Lab-Synth

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Lab-Synth
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Lab-Synth

Post by Lab-Synth » Wed Mar 18, 2020 11:33 am

Hello Synth enthusiasts!

I’m a physicist passionate with electronics and mechanics discovering the world of synthesizers at 39 years old. It seems that they are many links between my background and synthesizers even if I’m not a musician.

Why starting working on Synth? Because it will change from the majority of my electronic projects that are based on uC and SMD components. Playing with analog and through hole components will be a move back 25 years in time.

I started to work on a set of synth modules: VCO, VCA, ADSR taking inspiration from many posts in forums and on the web. In addition, I’m trying to develop a personal one called Twicer and also a sequencer.

The idea is to have a compact synth based on relatively simple modules in a 3U rack. I like to have a maximum of front face components (pot, switch, connector, LEDs, …) soldered directly onto the PCB. Then, the PCB is fixed to the front panel with these components. For the PCB, they have 2 faces with generous ground plane.

Here are some picture of the first prototypes: VCO and Twicer. Twitter is a module adding the double frequency and the fourth frequency.

If you are interested, I will post additional informations.

Cheers!
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snevlida14
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Re: Lab-Synth

Post by snevlida14 » Wed Mar 18, 2020 11:38 am

Most definitely interested. Keep it up :tu:

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Re: Lab-Synth

Post by jorg » Wed Mar 18, 2020 12:08 pm

Welcome aboard! One of the things I love about analog synthesis (besides the sound) is that it's based on physics. We're directly manipulating the behavior of electrons to make sounds. There's something beautiful about that.

I'm excited to see how your synth designs go - please keep us posted and don't forget to post some sounds!

Interesting transparent faceplates! Are those 3.5mm jacks, or 1/4" ? And what's the deal with the knobs? They look like banana jacks...

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Re: Lab-Synth

Post by KSS » Wed Mar 18, 2020 12:21 pm

jorg wrote:
Wed Mar 18, 2020 12:08 pm
And what's the deal with the knobs? They look like banana jacks...
Collet knobs without the snap-in covers.

@Lab-Synth: Welcome to MW!

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Re: Lab-Synth

Post by EATyourGUITAR » Wed Mar 18, 2020 2:59 pm

I no longer enjoy through hole soldering. it can make you sick even if you take precautions. I was doing it 8 hours a day at work. now my personal projects are PCB design and a reflow oven. I run away when the toxic fumes start. life is good. don't ever want to go back.
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Re: Lab-Synth

Post by thealienthing » Wed Mar 18, 2020 3:15 pm

Oof I love these. The (acrylic?) face plates are so cool. Definitely interested.

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Re: Lab-Synth

Post by Lab-Synth » Sat Mar 21, 2020 2:00 am

snevlida14 wrote:
Wed Mar 18, 2020 11:38 am
Most definitely interested. Keep it up :tu:
Thanks for your interest snevlida14.
jorg wrote:
Wed Mar 18, 2020 12:08 pm
Welcome aboard! One of the things I love about analog synthesis (besides the sound) is that it's based on physics. We're directly manipulating the behavior of electrons to make sounds. There's something beautiful about that.

I'm excited to see how your synth designs go - please keep us posted and don't forget to post some sounds!

Interesting transparent faceplates! Are those 3.5mm jacks, or 1/4" ? And what's the deal with the knobs? They look like banana jacks...
Thanks jorg! It is 1/4" Jacks. Do you think that it is better to use 3.5mm?
KSS wrote:
Wed Mar 18, 2020 12:21 pm
Collet knobs without the snap-in covers.

