Sigma studio / ADAU1452 set up & tuning advice

Hello ob,

oblong said:
1 - all speakers are wired separately to the amp judging by the schematics, but the eval board appears to have only 4 analog outputs

The AD1938 codec has 8 DAC so it has 8 analog outputs which means every 3.5mm jack has 2 channel one is left another one is right. so, the EVAL-ADAU1452REVBZ has 4 output jacks. so, it’s 4*2=8 analog outputs which is 8 channels in total.

As mentioned above, the EVAL- ADAU1452REVBZ has 8 analog outputs. The analog outputs can be directly connected to the TDF8541 power amplifier, and this analog power amplifier supports 4 channels as per that amplifier specification. So, I guess they use 2 TDF8541 analog power amplifiers, which is equal to our DACs. i.e 8 channels.

oblong said:
we have 14 speakers to tune. How do you do this?

We only have 4 stereo outputs available in the ADAU1452. We have four serial ports, and each serial port will support a single stereo (2 channels). If you go with stereo, you can only get 8 channels as an output.

If you want 14 channels output, then you have to use TDM. I see that you mentioned this digital power amplifier TAS6424-Q1. We can provide an I2S/TDM4 digital audio signal directly from Sigma DSP to this digital amplifier, and the digital power amplifier supports 4 channels as per that amplifier specification. If you use three TAS6424-Q1 digital power amplifiers, then you can get 12 channels out from the DSP as three TDM4 and feed it to that amp. You can config three serial output ports as TDM4 and send out the digital audio to your digital amplifier and you can use a stereo in the only serial port left. You can use the eval board and get it as an analog and connect it to the analog power amp or you can get that as an I2S digital signal too.

Anyway, you must use TDM for getting 14 channels out. it can be TDM4/TDM8. You can also use three stereos from three serial ports and a TDM8 from other serial port. It depends on what's on the receiving side and what format that receiving digital amp supports.

oblong said:
is it the case then that I would wire the board direct to the speakers & use Sigma Studio to tune them, completely bypassing the amp (there doesn't seem to be any way to tune the amp itself)?

No, you can’t do like that. The EVAL-ADAU1452REVBZ provides only line-level analog output, The line-level is with a maximum voltage of 2.8 V p-p, so you can’t drive the speaker directly; you can only drive the headphone.

If it's ADAU1467Z board then it will be easy since it has SDATAIOx pins. You can use 4 stereo (8 channels) outputs by using a single serial port whereas ADAU1452 can support a single stereo per serial port.

I generally covered what can be done. Please attach your hardware schematic and your project file. If you want to know about serial output ports and channel support then please look at page no 58 in the datasheet. The pic that you attached has two amplifiers. one is an analog and another one is digital. The digital one supports TDM4 I guess. So, how you planned to use this.

Kindly do reply if you have any queries, I will reply in detail.

Regards,

Harish

Hello ob,

I will add to what Harish is saying. There is some confusion here. Pretty much all automotive systems use a system controller of some kind to control the entire system. There will be one or two codecs if the amps have analog inputs but most systems these days are using digital input amps. Most automotive designs I have seen are using TDM-8 so each serial port can drive eight channels. Yes, there are four serial ports so that is 32 channels possible. You have to know the details of the hardware design and you have to have their SigmaStudio program before you even start.

Some hardware designs allow you to directly connect to the SigmaDSP but some do not. This means you have to use a custom software tuning tool that the company that designed the head unit wrote.

We do have an ability to create a tuning tool in SigmaStudio but again, it needs to be customized to the hardware. If you can get the SigmaStudio program then you will have access to all the filters. The tuning tools are designed so you will not have access to some things not related to tuning or that the designers do not think should be tuned like limiters to prevent clipping of the hardware.

Feel free to reach out to us directly and I can get you in touch with someone in the automotive group who will know more about this than I.

Are you working for the actual company that produced the amplifier/head unit?

Dave T

Hi Harishgowtham & DaveThib
Thanks both for taking the time to answer.

