Hi everyone,
I think I might have a potential ground loop issue between my DAC and crossover.
First let's cover some of the basic details of my setup. The DAC is a kit board from DIYHK and uses a ground plane. The crossover is a homebrew circuit constructed using some strip board with a ground bus. The DAC is supplied with 3.3V digital, 3.3V analog, and +-12V analog from a post regulator supply; the 3.3v and +-12V supplies have isolated grounds. The Crossover is fed from the same +-12V analog as the DAC, which creates a ground loop between the two boards when the audio signal is connected between the boards. This means that supply return currents for the opamps on the DAC have a second path to ground via the audio interconnection at the crossover. And vice versa, the supply return currents from the crossover's opamps could pass through the interconnect and return through the DAC's ground. Will this be a problem?
If I'm not mistaken, placing a parallel RC network in series with the signal ground at the crossover should force the opamp supply return currents to use their respective ground returns while minimizing any ill effects to the audio signal passing through the interconnect.
I am wrong on this assumption, and if so, what would be the best way to minimize crisscross return currents through the signal level interconnect wires? While a second isolated +-12V analog supply would correct this, I would prefer to not make the power supply any more complicated than absolutely necessary.
Similar question but different section of the circuit:
In a similar vein, I was thinking about adding cathode followers on the output of the crossover to add some minor 2nd order distortion. However, this would introduce a second ground loop through yet another signal level interconnect. The x-over is setup for 2.1 satellite stereo operation, with the crossover point at 80Hz and a summing amplifier to tie the left and right bass into one output. The cathode followers will only be on the L and R channels as it would be pointless to add one to the sub channel. To avoid crazy high voltages, I plan to use 8056 nuvistors (had them laying around from a random ebay purchase, picked them up for $3 a tube NOS). They're small and only require 24V at the anode and in a cathode follower setup they shouldn't introduce significant distortion from their low operating voltage. But please correct me if I am wrong.
The new ground loop issue stems from using the +48V of the +-48V power amplifier supply to derive the required 24V across the anode. The power amplifier is an ESP P101 setup that has an RC series connection between the signal input ground and the PwrAmp ground. So I was thinking of placing a similar RC network in the path to the 24V supply, to avoid unnecessary Vdrop after the regulator, and maintain keeping the signal ground at the PwrAmp isolated and prevent return currents from passing through the audio interconnect between the PwrAmp and x-over. Or would it be better to put the RC network in series with the signal interconnect between the x-over and PwrAmp input, similar to what I plan to do between the DAC and x-over? Once again, a separate isolated supply would obviate the ground loop, but make the power supply larger and more costly.
I think I might have a potential ground loop issue between my DAC and crossover.
First let's cover some of the basic details of my setup. The DAC is a kit board from DIYHK and uses a ground plane. The crossover is a homebrew circuit constructed using some strip board with a ground bus. The DAC is supplied with 3.3V digital, 3.3V analog, and +-12V analog from a post regulator supply; the 3.3v and +-12V supplies have isolated grounds. The Crossover is fed from the same +-12V analog as the DAC, which creates a ground loop between the two boards when the audio signal is connected between the boards. This means that supply return currents for the opamps on the DAC have a second path to ground via the audio interconnection at the crossover. And vice versa, the supply return currents from the crossover's opamps could pass through the interconnect and return through the DAC's ground. Will this be a problem?
If I'm not mistaken, placing a parallel RC network in series with the signal ground at the crossover should force the opamp supply return currents to use their respective ground returns while minimizing any ill effects to the audio signal passing through the interconnect.
I am wrong on this assumption, and if so, what would be the best way to minimize crisscross return currents through the signal level interconnect wires? While a second isolated +-12V analog supply would correct this, I would prefer to not make the power supply any more complicated than absolutely necessary.
Similar question but different section of the circuit:
In a similar vein, I was thinking about adding cathode followers on the output of the crossover to add some minor 2nd order distortion. However, this would introduce a second ground loop through yet another signal level interconnect. The x-over is setup for 2.1 satellite stereo operation, with the crossover point at 80Hz and a summing amplifier to tie the left and right bass into one output. The cathode followers will only be on the L and R channels as it would be pointless to add one to the sub channel. To avoid crazy high voltages, I plan to use 8056 nuvistors (had them laying around from a random ebay purchase, picked them up for $3 a tube NOS). They're small and only require 24V at the anode and in a cathode follower setup they shouldn't introduce significant distortion from their low operating voltage. But please correct me if I am wrong.
The new ground loop issue stems from using the +48V of the +-48V power amplifier supply to derive the required 24V across the anode. The power amplifier is an ESP P101 setup that has an RC series connection between the signal input ground and the PwrAmp ground. So I was thinking of placing a similar RC network in the path to the 24V supply, to avoid unnecessary Vdrop after the regulator, and maintain keeping the signal ground at the PwrAmp isolated and prevent return currents from passing through the audio interconnect between the PwrAmp and x-over. Or would it be better to put the RC network in series with the signal interconnect between the x-over and PwrAmp input, similar to what I plan to do between the DAC and x-over? Once again, a separate isolated supply would obviate the ground loop, but make the power supply larger and more costly.
- Status
- Not open for further replies.