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 Forum index » DIY Hardware and Software » Developers' Corner
Beginner needs advice to start with analog synth + sequencer
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dummy033



Joined: Nov 09, 2008
Posts: 2
Location: Germany

PostPosted: Sun Nov 09, 2008 4:21 am    Post subject: Beginner needs advice to start with analog synth + sequencer
Subject description: Basic questions on system design, not on analog synth components
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Hi all,
I'd like to start with DIY of analog synthesizers, but I have
some very fundamental questions, which I can not answer by myself
from the various resources on the Internet.
I'd be very happy to get your kind support!

What is my background?
- Technical background: Electrical engineer, i.e. I understand
the working principle of the circuits like VCO and so on.
- I've never seen a digital or analog synthesizer in reality
- Musical background: I wrote music on the Amiga platform with
a sequencer called MED/OctaMED. Then I switched to Cakewalk
and Logic on the PC.

What do I want to do?
- I want to get away from the PC, and generate sound from
the very fundamental electrical components - just out of
interest.
- But I don't want to just create cool "samples" which I can
later on use in offline compositions. My goal is to play
simple tracks LIVE, just like in a sequencer.
Target is electro/minimal techno sound, so only a few
tracks with a lot of real-time effect tweaking.
And I want to do that with a bunch of transistors and potentiometers Smile

What's my problem?
- I understand the fundamental function of the modules, e.g. VCO and so on.
and how the modules can be connected to generate the desired sound.
- But I absolutely do not understand how I can realize a sequencer
concept, i.e. how to periodically trigger the sounds of the
analog synth modules. E.g. to trigger a bassdrum on every 1/4 note
of the measure. I've seen that the basic input can be done with
a MIDI keyboard (and the MIDI2CV converter).
But how can I enter a cyclic sequence of trigger signals, which
are then played cyclically?
If you know the PC software Reverb: There are 16 switches for
every 1/16 of the measure, and if they are "on" the corresponding
sound is played on that corresponding note. Can that be realized
in hardware? How are the "live" guys doing that?

You see, I probably have some fundamental misunderstandings.
Before I start with the single components, I need to know how
to design the whole system (input, sequencer, synth modules,
output=amp/speakers)

Can you help me out?
- How can I realize a sequencer (without using a PC again Wink,
but a low performance MUC would be OK though). I.e. how
can I control the periodical triggering of the sounds?
- Can you recommend in that context a few DIY projects which
will work with my above wishlist, and can be realized by
a beginner (with technical skills though)?
There are so many on the web, but it's hard to understand
if they can be used with a sequencer principle etc. etc.
DIY project book recommendations are also very welcome!

Thanks a lot for your help.
Best wished from Tuebingen / Germany
Daniel
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DrJustice



Joined: Sep 13, 2004
Posts: 2114
Location: Morokulien
Audio files: 4

PostPosted: Sun Nov 09, 2008 6:53 am    Post subject: Re: Beginner needs advice to start with analog synth + sequencer
Subject description: Basic questions on system design, not on analog synth components
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First of all,

welcome to electro-music.com, Daniel!

dummy033 wrote:
- I've never seen a digital or analog synthesizer in reality

I'd recommend getting some hands on experience, even if it's just going to the local music stores to play around a bit with the synths on display. Perhaps there are some synth/DIY events near you sometime (any other German members are in the know?).

Quote:

- But I absolutely do not understand how I can realize a sequencer
concept, i.e. how to periodically trigger the sounds of the
analog synth modules. E.g. to trigger a bassdrum on every 1/4 note
of the measure. I've seen that the basic input can be done with
a MIDI keyboard (and the MIDI2CV converter).
But how can I enter a cyclic sequence of trigger signals, which
are then played cyclically?

If you want to capture MIDI notes into a step-time style sequencer, you really need a microcontroller of some kind. They usually come with serial ports that can be used to send and receive MIDI and they can drive a digital to analogue converter (some have DAC's built in too). This requires some programming, of course, but with your background that shouldn't be a problem.

The traditional hardware analogue sequencers are usually built around a counter driving a multiplexer which lets through the control voltage and gate signals for each step. They can be made very simple, with only a few IC's; e.g. look at the CD4024 counter and the CD4067 analogue multiplexer - these can form the basis of a 16 step sequencer. For some more esoteric stuff, check out the Klee sequencer.

Quote:
- Can you recommend in that context a few DIY projects which
will work with my above wishlist, and can be realized by
a beginner (with technical skills though)?

In our DIY section, there are threads on hundreds of projects for all kinds of synths, effects/processing and sequencers. There's so much that it may be a bit bewildering at first. Still, you could do worse than browsing around there for a few hours to get some inspiration and to see what others are building. I'm sure some of our DIY savvy members will jump in here with some concrete suggestion for starting projects - come on folks!