I don't work for the company that supplies the amp, I am working with an automotive company that has had the amp / speaker setup implemented using that amp supplier plus an external supplier who ( apparently) did the audio tuning.

The amp is driven from the Head Unit using CAN. The amp then directly drives the speakers: FLT, FRT, FLM, FRM, FLW, FRW, RLT, RRT, RLW, RRW, SL, SR, Sub & Centre. Each is separately connected (2 wires per speaker: +/-).

This is as much as I have got out of the amp supplier to explain how to set up for audio tuning (the external supplier has only provided the dsp.proj):
me: can you clarify whether the hardware you suggest we use is this: https://www.analog.com/en/design-center/evaluation-hardware-and-software/evaluation-boards-kits/EVAL-ADAU1452RevBZ.html#eb-overview
supplier: the kit is ADI SigmaDSP official tool,We use the same tool.
me: Is there a way to read the set frequencies / q / dB settings & filters from the amp itself? And is there a way to tune it directly? This would be ideal since it is wired up to all the speakers & we need to work with all of them at the same time, within the car.
supplier: There is no way to do it. It was all tuned by ***** before and then integrated it by us. The requirements document did not specify the tuning parameters, so it is a pity that we are only responsible for integration
me: Do you have a drawing or schematic of how you set this up? Are you wiring from the board directly to multiple speakers? I am unclear how you can tune a 14 speaker system from 1 board all at the same time since the schematic shows that every speaker is separately wired from the amp. Could you clarify for me how you tune it with 1 kit? Thanks
supplier: *silence*

...I have to agree with them that it is a pity, but it doesn't really help me...

Anyway they seem to feel it's got to be tuned using that kit, so they must have set it up to provide the 14 speaker channels. I was thinking that maybe what i need to do is get hold of the connector from the amp & wire the kit up to that. But I don't know how to do that from the 4 outputs, ie how do you ensure the correct speaker is receiving the correct band? I have spent some time looking at the sigma project files & it looks like it has been set up to connect to each speaker, it's more the hardware side I'm not understanding atm.

If you are able to dm me I could share some of what I have, let me know if you think you can help me further - all very appreciated & thanks again,

ob

Hello ob,

The evaluation board will not be terribly helpful with the exception of learning what their program is doing. You will really need to be on the actual hardware to do the tuning.

Often times the initial project files only has some default filter parameters and the filters are updated shortly after powerup by the head unit. The head unit is often booting up the DSP as well. There are some automotive amps that will seflboot and then the head unit will certainly update the filters. So you cannot trust the filter parameters you see in the SigmaStudio project are the actual ones being used. What you are trying to do is simple and not difficult to learn how to do in SigmaStudio, however, the bureaucracy is what makes this all so difficult. If you can gain control of the DSP and work on new filter settings, then the challenge will be in how to load those in the next time the car is started up! If it selfboots then you could save the settings to the program stored in EEPROM but then you have to hope the head unit does not override them!

If the head unit boots the DSP then you have to change the head unit programming and that is about as next to impossible as it gets. It is easier to get congress to agree on any subject than it is to get head unit software changed. LOL

From your conversation, it seems all you will need is the USBi to communicate with the amp. The USBi will come with the evaluation board kit.

Your conversation with the company is very familiar and sounds like conversations I have had. You are very lucky to get the DSP project file out of them!! They return parts to us for failure analysis that have failed and when I ask for the project file it is like pulling teeth to get it out of them!

I need to get someone else involved here who is in the automotive group. I am technically in the consumer group. He might be able to help out more. Plus, this conversation is probably best to proceed off forum.

Thanks,

Dave T

Oblong,

I'd be happy to support you, but I don't think this public forum is the correct place. I have sent you an email offline in the hopes that we can set up a call.

Best regards,

Ken

Hi Ken.M,

thankyou I really appreciate it. I will respond to your email, I just received it.

Speak to you soon

ob

Hi @Ken.M, i emailed you last week, just wondering if you received it? Thanks, ob