Could someone please help - I am having an issue where on power on I get a pop through my speakers (or headphones) and power off a pop followed by a short high-frequency sort of garbled/scratchy noise for a second.
I measured for DC offset at the loudspeaker terminals. With no music playing and with the Placids off, I get a reading of around 23mV. When on, this is around 24mV. When I power off, I get a spike for half a second up to around 150mV, dropping to around -24mV then back to 24mV. These measurements were from the Right Channel, strangely, the Left Channel measured at 5mV more.
I am really at a loss as to what the issue is. At first I thought it was an issue with the power supply and DC offset, but I have been starting to think it is an issue with the grounding scheme of the outputs. When I disconnected the balanced XLR cables from my two NCore amplifiers and listened through headphones I don't get the pops and noise. It is all wired as I have seen in the guidance - Positive, Negative and GND wired from the IVY-III to the outputs, Pin 1 not connected to chassis (connected to signal GND), at the NCore side this is the same but Pin 1 is also connected to the chassis. I understand the AES standard is that signal ground is not connected to pin 1 and pin 1 goes to the chassis ground, so I tried this and it makes no difference. I am starting to wonder what else the issue may be? I had a problem with the AVCC module on the Buffalo III board in that it blew and the replacement was a AVCC-SR. Could this be the issue if the other boards are Tridents and not Trident-SR?
I am running out of ideas on what is the issue, any help would be greatly appreciated.
Further details on build as below:
Buffalo III DAC
IVY-III
SPDIF input board
OTTO-II
Raspberry Pi with Kali Reclocker
Amanero USB
Arduino Due with DimDim shield to control the DAC
Placid HD
Placid HD Bipolar
AMB Sigma11 PSB for the Arduino and RPi
I measured for DC offset at the loudspeaker terminals. With no music playing and with the Placids off, I get a reading of around 23mV. When on, this is around 24mV. When I power off, I get a spike for half a second up to around 150mV, dropping to around -24mV then back to 24mV. These measurements were from the Right Channel, strangely, the Left Channel measured at 5mV more.
I am really at a loss as to what the issue is. At first I thought it was an issue with the power supply and DC offset, but I have been starting to think it is an issue with the grounding scheme of the outputs. When I disconnected the balanced XLR cables from my two NCore amplifiers and listened through headphones I don't get the pops and noise. It is all wired as I have seen in the guidance - Positive, Negative and GND wired from the IVY-III to the outputs, Pin 1 not connected to chassis (connected to signal GND), at the NCore side this is the same but Pin 1 is also connected to the chassis. I understand the AES standard is that signal ground is not connected to pin 1 and pin 1 goes to the chassis ground, so I tried this and it makes no difference. I am starting to wonder what else the issue may be? I had a problem with the AVCC module on the Buffalo III board in that it blew and the replacement was a AVCC-SR. Could this be the issue if the other boards are Tridents and not Trident-SR?
I am running out of ideas on what is the issue, any help would be greatly appreciated.
Further details on build as below:
Buffalo III DAC
IVY-III
SPDIF input board
OTTO-II
Raspberry Pi with Kali Reclocker
Amanero USB
Arduino Due with DimDim shield to control the DAC
Placid HD
Placid HD Bipolar
AMB Sigma11 PSB for the Arduino and RPi
I had posted there the other day but haven’t had a reply and thought this forum may reach more people.
Good question, I got exactly the same issue and was/am never able to solve it (I always need to turn off the amps first, otherwise indeed "a short high-frequency sort of garbled/scratchy noise for a second" happens when I power off the DAC first).
This with a similar setup(ncores/b3) and I tried the same things with pin 1.
Any input on this subject is more then welcome!
We must be doing something wrong.
This with a similar setup(ncores/b3) and I tried the same things with pin 1.
Any input on this subject is more then welcome!
We must be doing something wrong.