Mini Synth filter sweep

[LorenZo-m05]

Hi,
I am interested in the filter sweep section of Electro Harmonix Micro Synth.

Could you suggest me pcb, layouts, strip board or clones project??...

I found schematics in the forum: http://experimentalistsanonymous.com/diy/Schematics/Guitar%20Synth%20and%20Misc%20Signal%20Shapers/

Thank you in advance for your replies.

[Kipper4]

Welcome to the forum Lorenzo.
There are several with the synth tag could you be a little clearer as to which schematic you are referring to?
Eg: 3rd one down the list.
Thanks

[Mark Hammer]

The older Micro-Synth schematics come from a time when the CA3094, used in the filter section, was generally available (even if it was no longer in production).  At this point, they are hard to find, and pricey when you find them.  As I understand it, the circuit has been redesigned to accommodate use of still-available chips like the LM13600 and LM13700.  You'll probably want to use a schematic using those.

Also note the difference between Micro-Synth and Mini-Synth, since one will get you the wrong schematic and the other get you the right one.  This is the Mini-Synth, which was a fun little box: http://www.vintagesynth.com/misc/eh_minisynth.php

[LorenZo-m05]

Thank you for your replies.
I'm reffering to 11ht schematic down the list.
I am just interested in attack/sustein control, something like Boss sg1... And the filter section, expecially the resonance enancer.
I just notice that in Micro-Synth schematic they use CA3094... or EH1040.
I don't know if it is commonly avaiable, aniway it has to much stuffs and wants a +9V and a -9V power supplies.

Any suggestion?

[LorenZo-m05]

I found some CA3094...

[Scruffie]

There's no project for what you're asking i'm afraid, it's not as simple as just putting that single section in a pedal, it would need designing.

My advice, sell the CA3094 to those that need them for small stone etc. repairs and buy a microsynth or build something else that does the same job.

[StephenGiles]

There's no project for what you're asking i'm afraid, it's not as simple as just putting that single section in a pedal, it would need designing.

My advice, sell the CA3094 to those that need them for small stone etc. repairs and buy a microsynth or build something else that does the same job.

Yes, you need most of the control circuitry as well for triggering (one R or two??) the sweep generator - which as I stated above does not follow input dynamics, other than to either trigger or not. I'm surprised that nobody has cracked an input dynamics following add on for this, which, together with a 13600 version of the filter could be interesting!

[LorenZo-m05]

or build something else that does the same job.

Any suggestions?

[Mark Hammer]

What distinguishes the Micro-synth filter is that it is a 3-pole, or 18db/oct, lowpass filter.  The crown prince of lowpass filters is the Moog 4-pole, best exemplified by the Mini-Moog.  A 3-pole comes much closer than the usual lowpass or bandpass filter types found in many pedals, and I imagine a 2-pole lowpass might even do

The DOD FX25 uses an LM13600 dual OTA chip to produce a state-variable filter  Only the bandpass output of that filter is used in the commercial product, but I've had success using the lowpass output instead of the bandpass, in a pedal I made for a bass-playing friend.

What the FX25 doesn't do, however, is provide the slow attack that the Microsynth does; largely because the Microsynth uses a sort of triggered envelope generator, and the FX25 relies purely on the envelope of the input signal

If Steve Giles chies back in here, he has a whole whack of designs that apply that Microsynth transient generator to filters of various sorts.  I'm sure he'll have some good ideas.