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 Forum index » DIY Hardware and Software » YuSynth
Minibrute schematics vs Yusynth + some potential mods
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radray



Joined: Sep 21, 2014
Posts: 3
Location: United States

PostPosted: Thu Oct 02, 2014 9:45 pm    Post subject: Minibrute schematics vs Yusynth + some potential mods Reply with quote  Mark this post and the followings unread

This topic is for the folks who love reading synth schematics and for those looking for some mods for the Minibrute.

I found out last week that the Minibrute schematics website by Yves Usson is up and running http://hackabrute.yusynth.net/index_en.php. I immediately began reading all the pages, looking for patch points and finding out how the heck the Sub oscillator works. Then I began going page by page comparing schematics with Yusynth designs to see what may be different. Most areas have some subtle changes others are drastic.

Super Saw/Saw Animator-
Some Yusynth modders may notice the Super Saw/Saw Animator has the triangle to sine mod for the lfo as seen here http://electro-music.com/forum/topic-18854.html. It's pretty noticeable when using the Yusynth module next to the Minibrute. The Minibrute Super Saw is a much smoother LFO to the stock Saw Animator.

Metalizer/Wavefolder-
The most obvious change is the Metalizer. I expected as did many on the web that it would be the same as the Yusynth Wavefolder but to my not so smart eyes it looks more like a CGS29 Wave Multiplier using transistors instead of diodes. If you can break this circuit down or link to where it has been used please speak up. I have to guess and suppose that the use of a different circuit is because Jürgen Haible designed the circuit in the Yusynth module.

Something I didn't expect to see was Velocity CV being used to control the depth of Envelope 1 with an OTA. I didn't think there was Velocity CV implemented in the Minibrute. I have never noticed any change in depth before but it's there so maybe simpler patches will show it off. I intend on probing it to see how much range is there in the hopes of adding a velocity CV output. And now that I think of it how the heck could that work since the envelope has to decay after a key is released. Hmmm probing should give some answers.

Another thing that I was surprised to see was the use of TRS jacks on the CV in's with the ring connected to +12V through a 10k current limiting resistor. So this means you can use an expression pedal or volume pedal to control those inputs not just a CV pedal as many have thought. Why the heck the manual doesn't mention this I have no idea. I tested it out with a multimeter and sure enough just under +12V is on the ring. Then I used an Ernie Ball Jr. volume pedal and a 3.5mm trs to mono left right splitter to test it out. Of course with a 12 octave range the pitch input can go beyond human hearing but the filter and VCA inputs were very usable. You could rig something up to drop the voltage a bit for the pitch but for the VCA it felt like the full range of the pedal was used.

One other neat thing according to the schematic is that there is already traces set up for soft and hard sync connections to the VCO. Sweet! Should be simple to add an input port for syncing to external VCO's.

Well I'd love to hear other folks thoughts on this sweet gift from Yves and Arturia and some kind of description of the Metalizer circuit.
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a100user



Joined: Oct 28, 2003
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PostPosted: Thu Oct 02, 2014 11:45 pm    Post subject: Reply with quote  Mark this post and the followings unread

Nice work

I'll be watching this space Smile

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radray



Joined: Sep 21, 2014
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PostPosted: Thu Oct 09, 2014 7:37 pm    Post subject: Reply with quote  Mark this post and the followings unread

So I did a bit of probing last night just checked out spots for tapping Aftertouch CV, Mod Wheel CV and Velocity CV signals. I found that the Leafcutter mod points for Mod Wheel "PT655" and Aftertouch "PT656" found here http://leafcutterjohn.com/?p=1887 are pre processor and only get around 1 volt of CV max so I tested the post processor points Aftertouch "PT676" and Mod Wheel "PT674" and got about a 0-10v CV range so I would recommend using these points for Mod and After Touch over the Leafcutter ones. Since the After Touch is post processor it's response will of course follow the software settings of lin, log and anti.

Now for the Velocity CV results. In order for the Velocity CV to have an effect on Envelope 1 output depth while letting Envelope 1 decay after a note is released the Velocity CV will hold it's value until the next note is played. The softest key press gives a reading of 8.5v and the hardest (or quickest) key press gives a reading of 9.5v. Not a whole lot of range + that's a high offset. So if I end up using the Velocity CV I'll have to set up a circuit to subtract 8.5v followed by a gain stage to get it to a 0-10v range. Could be worth it.

