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Parallella Community Supercomputing for Everyone 2017-03-01T10:37:04+00:00 https://parallella.org/forums/feed.php?f=51&t=1752 2017-03-01T10:37:04+00:00 2017-03-01T10:37:04+00:00 https://parallella.org/forums/viewtopic.php?t=1752&p=18634#p18634 <![CDATA[Re: Audio playback]]>
below, my vhdl code to test feasibility. data transfer rate cd to bram = ~15Mbytes/s

Easy and low cost method but there are not enough gpios left over on the Parallella to accomodate everything.

Two and half years have passed already since I got my first Parallella and it has been incredibly fun.

Thank you

Statistics: Posted by patc — Wed Mar 01, 2017 10:37 am

]]> 2017-01-18T22:50:20+00:00 2017-01-18T22:50:20+00:00 https://parallella.org/forums/viewtopic.php?t=1752&p=18518#p18518 <![CDATA[Re: Audio playback]]>

Statistics: Posted by patc — Wed Jan 18, 2017 10:50 pm

]]> 2016-12-04T22:11:09+00:00 2016-12-04T22:11:09+00:00 https://parallella.org/forums/viewtopic.php?t=1752&p=18353#p18353 <![CDATA[Re: Audio playback]]>

A comment regarding the digital amps limited output power (15W/channel)
for contemporary music the average audio level is pretty high so everything is fine, but for classical music the average can be much lower resulting in a volume not always as loud as I would like it to be (when the neighbour is out)

In my setup the loudspeakers have the following sensitivity:
- bass -11dB
- low midrange 0dB (reference)
- midrange -2dB
- high -5dB

so the max volume is pretty much limited with the bass.

Now the SSM-3582 from Analog Devices can be set to a volume higher than 0dB provided the input maximum level doesn't exceed the corresponding increase in the negative scale. For example if the SSM-3582 volume is set to +3dB, the input peak should never exceed -3dB else there will be clipping.

So when the average audio level is low, it seems okay to increase the volume level up to around +6dB (high minus bass) as there is low risk for bass (20 to 300 Hz) to ever clip. And to stay on the safe side anyway, the FPGA constantly compares the samples after bass crossover with the max value set by the PS and sends an interrupt to the PS in case of peak excess so that the PS can decrease the volume level to avoid clipping.

Note that after room correction convolution done in the PS, the data is sent to the FPGA which does the crossover FIR for each channel and then sends data directly to the respective SSM-3582 using the I2S protocol. SSM-3582 settings, like volume setting, are done by the PS with the I2C protocol.

Statistics: Posted by patc — Sun Dec 04, 2016 10:11 pm

]]> 2016-11-16T10:34:24+00:00 2016-11-16T10:34:24+00:00 https://parallella.org/forums/viewtopic.php?t=1752&p=18294#p18294 <![CDATA[Re: Audio playback]]>
The Vivado Integrated Logic Analyzer (ILA) is an outstanding tool but can be frustrating to operate. Many times I found myself in the situation where I placed debug marks on the synthesized schematic, set up debug core and got everything working fine but then after changing the design a bit to try out something else, I could get some constraint missing errors which sometimes could be solved by disconnecting completely the debug core and doing a setup again, but some other times I had to revert to a version without debug and restart from scratch (okay, still have tons to learn about Vivado).

Eventually my Good Star kicked in as I found out a method which works great:

- add an AXI_GPIO IP to the design and set the GPIO Width to the number of desired probes (All Inputs)
- mark the GPIO as Debug and Run Connection Automation to add and set a SYSTEM_ILA IP (picture #1)
- from the HDL wrapper, pass the gpio_rtl_tri_i to the desired module to debug (picture #2)
- connect to the signals to analyze (picture #2)
- debug (picture #3)
- make changes and re-generate without having to worry any longer about mismatch hassles
- solve the problem in no time and go sip a beer!

More generally, if possible, try to isolate the problem and make the design as small as possible so that it doesn't take too much time to build.

I suppose this method is described somewhere because the Run Connection Automation is setting ILA properly.

For the story, I had 4 sources outputting with different SPDIF interfaces 24-bit @88200 to a Zynq emio set as spdif input. 3 sources were working flawlessly but I got only garbage from the fourth one. Yet when this source was connected to some other equipments, everything was perfect so it had to be something in the vhdl code. For this kind of problem it's necessary to take a close look deep down at the real time data and I find the ILA "best of the class".

