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freeDSP V2.0 (ADAU1452) developement thread
freeDSP V2.0 (ADAU1452) developement thread
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Old 25th May 2015, 09:57 AM   #31
doctormord is offline doctormord  Germany
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Default freeDSP V2.0 (ADAU1452) developement thread

No one uses tantal for the reason of war/blood... Tantal is a Nono.
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Old 25th May 2015, 10:58 PM   #32
Pitrsek is offline Pitrsek  Czech Republic
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hmmm what a mess... did not know about the issue, TY for heads up

Luckily there's a polymer aluminum cap in the same package(EEFCX0G221XR), cost almost the same.

I have to source a proper/detailed model for RPi, so I can see if there is room for a ordinary polymer aluminum in a can package.

Regarding power supply impedance modeling - I use models from Panasonic and TDK. Although mounting inductances are calculated by ALTERA PDN tool, i use spice for the simulation(PDN tool does not work properly in OO).

Last edited by Pitrsek; 25th May 2015 at 10:59 PM. Reason: typo
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Old 27th May 2015, 07:21 PM   #33
webby is offline webby  United Kingdom
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Hi All,
I am following this thread with great interest, as I concluded the original Freedsp is a bit limited for my needs.
I am planning to Use a DSP as a 2 x 4 channel crossover. I currently use vinyl, Flac media or radio streaming. I have an RPI with IQaudIO.com Pi-DAC with a Audiophile TI Burr Brown 32-bit/384kHz DAC (TI PCM5122) running Rune Audio interface. Works really well into a TPA3116D2 Amp powering my 4 way transmission line speakers.

I am planning to go active and was looking at MiniDSP, these are my concerns;
The Noise floor, Maximum output voltage 0.9V, 48kHz sampling rate, I think a minimum 96kHz for hi res audio, Linux support. I would need the 2 x 8 mini DSP, $300.

REW integration and ability to adjust parameters on the fly are big plus points.

My system idea, 4 x TPA3116D2 boards, FreeDsp 2.0 and dac & RPI combo. With the ability to measure and adjust on the fly. Like MiniDSP + REW.
Does this sound a reasonable goal?

Many Thanks
Ian
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Old 4th June 2015, 02:53 PM   #34
Piersma is offline Piersma  Netherlands
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Default Volume control

Have you considered a (shared) hardware volume control on the separate output channels? Any thoughts?
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Old 12th August 2015, 02:43 PM   #35
webby is offline webby  United Kingdom
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Hi all,
is there any progress with 2.0?
I’m really keep to get a dsp?
Cheers,
Ian
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Old 30th September 2015, 07:15 PM   #36
Pitrsek is offline Pitrsek  Czech Republic
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Default Not dead :)

Hi,
sorry for a long time without any updates/replies. I was spending my summertime outside. I got back to the project at the begging of September. It took way longer to get the board to shape that I liked(enough plane capacitance, good grounds etc.) on 4 layers.... Finally, it's done.
I've just placed order for 10 prototype boards at Elecrow, let's see how log will it take - my estimate is 2-3weeks. It's just guess, I haven't ordered from them before.
The design is a bit different from last time. I wanted to have something to play with and play on(my speakers are waiting on it), so skipped larger 10cm wide variant with smps for opamps in favor of smaller RPi HAT module(changed name to reflect it).

Power supply:
LP5907 for oscillator, pll, and ADC
LM3370SD for 3v3 and 1v2

Clocks:
single crystel oscillator
selectable external clock
4 MCLK outputs via U.FL

I/O:
bidirectional to RPi
3x full I2S outputs
3X I2S input with shared bit clock and world clock
4X MP
4X AD
SPDIF IN - 3,5mm mini toslink

@Piersma - if you mean analog volume control, no, I did not consider it. I will most probably use volume in dac, or in DSP

@webby - sorry i do not know what is rew. Last time I checked AD site, the auto tune feature was not ready for ADAU1452. Changing parameters on the fly is possible with AD programming board. Dunno how difficult it is when uC is in control of ADAU. I haven't really researched this area yet.
Attached Images
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File Type: png bare.PNG (224.4 KB, 932 views)
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Old 2nd October 2015, 08:08 AM   #37
mhelin is offline mhelin
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Question is how good the ADAU1452 is at removing the jitter from the RPI I2S port which contains quite a lot jitter. Anyway, RPi can be used as a control front end to DSP anyway, which enables the use of wireless technologies. So you could for an instance have an iOS or Android GUI controlling the volume and the input source selection for the DSP running the digital crossover application.

Last edited by mhelin; 2nd October 2015 at 08:13 AM.
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Old 2nd October 2015, 09:37 AM   #38
Pitrsek is offline Pitrsek  Czech Republic
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The idea is to use RPI as slave to ADAU, which should be according to the documentation of RPi SOC possible. So ADAU will be the clock source - hopefully with very low jitter. We will see
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Old 2nd October 2015, 10:07 AM   #39
drojf is offline drojf  Australia
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Quote:
Originally Posted by Pitrsek View Post
I've just placed order for 10 prototype boards at Elecrow, let's see how log will it take - my estimate is 2-3weeks. It's just guess, I haven't ordered from them before.
I've ordered from Elecrow and they are very fast - the times they state (4-7 dats) are more or less correct, and they will take a picture of your pcb before they send it out (as 'proof' that they're not faking shipping time as production time). The longest waiting time is probably for the shipping, depending on what shipping option you chose, and where you live.
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Old 3rd October 2015, 08:42 AM   #40
Pitrsek is offline Pitrsek  Czech Republic
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Ah, that's nice. Thank you for the info drojf.

I'm now pondering about the DAC. Two options:
1) 10cm wide board with balanced output, as envisioned earlier in this thread.
2) small, elegant add-on module for RPI+DSP combo, similar footprint,most probably single ended
What would you prefer?
Good news, digikey is stocking AK4458VN
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