Beginner questions regarding 3e-Audio DSP

PSA78

Member
2019-07-23 12:51 pm
Hi,
so I have some questions that I hope someone can help me with, or just possibly point me in the right direction to find them.
I have ordered 2 DSP units from 3e-Audio for a future 3-way speaker setup, but have some concerns how to implement them in the best way for my use.

1) I have two sources for audio, TV (optic), PC (anything possible except Bluetooth), so my first question is regarding input choices, is there any easy/good ones that is simple to connect to these 2 boards simultaneously?
I'm not sure if source select is even possible on the DSP units, so might need that anyhow.

2) Volume control, there is a board for each of these modules, but is there an easy way to control both simultaneously? Perhaps something to some other DSP unit will work for this... :confused:

As it is right now, I've got an amplifier that I can separate the pre-amp and amp on the back, so all is not lost if it's hard to implement. I also bought a (generic) DAC recently that I could use to get the optic output from the TV in to this older amp (RCA output), if I need to use it for source and volume control.

3) I have not decided yet on amplifiers for my project, is there something I should look for or avoid? My concerns are that this DSP has balanced outputs, and if the output is strong enough to drive amplifiers that don't have op-amps.

Sorry for my lack of knowledge, I'm not afraid to do some research of my own, but it's hard when you don't know exactly where to start looking. :)

Oh, and anything more precise than soldering cables is out of the question as my hands shake pretty bad. :wave:
 
May I ask what you have done so far? Read all the documentation? Read the ADAU1701 data sheet?

When you get the boards you should reverse engineer them as much as possible. Sketch out the circuit, which should be easy if the board is 2-sided. Make a list of all the chips on the board and look up the data sheets.

Pretty soon you will know everything about the boards themselves. Then the only questions will be how to implement them into an overall system design. Are you up to doing all that?
 

PSA78

Member
2019-07-23 12:51 pm
I have read the documents for the particular board, but that didn't give me much...
I have read a bit about the chip, but I'm not aware of how they have implemented it, so I'm not sure what is relevant for me.
I have downloaded Sigma studio and the file for this board, but have not yet had a chance to get in to it.

Might have taken a big step off the deep end... 😂But I tend to manage over time, just hoped someone well educated on the subject might point me in the right direction to help save some time investigating unnecessary things. 🙂
 
Probably depends on how the boards are implemented and what you want to do.

Linking the volume controls should be doable, possibly by more than one means.

Do you know if they are using the DSP chip internal ADC and DACs? How the GPIO pins are being used? How you would like to bring audio into the boards and from what source? How you would like export audio from the boards? Do you plan on putting the boards in a central box, or one board at each speaker?

In other words, there are lots of things we don't know about what you want to do, what is possible by default with the boards your ordered, and or how willing you might be to modifying the boards if it would help your system design goals.
 

PSA78

Member
2019-07-23 12:51 pm
I haven't really decided on much at all, I'm open for different suggestions. I have looked for a DSP for some time and this one was mentioned several times, and being on a shoestring budget I pulled the trigger.
I just have two sources for audio, PC as media center, and I would like to add the optic audio output from the TV sometimes (movies broadcasted). TV output is fixed, so I need level control.

I'm not against putting the DSP inside the box I will need to build for the amplifier modules, but some recommend not doing so on a first build due to interference issues.

The speakers will follow a simple strategy of using available 2 ways kit that I will complement with a larger Woofer, and instead of paying for passive filters I thought I could put the money towards another amplifier (nothing too fancy). So if all else fails I could do a 2.2 system, but I haven't given up yet. 🙂

Though I have plenty of time to learn I still need to be realistic, I have a couple of years education on car electronics and an interest, but getting in as deep as some of you have isn't realistic for a first time.
So existing boards and cables to implement is probably my level, not soldering boards etc. 🙂
 
I have two of these boards and have thought about have one pot for both volume controls (or, for that matter, any of the pot controls).