Statistics: Posted by patc — Wed Nov 16, 2016 10:34 am

]]> 2016-12-05T16:42:07+00:00 2016-10-28T09:46:56+00:00 https://parallella.org/forums/viewtopic.php?t=1752&p=18200#p18200 <![CDATA[Re: Audio playback]]> Quad 2x15W digital amps

Same box but new backpanel plate and 300W SMPS instead of 120W linear power supply (actually 200W SMPS when there is no fan)

15W/channel doesn't seem much but it's more than enough in my setup. Later on I might try to beef the bass channel up to 30W or 60W to get some more extra headroom.

Statistics: Posted by patc — Fri Oct 28, 2016 9:46 am

]]> 2016-09-12T13:06:37+00:00 2016-09-12T13:06:37+00:00 https://parallella.org/forums/viewtopic.php?t=1752&p=17972#p17972 <![CDATA[Re: Audio playback]]>
Added the IR receiver. The driver is wrapped into a master AXI stream linked to an AXI stream FIFO which generates an interrupt to the cortex ARM everytime a key is pushed on the remote. The IR cover was scrapped from an old laptop.

Current setup fully operationnal
upsampling to 88200 - digital room correction - FIR crossovers
- low-pass 300Hz -> digital amp SSM-3582 -> Altec 515 in Onken cabinet
- band-pass 300Hz-3000Hz -> 300B tube amp -> YL-55000 compression drivers with MB-90 horns
- high-pass 3000Hz -> Denon analog amp -> Visaton MHT-12 ribbon tweeters

Statistics: Posted by patc — Mon Sep 12, 2016 1:06 pm

]]> 2016-07-26T08:38:16+00:00 2016-07-26T08:38:16+00:00 https://parallella.org/forums/viewtopic.php?t=1752&p=17860#p17860 <![CDATA[Re: Audio playback]]>
image #2: measurement microphone ADC module squeezed on the side panel. The part not populated yet is the provision to connect to a 48V phantom feed supply for microphone if needed.

image #3: build of this project basically completed (IR receiver still missing though). Next on the line: measurements, calibrations and testing.

So far all the functionalities seem to be working pretty well. I'm curious to compare the 3 different channels digital amp/DSD/NOS-PCM with each other on full-range speakers, then go tri-amp.

Statistics: Posted by patc — Tue Jul 26, 2016 8:38 am

]]> 2016-07-08T12:42:49+00:00 2016-07-08T12:42:49+00:00 https://parallella.org/forums/viewtopic.php?t=1752&p=17829#p17829 <![CDATA[Re: Audio playback]]> cf. picture below: buck converter module on the right handside which I received a couple of weeks ago from China (ebay)

Regarding my current setup, so far I'm pretty happy with the OPA549 and it just gets mildly warm. The load is 8 Ohms so it's not like having to dissipate a lot of power when the output voltage is low.

AFAIC I'm pretty curious to listen compare linear vs switching PS

Statistics: Posted by patc — Fri Jul 08, 2016 12:42 pm

]]> 2016-07-05T21:56:09+00:00 2016-07-05T21:56:09+00:00 https://parallella.org/forums/viewtopic.php?t=1752&p=17823#p17823 <![CDATA[Re: Audio playback]]>
I'm looking at making my porcupine pins drive all kinds of digital audio controls from C using Vivado_hls, that should make things a lot easier! Quality digital volume controls, existing and self-made DACs, audio synthesis blocks with simple outputs like square wave oscillators without a fixed sample frequency, communicating over MIDI, wireless control via a simple Android App, lots and lots of possibilities still.

T.

Statistics: Posted by theover — Tue Jul 05, 2016 9:56 pm

]]> 2016-07-05T12:07:23+00:00 2016-07-05T12:07:23+00:00 https://parallella.org/forums/viewtopic.php?t=1752&p=17820#p17820 <![CDATA[Re: Audio playback]]>
For the TAS5112A digital amp volume control, I selected an OPA549 from TI with an AD5142A digital potentiometer from AD to make the H-bridge power supply programmable from 1V to 29V and it is part of the power supply PCB. However with hindsight, if I had to do it again I would put both the OPA549 and digital pot in the digital amp enclosure.

