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Hello, I have got a problem with my OTTO2. the setup = toslink> S/PDIF Transceiver Module > metronome >B2 DAC. Without the Otto the sound is good but with it there is almost no music and a lot of crackling sound. The I2s lines are about 8cm totally, coax or single wire made no difference. Especially the BCK wire is very sensible. When i connect that wire directly from Tranceiver module to the metronome all static is gone. That wire is 7cm in length. Hopefully it's not the lenght of the i2s wires....  IMAG4924.jpg (116kb) downloaded 16 time(s).
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Wire length, by itself, is not a factor. The I2S lines can be different lengths without any issues (within reason). Light speed covers a few centimeters pretty quickly compared to the data rates we are talking about. What IS important, and what wires are nearby the data lines. Any power wire will pick up noise from the data lines, especially bit clock, which is particularly noisy, but all can be offenders. You want to keep them from crossing each other and away from power leads. What are those wires running under the OTTO? That might be the cause of the noise. [EDIT] Also, the I2S wires are really close to the signal output wires, also a likely cause of noise. Edited by user Monday, March 29, 2021 1:46:18 PM(UTC)
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Thank you very much for answering Brian, So you think those data wires "broadcast" noise into the powersupply wires which results in crackling sound? That should explain why my CDPRO cable never gave any problems, even before the use of Transporters. Those wires underneath are indeed powerleads for everything except the B2 DAC. I changed the position of the OTTO, soldered it directly on the transceiver module and used coax for every signalwire. The coaxcable is the same what is used for Wlan in laptops. That helped a lot but the sound still spikes. Does it help to use shielded powerleads & signalwire or use a small resistor 33Ohm in the every I2s wire ? Best regards, Erik. IMAG49c28.jpg (165kb) downloaded 15 time(s).Edited by user Monday, March 29, 2021 6:32:43 PM(UTC)
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IMAG4936-20210404-12515342.jpg (183kb) downloaded 5 time(s). IMAG4937-20210404-125152812.jpg (220kb) downloaded 6 time(s).Okay, i solved it..... It's a fault in the WM8804 manual. AIFCONF1 en AIFCONF0 are swapped on the board, don't follow the text just set the tristate as 1-0-0-1. Sigh!
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I did some checking and the error is actually in the silk screen of the new version of the board. Nice catch.
Sorry about that.
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Unfortunately, it doesn't change the fact that the noise get's back as soon as i insert the OTTO in the I2S circuit. Changed the powersupply for the OTTO to battery, used coax or straight wire, short or longer, unused inputs are connected to ground, resistorbanks soldered. Nothing helped. The location of the OTTO doesn't change the noise. Switching works fine. To be short, everything works fine without the OTTO switch: toslink> S/PDIF Transceiver Module >B2 DAC version 1.0 I'm out of options and about to cancel my project for more inputs. Edited by user Thursday, April 8, 2021 3:39:08 PM(UTC)
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Changed the FST3257 for a pin compatible 74HC157, works like a charm.
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