Digital X-over Prototype

blu_line · 19th October 2005, 05:49 PM

Screaming of Joy

I have done it !

My prototype digital cross-over is working !

It is based on :
- A CS8420 to convert SPDIF to I2S Left justified
- An AL3101 DSP doing the actual algorithm
- An UDA1328 (for now) converting the filtered signal to analog
And as last, a 16F84 as controller.

The Algorithm is just an IIR of an 4th order Linkwitz-Riley, or better a squared butterworth. Later on i hope to do some FIR filtering

Now i can start thinking of making it more mature (advanced, whatever)

Let me now what you think of it !

grtz

Simon

illusionxx · 20th October 2005, 10:42 AM

The AL3101 DSP is too slow for FIR filters. FIR Filters need much more processing power then IIRs.

lenz · 20th October 2005, 04:44 PM

Even the ADSP 21065 (like in the Behringer DCX) has not enough
performance for good FIR filters.
Except you need`t for one channel.

mhelin · 24th October 2005, 12:31 PM

How did you interface the PIC & Alesis chips? Does the PIC load the program into AL3101, where does it store it (on PIC there isn't enough FLASH to store the whole program)?

You can use it for FIR, though only ~500 point IR for stereo and ~1000 (maybe not quite) for mono filter. You first implement either the HP or LP and then subtract the other one (single cycle). For baffle step compensation and some other EQ needed (depending on drivers) you also need some cycles. Anyway, less than 100 points is OK for bare xover functionality. Problem is the latency (1/2 of the IR length).

blu_line · 26th October 2005, 07:09 AM

Quote:

How did you interface the PIC & Alesis chips? Does the PIC load the program into AL3101, where does it store it (on PIC there isn't enough FLASH to store the whole program)?

The Program is loaded from a eeprom.
The AL3101 can do that by itself!

Quote:

Problem is the latency (1/2 of the IR length).

Can also be compensated for, by a delay !?

best regards

Simon

investigacion · 8th May 2010, 03:44 PM

I am interested in DSP project with AL3101 DSP procesor, please send me more info PM. Thanks,

Quote:

Originally Posted by blu_line

The Program is loaded from a eeprom.
The AL3101 can do that by itself!

Can also be compensated for, by a delay !?

best regards

Simon

19th October 2005, 05:49 PM	#1
blu_line diyAudio Member Join Date: Jan 2002 Location: The Netherlands	Digital X-over Prototype Screaming of Joy I have done it ! My prototype digital cross-over is working ! It is based on : - A CS8420 to convert SPDIF to I2S Left justified - An AL3101 DSP doing the actual algorithm - An UDA1328 (for now) converting the filtered signal to analog And as last, a 16F84 as controller. The Algorithm is just an IIR of an 4th order Linkwitz-Riley, or better a squared butterworth. Later on i hope to do some FIR filtering Now i can start thinking of making it more mature (advanced, whatever) Let me now what you think of it ! grtz Simon

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20th October 2005, 10:42 AM	#2
illusionxx diyAudio Member Join Date: Oct 2004 Location: Stuttgart	The AL3101 DSP is too slow for FIR filters. FIR Filters need much more processing power then IIRs.

20th October 2005, 04:44 PM	#3
lenz diyAudio Member Join Date: Nov 2002 Location: germany	Even the ADSP 21065 (like in the Behringer DCX) has not enough performance for good FIR filters. Except you need`t for one channel.

24th October 2005, 12:31 PM	#4
mhelin diyAudio Member Join Date: Apr 2003 Location: Tampere Finland Europe	How did you interface the PIC & Alesis chips? Does the PIC load the program into AL3101, where does it store it (on PIC there isn't enough FLASH to store the whole program)? You can use it for FIR, though only ~500 point IR for stereo and ~1000 (maybe not quite) for mono filter. You first implement either the HP or LP and then subtract the other one (single cycle). For baffle step compensation and some other EQ needed (depending on drivers) you also need some cycles. Anyway, less than 100 points is OK for bare xover functionality. Problem is the latency (1/2 of the IR length).

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