@Lab-Synth: Welcome to MW!
Exactly KSS.
EATyourGUITAR wrote:
Wed Mar 18, 2020 2:59 pm
I no longer enjoy through hole soldering. it can make you sick even if you take precautions. I was doing it 8 hours a day at work. now my personal projects are PCB design and a reflow oven. I run away when the toxic fumes start. life is good. don't ever want to go back.
EATyourGUITAR, agree in principle but still happy to rediscover through hole components ;)
thealienthing wrote:
Wed Mar 18, 2020 3:15 pm
Oof I love these. The (acrylic?) face plates are so cool. Definitely interested.
Yes thealienthing, acrylic. The idea was to use that for the prototypes but I'm thinking about keeping that concept.

I will post the electronic schematic v1.0 that need corrections/improvements today.

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Re: Lab-Synth

Post by Lab-Synth » Sat Mar 21, 2020 2:38 am

Some details about the red module that I call Twicer:

Please tell me if there is any mistake in my reasoning or if you have ideas.

A full wave rectifier (IC1A&B) is followed by a DC remover (IC1C) to double the frequency. It works well with triangular waves because we end up with a triangle with twice the frequency. It don’t work with square wave. With sine wave, we do not obtain exactly a sine wave but it could be interesting (some kind of distortion).

IC1D is an inverter (shift of 180°) or an all pass filter with a shift around 90° depending on the frequency. To obtain one or the other, we have to select R11, R14 and C10. The switch S1 bypasses this filter but not in the initially expected way. This have to be corrected in next version.

IC2 does exactly the same.

Finally, IC3 mixes the input with the wave having twice frequency and fourth frequency. That why it is called Twicer.

Since I’m not an experimented musician, I’m working basically with an oscilloscope. I need your help to evaluate the interest of this from a musical point of view. In particular, for the inverter/shifter. It change a lot the wave on the oscilloscope but I don’t know if it is interesting for ears.

I should record some samples.
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Re: Lab-Synth

Post by KSS » Sat Mar 21, 2020 4:56 pm

Lab-Synth wrote:
Sat Mar 21, 2020 2:00 am
It is 1/4" Jacks. Do you think that it is better to use 3.5mm?
The answer depends onyour goal for your work. 3U modules with 1/4" 6.35mm jacks are almost never seen except as part of a system designed for personal use. If you want to sell something -which you cannot do until you have 100 MW posts- then you will want to choose which formt(s) you intend to support. Designing a multiple PCB package is how many now deal with gatting the most from their work. The main module circuitry is on a PCB which will fit the 3U euro-Frac, and ideally can handle both 12 and 15V supply rails. This is then paired with a format specific 'panel PCB' -or used alone with flying wires to the panel components.

This arrangement also works for the 4U crowd, but you also need to address the possibly different waveform amplitude and expected CV ranges. That's really true for any well-designed offer, IMO. Trying to be too universal can end up being a not-so-great thing. Consider the cost and time of support for your offering, and factor that into your decision. Take a look at the TTSH and other build threads to get a sense of what you're up against in offering DIY.

So it really depends on what you're trying for. And what you're willing to do to support the choice you make.

I did once design a 3U set of modules with 1/4" jacks, and they do not suffer for the rare combination. They were clones of the old E-Mu modular, which was 3,6,or 9" wide and 6" tall so the change to 2.4, 4.8 and 7.2 x 5.25" still gave good panel spacing for jacks and parts. And 3.5mm jacks could still be used instead. Unfortunately Dave Rossum -who had said he was *never* going to get back into modular- instead did exactly that. :bang: But it did show that tiny HP saving modules are not the only way to do 3U modular.
thealienthing wrote:
Wed Mar 18, 2020 3:15 pm
Yes thealienthing, acrylic. The idea was to use that for the prototypes but I'm thinking about keeping that concept.
The wow or cool factor of acrylic panels can fade quickly once stress cracking and panel flexibility start to affect the reliability of your PCBs. I would advise against them for a DIY product. But as the reply here shows, some people really like them. Suggest favoring panel strength and durability over panel wow. You can always offer the design files and most people can find a hacker or fablab with a laser engraver to make their own if they really want them.

