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Korg Volca Beats separate outputs - abusing a balanced input

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Korg Volca Beats separate outputs - abusing a balanced input

Postby BillB » Thu Feb 20, 2020 12:09 am

Hi folks

I have written an article for my new website here:
https://www.2btech.co.uk/drums/Korg-Volca-Beats
Very early days for the website, which will document my findings with various bits of gear - so far two synths and a drum machine! More promise than content at present!

Anyway, you will see that I have added separate outputs to a Volca Beats, based on an Instructibles article, but with a twist for getting at the snare sound. In the section headed
+ 1 - 1 = 0
I discuss the use (abuse?) of a balanced input to subtract one signal from another, to obtain a clean snare sound. My concern is that I may not have described the action of balanced connectors and inputs as clearly and technically correctly as I might have. So could I ask those who know to take a look and suggest any improvement in the wording?

And out of interest, do balanced inputs have other funky uses, apart from cancelling noise?
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Re: Korg Volca Beats separate outputs - abusing a balanced input

Postby N i g e l » Thu Feb 20, 2020 12:53 am

balanced signals also reduce earth loops (which can lead to mains hum or computer noise)


website looks interesting, ill give it a read tomorrow.

:)
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Re: Korg Volca Beats separate outputs - abusing a balanced input

Postby BillB » Thu Feb 20, 2020 1:01 am

N i g e l wrote:website looks interesting, ill give it a read tomorrow.
:)

Won’t take long... ;)
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Re: Korg Volca Beats separate outputs - abusing a balanced input

Postby Hugh Robjohns » Thu Feb 20, 2020 11:18 am

BillB wrote:My concern is that I may not have described the action of balanced connectors and inputs as clearly and technically correctly as I might have. So could I ask those who know to take a look and suggest any improvement in the wording?

It makes sense to me.

A 'balanced input' is really a misnomer; it is more correctly termed a 'differential' input because the circuitry looks for the difference between the signal voltages on the two (hot and cold) input lines. So, in effect, it subtracts one input signal from the other and outputs the result -- exactly as you have described.

And out of interest, do balanced inputs have other funky uses, apart from cancelling noise?

It has been alluded to above ... but as a differential input is only interested in the difference in voltage between its two inputs, there is no inherent reference to the reference ground -- unlike an unbalanced input. Consequently, the input signals do not have to be referenced to ground, and in fact no ground connection is required at all... which means signals can be passed without a ground reference connection. If there is no ground connection between two the source and the differential input, there can be no circulating ground currents -- or ground loops. Yay!

H
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Re: Korg Volca Beats separate outputs - abusing a balanced input

Postby BillB » Thu Feb 20, 2020 3:50 pm

Hugh Robjohns wrote:It makes sense to me.
That's a relief :D
Thank you, Hugh.
And out of interest, do balanced inputs have other funky uses, apart from cancelling noise?


I suppose I was meaning are there any clever tricks in terms of stereo image, EQ, FX...
Erm, like... what would happen if you have an input signal to a time delay FX (echo / reverb) and you subtract the input from the output. It might give a kind of 'dry defeat' where none exists in the FX unit, obviously depending on how much difference (time and frequency) there is between the output and input.
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Re: Korg Volca Beats separate outputs - abusing a balanced input

Postby Hugh Robjohns » Thu Feb 20, 2020 4:02 pm

The classic one is to connect an unbalanced stereo source (eg, a headphone output) to a balanced input. In that case, everything panned to the middle (and therefore the same on both channels) is removed, leaving only things which are panned towards the sides (or have incoherent outputs, like reverbs). So typically, all the kick drum, snare, bass and vocals disappear...
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Re: Korg Volca Beats separate outputs - abusing a balanced input

Postby N i g e l » Fri Feb 21, 2020 12:04 am

Nice crisp fresh looking web site !

I was a bit surprised about the snare correction mod - did Korg really get that wrong or is it a feature to allow a more gritty snare sound ?
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Re: Korg Volca Beats separate outputs - abusing a balanced input

Postby BillB » Fri Feb 21, 2020 12:47 am

N i g e l wrote:Nice crisp fresh looking web site !

Why thank you, but I can’t take any credit:
https://datenstrom.se/yellow/
Simplest Content Management System I have found, flat file, editable via html or by creating /editing simple text ‘markdown’ files. Once you learn a few wrinkles, it is really easy to use and edit, and not a MySQL database in sight.

I was a bit surprised about the snare correction mod - did Korg really get that wrong or is it a feature to allow a more gritty snare sound ?

