[sdiy] convolution

[Ian Fritz]

Dustin/Scott/List --

I have a kind of convolver in my physical-modeling clarinet.  It uses a 
commutatating set of S/H's to produce the delay, which results in an output 
wave with eight steps per wave cycle.  It's not exactly what you want to 
do, since it convolves the input wave against a "function" set by three 
pots, but it might be a starting point for some interesting low-res 
experiments.

http://home.earthlink.net/~ijfritz/pm_close.htm
http://home.earthlink.net/~ijfritz/pm_cir3.htm

   Ian



At 04:03 PM 6/17/05, Scott Juskiw wrote:
>The few times I've seen this done "ala analogue", the basic technique used 
>a line of multipliers being fed by dual BBDs. The two input signals are 
>fed to the BBDs and each set of tapped outputs feeds a multiplier. It sort 
>of looks like a ladder with the BBDs being the two long side pieces and 
>each rung of the ladder being a multiplier. Correlation is also done in a 
>similar way. The big issues with this approach are: it takes a lot of 
>hardware, and it uses BBDs. So is it totally analogue? Not really. I was 
>looking at an article in Electronotes recently about a 
>convolver/correlator using an big fat expensive chip that had dual BBDs 
>and a mess load of multipliers. But that chip isn't made anymore.
>
>>i have asked this before ...but i dont know if it made it to the list ... 
>>EMU samplers have a effect that they call "transform multiply" ...taken 
>>from the E4xt Manual "Transform Multiplication: this function merges two 
>>sounds together in a unique way which can create many strange and 
>>beautiful sonic textures. Frequencies common to the original sounds are 
>>accentuated while uncommon frequencies are discarded"
>>
>>  it is my understanding that this is called "convolution" and it seems 
>> to me that this can be done in the analog realm also. but i am not sure 
>> how exactly.
>>  thoughts? ideas ? somehow this makes me think of balanced modulation 
>> and using multiple balanced modulators to "narrow down" the frequency 
>> ranges of the input signals ..