I traced the Volca Beats, schematic/layout + some new mods

From circuitbending to homebrew stompboxes & synths, keep the DIY spirit alive!

Moderators: Joe., lisa, luketeaford, Kent

Post Reply
User avatar
Dimitree
Veteran Wiggler
Posts: 657
Joined: Mon Aug 01, 2011 9:59 am

I traced the Volca Beats, schematic/layout + some new mods

Post by Dimitree » Thu Dec 14, 2017 1:47 pm

hi everyone,
I had some spare time to waste in tracing the Volca Beats and then analyzing the circuit.
So I'm uploading here the schematic, a component layout and some mods that I've done to make it sound more like a TR808.
it is all explained in the attached pdf

I'm not a drum machine expert (this is my only drum machine) and don't have a superior hear, I'm sure this can get better, so please don't bang on me :lol:
For example, the hats are not really similar to TR808 but I still prefer them now rather then the original on the Volca.
Also, with the schematic/layout should be easier to implement mods like individual out or adjusting the mix levels.

here is a quick comparison between my mods with TR808:
https://soundcloud.com/user-32380672/vo ... s-vs-tr808

sorry for my english,
I hope you find it usefull. I always get huge helps in this forum, so I hope this is a little way to thank you all.
You do not have the required permissions to view the files attached to this post.

User avatar
CeeJay
Wiggling with Experience
Posts: 283
Joined: Wed Jul 17, 2013 7:09 pm

Post by CeeJay » Thu Dec 14, 2017 3:00 pm

Wow, thanks!
That‘s a lot of work you have done!

User avatar
minisystem
Common Wiggler
Posts: 164
Joined: Wed Dec 26, 2012 5:16 pm
Location: Toronto
Contact:

Post by minisystem » Thu Dec 14, 2017 4:45 pm

Cool. Looking forward to digging into this. I traced just the Beats snare a while back: http://system79.com/volca_beats_sch.pdf

User avatar
minisystem
Common Wiggler
Posts: 164
Joined: Wed Dec 26, 2012 5:16 pm
Location: Toronto
Contact:

Post by minisystem » Thu Dec 14, 2017 4:50 pm

That PCB layout artwork is something else! :hail:

spacedumpster
Learning to Wiggle
Posts: 11
Joined: Wed Dec 13, 2017 10:40 pm
Location: Ohio

Post by spacedumpster » Thu Dec 14, 2017 7:48 pm

awesome! so hesitant to crack open gear i've spent any amount of money on but i am tempted.

User avatar
555x555
Common Wiggler
Posts: 231
Joined: Wed Jun 08, 2016 12:59 pm
Location: California

Post by 555x555 » Thu Dec 14, 2017 8:06 pm

Oh, wow. Thanks! This will save me a lot of time...

User avatar
brawnywynn
Learning to Wiggle
Posts: 23
Joined: Tue Sep 16, 2014 12:55 pm

Post by brawnywynn » Fri Dec 15, 2017 2:36 pm

Amazing work Dimitree! Thanks!! :yay: 8-)

funky catsmell
Common Wiggler
Posts: 88
Joined: Fri Jul 07, 2017 12:11 am

Post by funky catsmell » Sat Dec 16, 2017 12:44 pm

incredible! now for a trigger input mod :nana:

funky catsmell
Common Wiggler
Posts: 88
Joined: Fri Jul 07, 2017 12:11 am

Post by funky catsmell » Sun Dec 17, 2017 12:00 am

Image
built this real fast. it doesn't work, but it does cause the kick to only trigger when gate is high. not the goal but nothing blew up. ideas?

User avatar
Dimitree
Veteran Wiggler
Posts: 657
Joined: Mon Aug 01, 2011 9:59 am

Post by Dimitree » Sun Dec 17, 2017 11:03 am

I'm afraid you can't just do that to trigger a drum sound.
The Volca uses a pair of signals: a short trigger (0V to 3.3V, 15mS) to excite the bridged t-network, but then it also provides an envelope to each VCA following the corresponding sound generator (Q10-A for the kick, for example).

So you also need to open the VCA (and keep it open as long as you like) when you send the trigger.

Also, you can't trigger the hats and the pcm sounds.
Maybe you'd be better to use MIDI.

