I Am New

Hello Stan,

Like you, I came to SigmaDSP from a strictly analog design background. Many new to SigmaDSP start out with the ADAU1701. Its confluence of features allows for a straightforward path from analog to DSP:

The ADAU1701 can self-boot from an external E2PROM -- no system microcontroller needed.

Its built-in converters provide analog-in, analog out simplicity

The ADAU1772 could have been your ultimate one-chip solution -- of all the SigmaDSPs, it alone has four ADC inputs, configurable to mic or line. It's low-power and compact. I only hesitate to recommend it because its SigmaDSP programming is much more limited than all others. It has filters and such, but its only dynamic function is a volume limiter. Primarily designed for noise-cancelling headphones, it may not handle your ducking and gating operations.

The ADAU1761 is another possibility -- also with low-power operation and on-chip mic preamps. Unfortunately it doesn't self-boot, so running without SigmaStudio connected requires a microcontroller on your finished board. I'm assuming that, since you're coming from an analog background, you would prefer not getting involved with a microcontroller.

Thus it seems we're back to the ADAU1701 even though it has only two analog inputs and no mic preamps.

Your final product could run two ADAU1701s in parallel, or supplement one ADAU1701 with an external codec -- for example, the AD1938, which features a standalone (no programming needed) mode. You connect the codec to the ADAU1701 via their I2S pins. You can even have two ADAU1701s transfer audio between themselves this way. Where I work we manufacture a 12-input gated mixer whose six ADAU1701s move audio signals among themselves over their I2S/TDM bus. It's also possible to have two ADAU1701s transfer a few digital signals -- such as gate on-off -- between themselves via their GPIO pins. One more idea: you could use just one ADAU1701 while pressing two of its Auxiliary ADCs (normally used for analog control inputs such as volume pots) into service as audio ADC inputs. They're only 8-bit, though, limiting this use to "communications quality" applications.

Any SigmaDSP except probably the ADAU1772 family can do your desired ducking and gating features and more. And depending upon your finesse with the program, they will perform with fewer side effects than most analog designs. The transition from analog to digital can be really fun -- you won't burn your fingers soldering on a SigmaStudio program! I need to warn you of a few "gotchas" which are no problem as long as your application tolerates them:

DSPs introduce a small delay (latency) from input to output -- about 1 mS for the ADAU1701 (the ADAU1772 is much faster).

DSPs (except low-power models) use more power than analog circuits.

Since the ADAU1701 (and a few other SigmaDSPs) can self-boot, any way you can get your SigmaStudio compiled code into an E2PROM is fine. For test purposes, SigmaStudio can directly write to the ADAU1701MINIZ evaluation board's E2PROM. For production quantities you could program E2PROMs off-board with a suitable programmer, or buy pre-programmed chips. Search this forum for additional programming ideas. Additional possibilities open up both in booting the DSP(s) and with runtime control when your system includes a microcontroller -- but course, this adds complexity.

In short, you won't go wrong getting your feet wet with an ADAU1701MINIZ board, even though it alone cannot implement your entire four-input solution at once.

Best regards,

Bob

Thank You, Bob for the incites, Much Much Help,

Latency is why I been staying away for this stuff, It has to think, not like Analog,

Quick ? What about the ADAU1452, as the EVAL1452 is 4by8 Analog, 4 in and 8 out

Hello Stan,

This is actually a good choice, especially if you would like to see your entire project implemented before laying out your own pcb. I didn't consider it because the ADAU1452 lacks on-chip converters -- but really, there's no one-chip solution for your requirements anyhow. The EVAL-ADAU1452 (formerly the ADAU1452MINIZ) board is more hardware for the same cost as other ADI eval boards. And the ADAU1452 itself has enough capability to run what you're looking to do now, with lots of room for stuff you'll think of later. This is especially true now that ADI's programming team has diligently provided a full set of algorithms (SigmaStudio blocks). Back when the -1452 was not so well supported, I did some experimenting with a complex SigmaStudio flow just to see how much one could do with it: see Huge project to fill up a ADAU1452 and make it do something The ADAU1452 has now been around long enough to have a decent amount of docs on EZ and at the SigmaStudio wiki SigmaStudio and SigmaDSP Documentation [Analog Devices Wiki]

Looking ahead to laying out your own pcb -- the ADAU1452 really needs a four layer board (also recommended for other SigmaDSPs, but where I work we've gotten away with a two layer board for a ADAU1701).

Latency is introduced mainly by the codecs / converters, which include digital anti-aliasing (input) and reconstruction (output) filters. The typical 1 mS latency is not an issue in most applications -- it represents about one extra foot of sound travel between a loudspeaker and a listener.

Best regards,

Bob

Hi Bob

Thanks again for your help

I just order the 1452 Eval, If I can get my whole project to work on it, I would feel better as I will be able to hear how it sounds, If it's It, Than I will go forward and get a PCB proto made, It might cost more for 4 layer but it might be smaller in size as I was looking in to that, I also seen on here on how people are doing the Gateing and Ducking,

Man I wish the DSP Concepts software was not so expensive as they got a Gate and a Ducker all set up and good to go, It will be inserting to how SS deals with those chores,

Thanks Again

Stan