One thing is certain, you are set for endless hours of fun Very Happy

DJ
Edit: typo
--

Last edited by DrJustice on Sun Nov 09, 2008 1:40 pm; edited 1 time in total
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BananaPlug



Joined: Jul 04, 2007
Posts: 307
Location: Philly
Audio files: 5

PostPosted: Sun Nov 09, 2008 9:02 am    Post subject: Reply with quote  Mark this post and the followings unread

Quote:
What's my problem?
- I understand the fundamental function of the modules, e.g. VCO and so on.
and how the modules can be connected to generate the desired sound.
- But I absolutely do not understand how I can realize a sequencer
concept, i.e. how to periodically trigger the sounds of the
analog synth modules. E.g. to trigger a bassdrum on every 1/4 note
of the measure. I've seen that the basic input can be done with
a MIDI keyboard (and the MIDI2CV converter).
But how can I enter a cyclic sequence of trigger signals, which
are then played cyclically?
If you know the PC software Reverb: There are 16 switches for
every 1/16 of the measure, and if they are "on" the corresponding
sound is played on that corresponding note. Can that be realized
in hardware? How are the "live" guys doing that?


Well if you don't go the MIDI route then it all depends on what you modules are available and what you need to do.

If your sequencer has multiple channels (multiple rows of knobs) one row can VC the clock source to affect note timing. That's hard to get right though. A better way to do it is to use a fast clock fed into a voltage controlled divider and VC that with a row of the sequencer.

Some sequencers have a row of toggle switches for putting out a pulse at particular stages. Actually some sequencers only do this and don't have knobs. These are ideal for triggering percussion, etc. Also, for a sequence which has just long and short notes one of these would be enough to manage the note timing.

You might gain some insights by reading the descriptions of Ken Stone's modules. http://www.cgs.synth.net/
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Rykhaard



Joined: Sep 02, 2007
Posts: 1290
Location: Canada

PostPosted: Sun Nov 09, 2008 11:00 am    Post subject: Reply with quote  Mark this post and the followings unread

Surprised Surprised Surprised - WARNING!! THIS IS A HUGE MESSAGE!! Surprised Surprised Surprised

---------------------------------------------------------------------------------------

You're goal, if I am not mistaken, is not too distant from mine:

- I originally worked with guitars / etc. (late 70's)
- moving to keyboards (all live) in the early 80's to mid 80's
- Atari ST then PC for sequencing from mid 80's to early 90's
- building a modular synth early to late 90's
- software only '01 to middle of '05
- desire to build a modular for live sequencing (no computer) middle of '05 to now

Within the last few days, I have finally reached the point in building stuff, where I may start composing, live, with sequencers that I've so far built.

This goal is not a slight one though and that is to be kept in mind from the beginning.

Let us consider the live sequencing of 1 voice. (A melodic one, as opposed to a percussive one.)

As a bare minimum, you will need: (spelling out instead of as VCO, for clarity)

- 1 Voltage Controlled Oscillator with the 1 Volt / Octave control ability, for, reliable predictability

- 1 Voltage Controlled Amplifier (to make the VCO audible or not)

- 1 simple Gate On / Gate Off sequencer, to control the VCA that has the VCO audio passing through it

- 1 Power supply to run the above 3 units

A unit as simple as that, would allow you to create a series of VCO ON / OFF sounds, controlled by the sequencer, in real time. (Assuming that the sequencer has an On / Off switch for each of it's steps).

To enable melody creation with the above setup, your sequencer could have a Control Voltage pot, on each of it's # of steps. This would allow you to change the pitch of each of it's ON steps, as the sequencer is cycling. Achieving exact tuning notes, could be a little more difficult whilst this type of sequencer is cycling, unless you had a limited voltage range, around each of the Control Voltage (CV) pots. Say - a full pot rotation of 1 volt, would make it easier to attain exact Semitone tunings on each pot, as the sequencer cycles, but your pitch range for the VCO would be a little bit limited.

Having 2 volts range around the pot would give you a little more range for the VCO, but with a decrease in the area available for reaching the proper tuning of the semitone, it would become a little more difficult.
Many of the sequencers available for building, using this type of tuning have a CV range within the 5 to 10 volt range. At least 1 sequencer from Ray Wilson's Music From Outer Space web page, ( http://www.musicfromouterspace.com/ ) has a Coarse Voltage range and Fine Voltage range control, on each of it's 16 steps.

(I myself have built 1 full M.F.O.S. Sequencer as well as 2 of the digital section only, of the MFOS Seq. - for drum / Gate control only. This sequencer is considered for Advanced builders. As long as the instructions are properly followed, it is not a difficult build. Minorly time consuming, only. There also is an entire area here dedictated to Ray Wilson's modules, as well. Ray has boards for a full modular available, as well at very good pricing. Smile )

Now - to veer off on an angle. I myself am not a fan of having a sequencer in which I have to adjust the tuning of each step with a pot. Since the early 80's, listening to Tangerine Dream, Depeche Mode, Erasure, Jean Michel Jarre and etc., having I wished to have sequencers where I could control a rotary switch on each step to change the tuning by semitone and / or octave.

