 16384
15-Bit = 32768
16-Bit = 65536
24-Bit AD is for very advanced/expensive Bench Multimeters...7.5 6.5 Keithley, Agilent, Rigol, Fluke, Siglent, HP, etc...

for all controls to have 14-Bit resolution, 32kbps is Not enough, barely works for MIDI.
the idea is Not to re invent the wheel, to make MIDI v4, is to use what is already available.

i had the Novation SL 61 mk1 Keyboard with AutoMap, and the 128 steps without lag, was very annoying... Yamaha DSP Factory + Nuendo 3 / Cubase implementation was much better, moving the Mouse Wheel feels way better, less noticeable.
Also AutoMap cannot be implemented with Protools 12 security methods.

the same EQ plugin with Mouse had a lot better resolution, with CC was very disappointing when i want to dial a specific frequency between CC 70 -&- CC 71, very disappointing. 

#8. Focusrite 18i20 Mk2 has Digitally Controlled volume, very interesting design...

 

[JohnRoberts]

#2. MIDI 14-Bit is a nice idea, but is Not compatible, Not supported,
for example:
Peavey Cakewalk Studio Mix controller, it was revolutionary, 14-Bit MIDI controller...
what happened?
Died... Abandonware, Obsolete.
software developers never supported 14-Bit MIDI controllers...
someone did a custom firmware chip and a software,  to make it more compatible,
but also disappeared...
forgotten.
most Peavey Studio Mix owners never purchased the upgrade.
Abandonware,
and still is an amazing hardware, advanced for its time, but if software developers dont support it, its useless.

I can not speak about the software support (Cakewalk) but I know a little about the hardware effort (the Studio mix product manager reported to me inside Peavey). 

Yes this was a pretty slick piece but the market did not embrace it.. I don't know if there was a chicken/egg thing with poor market acceptance leading to insufficient software support, or insufficient software support causing the weak market performance. Either way I ended up with a pile of unique hardware I had trouble moving even when discounted below my cost.

That is often the case with novel products, great enthusiasm and optimistic market projections before the market reality, that did not deliver the numbers.

JR

 

[Juanpcdiy]

Returning to the topic...
2nd Chapter:
Hardware Approach.

Invasive vs. Non Invasive...

2 different approaches,,,
mixanalog is Invasive,
https://youtu.be/ymK71LwNxWw?t=40
https://www.instagram.com/p/BfiSGRAhV_b/

accessanalog is Non-Invasive.
https://www.instagram.com/p/BtMcEY1h6Oi/

Pros & Cons:
Non-Invasive actuator pressure must be as low as possible to avoid increasing wear damage.
Invasive can affect sound, in some equipment, there is a risk of inducing EMI, RFI into the equipment if Not done properly.

Non-Invasive is easy to implement, servos are available from all sizes, but is louder/noisier, also increase power consumption.
Invasive can last longer, has almost No moving parts apart from Relays that can be replaced by IGBT or MOSFETS or JFETs, or BJT = Silent, can have No moving parts, but where absolute signal integrity is required Relays may be the best option..

TQ2-5V is a proven part...

thoughts?

invasive seems a lot more work...
dont know why i like more the invasive approach.
probably has more accuracy and repeat ability.

for example:
My RSP Saturator Drive control has 10KB, i have installed A & C types, or has C and i have installed A & B types, cant remember,
anyway... one type is very aggressive, the other is too soft, the original had a nice balance... but its imposible to find, very rare..
i think original was type C, and Now i have B in once side and A in the other... to have 0 Drive i must have completely different settings. Drive goes from -3dB to Way too loud. LOL Jajajajajaja
https://groupdiy.com/index.php?topic=37133.0

if using the invasive approach equipment can be improved to have different curves in potentiometers...
maybe someone likes more A, or B or C type Potentiometers...
Equipment can be improved with invasive technology.
also some brands of pots sound better than others, even having same resistance... dont know why...
fake alpha does Not sound as good as generic unbranded type, for example.

http://www.alphapotentiometers.net/html/taper_curves.html
http://www.alphapotentiometers.net/html/24mm_pot_2.html

on the other hand, a Knob or connector from the pot to the servo can be done very easy with 3D printers,
STL files, nylon or PLA, or ABS...
external approach is easier but Not as powerful.

https://www.servocity.com/servos

 

[iampoor1]

The problem with a project like this is defining its scopes and limitations.  ;D

The relay control approach is right for some applications, the VCA approach is right for some applications, and the Digital pot is perfect for some applications (AD5290 is the best I know of).