One more suggestion. Design and build what YOU want, HOW you want it. Supporting anything else is just another real job for pay. In this crowded market in these complicated times, you don't want to be trying to chase an elusive target. YMMV.

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Re: Lab-Synth

Post by Lab-Synth » Sun Mar 22, 2020 10:18 am

KSS wrote:
Sat Mar 21, 2020 4:56 pm
The wow or cool factor of acrylic panels can fade quickly once stress cracking and panel flexibility start to affect the reliability of your PCBs. I would advise against them for a DIY product. But as the reply here shows, some people really like them. Suggest favoring panel strength and durability over panel wow. You can always offer the design files and most people can find a hacker or fablab with a laser engraver to make their own if they really want them.
Yes the acrylic is brittle and the attachment points will certainly break. The design could be adapted to minimize the risk. Just now, I'm experimenting 3D printed front panel. The ABS is stronger and a reinforcement structure can be added to the part.

The quarantine is a good opportunity to experiment ;)
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Re: Lab-Synth

Post by EATyourGUITAR » Sun Mar 22, 2020 10:22 am

Lab-Synth wrote:
Sun Mar 22, 2020 10:18 am
I'm experimenting 3D printed front panel. The ABS is stronger and a reinforcement structure can be added to the part.
try glass reinforced nylon. nylonG is the name brand. I think the generally accepted rule is that 3mm is the maximum thickness in 3U. with glass reinforced nylon I think you can totally do 2.5mm that would be preferable to people who do not want to buy screws twice.
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Re: Lab-Synth

Post by jorg » Sun Mar 22, 2020 12:39 pm

If you're going for 3U, most people will assume you mean "Euro" and Euro uses 3.5mm jacks.

I like the 3D printed panels. You could go a little crazy with that. ;-) :tu:

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Re: Lab-Synth

Post by Lab-Synth » Mon Mar 23, 2020 9:44 am

Result of the first test for printing front panels.

The design could be much more complex with relief, pattern...
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Re: Lab-Synth

Post by KSS » Mon Mar 23, 2020 3:27 pm

Suggest using A,D on first row and S,R on second.
This way the upward moving parameter knobs are on the left and the downward moving parameter knobs are on the right.

This relates to and reflects the actual readout of the voltage as displayed over time, like you will see with an Oscope or Oscope module.

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Re: Lab-Synth

Post by Lab-Synth » Tue Mar 24, 2020 4:58 am

Thanks all for your remarks. That helps me a lot.
KSS wrote:
Mon Mar 23, 2020 3:27 pm
Suggest using A,D on first row and S,R on second.
This way the upward moving parameter knobs are on the left and the downward moving parameter knobs are on the right.

This relates to and reflects the actual readout of the voltage as displayed over time, like you will see with an Oscope or Oscope module.
Yes I realized that mistake during the first tests. I have to change that for the next version.

Speaking about oscilloscope, here is the result.
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Re: Lab-Synth

Post by Lab-Synth » Fri Apr 03, 2020 1:10 am

Hello,

Here is a video of the first test of my first modules.



The modules under development now are: a LFO, a mixer and a sequencer.

For the sequencer, I plan to base it on an Arduino micro but still thinking about it. If you have any ides or inspiring projects...

Have a good synth day!

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Re: Lab-Synth

Post by jorg » Fri Apr 03, 2020 9:52 am

Very good results!

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Re: Lab-Synth

Post by Lab-Synth » Sat Apr 04, 2020 1:11 am

jorg wrote:
Fri Apr 03, 2020 9:52 am
Very good results!
Thanks Jorg!

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Re: Lab-Synth

Post by Lab-Synth » Sat Apr 04, 2020 1:12 am

I started to compile the informations about my modules in a website. Here is the address:

Lab-Synth website

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SphericalSound
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Re: Lab-Synth

Post by SphericalSound » Sat Apr 04, 2020 5:40 am

Deffo arduino is the best for sequencers. Looking good, keep on documenting it -;)

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