Hello, I plan on using SigmaStudio with an ADAU1701, such as the DSPs available from Parts Express, Wondom (Sure Electronics), or TinySine. My audio flow is 2 in, 4 out with some slight differences from most 2x4 projects. My hope is to determine if this planned setup will work conceptually before ordering any hardware. Once confirmed, I’ll do a much deeper self-study of SigmaStudio. See attached audio workflow.
BTW, some of the Dayton, Wondom (Sure Electronics), and TinySine amplifier boards also come with DSPs. I believe it is possible to stream Bluetooth audio to a slave (e.g., from primary DSP to amplifier DSP), but I am worried about BT connection reliability. My preference is to have a physical connection between the DSP and amplifiers or use an amplifier with a DSP for sub-bass and physically connect to the other two amplifier. I’m not sure if the latter is possible, but it would be preferable to use a DSP/amplifier and send digital audio to the two other amplifiers. Essentially, I would only need to purchase 3 boards (3 amplifiers - on w/DSP vs. one DSP board and 3 amplifiers). Is this possible?
Thank-you for providing feedback.
- Is this audio flow possible with SigmaStudio via an ADAU1701?
- Does the order of the audio flow follow best practices? E.g., it is not clear to me where to best adjust volumes/tone levels.
- If the DSP is limited with GPIO analog inputs for the potentiometer volume/level controls, can they (e.g., bass & sub-bass levels) be adjusted at/before the amplifiers with potentiometers?
- If GPIO analog inputs are limited, I don’t have to have the midrange control. The purpose of the Analog & Bluetooth volumes is to adjust the volumes of these two inputs relative to each other. To save a GPIO analog input pin, can I instead use a potentiometer balance control to adjust these two input volumes relative to each other?
- Can the ADAU1701 combine both audio inputs (analog w/AptX HD) as planned?
- Some SigmaStudio projects have a DC block filter at the input. What is the purpose/benefit of this? Should I add it to my audio flow?
- Am I missing any elements?
BTW, some of the Dayton, Wondom (Sure Electronics), and TinySine amplifier boards also come with DSPs. I believe it is possible to stream Bluetooth audio to a slave (e.g., from primary DSP to amplifier DSP), but I am worried about BT connection reliability. My preference is to have a physical connection between the DSP and amplifiers or use an amplifier with a DSP for sub-bass and physically connect to the other two amplifier. I’m not sure if the latter is possible, but it would be preferable to use a DSP/amplifier and send digital audio to the two other amplifiers. Essentially, I would only need to purchase 3 boards (3 amplifiers - on w/DSP vs. one DSP board and 3 amplifiers). Is this possible?
Thank-you for providing feedback.
Attachments
In my humble opinion, you have too many volume controls. Usually, after setting up the speakers, there is no need to adjust the volume in the bands. Selecting the volume in bands by ear is a very non-trivial task; I abandoned this function.
I gave up analog volume control a long time ago; using a 24-bit data stream there is no particular benefit in analog volume control, i.e. I adjust the volume on the side of the digital audio source.
Conceptually, your project is working, but in relation to adau1701 you will not get high results because ADCs in ADAU are not very good. I long ago abandoned the analog sound source in favor of digital ones, thereby getting rid of many problems.
Adau1701 is not the best option for implementing an audio system with a good sound level. If sound quality is more important to you than functionality, then take a look at my Board, it provides a higher level of sound, but at the same time you will have to reconsider your conceptual approach. If volume control in each band is very necessary for you, then I have a similar slightly larger board with six auxiliary ADCs.
I gave up analog volume control a long time ago; using a 24-bit data stream there is no particular benefit in analog volume control, i.e. I adjust the volume on the side of the digital audio source.
Conceptually, your project is working, but in relation to adau1701 you will not get high results because ADCs in ADAU are not very good. I long ago abandoned the analog sound source in favor of digital ones, thereby getting rid of many problems.
As far as I know, ADAU does not have an automatic input selector, i.e. you need to use an external signal to control the inputs to the adau, or you can simply sum both inputs inside the adau, but then you need to make sure that the signal arrives at only one input.
To get rid of the accidental appearance of constant voltage at the output of the ADAU, you need to use this block. There is an unpleasant thing in the adau, when after turning on the adau there is no signal at the digital inputs, the receiver buffer contains garbage, which leads to the appearance of a constant component, this module prevents the passage of the constant component to the output of the adau. With all this, often when a signal appears, the buffer is reset to zero and a click is heard in the speakers. To get rid of this effect, you need to make sure that the signal is already there before power appears on the adau.
Adau1701 is not the best option for implementing an audio system with a good sound level. If sound quality is more important to you than functionality, then take a look at my Board, it provides a higher level of sound, but at the same time you will have to reconsider your conceptual approach. If volume control in each band is very necessary for you, then I have a similar slightly larger board with six auxiliary ADCs.
@uriy-ch Thank-you for your insights. I concur with your thoughts regarding tone control and will eliminate many of them. After further investigation, it seems the ADAU1701 boards are limited to 4 potentiometers anyway. Obviously I want good sq as reasonable, but the analog source is low sq, so a less than optimal ADC is not a concern. Thank-for explaining the need for the DC block and linking your project!
I realized my title is incorrect. My goal is for simultaneous playing of the AptX HD and analog sources. So it is really a 3x4 (mono analog input) or 4x4 mixer setup. It doesn't seem that one ADAU1701 can handle four inputs from two source types simultaneously, but two can. Per this Wondom video @2:18:
However, the analog source will be intermittent (voice interjection), so I was hoping to be able to attenuate the digital source when then analog source exceeds a threshold. This was not my initial plan, but after seeing this Wondom video which attenuates the audio signal with an IR sensor, having attentuate for better voice clarity is desirable. If the signals are mixed before the DSP, as mentioned in the quote above, this goal may not be impossible. Instead, I may just use a passive mixer after the DSP to mix in the analog signal.
FWIW, for others considering the affordable ADAU1701 DSP boards, Wondom has numerous configuration setup videos on its YouTube channel and Parts Express has very good written documentation.
I realized my title is incorrect. My goal is for simultaneous playing of the AptX HD and analog sources. So it is really a 3x4 (mono analog input) or 4x4 mixer setup. It doesn't seem that one ADAU1701 can handle four inputs from two source types simultaneously, but two can. Per this Wondom video @2:18:
In my application, that is good news as it effectively answers questions #1 & #5, which were my biggest concerns.
However, the analog source will be intermittent (voice interjection), so I was hoping to be able to attenuate the digital source when then analog source exceeds a threshold. This was not my initial plan, but after seeing this Wondom video which attenuates the audio signal with an IR sensor, having attentuate for better voice clarity is desirable. If the signals are mixed before the DSP, as mentioned in the quote above, this goal may not be impossible. Instead, I may just use a passive mixer after the DSP to mix in the analog signal.
FWIW, for others considering the affordable ADAU1701 DSP boards, Wondom has numerous configuration setup videos on its YouTube channel and Parts Express has very good written documentation.