It might make sense to implement all of these as possible options, within a framework, and then develop it bit by bit (no pun intended)

Also, my vote is for NRNP midi.... 14 bits is enough resolution. There are enough challenges with implementing something like this in the first place, no need to reinvent the wheel......

 

[gyraf]

Non-Invasive is easy to implement

It most certainly ain't.

I've been working on this on and off for 6-7 years, and haven't found a solution that works even halfway well half the time. And I was not the only one researching in that direction.

Chris Barett of accessanalog.com is a bona-fide mechanical genious, that's how he managed to pull the stunt with that working system. I had a chance of a very-close look at NAMM, and what he does is not trivial, nor to be underestimated, even though the superficial impression is simple enough.

Jakob E.

 

[iampoor1]

It most certainly ain't.

I've been working on this on and off for 6-7 years, and haven't found a solution that works even halfway well half the time. And I was not the only one researching in that direction.

Chris Barett of accessanalog.com is a bona-fide mechanical genious, that's how he managed to pull the stunt with that working system. I had a chance of a very-close look at NAMM, and what he does is not trivial, nor to be underestimated, even though the superficial impression is simple enough.

Jakob E.

+1

I think the OP thinks this is FAR easier than it really is.

 

[abbey road d enfer]

My RSP Saturator Drive control has 10KB, i have installed A & C types, or has C and i have installed A & B types, cant remember,
anyway... one type is very aggressive, the other is too soft, the original had a nice balance... but its imposible to find, very rare..
i think original was type C, and Now i have B in once side and A in the other... to have 0 Drive i must have completely different settings. Drive goes from -3dB to Way too loud. LOL Jajajajajaja
https://groupdiy.com/index.php?topic=37133.0

if using the invasive approach equipment can be improved to have different curves in potentiometers...
maybe someone likes more A, or B or C type Potentiometers...
Equipment can be improved with invasive technology.
also some brands of pots sound better than others, even having same resistance... dont know why...
fake alpha does Not sound as good as generic unbranded type, for example.

That is a new one for me, the sound of potentiometers! I knew all the crap about the sound of rectifiers, power cables, but now, that's a new high.
I'm eager to hear about the sound of switches.
Replacing a RevLog type with a Lin type only changes the way the effect changes with percentage of rotation. Indeed, for identical positions of the pot, the effect will be different, except at the ends. I would be very surprized if it's not what you hear.

 

[mhelin]

I can not speak about the software support (Cakewalk) but I know a little about the hardware effort (the Studio mix product manager reported to me inside Peavey). 

Yes this was a pretty slick piece but the market did not embrace it.. I don't know if there was a chicken/egg thing with poor market acceptance leading to insufficient software support, or insufficient software support causing the weak market performance. Either way I ended up with a pile of unique hardware I had trouble moving even when discounted below my cost.

That is often the case with novel products, great enthusiasm and optimistic market projections before the market reality, that did not deliver the numbers.

JR

I still have StudioMix though it doesn't have much use.  It had a software bug which was never fixed, it caused random values to LSB of the 14-bit NRPN's used in automation so when there was some workaround in Cakewalk the resolution was not fully used. Some engineer in Germany though found and fixed the bug and was selling a new ROM with some enhanced features, never bought it cause I happened to locate the problem area in ROM code as well and fixed 8051 assembler code bug there. I also created another ROM image. It is still in the file area of StudioMix Yahoo group, I guess. The buttons on the device are heavy and springy, not very good to use. It also had a mic pre (mic in line out).

