Modeling the Stringz-n-Thingz Synth

[amz-fx]

Not exactly effects related, but I thought you might enjoy reading how I started a very simple music project and ended up killing most of a day!

Modeling the Stringz-n-Thingz Synth, in my blog: http://www.muzique.com/news/

Enjoy,

Jack

[pinkjimiphoton]

thanks for the headsup Jack!! <3
your blog always is worth reading anyways,  always good to be reminded!
rock on sir!
peace

[amz-fx]

Jimi,

Many thanks for your kind remarks!

I always enjoy reading about your adventures in fuzz, so keep it going!

Best regards, Jack

[Ice-9]

Hi Jack, Good to see you got your Endian bytes the right way around   . Nice read about creating your own sound sample set for Kontact to use in a DAW.

[pinkjimiphoton]

hi jack,
THANK YOU my friend for, well, everything!!!

i am gonna have to re-examine wavosaur, i've been using audacity for years now. well, maybe should say HAVEN'T used it in years, its been a while.

keep on rockin!

[amz-fx]

Apparently I don't know my Endian from a hole in the ground, but Wavosaur got me fixed up. 

It was a fun project that consumed much more time than I had anticipated. The fact that I was so rusty in programming for Dos/Win had much to do with it, since I have only been coding for micros for years.

Best regards, Jack

[amz-fx]

I finished assembling the samples into an instrument in Kontakt. This project was a success, but also a big failure.

It was a success in that I was able to duplicate the sound of the ancient synth, and in the process, I learned a lot about making instruments from samples in Kontakt.

It was a flop in that the Stringz-n-Thingz is one of the most cheesey sounding 1970s string machines. It sounds much like a cheap organ sent through a chorus box, and when I listened to some demos on Youtube, the original sound was very similar to my sampler instrument.

Fortunately, there are some features in Kontakt that can be added to the model which make it much more useful, though still with a retro string ensemble sound.

Fun project, and I will use it as the base instrument when I start learning the Kontakt scripting language.

Thanks for reading and sending your comments!

Best regards, Jack

[anotherjim]

Not many commercial string machines use pulse wave. The classic wave is high-pass filtered square wave, but for realism that at best spans 2 octaves. Several instruments split the keyboard in 2 octave spans. An octave lower in turn, Viola and Cello/Bass all have different size filters from the Violin.

The classic string chorus had x3 TCA350 BBD in parallel. Probably the shortest BBD used in audio. 288 stage IIRC. 2 Sine LFO's at about 0.6Hz and 6Hz mixed to each BBD clock. The 0.6Hz one is phase shifted by RC networks to give 120deg phase difference between each BBD modulation. The string voices were either fed in to all 3 BDD or split Violin or Viola or Cello into one BBD each.
The Paia design is maybe closer to the 2 BBD scheme Korg and Roland used, still with 2 LFO frequencies.

For generating samples, did you know you can get Adobe Audition3 as "abandonware" from Adobe? This is the old CoolEditPro in a more recent guise. Generate waveforms directly and more. It works in Windows7, I don't know about Windows10.

[amz-fx]

Thanks for the comments, Jim.

I was looking to duplicate the Paia synth just as a way to learn the sampler program and not much more. It was successful in that, and the sound that I generated was quite close to the original Paia design. (i just didn't remember it being so crappy) 

The two delay lines in the Stringz-n-Thingz are identical except for the value of one resistor in the clock driver, which prevent the two from having the exact same delay time. That was easy to simulate in the software.

I also included a bass section (not in the original hardware) for which I used a sawtooth wave as it is more representative of the real sound and has many more harmonics. I just generated the sawtooth with software and did not take the time to re-program my pulse generator program.

When I started to modify the instrument to improve the sound, I also added some filters in Kontakt and a little bit of vibrato. A big improvement.

I was a licensed user of Cool Edit Pro from before the Adobe purchase so I am familiar with the software. The original doesn't run well under Win 10 and I didn't want to struggle with it at the time. Audacity is a decent alternative but for just editing wav files, Wavosaur is easier and just as effective for most operations.

Thanks again for your comments!

Best regards, Jack

[Mark Hammer]

It was my understanding that multi-phase choruses were often the basis of string-synthesizers during that era.  I think the Solina used 3 BBDs.  I'm looking at the Roland RS-101 string synth and it seems to have a quartet of MN3002s. 

[amz-fx]

There is a nice video file on Wikipedia that demonstrates the changing harmonics as the width of a pulse wave varies.

https://en.wikipedia.org/wiki/File:Duty-Cycle-and-Spectrum.ogv

if D = duty cycle, the 1/d harmonics are missing. So at 25%, multiples of 4 are zero, i.e. 4, 8, 12, 16 and so on.  (1/0.25 = 4)

When the duty cycle is 12.5%, the missing harmonics are multiples of eight, so 8, 16, 24 and so on. The video shows this clearly.

If it is a square wave, the duty cycle is 50% so the 2x notes are missing...  2,4,6,8 which leaves only the odd harmonics.

regards, Jack

[anotherjim]

Actually, I usually have to use pulse or PWM to get close to string machine sound on most general synths. It ought to be sawtooth,  but that always seems too smooth.

Although it isn't a well known commercial product, Tim Orr's "String Thing" that was an ETI magazine project is a well described example of a Solina type string machine.
Aug, Sep '79 issues here...
https://www.sdiy.info/w/ETI_SDIY_articles_index

[jimbeaux]

Slightly OT - but there's a DIY article in the September 2017 issue of Nuts and Volts on building a FAUX MIDI Mellotron using a Raspberry Pi, open source sampler software, and free Mellotron samples (strings, choir and flute - also other free samples are linked).

A few additional parts like - LCD screen, USB DAC, MIDI controller & flash drive are needed - but looks like fun, cheap and definitely easier to build than the real deal.

[ElectricDruid]

Given that the Mellotron is basically a large tape-based sampler, it does rather lend itself to being copied like that. As long as you remember to keep the frequency response hopeless and turn the background noise right up, it'll sound just like the original!

T.