Option one (guaranteed) - use a dual gang pot and connect to both units

Option two (untested) - use one board for the voltage source and send the attenuated voltage back to both boards. Though, now I type that out it might present a problem with the ground, especially if you want to keep both boards isolated from one another like I do)
 

PSA78

Member
2019-07-23 12:51 pm
I have two of these boards and have thought about have one pot for both volume controls (or, for that matter, any of the pot controls).

Option one (guaranteed) - use a dual gang pot and connect to both units

Option two (untested) - use one board for the voltage source and send the attenuated voltage back to both boards. Though, now I type that out it might present a problem with the ground, especially if you want to keep both boards isolated from one another like I do)
With my limited knowledge I wasn't sure on how the pot changes the level on the board, but figured Maybe something like a stereo pot could control both boards at the same time.

I had originally thought that I would be using my old trusted amplifiers pre-out and just two RCA cables to the two DSP units. But, eliminating unnecessary parts in the signal path seems to be the way towards better sound, and I only have two sources for audio so I got to thinking... and here I am... 😂
 

ernperkins

Member
2009-11-24 8:39 pm
Hi,
so I have some questions that I hope someone can help me with, or just possibly point me in the right direction to find them.
I have ordered 2 DSP units from 3e-Audio for a future 3-way speaker setup, but have some concerns how to implement them in the best way for my use. :

Do you know that for a three way speaker you’ll need to create and program a new SigmaStudio project? The 3e Audio DSP comes programmed with a 2.2 (two channel, two way) SigmaStudio project. 3e Audio provides the SigmaStudio source code on their website. I’ve attached their crossover schematic and crossover settings. Note that it uses only two way crossovers and that each crossover is set up the same: 4th order Linkwiz Riley at 300 Hz. There is no existing band passed output that would be needed for a mid in a three way. Perhaps you know all of this, but it wasn’t evident from your post.
 

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PSA78

Member
2019-07-23 12:51 pm
Do you know that for a three way speaker you’ll need to create and program a new SigmaStudio project? The 3e Audio DSP comes programmed with a 2.2 (two channel, two way) SigmaStudio project. 3e Audio provides the SigmaStudio source code on their website. I’ve attached their crossover schematic and crossover settings. Note that it uses only two way crossovers and that each crossover is set up the same: 4th order Linkwiz Riley at 300 Hz. There is no existing band passed output that would be needed for a mid in a three way. Perhaps you know all of this, but it wasn’t evident from your post.

I do believe I've read somewhere that it comes in a 2 way or 2.2 configuration.
I need to sit down with Sigma studio and learn a bit about it, lots of 'strange' symbols... :eek:
I have also just started to learn Vituixcad 2, and it seems to be able to produce files for DSP (if I didn't completely mistake what I read... :confused: ).
Anyhow, I need to do a lot of simultaneous reading and learning, but I tend to like that. :p

But as I'm facing this mountain, any guidance is always helpful, I don't expect anyone to carry me, just show me the path if you got the time. :)
 

PSA78

Member
2019-07-23 12:51 pm
Analog Devices has a nice Wiki that's been helpful to me: SigmaStudio and SigmaDSP Documentation [Analog Devices Wiki]. They also have an "Engineer Support Zone" forum that can be helpful (you'll have to register): SigmaDSP Processors and SigmaStudio Development Tool - EngineerZone.

Great! :)


Just to touch on one of my original questions, can you connect a balanced out-put to a regular single-ended? Or do I need a converter?
I haven't decided yet on amplifiers, but figured it would be best to sort some basic things out first, maybe it will in my decision. :)
 

ernperkins

Member
2009-11-24 8:39 pm
Great! :)
Just to touch on one of my original questions, can you connect a balanced out-put to a regular single-ended? Or do I need a converter?

