Hello everyone,

it's been a while ago since someone asked here for an DSP eval board (for
audio processing) that's got a SAR analog-digital converter.
Theoretical it should be possible to reach very low delay between an audio
input and the output after processing by a DSP.
Does anyone know a device with a fast SAR ADC (that could be used for audio
processing)? A board with suiting anti-aliasing filters, floating point DSP
and fast DAC would be perfect.
Have you got an idea, what the minimum expected delay could be?

Thanks in advance!
T.

p.s.: in one thread someone mentioned that there are a lot of micro control
eval boards that have a SAR ADC. I have no experience with micro
controllers at all. Is it possible to use them for complex audio processing
algorithms?

"Thomas6666" <61878@dsprelated> wrote in message 
news:h...@giganews.com...
> Hello everyone,
>
> it's been a while ago since someone asked here for an DSP eval board (for
> audio processing) that's got a SAR analog-digital converter.
> Theoretical it should be possible to reach very low delay between an audio
> input and the output after processing by a DSP.

Typical audio ADC/DAC pair has a turnaround delay at the order of hundreds 
of microseconds. Why isn't it enough small for your application?

> Does anyone know a device with a fast SAR ADC (that could be used for 
> audio
> processing)? A board with suiting anti-aliasing filters, floating point 
> DSP
> and fast DAC would be perfect.
> Have you got an idea, what the minimum expected delay could be?

There are many sampling ADCs/DACs with ~16 bit resolution and ~MHz rates; 
they could be as well used for audio. The only problem is price. You can 
connect an evaluation board for such ADC/DAC to a DSP board.
The minimum turnaround delay would be 1 sample for ADC + 1 sample for DAC + 
1 sample for processing.

> p.s.: in one thread someone mentioned that there are a lot of micro 
> control
> eval boards that have a SAR ADC. I have no experience with micro
> controllers at all. Is it possible to use them for complex audio 
> processing
> algorithms?

It depends.

Vladimir Vassilevsky
 DSP and Mixed Signal Consultant
 www.abvolt.com

A possible alternative to a SAR is a sigma delta converter with digital filters optimized
for low group delay.  An example is the new adau1772 from Analog Devices.  Group delay less than
40us from analog in-to-out at fs= 192k. On-chip dsp is dedicated to iir filtering.  Low power
for battery operation. 


Bob

On Monday, September 3, 2012 7:41:00 AM UTC-5, Thomas6666 wrote:
> Hello everyone, it's been a while ago since someone asked here for an DSP eval board (for
audio processing) that's got a SAR analog-digital converter. Theoretical it should be possible
to reach very low delay between an audio input and the output after processing by a DSP. Does
anyone know a device with a fast SAR ADC (that could be used for audio processing)? A board with
suiting anti-aliasing filters, floating point DSP and fast DAC would be perfect. Have you got an
idea, what the minimum expected delay could be? Thanks in advance! T. p.s.: in one thread
someone mentioned that there are a lot of micro control eval boards that have a SAR ADC. I have
no experience with micro controllers at all. Is it possible to use them for complex audio
processing algorithms?

Talk to Al Clark at Danville Signal Processing. He had a Shark with 4-channel A/D and D/A

maury <m...@core.com> wrote in
news:0...@googlegroups.com: 

> On Monday, September 3, 2012 7:41:00 AM UTC-5, Thomas6666 wrote:
>> Hello everyone, it's been a while ago since someone asked here for an
>> DSP 
>  eval board (for audio processing) that's got a SAR analog-digital
>  converter. Theoretical it should be possible to reach very low delay
>  between an audio input and the output after processing by a DSP. Does
>  anyone know a device with a fast SAR ADC (that could be used for audio
>  processing)? A board with suiting anti-aliasing filters, floating point
>  DSP and fast DAC would be perfect. Have you got an idea, what the
>  minimum expected delay could be? Thanks in advance! T. p.s.: in one
>  thread someone mentioned that there are a lot of micro control eval
>  boards that have a SAR ADC. I have no experience with micro controllers
>  at all. Is it possible to use them for complex audio processing
>  algorithms? 
> 



> Talk to Al Clark at Danville Signal Processing. He had a Shark with
> 4-channel A/D and D/A 
> 

Thank you Maury,

Our 4 channel A/D & D/A boards are sigma delta - not low latency. We do have 
a small module based on ADI PulSAR ADC that you could interface to a SHARC. 
Email me if you are interested.

