Hi D.

Yeah, DC Offset could be covered in what is digital Audio, or maybe briefly mentioned. The thing is that it needs patches to explain and show how adjusting the DC Offset works.

I know things must be kept as simple as possible, but not simpler than that, because it could be misleading. I had that problem myself when teaching with Floss Manuals, students had doubts why the square and sawtooth oscilators were different, or "wrong".

The DC Offset is an extremely important parameter that should be a part of the synthesizer section of Floss Manuals. It could also be a part of the Amplitude Modulation Examples. Actually, changing DC Offset is all it needs to change from an Amplitude Modulation to a Ring Modulation. So having a DC Offset parameter there can explain the differences between the two.

For instance, I find the osc7.pd example really misleading. At first, it is supposed to be a Ring Modulation instead of an Amplitude Modulation, since there is no DC offset in the modulator sigal. But, as the sawtooth wave oscilator has a DC Offset (that shouldnt be tghere anyway, and it is not even mentioned), it is actually an Amplitude modulation after all, with the Remark that the Carrier signal has the role of the Modulator signal, and Not the carrier signal itself. So, in any way (either presenting it as a Ring Modulation or Amplitude Modulation) corrections should be made.

So I dont see a way of not editing these patches, because it could be even more confusing if we would write a disconected chapter that complements and gives the tools to correct things that could have been presented before.

I just don't see how simplicity here compensates the misleading way the theory is presented.

The DC Offset is the main problem I see in Floss Manuals. And I actually give my students an altered version of Floss Manuals to work with because of that. I am developing a book of my own that complements well with the Floss Manuals, but I still need to do make this Remark.

I could show my book, but it is in Portuguese only, so far... 

by the way, we have people in Brazil who would like to collaborate and translate this to portuguese.

I can send you a triangle wave oscilator right away.

cheers
alex


On Mon, Mar 30, 2009 at 11:56 AM, Derek Holzer <derek@umatic.nl> wrote:
Actually, DC offset could be covered in "What is Digital Audio", since it is a concept that needs explaining. Then, my suggestion still is to include it after the basics of the Square Waves. I'd like to keep the patches there as simple as possible, and since the DC Offset can be done at the end, why not have it there?

Triangle wave would also be good. Write it first and we'll see where exactly to put it.

D.


Alexandre Porres wrote:
sure, I could do both.

But I think it would be inportant to start just after
 
   * AUDIO TUTORIALS
   * SimpleSynthIntroduction
     <http://en.flossmanuals.net/PureData/SimpleSynthIntroduction>



and before the oscilators with the Short DC offset chapter.

Then edit and correct the oscilator patches with values from -1 to 1

I also can create and put in the oscilator chapter a Triangle wave oscilator made with phasor

what do you say?

Cheers


On Mon, Mar 30, 2009 at 11:43 AM, Derek Holzer <derek@umatic.nl <mailto:derek@umatic.nl>> wrote:

   Alexandre,

   Yes please, get on board!

   In the case of the square wave chapter, I had assumed that doing it
   with digital logic would result in either 0 (no amplitude) or 1
   (full amplitude). So there shouldn't be any DC offset when it's at
   0. Of course, there are some other real-world problems with those
   patches, namely that there is also no antialiasing.

   Since the FLOSS Manuals are "modular", they can be remixed as needed
   for any kind of workshop, class or curriculum, including or leaving
   out sections from all the different FLOSS Manuals as needed.

   So my suggestion to you would be to write a short chapter on DC
   offset which can then be referred to in the square wave tutorial, or
   in any other tutorial or manual where such a situation might arise.

   Likewise, I'd love it if someone could do a single chapter on the
   different antialiasing methods (Miller's, Frank's...). The idea
   would be to simplify the explanations so that one doesn't need a
   background in DSP or computer science in order to understand them.

   Would you be interested to do either of those?

   D.

   Alexandre Porres wrote:

       Hi, I am really interested in helping!

       I actually have some stuff I wanted to "corrrect", or bring some
       attention to, like the DC OFFSET. You dont cover it, and when
       you show how to get a Square Wave, the DC Offset is not properly
       adjusted.

       thanks

       cheers

       On Mon, Mar 30, 2009 at 11:20 AM, Derek Holzer <derek@umatic.nl
       <mailto:derek@umatic.nl> <mailto:derek@umatic.nl

       <mailto:derek@umatic.nl>>> wrote:

          Hey Alexandre,

          I just posted the announcement of the Pd FLOSS Manuals Book
       Sprint:

          http://lists.puredata.info/pipermail/pd-list/2009-03/069107.html

          I was wondering if you'd be interested to help out next
       weekend? It
          shouldn't be a problem to contribute remotely, and it would
       really help
          build up the momentum to finish this manual.

          Have a look over the topics and see if there is anything
       you'd like to
          cover and let me know.

          Best!
          Derek

          --    ::: derek holzer ::: http://blog.myspace.com/macumbista :::
          http://www.vimeo.com/macumbista :::
          ---Oblique Strategy # 11:
          "Always first steps"





       --        Alexandre Torres Porres
       cel. (11)8179-6226
       Website: http://porres.googlepages.com/home
       http://www.myspace.com/alexandretorresporres


   --    ::: derek holzer ::: http://blog.myspace.com/macumbista :::
   http://www.vimeo.com/macumbista :::
   ---Oblique Strategy # 109:
   "Lost in useless territory"




--
Alexandre Torres Porres
cel. (11)8179-6226
Website: http://porres.googlepages.com/home
http://www.myspace.com/alexandretorresporres


--
::: derek holzer ::: http://blog.myspace.com/macumbista ::: http://www.vimeo.com/macumbista :::
---Oblique Strategy # 67:
"Emphasize the flaws"



--
Alexandre Torres Porres
cel. (11)8179-6226
Website: http://porres.googlepages.com/home
http://www.myspace.com/alexandretorresporres