[sdiy] Why Bands for String Filters and Narrow and Numerous

[Michael Zacherl]

On 1.Jul 2017, at 22:54 , Ben Bradley <ben.pi.bradley at gmail.com> wrote:

> The amplitude of BBDs are analog, but they are discrete-time sampling
> systems, thus you need a low-pass filter in the input to prevent
> aliasing (the original DSP textbook was renamed for a later edition
> "Discrete-Time Signal Processing"). Some other things are
> discrete-amplitude, such as flash (but not like the memory, nor the
> web programming language) A/D converters, thermometer encoders, and
> the famous LM3914/LM3916 dot-bar LED drivers that largely replaced
> VU-style meters. Most stuff that's called "digital" is both
> discrete-time and discrete-amplitude.
> 
> As far as a discrete-component BBD, at least one even larger
> component-count SMT board has been made - here's a discrete-component
> 6502 microprocessor:
> 
> http://monster6502.com/

I came across this a while a go. I like it! 
The 6502 was my favourite CPU back then, mostly got in touch with it when 
programming a IIe.

> At that price, both time and money, you're better off buying a bunch
> of "original" SAD1024s off ebay until you luck out and find one that
> actually works.

Indeed, but I should be hunting for a couple of mn3005 since I good two 
Blacet Time Machines in the never ending queue.

They could offer some chorus/string-like effect, if I’m lucky.

> Back to the original subject of using a large number of filters to
> simulate an acoustic instruments' body, I wonder a few things that
> perhaps experiments could tell. As these are relatively high Q
> filters, Is the actual resonance/ringing of each filter important, or
> is the main importance to the sound just the highly varying frequency
> response? If one did an FFT of the filter bank and used the output for
> an inverse FFT to filter a musical signal, would it sound the same
> (within the limits of the FFT resolution, etc) as the filter bank?
> 
> I have a few acoustic guitars of varying quality. I wonder if I could
> excite the bridge with a speaker voice coil using a sine sweep to get
> the frequency response, then use the response as a filter for various
> waveshapes, could I get something out that sounded somewhat like the
> guitar?
> 
> 
> On Sat, Jul 1, 2017 at 2:25 PM, Michael Zacherl <sdiy-mz01 at blauwurf.info> wrote:
>> 
>> On 1.Jul 2017, at 11:14 , rsdio at audiobanshee.com wrote:
>> 
>>>> I say, discrete BBD madness!
>>> OMG. I'm trying to imagine a PCB with 1024 capacitors, 1025 FETs, and a pair of non-overlapping square wave oscillators.
>> 
>> I seriously considered that some time ago and found it won’t work on the comparatively large scale of an SMT-PCB and potential varying tolerances of the components. Besides the sheer number of parts involved. But then again it looked like a perfect job for automated SMT, at the first glance.

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