Re: DSP ... DJRND2 and TC Dual Delay...

[PERILLE <perille@club-internet.fr>]

Mathias wrote :

> Kims point is great to explain why the cheap multieffect things have 
>short
> loop times.
> 
> But the new t.c. two seams to be just a delay, so I'm not sure there is a
> DSP in it. To comunicate with a cheap CODEC, its almost necessary to use
> one nowadays, but t.c. maybe does not use a cheap CODEC :-)
> 
> In the t.c. 2290 and PCM42 neither sound nor sound memory adresses are
> runing through the processor. It only sets the adresses acording to delay
> time and then a counter runs through the whole range and the sound just
> goes in and out all the time. Thats why its possible to expand the memory
> in the PCM42 by adding  counter chips.
> 
> When we started with the LOOP delay, whe thought a lot about using a
> ADSP2105, which even in '92 was not very expensive.
> Taking chances to speak out Dr. Perilles secret ;-) :
> Since the DRAM has column and row adressing, we can send out each part
> separately and even save adress register chips.
> In the future, it will take memory mapping to organize various loops in 
>the
> big memory. Maybe he did that?

Yes, it deals with memory mapping such a way that a single pointer is
only needed to be computed in real time for every loop => maximum
polyphony.



> 
> Did someone buy the DJRND2? 

Yes, I have purchasers


> Since at the time, there is no other dedicated
> looper product available...
> Its made for DJ and maybe less handy for a instrumentalist (you have to 
>tap
> tempo before recording, right?), but certainly new ideas would come up...

I'm gone into BPM looping orbit


> 
> As I understand it has no MIDI, but it syncronizes to the music by
> analizing it, is that correct? Pretty interesting...

Not automaticaly, you use headphones to synchronize your tempo in real
time (TRIM tempo)


> 
> How do you say: DJRND2? It looks so twisted...

DJRND2 stands for DJ RouND sampler 2


> Has it been discussed on the list before?

Yes, and Kim has made a sum up about the subject on annihilist site.


> 
> >> the reason for this is not the price of memory, but the price of
> >> processors. DSP processors usually have small address spaces, so they 
>can
> >> only access small amounts of memory. The DSP procs that have large 
>address
> >> spaces are very expensive, and not likely to be used in low/mid range 
>audio
> >> products. The cheap DSP procs have much smaller memory area (usually
> >> requiring expensinve sram memory chips), which is why you see them 
>with
> >> small loop times. This is why signal processing boxes are usually not 
>well
> >> suited for looping. Looping isn't a DSP function, it needs big address
> >> area, good address calculation, and good real time operation. It 
>doesn't
> >> need dsp.
> >
> >For instance, DJRND2 is totally based upon one single ADSP2105 directly
> >addressing 14 stereo loops simultaneously from one EDO/FPM 16Mbyte RAM
> >module. How is it possible ? => Claimed in my PCT
> 
> oh, its not a secret? :-) What is PCT?

PCT stands for international patent


> 
> >> When a looper function is put into a dsp box, it usually has a
> >> small loop time and practically no user interactivity, since the
> >> architecture of these boxes is not designed for much user interaction.
> >
> >Sure ?
> >
> >> The box is just supposed to sit there running its dsp algorithm on an 
>audio
> >> stream, not bounce all around it's memory responding to user inputs. 
>So
> >> when you see dsp device touting looping ability, don't get your hopes 
>up
> >> too high because it probably won't be that great.
> >
> >Sure ?
> >
> >>
> >> Loopers usually are based on low-cost microprocessors, which 
>typically have
> >> large address spaces even on the cheap processors. The latest low-end 
>procs
> >> have built in SDRAM memory controllers and can access 512MB or more 
>with
> >> no additional parts. But these procs are not terribly well suited for 
>DSP,
> >> which is why most loopers don't have fancy signal processing along 
>with it.
> >> These devices are great for having large memory space and being able 
>to
> >> bounce all around the address area at the whim of the user. They can 
>have
> >> very responsive types of interfaces, where the user can execute all 
>sorts
> >> of commands and functions and the looper responds immediately. They 
>are
> >> also built for having lots of control input/output, for buttons, 
>knobs,
> >> displays, etc. As the cheap procs continue to get faster and more 
>powerful,
> >> you'll probably start seeing some more interesting dsp functions in 
>them,
> >> but not on a par with something based on a powerful dsp chip. The best
> >> approach is to marry a dsp and a microprocessor together, but that 
>drives
> >> the cost up.....
> >
> >Sure ?
> >Emmanuel
> 


> Maybe you did not find the right tone yet to advert your invention, 
>brother
> Emmanuel. I never did either, it takes at least 3 persons for a good
> product:
> -  the inventor  (sees what shall be working)
> -  the tester  (sees what does not work)
> -  the salesman  (sees what the public wants)

It is sometimes hard to teach people a new way to loop, but I know most
will come in sooner or later.

My story sounds to me like a famous U.S Western movie about the man who
knew where the railway was exactly supposed to go throw the desert. He
had forseen the very place miles around where the train had to go across
... he purchased this place and built a station as tracks were not
settled yet ... but he was right, it was the only place miles around in
the desert where water could be dig out. Hope I will not finish like
this man.


> 
> good luck
> Matthias

Thank you Matthias