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minisharc preamplifier/crossover - diy mainboard 4 years 10 months ago #28902

  • ioannidis
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hello,
just wanna share with you my new preamplifier project. The preamp will use the minisharc board and its i2s-spdif input - outputs. I designed the pcb by myself . the pcb was manafactured by PCBWAY as i always prefer for they quality and prices. You can see on the photos my progress. The board is not completely populated yed. I will update this post when it will be completed. The board is 4 layer design with 3 analog inputs, 2 spdif coax, 2 spdif optical, 1 i2s input, 8 analog outputs and one coax output. For analog converter i am using the cs5361 , for the dac's four pcm1794a, for the digital receiver the cs8416. I am using 2 ic for i2s input selection, 3 ics for the clock buffer-driver after the minisharc and before the dac's, the cs3318 for volume control and opa1642 everywhere. Everything is controlled with pic microcontroller and remote control. this board has everything exept the power supply which i am designing right now.
what do you thing about this design?

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minisharc preamplifier/crossover - diy mainboard 4 years 10 months ago #28903

  • ioannidis
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forgot to ask something. The memory slot on the minisharc board is to store the configuration? What card i will need to put on it? 1mb, 2mb?

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minisharc preamplifier/crossover - diy mainboard 4 years 10 months ago #28916

  • ioannidis
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today i soldered almost all remaining parts except 4 pampas which i don't have yet. So, after i put all the parts i had , including the minisharc i fired it up and start checking if and how it works.
The mini shark is working at 48k sample rate, the analog to digital converter also (but it can be changed to 96 or 192 via on board dip switch). The shark recognise the i2s input and shows input level. The cs8416 is working fine also. All the inputs can be switched via remote or rotary encoder and be displayed on the led display. The communication to the cs3318 digitally controlled volume control ic is working fine. With the oscilloscope i can measure about 1mVpp noise at the analog outputs when there is no signal at the input and with the volume at max level (+22db) Of course i will never use that level with my power amplifiers. When the level is lower (for example -20db) then the noise is about 5 times lower but again that volume level is high. The sine waves i tried from 20 to 20khz have no visible distortion at all (always using only oscilloscope).
I noticed that the opamps in the dac I/V stage get quite hot. (of course you can keep your finger on it). I measured the opamp current drawn and on the negative rail the current is higher.
Also the cs3318 is hot too so i put on it a small heatsink (but it is really not needed) which i already had from other circuit.
Now i am designing the power supply for this unit. It will use low noise low drop linear regulators. The power supply board must give the following outputs: +5v for the microprocessor circuit that will be always on (stand-by), one 5v output (from this output are powered all the ic's and almost each of them has it own 3,3 low noise regulator on the dsp board) and the +-12V for the opamps. The cs3318 is powered from the +-12v rails and via ultra low noise LDO regulators (tps7a4901 and tps7a3001) to +-9V and 3,3V from separate regulator for it's digital power needs.
I am designing now the power supply unit because i was not sure if the dsp will work but now i know that it is working fine the supply board can be build.
One think i will also need is a usb to i2s or bluetooth to i2s board. What is your opinion about this? Usb is better for sound quality or i can find a decent bluetooth for streaming music? do you have to suggest some boards? There is no need for these board to have isolated i2s output because my i2s input is already isolated.
The following user(s) said Thank You: Lielcic

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Last edit: by ioannidis.

minisharc preamplifier/crossover - diy mainboard 4 years 10 months ago #28920

  • john.reekie
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Impressive work :woohoo: :woohoo:

For USB to I2S there is miniDSP USBStreamer. That is multichannel. There are also boards from JLsounds.com and amanero.
I am not miniDSP support.

"You must ask the right questions." - Dr. Alfred Lanning's hologram.
-> Have you read the User Manual??
-> Have you drawn and posted a diagram?
-> Have you posted a screenshot?
-> Have you posted your config file?

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minisharc preamplifier/crossover - diy mainboard 4 years 10 months ago #29273

  • Lielcic
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Wow, what a complex and nice PCB ! so great the work. :woohoo:
I saw many people make PCB prototypes on PCBWay.com , the quality seems good, how about their turnaround time ? I just wanna have a try to their service.

Thanks
Liel

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minisharc preamplifier/crossover - diy mainboard 4 years 10 months ago #29276

  • ioannidis
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hello, without extra charges they can have ready for shipping your board in 3-4days. Then and via honking post it takes about 12 days to arrive to Greece. of course you can choose faster shipping services also. I have ordered from them about 5 times and the boards are always ok.

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minisharc preamplifier/crossover - diy mainboard 4 years 1 month ago #33162

  • Torby
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I personally use seeed studio fusion for pcb manufacturing , what a fantastic service that guy offers! 10 boards, up to 10x10 are only 4.9. Plus you can vscore identical boards within that dimension for free.

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minisharc preamplifier/crossover - diy mainboard 6 months 3 days ago #55047

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hello,
just wanna share with you my new preamplifier project. The preamp will use the minisharc board and its i2s-spdif input - outputs. I designed the pcb by myself . the pcb was manafactured by PCBWAY as i always prefer for they quality and prices.

the one by pcbway is perfect for a preamplified indeed BUT more challenging project would require ceramic PCB or even metal one

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