You can use the v+ and ground from the balanced DSP output and connect those to a single ended amp input. You will lose 1/2 the max voltage and the Common Mode Rejection (CMR) advantages of a balanced output. For fixed output amps you'll need to calculate the max voltage it needs based on the amp's gain and maximum output.
 

PSA78

Member
2019-07-23 12:51 pm
You can use the v+ and ground from the balanced DSP output and connect those to a single ended amp input. You will lose 1/2 the max voltage and the Common Mode Rejection (CMR) advantages of a balanced output. For fixed output amps you'll need to calculate the max voltage it needs based on the amp's gain and maximum output.
That makes sense, I'll see what I can find that works best for me.
Thank you for your reply! 🙂
 

PSA78

Member
2019-07-23 12:51 pm
Just some notes on what limits there might be to my ideas.

I'm having trouble finding Optic (S/PDIF) to I2S (board) that I could incorporate as an input source, if I want to use the DSP board(s) as a pre-amp as well.
Even if I did find that, it would need to split the left + right channel to each individual DSP board, or I would have to transfer the signal between the two DSP units at the input stage.

I have found a board from Wondom (guessing the same as Sure Electronics etc), that has S/PDIF input to I2S based on a WM8804 chip from Wolfson. Maybe it's the ticket to get things working... :confused:


Anyhow, just thought I should write down some of my exploration, you never know when someone has help to offer, or might read something that helps them. :)
 

PSA78

Member
2019-07-23 12:51 pm
Just a quick update as I sent an email to 3E, maybe it can be useful to someone else.
I tried to explain that my plans are a couple of 3-way speakers and I'm trying to figure out what would work best for my use.
1. Analog input and using one board per channel.
2. Digital or analog input and using one board for TW/MR and one board for W, with digital transfer between the boards.
3. Or keep it simple and use passive crossover for TW/MR <-DSP-> W.

Anyhow, here is the questions and the answers I got:

Q: The 2x I2S (J5) on the middle of the board, can I send audio from board nummer "1" to the board nummer "2"?
A: yes,there is 2 I2S output -DATA_OUT0 and DATA_OUT1 , but please DSP only support SLAVE I2S output

Q: If so, can I still use the other connection on board nummer "1" for I2S audio input (from outside source)?
A: yes,there is 1 I2S input -DATA_IN0 ,but please DSP only support SLAVE I2S input

Q: Is the analog input (PJ1) on the board compatible with S/PDIF input?
A: no,it is only analog input to ADAU1701 ADC port

Q: What can the J4 and J6 be used for?
A: J4 also GPIO connector (see datesheet)and J6 for EEPROM you don't need care(no function)
 

ernperkins

Member
2009-11-24 8:39 pm
Just a quick update as I sent an email to 3E, maybe it can be useful to someone else.
I tried to explain that my plans are a couple of 3-way speakers and I'm trying to figure out what would work best for my use.

The most straightforward approach (to me) for a 3-way speaker is to add a cheap I2S DAC for the extra two channels. Details on how to do this can be found in posts 16 and 20 in this THIS thread.

The only drawback is you'll need 6 pole speaker-out/speaker-in connectors for the 3-way connections. The Amphenol AC6AMDZB 6-pole panel mount and AC6AM 6-pole cable mount connectors are the least expensive that I've found to date. Or you could go with Neutrik 8 pole connectors (more expensive). Mouser has both.

Cheers.
 

PSA78

Member
2019-07-23 12:51 pm
The most straightforward approach (to me) for a 3-way speaker is to add a cheap I2S DAC for the extra two channels. Details on how to do this can be found in posts 16 and 20 in this THIS thread.

The only drawback is you'll need 6 pole speaker-out/speaker-in connectors for the 3-way connections. The Amphenol AC6AMDZB 6-pole panel mount and AC6AM 6-pole cable mount connectors are the least expensive that I've found to date. Or you could go with Neutrik 8 pole connectors (more expensive). Mouser has both.

Cheers.

Thank you, I will look in to it! :)