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I'm getting lots of static when I plug a USB source into the USB module. Here's the setup:
USB Module>OTTO switch>Dual Differential OPUS DAC setup (grounds not connected)>Ballsie>Single ended and balanced outs.
I've got the SPDIF receiver attached to the other input on the OTTO and while the instructions on the main page say to connect a switch to the ground and TR points on the OTTO switch that doesn't seem to work, but if I connect the switch (SPDT) to the 5V and TR that seems to trip the mechanism.
Anyway, when I have the spdif running I don't get any static, as soon as I plug in a USB cable I get static, regardless of whether there's anything hooked up to the USB or not. As soon as I unplug the USB cable the static goes away. If I only have the USB connected then I still get static. I've tried this with various USB cables of varying length and plugged into an iMac or a MacBook as source.
Any help is appreciated.
Thanks,
Thrice
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You will need to have the I2S grounds from the two receivers connected to the OTTO, so that voltages from the two sources are at the same potential, as power for the USB module is coming from the USB bus. Is this the case?
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Brian Donegan wrote:You will need to have the I2S grounds from the two receivers connected to the OTTO, so that voltages from the two sources are at the same potential, as power for the USB module is coming from the USB bus. Is this the case?
Yes initially that is the case, but with the SPDIF ground attached to the OTTO, I get static through the SPDIF line with music playing, USB works fine when I switch over to it. Once I remove the ground connect for the SPDIF line, the static goes away, but then the USB modules doesn't work properly. I can't seem to win. I would also mention that the switch used for the OTTO is wired as follows: 7.5V from LCPS to the 5V terminal One wire from switch to the TR terminal Ground to the ground terminal the other wire from the switch is connected to the 5V terminal, which goes against the idea of tying TR to ground, but when I tried that the relay wouldn't switch...perhaps the diode is on incorrectly, I followed the solder mask, perhaps it's wrong and that's where I'm having some ground issues?
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I see the description for the OTTO has been updated ;)
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Ok, you definitely need those grounds connected. We can target the static now.
Is there anything tying the DAC's ground to the receiver's ground? How is the LCDPS split between the DAC and S/PDIF receiver?
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Brian Donegan wrote:Ok, you definitely need those grounds connected. We can target the static now.
Is there anything tying the DAC's ground to the receiver's ground? No, I only connected the 4 data lines off the OTTO to the two DAC modules. The otto is stacked on top of the modules for the shortest possible wiring. Quote:How is the LCDPS split between the DAC and S/PDIF receiver? I have them split via digital and analog. So one side of the LCDPS feed all the analog PS and the other side feeds the digitl...this means that the digital side feeds the digital PS for the DAC boards and the SPDIF receiver as well.
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Add a jumper between the two output ground of the LCDPS, so both grounds are at the same potential.
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Brian Donegan wrote:Add a jumper between the two output ground of the LCDPS, so both grounds are at the same potential. Thanks, I'll give that a shot.
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Both the USB and SPDIF receiver modules need to have their PCM out GNDS connected to the Otto on the input side.
You don't strictly need to connect the PCM output GND to the DACs as long as the DACs share a common ground with the receivers.
Cheers!
Russ
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No go, that made the static worse.
Would it be better if I hooked all the DAC power to one side of the LCDPS (both digital and analog) and then hooked the SPDIF receiver and OTTO p to the other side?
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Russ White wrote:Both the USB and SPDIF receiver modules need to have their PCM out GNDS connected to the Otto on the input side.
You don't strictly need to connect the PCM output GND to the DACs as long as the DACs share a common ground with the receivers.
Cheers!
Russ Would that be signal ground or power ground? Since the USB pulls power from the bus, do I need to connect that ground somewhere?
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There is a GND pin on the USB PCM Terminal Block connect that to the OTTO GND OTTO GND needs to be connected (in some way) to DAC GND.
Signal GND and Power GND are one and the same.
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Ok, let's recap...
USB and S/PDIF receivers should be connected to the OTTO with all 5 wires of the I2S ports. This will force their grounds to the same potential, which is required so that voltages in the I2S bus are the same.
The S/PDIF receiver should be connected to the LCDPS for 7.5V and GND.
The DAC boards should be connected to the LCDPS for +7.5V and GND. You can either split the supply to digital and analog, or receiver and dacs, will not matter too much. You should jumper the two ground terminals of the LCDPS so that both sides are of the same potential.
I2S from the OTTO to the DACs do not require the GND wires, but if you are getting noise, I would try adding them to see if it alleviates the problem.
After this is all hooked up, try measuring voltage between GND points on the different boards. If you find any significant DC voltage, it will point to what is likely the problem.
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Brian Donegan wrote:Ok, let's recap...
USB and S/PDIF receivers should be connected to the OTTO with all 5 wires of the I2S ports. This will force their grounds to the same potential, which is required so that voltages in the I2S bus are the same.
The S/PDIF receiver should be connected to the LCDPS for 7.5V and GND.
The DAC boards should be connected to the LCDPS for +7.5V and GND. You can either split the supply to digital and analog, or receiver and dacs, will not matter too much. You should jumper the two ground terminals of the LCDPS so that both sides are of the same potential.
I2S from the OTTO to the DACs do not require the GND wires, but if you are getting noise, I would try adding them to see if it alleviates the problem.
After this is all hooked up, try measuring voltage between GND points on the different boards. If you find any significant DC voltage, it will point to what is likely the problem.
Alright, I'll try all that when I get home tonight, but I'm pretty shure that's how I set it up initially and got problems. That's when I started messing with the grounds. We'll see how it works out. Thanks, Stephen
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Still no go, ground between boards measures at 0VDC s it's not that. It's isolated to the right channel, so I'm going to switchboards and see what that does.
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switched the boards...it's still the right channel.
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I think it's time for some pictures.
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