Statistics: Posted by patc — Tue Jul 05, 2016 12:07 pm

]]> 2016-06-07T16:27:29+00:00 2016-06-07T16:27:29+00:00 https://parallella.org/forums/viewtopic.php?t=1752&p=17720#p17720 <![CDATA[Re: Audio playback]]> Front Panel (1 Digital & 2 Analogs)
There was no way I could mill 8mm thick aluminium with my CNC so I just used it to make a guide from epoxy and bakelite leftovers and did the milling with my woodworking router.

A couple of mistakes though:

- I wore protection gloves during the milling thus didn't feel the aluminium getting hot to the point where the protective sheet (orange color) started to peel off

- the epoxy guide wasn't hard enough and slightly eroded after multiple passes

Still I'm pretty pleased with this first result with thick aluminium.

(CNC running with a STM32F4 under NETMF inside what used to be an old USB1.0 hub)

Statistics: Posted by patc — Tue Jun 07, 2016 4:27 pm

]]> 2016-06-05T15:56:14+00:00 2016-06-05T15:56:14+00:00 https://parallella.org/forums/viewtopic.php?t=1752&p=17707#p17707 <![CDATA[Re: Audio playback]]>
Since TI recommends a 70 microns copper layer thickness, I ordered the PCB on DFRobot.com and although I still need to make measurements, it seems to be working pretty well so far.

By reducing the number of taps from 63 to 31 for both bass and low midrange upsamplers, it seems that four upsamplers+sigma-delta modulators can fit in the 7020, so if everything works out well I intend to get 4 x TAS-5612 together with the Parallella in the same enclosure. And icing on the cake if I have enough GPIOs, squeeze a CD-ROM player in...

Statistics: Posted by patc — Sun Jun 05, 2016 3:56 pm

]]> 2016-05-14T09:42:18+00:00 2016-05-14T09:42:18+00:00 https://parallella.org/forums/viewtopic.php?t=1752&p=17540#p17540 <![CDATA[Re: Audio playback]]> - TAS-5112 digital amp (bass)
- DSD-DAC (midrange)
- DSD-DAC or NOS_PCM-DAC (tweeter)
- measurement microphone ADC

(any combinations possible, like a Lego! The only limitation is the number of FPGA resources which I'm getting pretty close to hit on the 7020 using something like: 3 stereo crossover FIR compilers with 1023 taps each, 4 stereo upsamplers, 3 stereo sigma-delta modulators...)

then 2 GPIO's are used for SPDIF input 1 & 2 and PROG_IO for the audio clock. The rest is being used for display and touchscreen

The audio oscillator is located very close to the connector and is powered with a dedicated ultralow noise LDO

I still have to build the midrange and tweeter DACs as well as the microphone ADC and the power supply but I intend to experiment a bit with the DSD1793 first (instead of the DSD1794 I've been playing with so far)

Statistics: Posted by patc — Sat May 14, 2016 9:42 am

]]> 2016-04-29T21:32:32+00:00 2016-04-29T21:32:32+00:00 https://parallella.org/forums/viewtopic.php?t=1752&p=17422#p17422 <![CDATA[Re: Audio playback]]> Digital amp output measurements

When comparing the homemade TAS-5112 digital amp with the high-end Tact M2150 under the same conditions, the TAS-5112 doesn't look too shabby

Statistics: Posted by patc — Fri Apr 29, 2016 9:32 pm

]]> 2016-04-20T16:06:33+00:00 2016-04-20T16:06:33+00:00 https://parallella.org/forums/viewtopic.php?t=1752&p=17394#p17394 <![CDATA[Re: Audio playback]]>
Bass are the most difficult part to reproduce and he designed and built his auditorium making the walls as horns integrating 12 Altec 515 !!! (picture #1 below taken from the Net)

So far I've been using a quad-digital amps setup but I always wanted to give a shot to the path: bass = digital and mid/high = analog

- low-pass 300Hz: dal/dar feeding a TAS-5112 IC (class-D amp)
- band-pass 300-4000Hz: dsd_clock/dsdl/dsdr feeding two DSD-1794 in DSD mode then class-A 300B tube amp
- high-pass 4000Hz: sck/pbck/plrck/pdata feeding two DSD-1794 in NOS-PCM mode then class-AB transistor amp

(since the DSP part is under the same hood this setup will be completely PLL-free, which was not the case with my Tact digital amps)

Basically every part has been tested individually and seems to be working fine (including the TAS-5112 for which I had an issue early on). Still a lot of work though to re-build and integrate everything together...

Statistics: Posted by patc — Wed Apr 20, 2016 4:06 pm

]]>