I am implementing a FIR with 512 taps emulating a guitar amp/cab Impulse Response from external wav file, using the DaisySP fir class . I can see the frequency response on the DAW spectrum analyzer plugin. As long as only the FIR is on, it looks and sounds fine. As I try to add distortion before, or reverb after the FIR stage, I see substantial harmonic content appearing at high frequencies (>10kHz) all the way up to the Nyquist freq (I am sampling at 48Khz). My distortion is x4 up-sampled with IIR AAF, the reverb has only delay lines, allpass filters and feedback. Both effects do not cause any noticeable aliasing. Any idea from where this aliasing is coming from?
Maybe you’re running out of processing time? What’s your block size? I had something perhaps similar happen when I ran out, it had 4 aliased images with a block size of 4
Hi, I’m wondering if you can point me in the direction of this IR loader?
So I’ve been commissioned to design a compact clean pedal platform amp (all of that is easy for me) but one of the requirements is a built IR cab loader which can run to both the amp and a DI out for front of house or recording.
I’m not at all a coder (I have barely been able to flash an eprom so far) but the daisy seed seems like a fairly easy to program DSP platform.
I’m curious if there are already any straight up IR loader programs out there for this platform?
To be clear not looking for an all in one amp modeler with IR as part of it but just a basic IR loader only.
If you (or anyone) has any links it would be much appreciated. I’d be happy to share some of the hardware designs I come up with in my project.
Hi,
This is how I implement the IR loader (I am assuming you were asking for the filter code and not how to read the actual wav file?) the code is not the cleanest (to say the least…) but it uses ARM CMSIS FIR which makes it very efficient. You can just omit the ToneStack part and you have to load your own data into the FIR (I read it from SD card or stream in via BL). With this I get 1024 taps at 20% CPU load. BTW, commented out is the original daisy FIR class if you want to explore that option. good luck!