Why so few direct digital amps?

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#41
Yes, lets keep the filter. And maybe this discussion is OT - thread owner to protest! 🙂

TA: No not really, once the signal has ben D/A converted it is vulnerable... I would like to stay in PCM as long as possible. My red box suggestion is; digital in - analogue out (power that is like 2 ohm / 10A). Goal: Total length of analogue path < 15 cm.

//

PS: I regard PWM as analog.
 
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#43
I agree - PWM is Analog!
Therefore the green box is close to the red one - the green box uses the pcm data or digital data or binary data and generates up to 8ch pwm (which allow to connect up to 8 red boxes). therefore it is where it is.

I also keep my filters in - but as said there is some flexibility which mosfet component to use one could play with that easily.

We are starting to discuss a detailed architectural conept, wo we should change to a new thread - I'm new to this forum (and still exploring what is already there) so I probably cannot open a new thread.
 
#45
TADIGITAL said:
A while ago we designed such a "direct digital amp" (electronic) for a customer using I2S audio data interface. System includes one board with TI's PWM modulator DSP and up to 8 power stage boards - this gives flexibility to use any number of channels (up to 8) for stereo/multichannel/bridged mono/active loudspeakers... with one interface board.

Power stages from TI are available with different ratings and due to the modularity it is easy to modify for high-end or multichannel, for small form factor, high or low power or for any other specific request. Hand wiring the demodulators or custom made demodulator inductors or industrial coils offer a huge range of flexibility there.

Audio relevant electronic was galvanically isolated (also I2C) and we used a beagleboard black to control the unit through simple software (which gives a lot of flexibility and can be replaced by whatever you want).

System audio interface accepts I2S which can be the output of any TOSLINK/Spdif/DAC converter (we never used the BBB's real time PRUS to generate the I2S but this potentially allows a perfect I2S output, externally clocked)

If there is interest to set up such a family of electronic boards for the DIY market post here. The DSP has a lot of SMD so we need a minimum quantity to produce it with little cost, the power stages can be small boards with SMD components populated and the - audio relevant - demodulator can be done by everyone's own flavor.
Click to expand...

Yes please! TAS5548 and TAS5614, 8 channels in/out. No need for DSP, I will use MiniDSP. I2S input of course!

Cheers,
Mike
 
#46
TADIGITAL said:
A while ago we designed such a "direct digital amp" (electronic) for a customer using I2S audio data interface. System includes one board with TI's PWM modulator DSP and up to 8 power stage boards - this gives flexibility to use any number of channels (up to 8) for stereo/multichannel/bridged mono/active loudspeakers... with one interface board.

Power stages from TI are available with different ratings and due to the modularity it is easy to modify for high-end or multichannel, for small form factor, high or low power or for any other specific request. Hand wiring the demodulators or custom made demodulator inductors or industrial coils offer a huge range of flexibility there.

Audio relevant electronic was galvanically isolated (also I2C) and we used a beagleboard black to control the unit through simple software (which gives a lot of flexibility and can be replaced by whatever you want).

System audio interface accepts I2S which can be the output of any TOSLINK/Spdif/DAC converter (we never used the BBB's real time PRUS to generate the I2S but this potentially allows a perfect I2S output, externally clocked)

If there is interest to set up such a family of electronic boards for the DIY market post here. The DSP has a lot of SMD so we need a minimum quantity to produce it with little cost, the power stages can be small boards with SMD components populated and the - audio relevant - demodulator can be done by everyone's own flavor.
Click to expand...

I would be very interested in something like this for an active crossover system. Optimized for sound quality over price. I would need 125+ watts/channel into 8 ohms and 200+ into 4 ohms for my 3-way speakers. I'm more interested in minimizing signal conversions than minimizing the length of analog wire, so I2S input -> PWM for all DSP processing and amplification -> speaker outs. Would this be possible?
 
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#48
Hi Guys
Very interested, but much of the comments above my understanding.

But I think I am interested.

Yes I would like an amp that takes digital from my PC and then amplifes this and sent to my speakers - without a DAC.....

Is this the correct understanding?
 
#49
foxint said:
Hi Guys
Very interested, but much of the comments above my understanding.

But I think I am interested.

Yes I would like an amp that takes digital from my PC and then amplifes this and sent to my speakers - without a DAC.....

Is this the correct understanding?
Click to expand...

I did it. I have a penny SA-XR55. It's awesome.

My chain is mackintosh -> pro fire 610 -> coax -> SA-XR55 -> DIY Loudspeaker based on eminence 102b the same of ZU audio speaker.

The sound is incredible
 
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