Hello,
I need a solution to go from a balanced DAC to unbalanced (RCA) inputs on one of my amplifiers and for subwoofer input.
I'm aware of 3 options
My searches aren't really finding some good "off the shelf" solutions. Bad terms, or something not really used / recommended. I don't know.
In anycase, I've found this, but being aliexpress - I don't know quality of the opamps in question and whether they are even genuine.
https://www.aliexpress.com/item/1005003718000938.html
Claimed to use a TI I believe INA137PA. Again.. whether genuine or not and whether this device is any good for the task.
powered by a suitable 15v AC supply.
If the above is suitable - dumb question. Can a single AC supply be wired to multiple boards? I assume if the current demands are less than the supply is capable of, no problem?
Thanks,
David.
I need a solution to go from a balanced DAC to unbalanced (RCA) inputs on one of my amplifiers and for subwoofer input.
I'm aware of 3 options
- Cable based - lifting or ground shields / pins as appropriate
- Transformer based - passive solution
- OPamp based - active solution
My searches aren't really finding some good "off the shelf" solutions. Bad terms, or something not really used / recommended. I don't know.
In anycase, I've found this, but being aliexpress - I don't know quality of the opamps in question and whether they are even genuine.
https://www.aliexpress.com/item/1005003718000938.html
Claimed to use a TI I believe INA137PA. Again.. whether genuine or not and whether this device is any good for the task.
powered by a suitable 15v AC supply.
If the above is suitable - dumb question. Can a single AC supply be wired to multiple boards? I assume if the current demands are less than the supply is capable of, no problem?
Thanks,
David.
I take it the DAC has a buffered output that is differential balanced, along the lines of an XLR L+R output? If so, just connect pin2 (+PH) OR pin3(-PH) to the centre pin on the RCA, the shield to pin 1 on the XLR and the ring on the RCA.
Thanks Guys. I did find this from the manufacturer of the DAC in question a Topping DM7 - who said this on audiosciencereview
"
Several people have raised questions regarding unbalanced connection using DM7.
In short, don't do it.
There are many nuances to this same as D10 Balanced. The fear came from us in the D10 Balanced days were that people would directly connect TS to RCA cable to the output shorting out the output stage. Even though it wouldn't damage it, it's still very not good to just short out an output of a device.
Regarding TRS to RCA cable that left + or - open, there can be small amount of residual DC offset at the output, last time I check it is smaller than D10 Balanced's. It's certainly not prohibited to do it although not recommended. The next stage should have DC blocking to make sure the DC offset from the DAC doesn't get amplified 20-30 times. And unfortunately unbalanced multiple devices connection will extremely likely cause ground loop. Even it is possible to do so without harm to any components. It likely would cause some degree of hum/buzz/high pitch noise from USB etc. It can be done but quality is not assured.
So in the end, balanced all the way will almost guarantee good quality audio in a system."
Now the above could result in much worse SINAD performance, or maybe the manufacturer is rightly protecting themselves from people destroying output stages by shorting the wrong pins etc....
"
Several people have raised questions regarding unbalanced connection using DM7.
In short, don't do it.
There are many nuances to this same as D10 Balanced. The fear came from us in the D10 Balanced days were that people would directly connect TS to RCA cable to the output shorting out the output stage. Even though it wouldn't damage it, it's still very not good to just short out an output of a device.
Regarding TRS to RCA cable that left + or - open, there can be small amount of residual DC offset at the output, last time I check it is smaller than D10 Balanced's. It's certainly not prohibited to do it although not recommended. The next stage should have DC blocking to make sure the DC offset from the DAC doesn't get amplified 20-30 times. And unfortunately unbalanced multiple devices connection will extremely likely cause ground loop. Even it is possible to do so without harm to any components. It likely would cause some degree of hum/buzz/high pitch noise from USB etc. It can be done but quality is not assured.
So in the end, balanced all the way will almost guarantee good quality audio in a system."
Now the above could result in much worse SINAD performance, or maybe the manufacturer is rightly protecting themselves from people destroying output stages by shorting the wrong pins etc....
