iomegaman

What are your thoughts on SHARC processors?
« on: June 07, 2017, 02:39:11 AM »
I just picked up a Crown USM 810 digital mixer and popped it open to notice it has 4 of the older ADSP-21065L sharcs in it...apparently this digital mixer does 32 bit floating point processing(it also does 24/48 ADDA) in an 8 x8 matrix...I( am not familiar with the CNET system it uses)...at any rate I was wondering about the quality of these processors according to the manual:

Different filter types include Low-Pass
Crossover Filter (1st-4th order), High-Pass
Crossover Filter (1st-4th order), Parametric
Equalization Filter (2nd order), Low-Pass
Equalization Filter (2nd order), High-Pass
Equalization Filter (2nd order), Low-Pass
Shelving Equalization (1st order) and HighPass
Shelving Equalization (1st order). 32
filters per DSP processor are available for a
total of 128 filters within the IQ-USM 810."

I am waiting for a usb>RS232 and a DB37f solder terminal to come in the mail so I can experiment ...it does use older 3 pin male barrier block cable connectors so I gotta find an appropriate replacement and solder some stuff together...I only paid $50 for this so its not like I am expecting much out of it...but there might be a nugget or two to be found in digging around in the filters...
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Re: What are your thoughts on SHARC processors?
« Reply #1 on: June 08, 2017, 05:28:46 AM »
In general, floating point DSP can work really well without any special care taken when coding an algorithm. For example, with a large dynamic range, it's less important to  sum intermediate products in a specific order to avoid precision loss, and there is less need for dither within an algorithm to avoid internal truncation problems. Of course, it's always good to consider precision loss when coding any sort of DSP algorithm, but in general, floating point tends to make that simpler and less prone to failure than using a fixed point DSP.

So, in general, floating point DSP is good. These days, modern general purpose computers can give us tons and tons of 64 bit DSP seemingly for free, so old chips from decade+ old boxes have to be put into perspective. What you can do now on a cellphone might exceed what you needed dedicated DSP chips to do back then. I'm not familiar with what the modern SHARC processors can do, but just as modern microprocessors have become very powerful, so have all of the rest of the chips that we have available.

I bet it won't sound awful, and that the overall performance in that Crown mixer is hobbled by the converters. If you can get some sort of digital output, you'd probably be a lot happier - old DACs from that period were frequently pretty foul.

iomegaman

Re: What are your thoughts on SHARC processors?
« Reply #2 on: June 08, 2017, 06:46:11 PM »
Thanks Monte! So I got a USB/RS232 cable in the mail and downloaded the software (older Win stuff) to control this thing...

Actually incredibly versatile...it allows me to send direct digital out (I will have to solder the DB37 port to various cables) I2s (which I can dump into my Lynx AES) so I now can have 8 more channels of analog to Digital, but here's the cool part it doubles every channel and allows you to set any kind of compression or EQ filtering you want (it has the typical AutoCad looking C+ boxes with filters and settings )and I can chain these settings in any order I want, it also has a room delay built into it and room management for "acoustically treating the signal)...these things apparently were used in churches and large auditoriums (lecture halls etc)...they come with a full range of compression variables (attack time/soft-hard-knee/release/ration) and a full band parametric eq (with totally adjustable frequency/Q)>>>

So a little solder work and I can set up multiple channels for whatever source I want and then save those "scenes" to my computer so I simply pull them up and load them...I can see this being pretty useful in setting up the drum booth/etc...

Built in limiters/ducking/filters/compression/its basically a UAD mixer from 10 years ago and I can completely bypass the DAC if I want...
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Re: What are your thoughts on SHARC processors?
« Reply #3 on: June 08, 2017, 11:53:40 PM »
Sounds like it will be a versatile processor! Eventide had a system for programming the DSP4000 (and others) that gave you modules that you could chain together, and that can be very useful for oddball processing.  Try to get digital input too so you can use it as a real time digital processor.

Have fun!