Home | ER-101 | ER-102 | ER-301 | Wiki | Contact

Bump Scanner Unit (formerly Bump Map)


#1

I have used bump maps in graphics and video, but I have never heard of this in a digital audio context. Is this an O|D original, as it pertains to the audio domain?


#2

Sweet Jeezus don’t tempt me as I’m still over here tripping on other stuff…


#3

Won’t be able to try 0.3 for a little while yet but sounds like this could be a pretty flexible distortion unit when an audio rate signal is the input.


#4

This will become famous for the dirtiest distortion in modular: no joke.


#5

From what I see so far, @Joe it looks like we could use this for conditions instead of rational VCA’s if running CV through it.

You can set:

Center, width, height and fade. It would output a signal based on the center position with a window the size of width. and yeah - oh man, running audio through this creates some absolute anger!!! Cool!


#6

Oh. Yeah!

When I read the description my head registered “parabolic wave shaper” with control over the parabolic equation. But sounds like this might be the windowing function we talked about in the sequential switch thread, eh?


#7

i think think so! It looks that way when i tested it with a sin wave, you could pic the part of the waveform level you want as a threshold (i believe this is the center), and then the height from that threshold in both directions is the Width. So if you were feeding it some CV - if it hits an exact spot, it’ll let it through the window and you can use that to make a trigger. Or, if audio, angry yuckiness! :slight_smile:


#8

Bump Map was inspired by @Joe’s sequential switch patch. :cowboy_hat_face:


#9

as i understand it this is a comparator…or sort of, it doesn’t create a gate or trigger, it just let’s a defined part of the incoming voltage through, right?


#10

You could use 4 Bump Maps controlling the levels of 4 VCAs whose outputs are all summed together to create this:

a144

http://www.doepfer.de/a144.htm

Here is the original picture from the thread where the Bump Map unit was first discussed:

The input value is on the X-axis and the resulting output is on the Y-axis. I like to think of them as “soft” selections. You are “selecting” a portion of the range of a signal. If you change the fade to 0 then it would be a hard selection (output is high only in a certain interval of the input).


#11

hm, ok so center determines the voltage where you select a portion of, width the q setting of that portion but what does height do exactly?


#12

In those terms, I guess you could think of height as equivalent to output gain (which can also be negative btw).


#13

ok, all clear now, very interesting unit i have to say :slight_smile:


#14

Can you guys share some use cases for the bump map? I don’t quite understand it yet.


#15

Essentially, you can use it as an n-channel crossfader. Examples include the A-144 MC above, the RxMx, or the Mixiplexer.

Right now, you could hack together a wavetable oscillator by using one Sample Player per waveform and using a bunch of these to crossfade between each player. You would set them up so that as they receive a shared voltage, only one Bump would be prominent at a time. The outputs of each Bump Map would control a VCA after each Sample Player, and the Sample Player outputs would feed a single mixer.

You could also hack together a quad panner using the same idea, but each VCA would have a separate channel output instead of being mixed together. You would also feed the four VCAs one shared input instead of four different inputs.


#16

Brilliant :+1:


#17

I’m not sure I see the point of overloading a term from computer graphics to describe a unit that implements an established and well known mathematical function. It’s more obfuscating than illuminating, in my opinion.


#18

Suggestions for names are always welcome. I just ask that you first test your idea using the Rename Unit function to see if it fits in the header.


#19

You got it. I’ll also try to eat a little breakfast before posting suggestions to cut down the curtness and pedantry. :wink:


#20

i build a video module that does this as a 40Mhz 4 input interpolating scanner. I just call it a video scanner

i loooove scanners and cronenberg