That's it for today stay tuned for more results and I'm still interested in a description/analysis of the Metalizer circuit.
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yusynth



Joined: Nov 24, 2005
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PostPosted: Tue Oct 14, 2014 4:34 am    Post subject: Reply with quote  Mark this post and the followings unread

Yes velocity was part of the initial specs in the MiniBrute, but as it is implemented in the MiniBrute it does not give an interesting result therefore it was decided to remove it from the list of official features rather than providing something that was not really OK. As a matter of fact we had no time t o solve this with respect to the deadlines.
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yusynth



Joined: Nov 24, 2005
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PostPosted: Tue Oct 14, 2014 4:39 am    Post subject: Reply with quote  Mark this post and the followings unread

Concerning the Metalizer (a yusynth Module will be soon published on my site) you are right concerning the fact I didn't use JH design for reasons of intellectual properties. I designed the metalizer by chaining basic cells similar to CGS52.
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yusynth



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PostPosted: Tue Oct 14, 2014 4:40 am    Post subject: Reply with quote  Mark this post and the followings unread

By the way if you design some nice hacking I'll be pleased to publish it on hackabrute.
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radray



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PostPosted: Fri Oct 17, 2014 9:56 pm    Post subject: Reply with quote  Mark this post and the followings unread

Thank you for the feedback Yves. I totally missed the "Simple Wave Multiplier" and it's even on the schematic for CGS29. head banging monitor The only info I can find on this circuit is at http://www.tradeofic.com/Circuit/3560-NONSELECTIVE_FREQUENCY_TRIPLER_USES_TRANSISTOR_SATURATION_CHARACTERISTICS.html I don't know if there was more in the article from Electronics Design. Seems to be used in some DIY guitar fuzz pedals as well.

This weekend I will be doing some probing around the LFO and Sub-Oscillator. Curious about the "CMD PWM" from the processor. Is it a compensation control for various speeds or some never utilized PWM processor control. For the Sub-Oscillator I will be using an audio probe to see what PT151 and PT152 sound like.
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quietchannel



Joined: Mar 19, 2009
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PostPosted: Mon Apr 20, 2015 10:35 am    Post subject: Reply with quote  Mark this post and the followings unread

Hey, radray and Yves!
I'm hoping you two might look over this thread and see what you think...
I am 'quietchannel' there.

https://www.gearslutz.com/board/electronic-music-instruments-electronic-music-production/956641-minibrute-pitch-mod-its-just-too-much.html


I hope I've correctly noted the best methods for these simple mods:
>> more subtly in LFO pitch modulation
>> more subtly in aftertouch response (vibrato and cutoff)
>> pre/post-filter patch points (ie: for using an external filter)
>> smoother VCO response on upper registers

Please let me know what you think!

Thank you so much, Yves!


Posted Image, might have been reduced in size. Click Image to view fullscreen.[/img]
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yusynth



Joined: Nov 24, 2005
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PostPosted: Wed Apr 22, 2015 11:59 pm    Post subject: Reply with quote  Mark this post and the followings unread

Your picture is hardly readable can you provide a higher resolution image?
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quietchannel



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PostPosted: Thu Apr 23, 2015 5:20 am    Post subject: Reply with quote  Mark this post and the followings unread

Thanks for the reply, Yves.

It seems that images are automatically resized for a smaller file size. Here's a PDF.


Arturia-MiniBrute-AnalogBoard-BottomParts MOD MARK UPS.pdf
 Description:

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 Filename:  Arturia-MiniBrute-AnalogBoard-BottomParts MOD MARK UPS.pdf
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blue hell
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PostPosted: Thu Apr 23, 2015 7:01 am    Post subject: Reply with quote  Mark this post and the followings unread

large images are resized, yes, but you can click on them to see the original.
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also .. could someone please turn down the thermostat a bit.
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Starspawn



Joined: Jun 14, 2013
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PostPosted: Fri Sep 11, 2015 2:34 pm    Post subject: Reply with quote  Mark this post and the followings unread

Hello, my arp direction mode rotary switch is broken, does anyone know the part number/type?
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Aednik



Joined: Nov 06, 2015
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PostPosted: Fri Nov 06, 2015 2:46 pm    Post subject: Reply with quote  Mark this post and the followings unread

radray wrote:
So if I end up using the Velocity CV I'll have to set up a circuit to subtract 8.5v followed by a gain stage to get it to a 0-10v range. Could be worth it.


This would certainly be worth it. Any news on implementing this? I would be willing to even pay for instructions on such mod circuit (or why not a retrofit kit?).
I would imagine a pot on the side of my Minibrute for regulating the amount of velocity controlling the cutoff. I'm really missing this. (And why not also one pot for velocity controlling the volume.)

I would also be very interested in instructions on how to regulate the amount of aftertouch (on cutoff and vibrato) and LFO pitch mod (as also Quietchannel requested), i.e. where to insert pots and which ones?

These mods alone would make the Minibrute perfectly expressive and playable. Or should I say conforming to the originally intended specs. Smile No modular ambitions for me this time.

Thanks in advance for any comments.
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