Gearslutz.com - View Single Post

dale116dot7 · 30th May 2009

Since I'm making a new PC board for my reverb - I built one and there are a lot of jumpers on it - I'm going to switch to a DSP56721, which has two DSP56300 cores, 248k (by 24 bit) internal RAM, 180 MHz, and an SDRAM interface. I'd like to put bulk delays in SDRAM and the smaller loops and allpasses and filters in internal RAM. Actually, with that much RAM, I doubt I'd even need the SDRAM for many algorithms - PC board design at 133 MHz is a bit tricky. Sticking to all internal RAM is comfortable, and with its internal SRC, I think a person could do a dry mix at 96k and down-convert to 48k for the reverb to keep the RAM use down. With two cores, it would certainly be possible to put one of them doing mostly internal small loops sample-at-a-time, and the other core dealing with longer loops in SDRAM and block processing them, or shuffle bits and pieces in and out of the internal SRAM.

That was the biggest complaint about SDRAM, but with a dual-core, I can see an easy way of organizing the software to take advantage of the simplicity of sample-at-a-time coding for some of the loops while also not choking SDRAM performance by doing out-of-page accesses all of the time while implementing things like long allpasses.

I think I'm going to try to put up some samples of my latest work on the algorithm we were working on. I added a lot of taps to the loops - brute force. It actually works pretty well without modulation with that many taps, I'm adding modulation this weekend. It is interesting to hear the sound as you slowly add taps. You can set the RT very low (I set it to zero) and diffusion to zero, and play a pulse (I use a click from a drum machine). You can hear gaps in the resulting sound and add taps to fill it in. At least that's what I was doing. But then you have to do a spectrum analysis with noise as the input to see the combing, and adjust things. I think I'm going to write up a little sheet in Excel to calculate the combing frequencies and try to optimize them that way, then try them on hardware - after getting the time-domain response close to how I want it.

NS: That's enough RAM to do some sampling like the 480L SME. Any programs like that on the '96?

30th May 2009	#90
dale116dot7 Lives for gear Join Date: Dec 2003 Location: Calgary, Alberta Posts: 815 Thread Starter	Since I'm making a new PC board for my reverb - I built one and there are a lot of jumpers on it - I'm going to switch to a DSP56721, which has two DSP56300 cores, 248k (by 24 bit) internal RAM, 180 MHz, and an SDRAM interface. I'd like to put bulk delays in SDRAM and the smaller loops and allpasses and filters in internal RAM. Actually, with that much RAM, I doubt I'd even need the SDRAM for many algorithms - PC board design at 133 MHz is a bit tricky. Sticking to all internal RAM is comfortable, and with its internal SRC, I think a person could do a dry mix at 96k and down-convert to 48k for the reverb to keep the RAM use down. With two cores, it would certainly be possible to put one of them doing mostly internal small loops sample-at-a-time, and the other core dealing with longer loops in SDRAM and block processing them, or shuffle bits and pieces in and out of the internal SRAM. That was the biggest complaint about SDRAM, but with a dual-core, I can see an easy way of organizing the software to take advantage of the simplicity of sample-at-a-time coding for some of the loops while also not choking SDRAM performance by doing out-of-page accesses all of the time while implementing things like long allpasses. I think I'm going to try to put up some samples of my latest work on the algorithm we were working on. I added a lot of taps to the loops - brute force. It actually works pretty well without modulation with that many taps, I'm adding modulation this weekend. It is interesting to hear the sound as you slowly add taps. You can set the RT very low (I set it to zero) and diffusion to zero, and play a pulse (I use a click from a drum machine). You can hear gaps in the resulting sound and add taps to fill it in. At least that's what I was doing. But then you have to do a spectrum analysis with noise as the input to see the combing, and adjust things. I think I'm going to write up a little sheet in Excel to calculate the combing frequencies and try to optimize them that way, then try them on hardware - after getting the time-domain response close to how I want it. NS: That's enough RAM to do some sampling like the 480L SME. Any programs like that on the '96?