There are a few sequencers that operate in this fashion, available on the market like this, but I myself am not able to afford them. Surprised Surprised Over the recent years in a few design attempts, I FINALLY came up with a 1 volt / octave one, that works, a couple of months ago and this past week have just completed enough small versions of it, to start composing with.

Back to the beginning though. What to control with the sequencer. Surprised Smile

For a simple voice, I require at the very least:

- a Voltage Controlled Oscillator fed into
- a Voltage Controlled Filter fed into
- a Voltage Controlled Amplifier

along with

- an Envelope Generator (EG) to control both the above VCF and VCA

- The pitch of the VCO is controlled by at least 1 of my 1 volt / octave sequencers
- The amount of frequencies that are allowed through the VCF (essentially acting like the Treble and Bass controls on a stereo system) are controlled by the EG
- The amplitude of the audio through the VCA is controlled by an EG as well
- When the VCF and VCA are allowing audio to pass through them, is controlled by the Gate ON / OFF of the above sequencer

The # of modules that are needed, to begin composing with, climbs fairly quickly.

Let's say that you would like to have:

1 - a simple sounding bassline
2 - a simple sounding melody / audio effect
3 - a simple sounding bass drum
4 - a simple sounding percussive sound

There, you will need at least:

1 - a VCO, VCF, VCA, EG and dedicated sequencer channel #'s 1

2 - a VCO, VCF, VCA, EG and dedicated sequencer channel #'s 2

3 - an oscillating VCF set up to oscillate when it is Triggered only from a dedicated sequencer channel to turn the sound ON and OFF

4 - an oscillating VCF as above, or a Noise source along with a VCA from a dedicated sequencer channel to turn the sound ON and OFF

and finally, a 4 input mixer, to mix all of your synthesizer's audio channels together

Your goal is not a simple task. Surprised It will take time to build, definitely. The value though, in creating music WITH something that you've built yourself (whether entirely from scratch, or from PCBs (blank circuit boards) that you've purchased from others, can be as rewarding / good feeling as heck! Smile Smile

The are a fair # of people on this wonderful Forum that are producing _EXCELLENT_ modules that we may purchase for absolutely great prices!

This makes it FAR easier than the way it were, a mere 10 years ago, when almost all circuit boards had to be built from scratch. Surprised Surprised

One avenue perhaps to try, would be going for Ray Wilson's Sound Lab synthesizer and his Baby sequencer that just came out. That would give you a sequencer as well as VERY cool setup to start out with! The Sound Lab is a complete 2 VCO synth. With his simpler sequencer, that could get you started straight away after building the pair. And from there, you could start deciding what other modules you would like to start adding to the setup. Smile

I also forgot to mention effects modules. In about the middle of this year, I finally got myself up to 7 units that will give me the Delay effect as well as 4 units that will give me at least, the Reverb effect. I've got enough there now for the effects side of things, to finally begin composing. Smile

(I also purchased the old Alesis MMT-8 MIDI sequencer, that I use in combination with a MIDI to CV Converter. I also bought a 2nd one in project form, to build myself - to give me 8 channels of MIDI to CV.)

I hope this pile of info. helps to give you an idea of things overall. There's a LOT to do, to come the point of being able to compose things live, in the synthesizer world. But it's overall worth - is immeasurable once you've brought yourself up to that point. Smile

And finally - the # of people that are on this Forum from whom you may obtain help, is unbelievably huge! Without help from many of them, I would NOT be where I am right now, with my ever growing modular. Smile

Thanks hugely everybody! Smile Smile
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dummy033



Joined: Nov 09, 2008
Posts: 2
Location: Germany

PostPosted: Mon Nov 10, 2008 2:55 pm    Post subject: Reply with quote  Mark this post and the followings unread

Hi all,

thanks a lot for your great answers!
Very helpful.

I'll get started with your advice, and I'm sure I'll be
back in about 6 months with a lot of questions à la
"why does my VCO not oscillate" Wink

Thanks again
Daniel
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gabbagabi



Joined: Nov 29, 2008
Posts: 651
Location: Berlin by n8
Audio files: 23

PostPosted: Mon Dec 01, 2008 9:33 am    Post subject: Reply with quote  Mark this post and the followings unread

Hi dummy033,

Do you want to make PCB´s at your own, or you want to buy KIT´s?

I found this, time ago: Simple & Good for starting:
http://www.floka.com/cmos/pdf/cmos_kurs2006.pdf

a simple 16 Step seq here:
http://www.floka.com/lofi/sequenz16.html

actually I build my Own based on this.



You can also use a roland TR 505 to Trigger something. The 505 is cheap, got Midi for sync, and has 8 Trirgger signals.
http://burnkit2600.com/gear/tr-505/#triggers

So You can Program Your Diy Stuff over the 505 Seq.

So I trigger my 808 Style BD and the Clock my Step Seq.


viel Glück
Gabbagabi
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