TAS5518-8182 project – beginners questions please help

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Hullo there :)
I am complete beginner in digital audio, and surely some basic issues are not so clear to me, so please do correct me wherever you think that I might be wrong, and please try to help me.

I plan to spend some time, (and to spend some more time of some of my electronically experienced friends ) building digital amp. based on TAS5518 and TAS5182 + fets..

So, I have several questions:

INPUT:

1. What do I need between spdif out of my cd player and TAS5518? Is it a kind of spdif receiver? The only schematics I have found is based on DIR1703 that is obviously obsolete... Couldn’t I somehow connect spdif out directly to 5518?
2. What could be used as interface to Firewire out of my future DVD player for receiving DVD Audio signal?

CONTROL:

Has anyone published schematics for control module (volume, eventual tone control…, mute… ) I could try to do that with PIC processor…

MIXING – inputs / outputs

What would be default behavior of the system if I plug in stereo signal. How could I implement the possibility to switch modes like:
- FL - FR (just front left and right outputs)
- FL - FR - Sub (front left, right subwoofer and eventually center)
- FL+RL - FR+RR - Sub (copying the signal to rear outputs also )

How do I do downmixing if I want to hear 5.1. signal to front speakers only (5.1, 6.1… to 2.0 or 2.1) ?


Is there better schematics than copying EVM module described with SLEA050 and SLEU064 documents (TAS5518-8182C8EVM)?

In the document SLEA050 on page 2 it is said: “The EVM, together with TI input board, is a complete 8 channel High-End digital audio amplifier system which includes digital input (S/PDIF), analog inputs, interface to PC and DAP features like digital volume control…”

What is TI input board? I couldn’t find any schematics or any other documents concerning that kind of board on TI site.

Enough questions for the beginning.

Please help.

Thanks.
 
Hi Velicko

The TAS5518-5182EVM is not the best system to start with for a beginner.

#1 I strongly recomend you to copy exactly the gerber files of the TI design, and then spend time on the PSU and frontend.

#2 The TAS5518 needs a microcontroller to set the I2C registers corectly after power-up, and you need also the microcontroller to adjust volume etc.

#3 Input.
A normal DVD player do either have a analog outputs for the 5.1 system, or has a AC3/DTS coded digital signal via the SPDIF outputs.
So you either need a ADC for the analog outputs from the DVD or you need a AC3/DTS encoder (A DSP)
- the easiest is to make a 6ch ADC in front of the TAS5518.

#4 Mixing/Inputs/outputs
Down-mixing is normally handled by the DSP, but the input mixer of the TAS5518 can do the job - there is no delay in the TAS5518 - so doing a real dolby downmix where you also need to take the different speaker delays intoacount is not possible.
Most DVD players do have a menu for speaker set-up and you should be able to do the controls you need in the DVD.

#5 Control
I have not seen any published schematic of a micro/pic controller for the TAS5518, but would also like to see a simple one. TI has not released any microcode or schematic for this - TI uses a PC program for demo of the fetures.

I hope this helps you further.
Best regards

Kim
 
Well, kims, thank you very much for answers.

I have found on http://laurent.legoffic.free.fr/TDAA8/ something that looks ok... Does anybody have a list of published projects that are based on any TI PWM modulator circuits?

I will try to make a control segment with PIC controller, and to add display later. The reason is that I have good friend that will help me with that, and he is using PIC controllers for years, and has a complete development system...

About downmixing, you are right. I will count on DVD player internal downmixing feature.

Concerning inputs - I do not (yet) plan to invoke any kind of analog inputs for an amplifier. Since I do not really use any analog source, and complete TI system is digitally based, it does not look "natural" to plug for example CD to analog in of almost digital amplifier. (It would be CD - DA -- AD - PCM TO PWM - PWM AMP... )

So, as I understood, I do need to use SPDIF receiver (like DIR1703) ro receive digital data from coaxial digital out from CD player? I will search these days for replacement of DIR1703...

The system should be done in a year maximum of time. I am not in a hurry because I am almost satisfied with the system I am currently using.

The initial plan looks like:
PHASE1:
- More planning :)
- Building initial input segment with Coaxial and Optical input (eventually AD)
- Building experimental Power Supply system.
- Building initial PWM modulator probably with TAS5518
- Building at least two PWM amplifiers with plan to build 7-8 of them.
- Experimenting with my horn speakers.

PHASE2:
- Planning and building digital crossover if it is possible with TAS5518, and if not... than with some audio DSP...
- Building up to 8 PWM amplifiers, with high quality power supplies (separate for every channel).
- Experimenting with feeding every single driver with it's own amplifier, tuning...


If there were such projects, please do tell me...

I will surely publish everything I am doing..
 
Digital audio

Hi Velicko,
I begin the simurall project with TAS5518 and TAS5631 can youhelp me in some questions:
do you realize your project?
how I can manage TAS5518 from MCU?
Do you make DTS or AC3 decoder for TAS5518 input?
How I can convert DVD output to TAS5518 input?
As you I don't want to convert analog to digital and digital to analog.
Do you know the way to do only digital amp. from DVD (Blu-Ray) to output.
Regards Dmitriy
 
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