Spin Semiconductor

Hi all, I'd like to use a pot for a pitch shifter, and quantize the pitch to semitones. Is there any way of doing this that will be more efficient than a bunch of skip statements? It seems like combining AND with EXP or LOG could do the trick, but I figure someone who understands the ramp parameters...

Hi all: I'm working on a simple one pole filter, where the frequency is variable from a pot or other code. This is what I have right now: equ lpcoef reg10 ; frequency coefficient equ lpstate reg11 ; filter state rdax lpstate, -1.0 ; subtract lpstate from current value in accum mulx lpcoef ; multiply...

I have built all-AP reverbs though. The first Midiverb had a few as I recall. Very limited RT range, but also very interesting. I find the delays of a typical loop add a 'space' that all-APs cannot deliver, and a certain relief from tweaking AP delay lengths. This makes sense to me, although it is ...

Thanks, Sean. I am thinking that this method should work fine, even with the variable speed clock of the Z-DSP. Since the built-in lowpass filters on the pots are implemented digitally, they should track exactly with the compensation filter code. So the code I posted should work regardless of clock...

I have been thinking about this issue for awhile, and I think I have a slick and simple solution to the pot speed issue. This should make a pot input usable for an expression pedal, for example. All that is needed is to counteract the action of the slow lowpass filter on the pot with a shelving hig...

Hi all,

I'm trying to get the most bang out of my pitch shifting code, for detuning operations. Can I use COMPA and COMPC in my cho instructions to get pitch shift happening with the opposite amount of pitch shift?

Thanks,

Sean Costello

I always thought "step flange" was a standard flanger, where the modulation waveform was quantized. So, instead of having a continuous triangle wave, you have a "staircase" triangle consisting of N number of steps. I think my Boss PH-3 phase has this as one of its modes. Sean Cos...

I think this is what Frank meant. It gives you 8 bit "white noise", you can change the AND mask to give more or less bits ie: and %000000000000000000001111 would be 4 bit. I haven't experimented to see what the maximum number of bits you can use is before it stops being noise. rdax adcl,1...

Noise is a special case, while the FV-1 does not have a random number generator the last few bits in a sample tend to be random due to noise in the surrounding circuit, power supply, etc. so take the last few bits and amp them up to the level you need. Do you have any example code for this, Frank? ...

Thanks Frank!

Hi all,

I know that some people have created variable speed clock devices with the FV-1, which would be a great way of having a "size" control. My question is, if you have a pitch shifter in your code, will the shift amount vary with the clock speed?

Thanks,

Sean

I am curious about the fact, that wavefront dsp chip and FV-1 are in some regards somewhat similar (and probably have a comparable performance, too), and there are interesting vocoder programs in AKIRA and other units (airfx) featuring wavefront's chip. My guess is that the products with vocoders a...

But it's not really a hard line between "polyphonic" and "monophonic" - The Whammy gets warbly, and so does the FV1 pitch transpose program, but in fact so do the HOG and POG - I've used both and gotten these warbly sounds in both. So you can minimize the phase cancellations to ...

I tried doing some simple auto-correlation on the FV-1. I couldn't get it to work. Theoretically, you could use the JAM instruction to get things to reset, but the problem is figuring out the proper reset point. The early de-glitching pitch shifters used dedicated auto-correlation boards for computi...

The drawing from the Spin Semi site is a Direct Form II allpass filter, while the figure from the sites you cite is a Transposed Direct Form II allpass topology: https://ccrma.stanford.edu/~jos/filters/Transposed_Direct_Forms.html The Transposed Direct Form II topology has much better performance in...