Hi All...
I have built numerous of different topology of amplifiers and they do sound different, subjectively. To my ears that each has their own "character" to work best for each different genre. A great commercial loudspeakers pricetag are on the high side, endup I am looking into high performance loudspeakers, especially the very famous Purifi, SBacoustics, Bliestma recently. I am very new to those parameters especially on the time allignment, cabinets calculation, and carpenter works. I guess I might end up playing a lot of different speaker drivers and variants of cabinets during this journey, so I might as well join into the digital community and neglect on passive XO, and reduce the difficulty on carpenter works.
To step up the game, I am trying to make myself a DSP for this, but in a very practical, elegant, useful, and ultimate way. Attached with the device architecture that I am looking for. The multilevel Halfbridge topology MA12070 are actually very smart, (I am working on it myself for the PV industries and I am trying hard to make a 24V rails to output a 240Vrms without any boost circuits in the circuits.) To reduce the complexity, there will be no AD/DA chips during the processing paths, so guys there will be NO AKM or Sabre or your beloved R2R voodoo on this.
-2 x 4Ways DSP
-8 x 120Watts
-2 x ADC for calibration
-Streaming capability, Tidal or whatsoever.
-Audiophiles said they dont need a TV for their hobby, but i need it definitely. So it must has a 4k HDMI output, or even a 8K output with RK3588.
-8.8"inch LCD on the device for GUI.
-etc etc.
I have pick the chassis for this application too, its a 80(H)x320(D)x280(W)mm and it looks great.
Heres another idea: With digital XO, i can set a variants of XO preset for different genre of Music, but thats a very future stuff as I need to modify the playback apps for it to switched automatically.
Any comments or any guys who wish to join the development are most welcome!
I have built numerous of different topology of amplifiers and they do sound different, subjectively. To my ears that each has their own "character" to work best for each different genre. A great commercial loudspeakers pricetag are on the high side, endup I am looking into high performance loudspeakers, especially the very famous Purifi, SBacoustics, Bliestma recently. I am very new to those parameters especially on the time allignment, cabinets calculation, and carpenter works. I guess I might end up playing a lot of different speaker drivers and variants of cabinets during this journey, so I might as well join into the digital community and neglect on passive XO, and reduce the difficulty on carpenter works.
To step up the game, I am trying to make myself a DSP for this, but in a very practical, elegant, useful, and ultimate way. Attached with the device architecture that I am looking for. The multilevel Halfbridge topology MA12070 are actually very smart, (I am working on it myself for the PV industries and I am trying hard to make a 24V rails to output a 240Vrms without any boost circuits in the circuits.) To reduce the complexity, there will be no AD/DA chips during the processing paths, so guys there will be NO AKM or Sabre or your beloved R2R voodoo on this.
-2 x 4Ways DSP
-8 x 120Watts
-2 x ADC for calibration
-Streaming capability, Tidal or whatsoever.
-Audiophiles said they dont need a TV for their hobby, but i need it definitely. So it must has a 4k HDMI output, or even a 8K output with RK3588.
-8.8"inch LCD on the device for GUI.
-etc etc.
I have pick the chassis for this application too, its a 80(H)x320(D)x280(W)mm and it looks great.
Heres another idea: With digital XO, i can set a variants of XO preset for different genre of Music, but thats a very future stuff as I need to modify the playback apps for it to switched automatically.
Any comments or any guys who wish to join the development are most welcome!
Attachments
Last edited:
A couple of quick questions - first - how do you get 120W from MA12070P? And the second is - are all your drive units the same sensitivity?
I am going to configure it in PBTL mode, each chip is running/channel, so the peak is rated at 120W on the datasheet. There are also VLP Gain/Level dB on the MA12070P that's controllable over the I2C line.
Looks from the DS for the MA12070P that you'll need rather low impedance loads to benefit from PBTL (2ohm typical). So are all your drive units 2ohm impedance?
Oh my bad, seems like the Vswing is limited. Then it should fall at 80W max at 4ohm....
I'd be a bit concerned over the gain structure when all you have is digital volume just prior to the DACs in the MA12070P. The SNR of MA12070P shows as a few dB worse than the chip minus the DACs (non-P version) : 45uV vs 140uV output noise implying the DAC part's dynamic range is significantly poorer than the amp's. You might just find yourself hankering after some analog volume control post-DACs to optimize your SNR.
I was looking at doing something very similar (but using CamillaDSP to one of miniDSP's USB i2s interfaces feeding the amps) but realised the output noise of the P version and the low output power wouldn't be worth the effort for my use case.
Yes you are right, I did noticed the P version suffering from poorer DNR too, let me think if i should add a ES9038PRO into it and make use of its 8 channels...
With the ESS9038 as the DAC you'd be sure your DAC wasn't the bottleneck in SNR.
I see, seems like adding an ES9038Pro and using the nonP version MA12070 is a more proper way for doing it. Having a 50Watts dynamic is more than enough for my room. And I can pull out each of the individual XLR signal too if any of the players would like to hook up with their beloved power Amplifiers instead of using the MA12070.
Pardon my ignorance, but what is the advantage of having a separate A/D convertor in the path, if the 12070 P version accepts I2S input?
The separate A/D isn't an A/D, its a separate D/A. The DAC inside the P version is a little noisy and there's no mitigation of that with an analog volume control after it - the DAC goes direct to the amp. Choosing a separate D/A allows selection of a lower noise DAC and also allows an analog volume control after the DAC, if that turns out to be helpful for optimizing SNR.
Revised with 6pcs PFFB TPA3255 that carries larger output power.
Updated the overall layout, things will break into 3 PCBs to make sure better flexibilities in future upgrades and maintenance.
Will be using the RockPi 5B and android 12 for the initial development.
Any suggestions are welcome!😀
Updated the overall layout, things will break into 3 PCBs to make sure better flexibilities in future upgrades and maintenance.
Will be using the RockPi 5B and android 12 for the initial development.
Any suggestions are welcome!😀
