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γ3 On the Move

gamma3, gamma24 (plug-in for the γ3)

Re: γ3 On the Move

Postby cobretti » June 21st, 2016, 2:49 pm

And what is weird, if the music playing from USB is louder, the popping noise and DC offsets gets also lauder.
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Re: γ3 On the Move

Postby amb » June 21st, 2016, 2:55 pm

That is weird. It's all digital stream, the 1s and 0s are the same 3.3V and 0V no matter what the encoded signal level is.
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Re: γ3 On the Move

Postby cobretti » June 21st, 2016, 3:00 pm

If the DAC are set for certain volume level, the popping noise goes also higher. So no problem there.
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Re: γ3 On the Move

Postby cobretti » June 21st, 2016, 3:02 pm

First I thought there is some development code in the firmware forgotten...........
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Re: γ3 On the Move

Postby amb » June 21st, 2016, 3:13 pm

Nope
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Re: γ3 On the Move

Postby amb » June 21st, 2016, 5:17 pm

So the popping noise level varies with the volume control? Did you actually try removing the ζ1 to test?

Also, make sure the IG and G grounds are isolated, and the USB connector shell does not short to the chassis.
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Re: γ3 On the Move

Postby cobretti » July 20th, 2016, 4:38 pm

Yes, the popping noise gets louder if the volume is higher. I tried another ζ1 from my y1.5. Same thing.
IG and G are open circuits. Practically in Gohms.
I am reviewing the instructions of basic sanity checks that say there should be infinite resistance between LVDD and G. It reads 960ohms (all cables from LCDuino unplugged). And 400 ohms when I plug all harnesses from LCDuino back to mother board. And that should be open circuit? Anyway, it is insignificant load of only 12.5mA. So the sanity check is little bit confusing. I think some points will never read open circuit.
On the isolated side, between GVDD and IG I read 1.17kohms (everything unplugged, α24 and γ24 modules pulled out).
Weird? Should it really measure open circuit? From loading point, these loads would also be in mA and would have no effect on PSU.
Do they seem too low? If so, my guess is that some of the isolators could be a problem.
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Re: γ3 On the Move

Postby cobretti » July 20th, 2016, 4:52 pm

BTW, I checked DIR LOCK, RDY and INT on γ24 side. INT always HI.
Fresh power up from st-by in USB mode: LOCK: HI ; RDY:LO . Don't understand why the DIR is ready when USB input selected.
switched to coax input, CDPlayer OFF , LOCK: HI ; RDY: HI ; Understand.
CDplayer turned ON: LOCK: LO ; RDY: LO ; Understand.
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Re: γ3 On the Move

Postby amb » July 20th, 2016, 5:53 pm

By "open circuit" I mean no obvious shorts (i.e. Not low resistance). If you use a manual-ranging meter set to 200 ohm scale, it should read "over range".

Whether your current measurements are sensible, I will need to verify by measuring mine.

BTW, I checked DIR LOCK, RDY and INT on γ24 side. INT always HI.

INT should be always high with the current firmware, which uses polling instead of interrupts.

Fresh power up from st-by in USB mode: LOCK: HI ; RDY:LO . Don't understand why the DIR is ready when USB input selected.

Is the CD player on when you checked this?

The DIR section in the SRC4392 operates independently regardless of how the signal path routing is set, so it's not an error to have the RDY being low when USB (serial port B) is selected.

switched to coax input, CDPlayer OFF , LOCK: HI ; RDY: HI ; Understand.
CDplayer turned ON: LOCK: LO ; RDY: LO ; Understand.

I wonder whether your CD player produces a 44.1kHz stream when it's powered up but not playing?

And if you switch back to USB, does the LOCK status go high?
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Re: γ3 On the Move

Postby cobretti » July 21st, 2016, 1:23 pm

By "open circuit" I mean no obvious shorts (i.e. Not low resistance). If you use a manual-ranging meter set to 200 ohm scale, it should read "over range".

There is no problem there, all readings are above 200 ohm.


Is the CD player on when you checked this?

No.

The DIR section in the SRC4392 operates independently regardless of how the signal path routing is set, so it's not an error to have the RDY being low when USB (serial port B) is selected.

Yes, I figured that out by doing these measurements. Well, RDY is LO when USB input selected, and HI when SPDIF input selected (with CDplayer OFF). So, RDY is for SRC, that should be OK.

I wonder whether your CD player produces a 44.1kHz stream when it's powered up but not playing?

Yes, it does. And once the γ3 SPDIF input lock on my CDPlayer (instantly and never fails), I can shut my CDPlayer OFF, and the γ3 has no longer issue when switching between inputs.

And if you switch back to USB, does the LOCK status go high?

Yes. LOCK: HI, RDY: LO
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