You will find many a conflicting view on that topic on the web, but most people (dare I use that phrase?) who are after an analogue snare sound probably won’t like what they get by default in the Volca Beats. In Paul Nagle’s review
https://www.soundonsound.com/reviews/ko ... -bass-keys
he said ‘I didn’t find the snare so instantly appealing’ (as the kick drum).

I listened to some of the YT comparisons, then opened it up and tried with and without the capacitor (well, tried a few and just picked the one whose sound I liked the best). Then gently soldered it in. My guess is that Korg may have messed up on this one, but have brazened it out as they couldn’t possibly handle all the recalls and mods. Others may think it fine, and deliberately designed for a crunchy sound.

At least it is hackable :thumbup:
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Re: Korg Volca Beats separate outputs - abusing a balanced input

Postby nathanscribe » Sun Mar 08, 2020 12:26 pm

Just seen this. Nice work on the Beats mod! I had one for a while and modded that snare, but drew the line at trying to fit a row of minijacks in there.
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Re: Korg Volca Beats separate outputs - abusing a balanced input

Postby BillB » Sun Mar 08, 2020 1:04 pm

Thanks, Nathan.

I'm now trying to persuade myself that it is the only analogue drum machine (well, analogue drum sounds) I'll ever need.

But MFB (301 Pro), Roland (TR-8), Behringer (RD-8 / RD-6) and Arturia Drumbrute...
are making that really difficult :headbang:

Good job I have got no more room for anything!

...except maybe an MFB 301 :shocked:
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Re: Korg Volca Beats separate outputs - abusing a balanced input

Postby nathanscribe » Sun Mar 08, 2020 1:35 pm

Always the way... :D
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Re: Korg Volca Beats separate outputs - abusing a balanced input

Postby Martin Walker » Sun Mar 08, 2020 11:31 pm

Clever and very useful mods Bill - well done! :clap:

I've still resisted buying a dedicated hardware drum machine, in favour of continuing with Sonic Charge's' Microtonic, which I'm still finding incredibly versatile for electronic percussion 'kits'. I've also got a host of drum machine samples.

Tell me, what is it about a dedicated drum machine that gets so many people fired up?


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Re: Korg Volca Beats separate outputs - abusing a balanced input

Postby BillB » Fri Mar 13, 2020 10:47 am

Martin Walker wrote:Tell me, what is it about a dedicated drum machine that gets so many people fired up?

Hi Martin

Truth be told, I don't want a drum machine, I want a drum synthesizer, something like the Vermona DRM3. I love the idea that percussion can be synthesized and that, although the key roles (thump of the bass, snap of snare/clap and click of the hats) are established, there is a lot of sonic scope as to how those roles could be fulfilled.

However, there is no drum synth under say £500, so I look to analogue drum machines to offer interesting, variable sounds, thus the list above. In my case, rhythmically, they would be driven over MIDI from either a Beatstep Pro or an Akai MPC1000.

That means that some of the fun things - like motion recording as part of a Volca Beats pattern - don't happen, but my logic is that I learn one (or two max) drum sequencers to drive all my rhythm sounds.

If anyone knows of a nice (cheap!) hardware drum synth, let me know. I love what MFB have done with MIDI control of the 301 Pro:
https://www.youtube.com/watch?v=FgcG1StojH0
but would probably be frustrated by the lack of separate outputs and no control of stereo panning.

My other thought is that my entire studio of synths could, of course, be a drum synthesizer, but I do like the appeal of a single location for a continuously variable set of percussion sounds.
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Re: Korg Volca Beats separate outputs - abusing a balanced input

Postby N i g e l » Fri Mar 13, 2020 4:55 pm

Martin Walker wrote:Tell me, what is it about a dedicated drum machine that gets so many people fired up?

:idea:
The symbiosis betwixt pattern generator and sound generator and general tweakability therof.
:beamup:

I have VSTs with classic samples and Waldorf's Attack VST as a specific drumsynth.

I bought a Volca Drum so that I could create patterns and fiddle with sounds away from the computer (ive not "created beats" sitting in the park or on a bus but never say never ! :smirk: )

Its a handy little unit and its not an 808 etc.
6 instruments each of 2 layers.
Great for messing about, probably not best for chaining patterns or live.
One bonus is that each of the 6 instrument tracks can be of a different length so the patterns can beat slip - eg like Steve Reich's clapping.

BillB wrote: If anyone knows of a nice (cheap!) hardware drum synth, let me know.

There was a h/w Waldorf "Rack Attack" but pricey on ebay, for 1/2 that you could get a blofeld module and set up a multi with 16 sounds, or even 8 sounds with 2 synth layers each. (other synths are available).

Then just add a controller: pads or sequencer, Im not in the know about modern devices,
somthing like a button pad matrix thing ?
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