I guess Korg added the VCAs so you can control the "part level", and also because without them the decay of the bridged t-network would be too long, so they cut it out digitally (just try to listen the sounds before the VCAs and you'll notice that they take really long time to actually decay)

User avatar
PWM
Ultra Wiggler
Posts: 974
Joined: Wed Feb 27, 2013 6:08 pm
Location: Amsterdam, The Netherlands
Contact:

Post by PWM » Sun Dec 17, 2017 11:18 am

Dimitree wrote:also because without them the decay of the bridged t-network would be too long, so they cut it out digitally (just try to listen the sounds before the VCAs and you'll notice that they take really long time to actually decay)
Don't be daft, no bass drum is too long! ;)

Great work reverse engineering the schematics!

User avatar
tito_tunes
Wiggling with Experience
Posts: 301
Joined: Fri Feb 20, 2015 1:33 am
Location: San Franpsycho

Post by tito_tunes » Tue Feb 26, 2019 4:56 pm

Do you know if it’s possible to defeat the gating of the kick? I don’t like how the decay envelope cuts off abruptly. Also do you know if it’s possiboe to replace the hat metal sound with white noise? Thanks!
danielriera.bandcamp.com

noiseygear
Learning to Wiggle
Posts: 9
Joined: Sat Jul 26, 2014 4:54 am

Volca Beats play button

Post by noiseygear » Mon Apr 01, 2019 4:07 am

Dimitree

Hey Dimitree! Thanks for all your work on the Volca Beats.

I would like to install a foot switch jack to start/stop the Beats. Do you know where I should wire it to trigger the play button? Thanks!

Sparkey
Learning to Wiggle
Posts: 5
Joined: Thu Feb 08, 2018 9:53 am

Re: Volca Beats play button

Post by Sparkey » Mon Apr 01, 2019 5:47 am

noiseygear wrote:Dimitree

Hey Dimitree! Thanks for all your work on the Volca Beats.

I would like to install a foot switch jack to start/stop the Beats. Do you know where I should wire it to trigger the play button? Thanks!
Can you wire something to connect to the sync-in jack socket, or are you using that to actually sync?

The sequencer is "paused" when there's a jack in the sync input (so you hit play and it lights up, but just sits there). If the correct pads on the jack socket were connected to a cable, you should be able to simulate a jack being inserted and then removed (switched off) to start playback with a footswitch.

It looks like something that bridged gnd and the jack side of R87 would do it - or maybe "PAD-6" whatever that is.

I've used the method of keeping a jack inserted in the sync socket while setting my Volcas up, and pressed play on all of them. Then I can pull the jack out of the sync socket on the first Volca, and they all start playing together.

quarterturn
Learning to Wiggle
Posts: 17
Joined: Thu Apr 04, 2019 10:49 am
Location: derptown

THANKS!

Post by quarterturn » Thu Apr 04, 2019 1:12 pm

Dimitree, thanks for posting your schematic. It enabled me to have a PCM output I could wire up using the minijack switch. This way, when unplugged, PCM goes back to the main mix and out when unplugged.
R143 connects to a via just above the LM324 and a tiny bit to the left. I used an exacto knife to CAREFULLY cut the trace at the via. At R143 there is room to solder on an 0805 4.7uF SMT cap to R143 to block any DC offset and prevent loud POPS when plugging/unplugging.
A wire from the other side of the cap goes to 'tip', GND goes to 'ring', and the other wire on the jack goes to the via. I use solvent plastic cement glue to hold the wire in place. The jack just fits in the area between 'click; and 'high pitch' knobs if you trim away the lip from the panel plastic and you tilt the boards in so the jack goes between the PCBs.

Seten10
1-Post Wiggler
Posts: 1
Joined: Fri Jan 10, 2020 10:24 am

Re: I traced the Volca Beats, schematic/layout + some new mods

Post by Seten10 » Fri Jan 10, 2020 10:37 am

There are two types of people - those that trace an entire schematic and those that cant even use it once its been traced.

My volca beats wont power up and it gives me P. Er. 1 which I read means the main controller IC isnt getting power. Wheres the power section of the schematic? I looked for a very long time but I'm probably just not very experienced reading schems - I was just looking for a place where "9V" came into the circuit but I couldnt find it.

BillB
1-Post Wiggler
Posts: 1
Joined: Sun Feb 09, 2020 3:47 pm

Re: I traced the Volca Beats, schematic/layout + some new mods

Post by BillB » Sun Feb 09, 2020 5:20 pm

Hi Dimitree

I registered on MuffWiggler just to be able to download your schematic. So thank you for your careful work on the Volca Beats and for so generously sharing. :yay:

Post Reply

Return to “Music Tech DIY”