Al Clark
www.danvillesignal.com

Hello,

Thanks to everyone for your replies.
Sorry for my late response. I've been on a vacation and had limited
internet access...

The ADAU1772 does not work for this idea. I'd like to implement an adaptive
algorithm. That's why I am looking for a programmable device.

Al Clark's module might be an option - depending on price and needed effort
to make it work ;-)

Unfortunately I am not that experienced in DSP programming. An
out-of-the-box solution gorgeous...

T.

On 9/21/2012 11:16 AM, Thomas6666 wrote:
> Hello,
>
> Thanks to everyone for your replies.
> Sorry for my late response. I've been on a vacation and had limited
> internet access...
>
> The ADAU1772 does not work for this idea. I'd like to implement an adaptive
> algorithm. That's why I am looking for a programmable device.
>
> Al Clark's module might be an option - depending on price and needed effort
> to make it work ;-)
>
> Unfortunately I am not that experienced in DSP programming. An
> out-of-the-box solution gorgeous...

What problem are you looking for a solution to?  That is pretty 
important if you are looking for a solution out of the box.

As to your original question about micros doing DSP, yes, there are some 
micros that are suitable for DSP.  I believe that ARM considers the 
Cortex M4 to approach DSP speeds of 1 MAC per clock (or maybe per 2 
clocks, not sure) once all the optimizations are working.  It has been 
awhile since I saw this presentation, but I believe they claimed you 
could do this from standard C code without special libraries or compiler 
features.

When you talk about a low delay between input and output, much of that 
depends on your algorithm.  If you need to accumulate a block of data to 
process, you can't even start the processing until the block is 
complete.  But if you are using an algorithm that processes data on the 
fly then you have a decent shot.  Remember that analog anti-alias 
filters can also add delay.

Rick

"Thomas6666" <61878@dsprelated> writes:

> Hello everyone,
>
> it's been a while ago since someone asked here for an DSP eval board (for
> audio processing) that's got a SAR analog-digital converter.
> Theoretical it should be possible to reach very low delay between an audio
> input and the output after processing by a DSP.
> Does anyone know a device with a fast SAR ADC (that could be used for audio
> processing)? A board with suiting anti-aliasing filters, floating point DSP
> and fast DAC would be perfect.
> Have you got an idea, what the minimum expected delay could be?

Hi Thomas,

If you're concerned about delay in conversion, why not consider flash
converters? I don't know of a lot of successive-approximation converters
still in use.

And if you're using it for audio processing, why do you care so much
about delay?
-- 
Randy Yates
Digital Signal Labs
http://www.digitalsignallabs.com

"Randy Yates" <y...@digitalsignallabs.com> wrote in message 
news:8...@randy.site...
> "Thomas6666" <61878@dsprelated> writes:
>
>> it's been a while ago since someone asked here for an DSP eval board (for
>> audio processing) that's got a SAR analog-digital converter.
>> Theoretical it should be possible to reach very low delay between an 
>> audio
>> input and the output after processing by a DSP.
>> Does anyone know a device with a fast SAR ADC (that could be used for 
>> audio
>> processing)? A board with suiting anti-aliasing filters, floating point 
>> DSP
>> and fast DAC would be perfect.
>> Have you got an idea, what the minimum expected delay could be?

> If you're concerned about delay in conversion, why not consider flash
> converters?

Find a flash converter with more then 12 bits of resolution.

> I don't know of a lot of successive-approximation converters
> still in use.

Most of MHz class sampling A/Ds are charge redistribution SARs.

> And if you're using it for audio processing, why do you care so much
> about delay?

There are applications like adaptive noise canceling where processing delay 
is crucial.

> -- 
> Randy Yates

Lamer.

"Vladimir Vassilevsky" <n...@nowhere.com> writes:
> [...]
> Lamer.

Come say that to my face. Chicken-shit pussy.
-- 
Randy Yates
Digital Signal Labs
http://www.digitalsignallabs.com