E: Yes, the file is still there:
https://groups.yahoo.com/neo/groups/studiomixmap_group/files
smix.zip

The enhanced fadeOS can be get from Sonicware:
http://www.sonicware.de/studiomix/studiomix_en.html

 

[Juanpcdiy]

#1. if i think its easy, i would Not ask open for public help...
i would do it my self.

#2. there are mercury filled relays in vacuum atmosphere because relays affect rise & decay time... mechanic has latency, Silver, Copper, Gold, Carbon, have different Electric Resistance.
temperature affects resistance,
if you cannot hear that, Not my problem...

can be measured with a powerful eqipment,
if you thinkan oscilloscope is better than your ears that have millions of years in evolution, think again. LOL Jajajaja.

has been proven that some chemicals reduce hearing ability,
https://en.wikipedia.org/wiki/Hearing_loss#Causes
https://en.wikipedia.org/wiki/Sensorineural_hearing_loss#Causes
https://en.wikipedia.org/wiki/Quinine#Beverages
https://en.wikipedia.org/wiki/Cinchonism
https://en.wikipedia.org/wiki/Ear_protection

"if i can´t nobody can, mentality..."
i think more: "if someone can, i can." LOL Jajajajajaja

Carbon has different states/types, Carbon is Not just 1...
and they all have different properties.
Diamond
Graphite
Graphene
Graphenylene
AA'-graphite
Amorphous
Fullerene
Carbide-derived carbon
Linear acetylenic carbon (LAC)
D Q T M-Carbon
Activated Carbon
Carbon fibers
etc...
https://en.wikipedia.org/wiki/Carbon_fibers
https://en.wikipedia.org/wiki/Activated_carbon
https://en.wikipedia.org/wiki/Allotropes_of_carbon
https://en.wikipedia.org/wiki/Electrical_resistivity_and_conductivity#Resistivity_and_conductivity_of_various_materials
https://en.wikipedia.org/wiki/Electrical_resistance_and_conductance#Relation_to_resistivity_and_conductivity
https://en.wikipedia.org/wiki/Admittance
https://en.wikipedia.org/wiki/Electrical_impedance
https://en.wikipedia.org/wiki/Electrical_reactance
https://en.wikipedia.org/wiki/Susceptance
https://en.wikipedia.org/wiki/Valence_and_conduction_bands
https://en.wikipedia.org/wiki/Skin_effect
https://en.wikipedia.org/wiki/Conductivity_(electrolytic)

#3. i like to write, helps to organize ideas... to see things i miss.

 

[abbey road d enfer]

if you thinkan oscilloscope is better than your ears that have millions of years in evolution, think again.

Typical audiophool speech...

Carbon has different states/types, Carbon is Not just 1...
and they all have different properties.

Do you think I don't know that? Potentiometers use carbon and various other substances, but their use is always to provide a variable resistance. Other properties are essentially irrelevant. Same with speaker cables; whether they are made of copper, aluminium, silver or gold, as long as they have the same resistance, their transmission properties at audio frequencies are identical.

https://en.wikipedia.org/wiki/Allotropes_of_carbon
https://en.wikipedia.org/wiki/Electrical_resistivity_and_conductivity#Resistivity_and_conductivity_of_various_materials
https://en.wikipedia.org/wiki/Electrical_resistance_and_conductance#Relation_to_resistivity_and_conductivity
https://en.wikipedia.org/wiki/Admittance
https://en.wikipedia.org/wiki/Electrical_impedance
https://en.wikipedia.org/wiki/Electrical_reactance
https://en.wikipedia.org/wiki/Susceptance
https://en.wikipedia.org/wiki/Valence_and_conduction_bands

https://en.wikipedia.org/wiki/Conductivity_(electrolytic)

You may accumulate loads and loads of internet sources, they all say the same, and may not be particularly relevant.

#3. i like to write, helps to organize ideas... to see things i miss. 

It's fine as long as you don't take too much bandwidth. At the moment you are essentialyy talking to yourself.